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Hydromermis contorta (Kohn) and Hydromermis pseudocontorta n. sp. are described from chironomids in Lake Itasca and Long Lake, Minnesota, respectively. The former was recovered from adult females of Glyptotendipes paripes (Edwards) and the latter from fourth-instar larvae of Chironomus sp. Hydromermis pseudocontorta n. sp. resembles H. contorta in cephalic structures, overall size, and the presence of a restricted trophosome in the female. The terminal mouth, long uterine and vulvar limbs of the vagina, and the strongly chitinized brownish spicule of H. contorta contrast with the subventral mouth, short vaginal limbs, and the light yellow spicule of H. pseudocontorta n. sp. Both nematode species emerge from the host as sexually mature adults and both species give evidence of mating while in the host. The H. contorta described by Welch is designated as a new species, Hydromermis albionis n. sp.

Based on internal structure, a new family of entactinarian radiolarians, the Kungalariidae, is described with three new genera and four species: Kungalaria newcombi, Cachecreekaria californiensis, Transylvanaria devaensis, and T. hattorii. Members of this family have an eccentric internal, nassellarian-type initial spicule with bar MB, rays A, V, L, I, and spine Ax; a medullary shell built above the plane of lateral rays as in the cephalis of many nassellarians; and a spherical to subspherical cortical shell around the medullary shell. This new family is part of a group of Triassic entactinarians structurally intermediate between Entactinaria, or spicule-bearing Spumellaria, and Nassellaria. The new genera and species described occur in the Rhaetian of Queen Charlotte Islands, British Columbia, Aalenian to early-mid Bajocian of central Japan, Cenomanian of California, and Coniacian of Romania.

Well-preserved Middle Cambrian radiolarian were recovered from the Beetle Creek Formation, Inca Formation, and Devoncourt Limestone, Georgina Basin, Australia. Unlike previously reported Early Paleozoic radiolarians, these Middle Cambrian Radiolaria have two diagnostic characteristics in common with siliceous sponge spicules that occur in the same faunas: their skeletal elements consist of hollow tubes, and when a spicule is present, all spicular skeletons, including the internal spicule, are point-centered. The faunas contain 6 new genera and 18 new species; most of them have one or more spicular skeletons. Two new families are established. One family has a spherical shell wall with one or more point-centered internal spicule(s); it is named here Archeoentactiniidae n. fam. and consists of three new genera, Archeoentactinia, Fungomacula, and Spongomassa. The other new family, Palaeospiculumidae n. fam., consists of a point-centered spicular skeleton without a spherical shell capsule; the family is composed of the single genus Palaeospiculum n. gen. The taxa belonging to this family might perhaps be considered to be sponge spicule, but they differ from sponge spicule because their skeleton has the same basic structure as in Palaeoscenidiidae, that is, the spicule consists of apical and basal rays. In addition to these genera belonging to the two families, two other genera are present. They are uncommon and are of uncertain taxonomic position at the family level. One of the two, Aitchisonellum n. gen., has a spherical shell without internal spicule, but it belongs to neither Inaniguttidae Nazarov and Ormiston 1984 nor Palaeoactinosphaeridae Noble 1994; it seems to fit best in the informal group of Palaeoactinomiids Holdsworth (1977). The other genus, Protobiramus n. gen., has no typical internal spicule, but consists of a biaxially arranged four-rayed spicule and repeatedly bifurcated branches of those rays; the branch tips are not merged. The difference in faunal compositions among the three Middle Cambrian formations examined is not great: the Beetle Creek Formation, Inca Formation, and Devoncourt Limestone faunas consist of 7, 23, and 8 species, respectively.

A new species of Rhabdochona from 2 species of freshwater fishes, Alloophorus robustus and Goodea atripinnis, is described from 2 lakes of the Mesa Central of Mexico. Rhabdochona lichtenfelsi n. sp. belongs to a group of species possessing inconspicuous bifurcated deirids and a prostom armed with 10 large teeth. It is distinguished from them because the left spicule is shorter, the tip is bifurcate, and both spicules lack a reflected dorsal barb. The new species most closely resembles Rhabdochona catostomi and Rhabdochona milleri but differs from them because the former possesses a left spicule tip with ventral barb, right spicule with reflected distal barb, and 5 pairs of postanal papillae, whereas R. milleri has 14 prostomal teeth, eggs rounded, and left spicule with slightly outlined bifurcation and right with a dorsal barb. Previous records of R. milleri in Mexico must be referred to R. lichtenfelsi.

While examining an imported Indonesian mangrove monitor, Varanus indicus (Reptilia: Sauria: Varanidae), for helminths, a new species of Hastospiculum was collected and is described as Hastospiculum spiralis n. sp. This species differs from all other members of the genus in caudal papillae number and arrangement, a pair of large cephalic papillae, and a spirally twisted left spicule in males. Additionally, H. spiralis n. sp. differs from certain Hastospiculum species by the right and left spicule lengths, egg shape, and the final host.

Strelkovimermis arkansensis n. sp. and Hydromermis welchi n. sp. are described from chironomid adults in Arkansas and Minnesota, respectively. The host of the former is Glyptotendipes paripes (Edwards) and of the latter Polypedilum (Polypedilum) nubeculosum (Meigen). Strelkovimermis arkansensis n. sp. most closely resembles Strelkovimermis buccalis Johnson and Kleve, 1996 and is separated from that species by color in the living worms, thickness of the cuticle, and length of the cephalic papillae. Hydromermis welchi n. sp. is similar to Hydromermis gastroviridis Johnson and Kleve, 1997 and is separated from that species by color in the living worms, structure of the spicule, and number of genital papillae. A variant of H. welchi n. sp. is described. Molting in S. arkansensis was apparently facilitated by having both postparasitic males and females in the same vial.

This is the first of two publications dealing with a study of the family Entactiniidae and the taxonomy of a diverse assemblage of Late Devonian spumellarians. A well-preserved radiolarian fauna from the Gogo Formation, Western Australia, has made it possible to clarify the relation of the shell wall and internal structure in this family. The entactiniid shell is of two types: spongy and latticed. The former has apophyses on rays of the internal spicule, whereas those with latticed shells have an internal spicule without apophyses. On the basis of the internal spicule structure the Entactiniidae can also be divided into four types: (1) six-rayed spicule without a median bar, (2) four-rayed spicule without median bar, (3) sixto eight-rayed spicule with a median bar, and (4) twelveto twenty-rayed spicule with a median bar. The Gogo fauna includes more than 100 species. Entