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the decline of the Colorado pikeminnow and other native fish species (McAda, 1983; Pimental et al., 1985). Populations of Colorado pikeminnow remain in the Green, White, Yampa, Colorado, and San Juan rivers (Minckley and Carothers, 1979; Holden and Wick, 1982; Platania et al., 1991; Tyus, 1991; Ryden and Ahlm, 1996). Colorado pikeminnow was listed as endangered by the United States Fish and Wildlife Service in 1974 (Federal Register 39:1175, 1974) and is protected by all states in its historic range (Propst, 1999). Colorado pikeminnow begin to feed on fish at 50 mm total length (TL; Vanicek and Kramer, 1969). Adult Colorado pikeminnow, which can achieve 948 TL in the San Juan River (Ryden and Ahlm, 1996), can take prey 1/3 to 1/2 their body length (Osmundson et al., 1998). Prior to the establishment of nonnative fishes, soft-rayed fishes were the only prey available to Colorado pikeminnow (Holden and Wick, 1982; Pimental et al., 1985). Establishment of nonnative, hardand spiny-rayed fishes, including channel catfish, (Ictalurus punctatus), exposed Colorado pikeminnow to a potential choking hazard which was previously nonexistent. Anecdotal reports of Colorado pikem nnow with channel catfish lodged in their throats (e.g., Vanicek and Kramer, 1969) were undocumented until 1983. McAda (1983) collected an adult Colorado pikeminnow (550 mm TL) from the Green River in 1974 with a channel catfish (120 mm TL) lodged in its throat. Three similar incidents subsequently were reported from the Green River in 1982 and 1983 (Pimental et al., 1985). Our collection of a juvenile Colorado pikeminnow with a channel catfish lodged in its mouth from the San Juan River offers a new perspective on this phenomenon, especially as it relates to recovery efforts for Colorado pikeminnow in the San Juan River. On 1 October 1999, at approximately 1145 h while electrofishing at river kilometer (RK) 138.4, 12.1 km downstream of the bridge at Montezuma Creek, Utah, we collected a subadult Colorado pikeminnow (346 mm TL) with a channel catfish (111 mm TL) firmly lodged in its mouth anterior to the gills. The channel catfish was alive and struggling, with spines extended. The dorsal spine had penetrated the roof of the Colorado pikeminnow's mouth and had entered the right eye socket causing distention and hemorrhagic swelling. Both pectoral spines had penetrated the sides of the Colorado pikeminnow's mouth. The posterior end of the channel catfish, from just anterior to the adipose fin, protruded from the Colorado pikeminnow's mouth. A strip of flesh about 10 mm wide was worn from the body of the channel catfish, where the Colorado pikeminnow's mouth would normally close. We photographed the fishes, then removed the channel catfish from the Colorado pikeminnow's mouth by severing the spines and backing the fish out of the mouth. Both fish were weighed and measured. The channel catfish was removed from the river and the Colorado

Double-crested Cormorants (Phalacrocorax auritus) wintering in the southeast delta of Arkansas were monitored via aerial surveys to determine their numbers and distribution. At least two surveys per month (December 1999-April 2000) were conducted. Each survey was comprised of two separate afternoon flights to cover the study area during the evening roosting period. Most of the two flights making up each survey were flown on consecutive days to reduce possible movement of cormorants between the two flight routes. December through February surveys all exceeded 15,000 individuals, except for early January, when there was an appreciable drop in numbers. The cormorant numbers peaked in early February at 26,822 individuals. During this study, cormorants utilized a total of ten night roosts within this catfish-producing region of Arkansas. This study area in southeast Arkansas encompasses the primary production acreage for the Arkansas catfish industry and is a likely attractant for the Double-crested Cormorant. This collection of baseline population data is important in researching the relation of the Catfish (Ictalurus punctatus) industry to growing cormorant numbers. These data will also provide a valuable base line in assessing cormorant population changes that might occur due to any future management strategies adopted by the United States Fish and Wildlife Service. Received 5 April 2001, accepted 5June 2001.

Several species of fish-eating birds are commonly observed near aquaculture facilities in the southern United States. An understanding of the relationships between these birds and specific commodities is needed to interpret and manage bird impacts to aquacultural production. We conducted two foraging experiments to evaluate the preference of Great Egrets (Ardea alba) for three specific size classes of Channel Catfish (Ictalurus punctatus). During six no-choice feeding trials, egrets consumed significantly more small (7.5-10 cm) fingerlings than medium (1518 cm) or large (23-25 cm) catfish. Egrets captured 19 large catfish, and ingested only two, even when no other fish were available. During two-choice trials, Great Egrets significantly preferred small fingerlings to medium-sized fish, and medium-sized catfish to large fish. Handling time was directly related to the size of catfish ingested. Handling time was inversely related to the number of catfish ingested from each size class, particularly when Great Egrets were given a choice between two catfish size classes. Thus, we infer that the ease of capture and physical defenses (e.g., catfish spines) associated with particular foods affect Great Egret foraging preferences. Management of Great Egret impacts to aquacultural production should focus on dispersing egrets from ponds containing small (

Adult, gravid female Neoergasilus japonicus Harada, 1930 are described from several species of fish from Lee County, Alabama. Samples of bluegill Lepomis macrochirus Rafinesque (n = 25), largemouth bass Micropterus salmoides La- cepede (n = 6), redear sunfish Lepomis microlophus Gunther (n = 5), and channel catfish Ictalurus punctatus Rafinesque (n = 1) were collected between November 1993 and May 1995. Prevalence of infection was 100% in all fish collected. The dorsal fin was the site of infection containing the highest number of parasites and the anal fin showed the highest frequency of infection. Morphological comparisons are made between this report and previous descriptions, and disparities among them are indicated. New hosts for N. japonicus include largemouth bass, channel catfish, and redear sunfish. This report is the first North American record for the genus Neoergasilus.

We examined the anatomical basis for locking and sound production of the pectoral spine in the channel catfish, Ictalurus punctatus. We separate two related phenomena, binding and locking, both of which previously have been termed locking. Binding of the spine can occur in various partially abducted positions by applying muscular force to actively engage two friction-locking mechanisms. The spine's dorsal process presses against the spinal groove of the cleithrum laterally, and its anterior process presses against a bony apron on the scapulocoracoid medially. Locking occurs when the spine is fully abducted and requires no additional muscular force. In this position, forward motion is prevented because the posterior end of the anterior process presses against an internal excavation in the lateral wall of the scapulocoracoid. Posterior motion is prevented by a catch that holds the anterior edge of the anterior process against the side of the elevated apron. The spine is unlocked by posterodorsally torquing the spine around its long axis, thereby lifting the edge of the anterior process above the imprisioning apron. Stridulation sounds are produced during spine abduction when ridges on the ventrolateral surface of the spine's dorsal process contact the ventrolateral wall of the cleithrum's spinal fossa. These sounds contain groups of pulses that vary in frequency, amplitude, duration, and pulse patterns. Individual pulses are generated by successive contacts of these ridges with the wall of the spinal fossa. The pulse frequency spectrum appears to be determined predominantly by the pectoral girdle, a nonspecialized acoustic radiator, and the swimbladder does not play an active role in sound production.

Pilum pilum gen. et sp. n. is described from the warmouth, Lepomis gulosus (Cuvier); brown bullhead, Ictalurus nebulosus (Lesueur); yellow bullhead, I. natalis (Lesueur); redbreast sunfish, L. auritus (Linnaeus); bluegill, L. macrochirus Rafinesque; spotted sunfish, L. punctatus (Valenciennes); and redfin pickerel, Esox americanus (Gmelin), from the Alabama River Drainage, brown bullhead from the Mobile Bay Drainage in Alabama, and pirate perch, Aphredoderus sayanus Gilliams, from an Atlantic Coast drainage in Georgia. The new genus most closely resembles the genus Acanthocephalus; it differs from this genus in having a distinctive pear-shaped proboscis, a long neck, and hooks which abruptly differ in size.

A total of 178 channel catfish (Ictalurus punctatus), 162 freshwater drum (Aplodinotus grunniens), 60 smallmouth bass (Micropterus dolomieui) and 2,488 yellow perch (Perca flavescens) were examined for larval Eustrongylides tubifex (Nitzsch 1819) Jagerskiold 1909 during 1973 and 1974. Older, large fish exhibited higher prevalence, larger mean numbers of larvae in infected fish, larger mean numbers of larvae in all fish examined, and wider range of intensity of infection. Infections were most extensive in yellow perch. The majority of larvae were removed from mesenteric cysts. Under experimental conditions, larvae migrated from cysts through the body wall when environmental temperatures reached or exceeded 40 C. Fourth-stage larvae removed from yellow perch successfully reinfected a variety of poikilothermous experimental hosts. Both young-of-the-year and I+ age/size class yellow perch exhibited increasing monthly larval worm burdens during portions of the sampling period. Older (II+) age/size class yellow perch did not exhibit significantly increasing worm burdens. No significant differences were noted in numbers of male and female larvae or in worm burdens in male and female yellow perch.

A new fossil ictalurid catfish, Ictalurus (Amiurus) hazenensis, is described from the Middle Member of the Truckee Formation, a diatomite deposit of Miocene age. The single specimen known consists of the complete skeletal remains of the anterior portion of the fish to the twelfth vertebra. In addition to possessing the advanced osteological features of the subgenus Amiurus, the specimen shares derived features of members of the natalis species group. Features considered derived relative to the rest of the natalis species group are the broad skull roof at the level of the epiphyseal bar, the opercle slightly narrowed and the angle between the dorsal and anterior edges 1100. Ictalurus hazenensis appears to be the sister group of the three extant members of the natalis species group. The specimen is important zoogeographically as it occurs outside the present range of the Ictaluridae and is the only fossil catfish known from Nevada.

The routine rate of oxygen consumption (V/sub O/sub 2//) was measured over an H/sub 2/SO/sub 4/ pH range of 3.5 to 7.0 for three species of freshwater fishes previously exposed for at least two weeks to pH 7.5 or 5.0. V/sub O/sub 2// was also measured at pH's from 4.0 to 7.0, in increments of 0.5 pH units, for each species after maintenance at the measurement pH. Preliminary tests showed that acute exposure to pH 3.5 (H/sub 2/SO/sub 4/) was lethal to all three species, and that only Lepomis macrochirus could survive exposure to 4.0 for at least two weeks. V/sub O/sub 2// did not show any significant decrease at pH's below 5.0 in Lepomis macrochirus or Carrasius auratus, but was significantly depressed in Ictalurus punctatus at pH 3.5. These results suggest that the importance of anoxia as a factor contributing to the death of fishes at low pH may vary among species. Mining operations and acid precipitation have produced large numbers of lakes and watersheds that undergo either chronic or acute episodes of low pH.

bryos of the cyprinoid teleost, Catostomus commersoni-which we will publish separatelywe had to define a closely spaced series of stages in their development. Such normal series are available for a growing number of teleosts (Ballard, 1972), but few are sufficiently precise and detailed for the needs of experimental embryologists. Teleost development shows enough variation in rates and in synchrony of events to make any normal series unreliable beyond the limits of the suborder, or the family, of the included species. We could not specify Catostomus stages, for instance, in terms of the normal series published for any other genera of the Order Cypriniformes: Ictalurus (suborder Siluroidei), or Carassius or Cyprinus or Notropis (suborder Cyprinoidei). The latter three (Cyprinidae) differ especially in details of development from Catostomidae (Mansueti and Hardy, 1967). Their eggs are smaller and hatch sooner, with marked differences in synchrony. On the other hand, the development of another catostomid, the lake chubsucker Erimyzon sucetta, has been found by Shaklee et al. (1974) to follow the stages proposed here for Catostomus. Only Stewart (1926) has reported any details of the embryonic development of Catostomus. He listed only three stages of the morphogenetic movements and five of organogenesis, and did not specify any rates of development. Ictalurus punctatus development was described by Saksena et al. (1961) in nineteen stages, but their series ends with the appearance of pectoral folds. The development of Ictalurus nebulosus was very well illustrated but less well defined in 53 stages by Armstrong and Child (1962). The stage numbering in these two catfish series draws apart after stage 7, the early blastula; stage 19 as described for punctatus seems equivalent to stage 27 for nebulosus. Time correlates are not given for either series. Three normal series are available for the goldfish Carassius auratus. That of Battle (1940) shows 19 figured stages to the time of disappearance of the yolk, but gives sparse detail to organogenesis and leaps too swiftly over the period of morphogenetic movements. The more exacting needs of the experimental embryologist are better served by a Chinese series (Anon., 1959) and a Japanese one (Kajishima, 1960). T e latter describes 28 stages and gives their time of appearance when incubated at 21 C ? 1. B linsky (1948) closely defined a series of normal stages for three species of the family Cyprinidae, Carassius auratus, Cyprinus carpio and Rutilus rutilus, but he did not give rates of devel pment and his illustrations were lost because of the war. However, this series, when c mpared with ours, best brings out the contrasts between cyprinid and catostomid development, which begin to appear before the end of epiboly. There are two other normal series available

The difficulty in distinguishing Ictalurus lupus from I. punctatus and the lack of information regarding all aspects of L lupus have led to some doubt about its specific status. The relationship of these two species is examined using enzyme electrophoresis and multivariate morphometry of external characters. Electrophoretic and multivariate analyses agree in dividing catfish samples from four rivers in Texas and Mexico into two distinct groups corresponding to I. punctatus and 1. lupus. They appear to be in contact in the Devils River where I. punctatus is known to occur and I lupus and several hybrids have been collected.

Objectives of the experiment were (1) to estimate the temperature tolerance and preference of channel catfish acclimated at six different temperatures and (2) to investigate relationships among temperature tolerance, temperature preference and acclimation temperature. In the thermal gradient the fish consistently chose temperatures higher than their acclimation temperature if they were acclimated at 12, 16, 20, or 24/sup 0/C, and a lower temperature when acclimated at 28 and 32/sup 0/C. This suggests that the fish were selecting optimum temperatures of 28 to 30/sup 0/C. Results also demonstrated a strong relationship between thermal tolerance, thermal preference and acclimation temperature. (CUJ)

Reproductive activity in the brown bullhead begins in May and spawning occurs in late May and early June at Munro Lake, Michigan. Most oviposition occurs during a 10to 15-day period each year. Adults care for eggs (embryos), larvae and juveniles as long as 20 days after oviposition. Males and females breed with only one mate in each season. Care-giving involves nest-building prior to oviposition, and then guarding embiyos, larvae and juveniles. In addition, embryos and larvae are fanned and manipulated by the parents at the nest site. Males alone give parental care more frequently than do females alone. When both sexes attend a brood, males spend more time with the brood and more time in close proximity to the offspring than do females. For these reasons, males can be viewed as the principal care-givers. Male parental care occurs throughout the Ictaluridae and biparental care is common in the genus Ictalurus.

Parental care characterizes the reproduction of the brown bullhead Ictalurus nebulosus. In nature, relatively few broods survive to the normal termination of parental care. Most mortality occurs early. Fishes, including conspecifics, consume bullhead eggs and young, and potential predators that approach a brood are frequently chased by an attending parent. Minnows and sunfishes are the most frequent intruders at nests. In addition to chasing intruders, parents prepare a nest site before oviposition, fan eggs and larvae and manipulate the egg mass orally. When both attending adults were experimentally removed from their egg mass, broods always failed to reach the larval stage of development. Most of these egg masses disappeared shortly after the parents were removed and before the larval stage of development was reached in control broods. This suggests that predation was a major source of brood mortality occurring in the absence of adults. However, in the absence of predation or when predators were excluded from an egg mass, all embryos still failed to survive to the larval stage of development. The risks of fungal infection and insufficient gas exchange are important factors in the maintenance of parental care, and all of these factors may have been important in the evolution of care-giving behavior.

Carassius auratus, Barbus conhus, Danio malabaricus, Catostomus commersoni, Notropis cornutus, Etheostoma caeruleum, and Ictalurus nebulosus were susceptible to Trypanosoma danilewskyi by intraperitoneal inoculation. Trypanosomes isolated from all species of susceptible fishes were infective to goldfish. No try- panosomes were detected in inoculated Semotilus atromaculatus, Ambloplites rupestris, Lepomis gibbosus and Percaflavescens. Fifty specimens were measured from each of 3 C. auratus, 2 B. conhus, 2 C. auratus inoculated with an isolate from a C. commersoni, 2 C. commersoni, and 2 E. caeruleum, for statistical analyses. The distance of the kinetoplast from the posterior end, length of free flagellum, nuclear length, and area of nucleus were similar among samples from the same host but differed significantly among samples from different host species. After discriminate analysis, samples from goldfish clustered into a tight group while those from the other fishes formed a loose cluster along the first canonical axis. Using the jacknife method of correct classification, 93% of trypanosomes from C. auratus, 36% from C. commersoni, 61% from C. commersoni-C. auratus, 25% from B. conhus, and 40% from E. caeruleum, could be correctly assigned to host species. However, only 1% of trypanosomes from C. commersoni would be classified as coming from C. auratus, 4% for C. commersoni-C. auratus, 0% for B. conhus, and 7% for E. caeruleum.

Attachment of Myzobdella lugubris to logperch (Percina caprodes) and brown bullhead (Ictalurus nebulosus) is described. Leeches usually are firmly attached to fins with the caudal sucker molded over a fin ray. The leech body is always directed posteriorly over the surface of the fins. Host tissue surrounding the leech attachment site is raised due to epithelial hyperplasia and hypodermal thickening. In brown bullhead, dilated blood vessels and hemorrhage are present around the attachment site, and hemorrhage occurs at the margins of the fin rays where the caudal sucker erodes the dermis. Epithelium is absent at the site of attachment in both fish species. An acellular layer is present between the caudal sucker and host tissues, and apparently is formed from secretions of several types of leech gland cells. The adhesion of the leech at the unprotected site on the fins probably is enhanced by the leech's body orientation which minimizes water resistance, caudal sucker secretions which likely complement suctorial pressure, and close concordance of the caudal sucker with the firm substrate provided by the fin ray. Localization of M. lugubris on the fins of the fishes may be determined in part by the preferred attachment of the caudal sucker to the fin rays. The piscicolid leech Myzobdella lugubris Leidy, 1851 predominantly attaches to the fins of a variety of fresh-water and estuarine fish species (Dechtiar, 1972; Daniels & Sawyer, 1975; Sawyer et al., 1975; Amin, 1981). However, nothing is known of the significance of the site specificity of this leech or the mechanism by which it attaches. Myzobdella lugubris recently was found firmly attached to the fins of logperch, Percina caprodes (Rafinesque), and brown bullhead, Ictalurus nebulosus (LeSueur). This study describes the method of attachment on the fin rays, and describes some caudal sucker secretions of the leech. The possible significance of these features to the usual localization of M. lugubris on the fins of logperch and brown bullhead is discussed. MATERIALS AND METHODS Nineteen logperch, 4.5-9.0 cm long, were collected in July 1980 with a seine along beaches of Lake St. Clair, near Tremblay, Ontario, Canada (42?18'N x 82?31'W). Logperch were placed individually in vials and pre1 Mr. Steve Nepzy and Mr. Kelly Munkittrick kindly provided preserved logperch and live catfish, respectively. Mr. Geoff Black, Mr. John Smith, and Prof. Roy C. Anderson, University of Guelph, reviewed the manuscript. This work was supported by a NSERC Operating Grant to Prof. Roy C. Anderson and NSERC Postdoctoral Fellowships to the authors. TRANS. AM. MICROSC. Soc., 101(2): 135-141. 1982. ( Copyright, 1982, by the American Microscopical Society, Inc. This content downloaded from 207.46.13.20 on Sat, 24 Dec 2016 05:14:24 UTC All use subject to http://about.jstor.org/terms TRANS. AM. MICROSC. SOC. served immediately in 10% formalin. Twenty-three brown bullheads, 14.625.7 cm long, were collected in April 1981 with a gill net in Hamilton Harbor, Lake Ontario, Canada (43?15'N x 79?51'W). Brown bullheads were examined alive and tissues with leeches attached were preserved in 10% buffered formalin or Gendre fluid (Humason, 1972). Fins of logperch and brown bullheads preserved with 10% formalin were decalcified overnight in 5% formic acid-formalin. All tissues examined histologically were dehydrated in an ethanol series, embedded in paraffin, and sectioned at 6-8 g/m. Sections were stained with hematoxylin and eosin, aqueous and alcoholic periodic acidSchiff (PAS) for possible mucopolysaccharides, Alcian blue (pH 2.5) for acid mucopolysaccharides, Gomori's Millon reaction for protein, and Mallory triple connective tissue stain (Pantin method, Humason, 1972). Specimens examined with SEM were postfixed in osmium tetroxide, dehydrated in an ethanol series, critical-point dried by CO2 substitution, coated with gold-palladium alloy and viewed with an ETEC Autoscan. Leech identification follows Sawyer et al. (1975) where M. morrei (Meyer, 1946) and Illinobdella spp. are treated as junior synonyms of M. lugubris. Voucher specimens have been deposited at the Canadian National Museum of Natural Sciences, Invertebrate Collection, Invertebrate Zoology Division, Ottawa, Ontario K1A OM8 (NMCIC 1981-589, -590, -591).

ceptional report which supports the concept of multiple fish hosts is presented by Lefevre and Curtis (1912, Bull. Bur. Fisheries 30: 105-201). It is important to remember that the laboratory infection of fish with glochidia may not represent the natural fish host specificity because there is no consideration of ecological and behavioral features. In developing an in vitro culture medium and process for transforming glochidia of freshwater mussels to juveniles, bypassing the fish host(s), Isom and Hudson (1982, loc. cit.) found evidence indicating that there is nonspecificity of fish host blood requirements. For example, successful transformation of Ligumia recta (Lamarck) glochidia was demonstrated in artificial medium with plasma from channel catfish (Ictalurus punctatus (Raf.)) and smallmouth buffalo (Ictiobus bubalus (Raf.)). In addition, Pleurobema cordatum (Raf.) glochidia were transformed in plasma from the above fish and also in plasma from the flathead catfish (Pylodictis olivaris (Raf.)) and common carp (Cyprinus carpio (Linn.)). Furthermore, species not reported (Fuller, 1974, loc. cit.) to have the channel catfish (Ictalurus punctatus (Raf.)) as a fish host (e.g., Fusconaia ebena (Lea), Anodonta imbecilis (Say), and Lampsilis ovata (Say)) transformed into juveniles using medium containing plasma from Ictalurus punctatus (Raf.). Results of these experiments indicate that the "essential" component in fish blood necessary for initiation of glochidial transformation is contained in the blood of all fish tested. There is an "essential" component, because transformation will not occur when the medium is used without fish plasma. Transformation also did not occur when the fish plasma was substituted with bovine or fetal bovine serum, or 100% fish plasma was used. These findings indicate that even though fish plasma seems essential for the initiation of transformation, there is no specificity for one host's blood by a given mussel species. This implies that there is no physiological plasma basis, other than possible immune response, for mussel host specificity. These findings represent a significant breakthrough for the potential conservation of freshwater mussels worldwide, many of which are threatened or endangered.

A potential organochlorine pesticide problem was identified near Mission, Texas, by the National Pesticide Monitoring Program. Fish samples from this site have consistently contained elevated levels of DDE since 1968. Surveys were made in 1976, 1978, and 1979 to determine the extent of organochlorine pesticide contamination in fishes and birds of the area. Freshwater fishes of the Arroyo Colorado, a major waterway traversing the lower Rio Grande Valley, were highly contaminated with DDE and toxaphene residues compared to samples from other areas in the Valley; both DDE and toxaphene ranged up to 31.5 ppm wet weight in whole-fish composite samples. In addition, median DDE residues in fish-eating bird carcasses from this area ranged up to 34 ppm wet weight, and 81 ppm in individual specimens. The levels of contaminants detected in fishes and birds were within, or above, the range producing adverse effects in certain species. The major sources of contamination to the Arroyo Colorado system likely stem from past and present use of persistent pesticides onesurrounding croplands, and possibly from an abandoned pesticide plant at Mission, Texas. In 1964, the National Pesticide Monitoring Program (NPMP) was established out of public concern over the increased development and use of organic and inorganic chemicals, and their subsequent impacts on the environment. Several government agencies became involved in various monitoring efforts; these included soil, air, water, crops, fishes, and wildlife. The U.S. Fish and Wildlife Service (FWS) began nationwide monitoring of organochlorine residues in fishes and birds in 1967 as part of the NPMP. The primary objective of the FWS program is the detection of nationwide residue trends in fishes and birds over time. A secondary objective is to identify geographical areas with unusually high residues that may warrant further study as to possible sources and adverse impacts on fish and wildlife populations. One such problem area or "hot spot" is located on the Rio Grande near Mission, Texas; fish samples from this monitoring station have consistently contained high DDE residues since 1968. Consequently, several supplemental surveys were conducted to determine the extent of DDE contamination in fishes and wildlife of the area and the possible sources of contamination. These surveys included sampling fishes at 12 sites along the main stem of the Rio Grande and at 3 sites in the lower Rio Grande Valley in 1976, and sampling fishes in 1978 and 1979 at 8 sites along the Arroyo Colorado, a major waterway traversing the lower Rio Grande Valley. In addition, fish-eating and passerine birds were collected at several localities in the lower Rio Grande Valley in 1978 and 1979. All fish and bird samples were analyzed for organochlorine residues. In this paper we present the results of those chemical analyses and discuss the significance of contamination on the affected populations. S ER NATURALIST 28(3): 5-333 AUGUST , 1983 This content downloaded from 157.55.39.208 on Wed, 28 Sep 2016 05:23:49 UTC All use subject to http://about.jstor.org/terms The Southwestern Naturalist TABLE 1.-DDE residues (ppm wet weight) in fish-composite samples from NPMP monitoring station no. 16 near Mission, Texas, 1968-1979. Ictalurus furcatus Ictalurus punctatus Dorosoma cepedianun Avg. Avg. Avg. Avg. Avg. Avg. Year DDE length (cm) weight (g) DDE length weight DDE length weight 19681 10.7 (2)2 26 112 0.6 (4) 42 560 2.3 (5) 31 224 19693 1.9 (5) 34 261 2.9 (5) 39 336 1.5 (5) 29 224 19704 4.0 (2) 41 485 7.3 (2) 43 560 3.9 (10) 29 224 1971 5.0 (6) 34 485 3.3 (6) 32 336 4.9 (6) 26 149 1972 4.4(4) 36 448 7.2(3) 39 410 1.1(10) 19 75 1973 3.9 (8) 48 298 0.5 (2) 25 112 1974 1.0 (10) 25 112 0.2 (5) 24 112 12.0 (5) 26 149 1976 1.7 (3) 32 224 1.7(10) 30 224 1978 2.5 (5) 35 336 2.2 (10) 25 112 1979 1.3 (10) 30 224 'DatafromHendersonetal.,(1969). 2Numberoffishineachcompositesample.. 3Data from Hendersonetal. (1971). 41970-1974 data fro Schmitt et al. (1981). MEHTODS.-Fishes were collected and stored according to the procedures outlined by Schmitt et al. (1981). In most instances, 2 composite samples, each of a different species and consisting of 2-10 adult fishes of uniform size, were collected at each station. The 1976 collections were analyzed at the Columbia National Fisheries Research Laboratory, Columbia, Missouri. Fish composites were ground and homogenized and processed for organochlorine analysis, which consisted of drying the fish tissue with anhydrous sodium sulfate, extracting the resulting mixture on a column with methylene chloride, and cleaning up the extract using gel permeation chromatography (Ribick et al., 1981). The clean extracts were separated first on florisil and then on silica gel prior to determinations of residues by gas chromatography. Limits of quantification were 0.01 ppm for organochlorine pesticides and 0.1 ppm for PCBs and toxaphene on a wet-weight basis. Fishes sampled in 1978 and 1979 were analyzed at Raltech Scientific Services, Madison, Wisconsin. The samples were ground and homogenized as described for bird carcasses by Cromartie et al. (1975) and Kaiser et al. (1980). The organochlorine contaminant analyses consisted of ether:petroleum ethel extraction of a homogenized fish-sodium sulfate mixture on a Soxhlet extractor, cleanup of the extracts on a partially deactivated florisil column, and separation of clean extracts into 3 fractions on a column of silicic acid. Determinations were made by gas chromatography and confirmed by mass spectrometry. Limits of quantification were 0.01 ppm for organochlorine pesticides and PCBs on a wet-weight basis. Birds collected with a shotgun or an air rifle in 1978 and 1979 were analyzed at the Patuxent Wildlife Research Center, Laurel, Maryland. Common and scientific names of birds follow the 34th Supplement to the A.O.U. Check-List (Auk 99(3), 1982). Before analysis, they were skinned, and the feet, beaks, wingtips, and gastrointestinal tracts were removed. The carcasses were homogenized in a food grinder and a 10 g portion was mixed with anhydrous sodium sulfate and extracted for 7 hours in a Soxhlet apparatus. The chemical procedures used were those described by Cromartie et al. (1975) and Kaiser et al. (1980). Limits of quantification for bird tissues were 0.1 ppm for organochlorine pesticides and 0.5 ppm for PCBs on a wet-weight basis. Residues in 10% of the bird samples were confirmed by mass spectrometry. Cross checks on fish samples were made between Columbia and Raltech, and data were comparable. In addition, cross checks were made on bird samples between Raltech and Patuxent and these results also were comparable. However, no cross checks were made on samples between Columbia and Patuxent. RESULTS.-Residues in Fishes.--Over the years, DDE residues have been detected at fairly high levels (Table 1) in whole-fish composites from NPMP station No. 16 near Mission, Texas (Fig. 1). Although DDE residues in fishes at this station have varied considerably among years, levels have not declined appreciably since the use of DDT was banned in 1972, as they have at most other monitoring stations across the nation (O'Shea and Ludke, 1979). A survey in 326 vol. 28, no. 3 This content downloaded from 157.55.39.208 on Wed, 28 Sep 2016 05:23:49 UTC All use subject to http://about.jstor.org/terms White et al.-DDE and Toxaphene Residues

Pomphorhynchus bulbocolli Linkins in Van Cleave, 1919, was considerably more common in fishes of the river-connected Tichigan Lake than of the landlocked Silver Lake, southeastern Wisconsin. It is reported from 17 species of principal, accessory, and occasional definitive hosts (new record in Moxostoma carinatum) and from 13 species of paratenic hosts (new records in Amia calva, Ictalurus punctatus, Lepomis cyanellus, and Pomoxis nigromaculatus). Infection patterns were influenced by fish species, feeding behavior, temperature, availability of intermediate host, type of water body, fish movement, and changes in fish host community. Host roles are not fixed but are often interchangeable. A seasonal cycle in prevalence, intensity, and maturation was evident, with greatest abundance and maturation during summer and recruitment during summer and autumn. Recruitment of new infections, development, and release of eggs, however, occurred all year. Sex ratio changed from near equal in new infections to one more highly in favor of females in older adults. Female fish were considerably more frequently and heavily infected than males. No relationship with fish age (size) was evident. Worms were mostly attached in posterior intestinal locations but initial establishment sites correlated with temperature. Translocation of P. bulbocolli due to competitive exclusion in concurrent infections was not observed. The significance of extraintestinal larval forms in the cycle of transmission was noted.

has 2N = 56; species currently placed in Ictalurus have between 48 (I. catus) and 62 (I. natalis and I. brunneus) with diploid numbers of 52, 54, 56, 58 and 60 present in one or more species. The members of the subgenus Amiurus have diploid numbers either greater than or less than 58, while both I. (Ictalurus) punctatus and I. furcatus have 2N = 58. An ancestral ictalurid karyotype of 2N = 58 with a relatively high FN (>80) is postulated, based primarily on the distribution of chromosomal states in the various ictalurid lineages as well as in peripherally related siluriform families (Bagridae, Pimelodidae and Ariidae). This karyotype may be ancestral for all siluriforms. Ictalurids (and siluriforms in general) have karyotypes characterized by many chromosomes with identifiable second arms (ranging from minute to large). Robertsonian rearrangements, including primarily centric fusions but also centric dissociations, appear to have been important in the evolution of ictalurid karyotypes. Interspecific karyotype differences cannot be totally explained as Robertsonian events; additional rearrangements such as pericentric inversions must be invoked to explain the karyotypic differences. There has been parallel evolution of the karyotypes within madtoms; there has been stepwise reduction of 2N from 54 to 42 in Schilbeodes and 52 to 40 in Rabida. The hypothetical common ancestor of the Noturus-Pylodictis line probably possessed a karyotype similar to that in Pylodictis with a 2N = 56 karyotype with a high FN (>80). Early stages of Noturus divergence may have involved initial reduction of the 2N to 54 with a high FN retained; such a karyotype is seen in Noturus gilberti (2N = 54, FN = 82) and is closely approached by Noturus flavipinnis with 2N = 52, FN = 82. Karyotypic data available provide little new insight into intergeneric relationships or intrageneric relationships in Ictalurus. Chromosomal data do, however, provide the basis for a new hypothesis on intrageneric relationships within Noturus. Relationships suggested by chromosomal analysis are consistent with some relationships postulated previously while differing in other respects. Emphasis is placed on the transformation of diploid numbers since difficulties are encountered in determination of accurate fundamental numbers due to the large number of chromosomes that possess second arms and the gradual change in the size and form of the elements in most karyotypes. Chromosomal similarities to the subgenus Schilbeodes as well as the lack of sufficiently unique morphological characters suggest the consolidation of the currently recognized subgenus Noturus with Schilbeodes.

Autopsies on 144 bullheads (Ictalurus melas and I. nebulosus) from North Dakota and Minnesota revealed a high incidence of diplostomulum-infected lenses. The majority of these lenses possessed dorsally situated cysts. The incidence and intensity of infection varied from one collection area to another, but the cysts typically housed more flukes than the lenses. Anatomical and histological comparisons between normal and parasitized eyes indicate that the cyst results from a herniation of the lens near the point of attachment of the dorsal ligament. The pressure required for this protrusion appears to come from the parasites, the hyperplastic lens epithelium, and the reactivity of the lens substance to the parasites. Cyst production, its effects, and its relationship to host age and worm burdens are discussed. The occurrence of strigeoid metacercariae in the lenses and optic chambers of fishes was first reported by von Nordmann (1832). Since then similar cases of parasitism have been recorded from many species of fish, presumably involving many species of flukes. An appreciation of their ubiquitous distribution can be gained from the synopsis of larval strigeoids by Hoffman (1960), and from various fish parasite surveys. Despite these numerous reports there appear to be only two accounts of such flukes being associated with abnormal growths on the fish lens. LaRue, Butler, and Berkhout (1926) reported the localization of diplostomulum metacercariae "in small knobs or projections from the lens" of Ictalurus nebulosus taken in Michigan. More recently in Britain Erasmus (1958) noted a rarely occurring "tumor-like" growth on the lenses of Received for publication 8 June 1964. * From a thesis submitted to the University of Minnesota in partial fulfillment of the requirements for the degree of Doctor of Philosophy. This work was supported in part by the following: National Science Foundation Fellowship for Teaching Assistants, 1962; National Institutes of Health Predoctoral Fellowship GPM-14,398-R1; and the American Cancer Society Institutional Research Grant IN-13D to the University of Minnesota. t Present address: Department of Biology, University of North Dakota, Grand Forks, North Dakota. Leuciscus idus which had been infected experimentally with Cercaria X Taylor and Baylis, 1930. The present study was undertaken when black bullheads, Ictalurus melas (Rafinesque), were found to possess a high incidence of protrusions on their lenses parasitized by diplostomulum metacercariae. The purposes of this paper are to report the incidence and intensity of infection, and to describe the pathological conditions seen in naturally infected bullheads. MATERIALS AND METHODS From 1957 to 1964 autopsies were conducted on 141 I. melas and 3 I. nebulosus collected from North Dakota and Minnesota. Localities, incidence of infection and cysts, and average worm burdens for I. melas are presented in Table I. The limited information for I. nebulosus is not included in tabular form, although all three specimens were infected. Until dissected all fish were held in large tanks supplied with running well water and compressed air. A daily feeding of uncooked oatmeal seemed to provide an adequate diet. The fish were killed by inserting a scalpel into their brains. The eyes were removed with iridectomy scissors and placed in 0.6% saline. By using fine forceps, dissecting needles, and microscalpel, the eye could be opened without damaging the lens or its cyst. The darker dorsal portion of the iris was used as a guide in orienting the excised eye prior to opening it. By using a dissecting microscope it was relatively easy to count the flukes within the freshly excised lens. Most of the cysts were too opaque to show all the worms, hence these structures were teased

a pore below the humeral process. The depressed pectoral spine overlies this pore and is then in contact with the secretion from the gland. Usually likened to a bee sting, the effect of the wound is temporarily extremely painful, but in our experience it is localized and rarely of long duration. The larger catfishes (e.g., Ameiurus and Ictalurus) share the stinging ability as young but the axillary gland is less well developed, especially in larger specimens. In Ictalurus lacustris the pore closes early in life. Schilbeodes is distinguished from the other genera of the Ameiuridae, except Noturus, in having the adipose fin adnate to the caudal fin. From Noturus, Schilbeodes differs in lacking the lateral backward projections of the transverse band of premaxillary teeth. Ten species of Schilbeodes are currently recognized (Jordan and Evermann, 1896: 144-149). Four of these have been discussed recently by Hubbs and Raney (1944), who indicated that certain changes in nomenclature were called for and that S. marginatus is a complex of two subspecies. Misled by the marked sexual dimorphism in S. eleutherus, Hubbs (1930: 432) reported females from the Ohio River drainage and Huron River, Michigan, as S. furiosus. When the differences were recognized as sexual, furiosus was regarded as confined to streams of eastern North Carolina, and was first treated as perhaps conspecific with eleutherus (Hubbs and Lagler, 1941: 65), and later as specifically distinct (Hubbs and Lagler, 1947: 73). The distribution of S. eleutherus (in the Ohio River basin including the Tennessee system, in tributaries to western Lake Erie, and in parts of the Arkansas River system) overlaps that of miurus broadly, and these species are sharply differentiated (Hubbs and Lagler, 1947: 72-73). In many localities they live together. Although for

A study was carried out to determine whether the black bullhead demonstrates a compensating peptic digestive capacity influ- enced by thermal acclimation. Crude pepsinogen extracts from entire stomachs of two groups of fish were used. One group was acclimated to 12C, the other group to 24C (all for more than 60 days). It was found that the extract from the group of fish acclimated to 24C showed higher peptic activity than that from the 1 2C acclimated fish. The high peptic activity in the 24C acclimated fish group seemed to repre- sent a reversed compensation. A slight difference between responses to substrate pH was observed. There were no detectable differences in temperature responses between the peptic extracts from the two labora- tory-acclimated fish groups. It was concluded that black bullheads probably have greatest digestive capacity during the summer months. During the winter they most likely exist at reduced activity levels on stored fat and glycogen. The results of previous investigations on digestive capacities in poi- kilotherms have varied with the species and with the particular digestive enzyme under investigation. Mews (1957) found that Carassius carassius (Lin.) had greatest alkaline proteolytic activity after being acclimated to summer temperatures. Leonard (1941) found that the feces of brook trout captured during the winter were made up of an undigested mass of organisms, some of which were alive. Amia calva Lin. and species of Lepomis have lower digestive capacities during the winter than during the summer (Riddle, 19095. The salamander, Necturus sp., was found to have a higher digestive capacity in December than in March. Riddle compared his findings with those of Gillespie (quoted by Riddle) who had found that the

Report of the collection and distribution in Oklahoma of six fishes not previously recorded from the state (Salmo trutta, Hiodon tergisus, Ictalurus nebulosus, Typhlichthys subterraneus, Fundulus catenatus, Roccus saxatilis) brings the total number of species known from Oklahoma to 167. Three of the six represent introduced forms. A list of all exotic fishes known to be introduced into Oklahoma waters, with the available history of introduc- tion, is included. Of the 14 known or postulated to be introduced, 5 are utilized as bait species and 9 were introduced as additional food for game fishes. Eight have had varying degrees of reproductive success; 5 of the game fishes were not expected to provide reproducing populations, and their success is depen- dent on continual restocking. Only the introduction of the tench, Tinca tinca, can be considered unsuccessful.

of the yellow perch (Perca flavescens), the white sucker (Catostomus commersoni), and the black bullhead (Ictalurus melas). The smallest collection, from the Butler Spring locality, contained two other species, a gar (Lepisosteus sp.) and probably the channel catfish (Ictalurus punctatus), which were also found at the Berends locality (Table I). Presumably, more collecting at the Doby Springs and at the Butler Spring localities would yield more species common to all three localities. The Doby Springs deposits contain several species of minnows not found at the Berends site and this possibly indicates that the locality was more of an upstream, pond situation with smaller streams flowing into it. The absence of the drum, gar, and channel catfish would seem to bear this out. LITERATURE CITED

Lipofuscin, which possesses a bright fluoresence under ultraviolet light, occurs primarily in nonreplacable cells such as those composing heart, brain and muscle (Hendley, Mildvan, Reporter and Strehler, 1963). Its deposition has been called a basic biological aging process. The effect of lipofuscin deposition on cellular function is largely unknown. However, certain cells, such as motor neurons in the aged person become packed with the particles, and it is thought that these cells may be impaired in their function because of this "varnish." In man, no lipofuscin was found in children under ten years of age (Strehler, Mark, Mildvan and Gee, 1959). In aged individuals, up to three mg. dry weight of lipofuscin per gram of wet heart tissue has been found (Hendley et al.. 1963). In studies of mammalian nervous systems, lipofuscin has been seen to accumulate with increasing age of the animal. The motor ventral horn cells of the spinal cord are the least resistant to deposition of the pigment in dogs and pigs. Pigment accumulation was observed in five-month-old dogs and six-month-old pigs (Few and Getty, 1967). Lipofuscin pigments are thought to be formed by a progressive oxidation of lipid moieties (Samorajski and Ordy, 1967). During the process of oxidation, the lipids pass through phases in which triglycerides and phosphatids are oxidized to intermediate stages and finally to the typical well-developed brown lipofuscin pigment (Kalidas, 1968).

Channel catfish, stocked in ponds, were given supplemental feed in early fall when provided with artificial light to extend the daylength to 15 hours. A similar experiment was conducted in early spring but the photoperiod was gradually increased to provide light from 13 to 20 hours daily. Fish grew during the experiment but efficiencies of food conversions were poor and fish in unlighted ponds grew as well as those in lighted ponds. Introduction Gross, Roelofs and Fromm (1965) determined food consumption, growth and food conversion efficiency of green sunfish (Lepomis cyvrellv) were influenced by photoperiod. Food consumption varied directly with the amount of light to which fish were exposed. Fish growth and efficiency of food conversion were closely correlated and were generally best in the increasing, poorest in the decreasing, and intermediate in the constant photoperiods. Shrable, Tiemeier and Deyoe (1969) noted rate of digestion in the channel catfish (Ictalurgs psnctatzls) was most rapid at water temperatures between 70 and 85° F and decreased at higher and lower temperatures. Asadi (1967) noted optimum environmental temperature for secretion of digestive enzymes of channel catfish was near 75° F. Producers of channel catfish fed in southern United States generally have been able to produce larger Esh during one growing season than producers in more northerrl areas. The annual duration of water temperatures above 70° F is longer in southern waters. Length of the photoperiods generally have been considered not important in promoting growth of channel catfish. Purposes of this study were to determine if fish growth could be Transactions of the Kansas Academy of Science, Vol. 72, No. 4, 1969. Published wf uly 15, 1970^ 1 Investigations were conducted cooperatively with the Kansas Agri. Exp. Station, Kansas Forestry, Fish and Game Comm., Bureau of Comm. Pisheries under P.L. 88-309 and Kansas Committee on Relation of Electricity to Agriculture. Contribution No. 1040, Division of BiologyNo. 691, Dept. of GrainScience and Isldustryand No. 158, Dept. of Agricultural Engineering, Kansas Agri. Exp. Sta., Manhattan 66502. 2 Division of Biology, Depattment of Grain Science and Industry andDep,artment of Agricultural Engineering at Kansas State University, Manhattan.'

in vertebrates by tissue transplantation. J. Genet. 58(1):7-24. . 1962b. Population genetics of the gynogenetic teleost, Mollienesia formosa (Girard). Evolution 16(4):497-504. . 1963. Population structure of the allfemale gynogenetic teleost, Mollienesia formosa (Girard). Proc. XVI Int. Congr. Zool. 2:170. MARTIN, F. D. 1964. The occurrence of Mollienesia formosa in the lower Nueces River of Texas. Tex. J. Sci. 16(4):453. MEEK, S. E. 1904. The fresh-water fishes of Mexico north of the Isthmus of Tehuantepec. Field Col. Mus. Nat. Hist. (Zool.), 5:1-252. MILLER, R. R. 1966. Geographical distribution of Central American freshwater fishes. Copeia 1966(4):773-802. AND R. J. SCHULTZ. 1959. All-female strains of the teleost fishes of the genus Poeciliopsis. Science 130:1656-1657. MINCKLEY, W. L. AND R. K. KOEHN. 1966. Notes on the poeciliid fishes Poecilia formosa vertebrates by tissue transpla tation. J. enet. 58(1):7-24. and Gambusia myersi from the Rio Tamesi system, Tamaulipas, Mexico. J. Ariz. Acad. Sci. 4(1):46-49. RASCH, E. M., R. M. DARNELL, K. D. KALLMAN, AND P. ABRAMOFF. 1965. Cytophotometric evidence for triploidy in hybrids of the gynogenetic fish, Poecilia formosa. J. Exp. Zool. 160(2):155-169. REGAN, C. T. 1913. A revision of the cyprinodont fishes of the sub-family Poeciliinae. Proc. Zool. Soc. Lond. 1913(2):977-1018. ROBINSON, D. T. 1959. The ichthyofauna of the lower Rio Grande, Texas and Mexico. Copeia 1959(3):253-256. ROSEN, D. E. AND R. M. BAILEY. 1963. The poeciliid fishes (Cyprinodontiformes), their structure, zoogeography, and systematics. Bull. Am. Mus. Nat. Hist. 126(1):1-176.

In the course of studies on the trematode parasites of Minnesota fishes, I have several times noted a form in the Channel Catfish (Ictalurus punctatus) which presents some very characteristic features. In the structure of the testes it represents not only a new species but an undescribed genus. The Channel Catfish in which these specimens were found were taken from the St. Croix River at Stillwater, Minnesota, on January 10, and from the Mississippi River at St. Paul, Minnesota, during its highwater stage on April 30 and again on June 22, 1927. In five out of sixteen of the fish, the minute flukes described below were found in folds of the intestinal mucosa. They were not found in any particular region, but were more abundant in the lower intestine where they were usually found with large numbers of a small Allocreadian species. Specimens of this species were obtained by stripping the mucosa and placing it in petri dishes in water, where the flukes soon betray their presence by their activity in freeing themselves from the mucosa. The adult distome is somewhat depressed, pear-shaped, with its greatest width near the anterior end of the testes. The neck region is mobile and translucent white in the living specimens, while the region posterior to the acetabulum is white and mostly opaque due to the presence of massive testes which nearly fill the posterior region. Eleven specimens were found to average 0.753 mm. in length and 0.340 mm. in width. The range in length for these specimens was from 0.404 to 1.434 mm. The range in width was 0.246 to 0.580 mm. Two well-developed suckers are present. The oral sucker at the anterior end of the body is ventral in position and in eight specimens averaged 0.107 mm. in transsection. Slightly anterior to and dorsolateral to the middle of the oral sucker are two papillae, one on each side. They measure about 25,A in width by 211A at the base in the extended condition. These papillae are scarcely noticeable in most fixed specimens and their presence might have been overlooked but for observation of the living specimens in which the hornlike papillae were demonstrated as the animal groped about in moving forward. The acetabulum is from one-fourth to one-third of the distance from the anterior to the posterior end of the body. In eight specimens it measured on the average 0.127 mm. in transsection, with a range of 0.102 to 0.176 mm. The

The artificial propagation of channel catfish has been done continuously by Kansas fishery workers since the early 1920's. Mr. John Murphree, now at the Durant Oklahoma Hatchery, contributed much to artificial propagation, feeding and rearing of channel catfish during his tenure with the Kansas Forestry, Fish and Game Commission. Mr. Seth L. Way, who succeeded Mr. Murphree as Superintendent of Fisheries for the State of Kansas, also contributed much to artificial propagation, hatching, feeding and rearing of channel catfish. Mr. Way invented and put into use a channel catfish incubator which is now being used by state and private hatcheries. Mr. Way's feeding and rearing techniques also have been adopted by several state and private hatcheries. This paper is a preliminary report of experiments with certain diets and concomitant growth and mortality data on channel catfish from fry to fingerling stage. It is hoped that the data may prove of value to fishery workers of other state or private hatcheries artificially producing channel catfish.

The Sunflower Army Ammunition Plant (S.A.A.P.), operated by the Hercules Powder Company at Sunflower, Johnson County, Kansas, discharges waste containing sulfuric acid neutralized with slaked lime into Kill Creek, a tributary of the Kansas River. Channel catfish, Ictalurus punctatus (Rafinesque), are indigenous to both streams. Twelve channel catfish, kept in a synthetic waste approximating that of S.A.A.P., died within two days when a suspended solids concentration of 24,200-30,400 mg/1 was maintained by vigorous aeration. Ten out of 15 channel catfish survived in synthetic waste for the 22-28 day duration of the experiments when a suspended solids concentration of 367-509 mg/l was maintained by moderate aeration. Eleven of 12 catfish survived 22-28 days in synthetic waste from which all settleable solids were removed, and 17 of 22 catfish kept in tapwater as controls survived 22-28 days. No significant mortality occurred among Notropis lutrensis, Notropis umbratilis, Lepomis cyanellus, Gambusia affinis, and Ictalurus melas kept in synthetic waste during preliminary tests. Transactions of the Kansas Academy of Science, Vol. 72, No. 1, 1969. Published June 11, 1969.

During several summers the writer has been making a somewhat extensive study of the myxosporidian parasites of fishes from the Mississippi River at Fairport, Iowa. In the course of these investigations a number of channel catfish, Ictalurus punctatus, have been examined for parasites and one individual was found to be badly infected with a new species of Henneguya. This species is notable for a number of exceptional and interesting characteristics, and for that reason it has been thought advisable to publish an account of it in advance of the main results of the investigations. This species, for which I propose the name Henneguya plasmodia occurs in the epithelium of the gill filaments as a small amoeboid plasmodium. It never forms cysts as do the other Myxosporidia occurring on the gills but retains its amoeboid form throughout life. It is apparently not common since it was found in only one fish t out of 29 examined. In this case, however, it was present in enormous numbers.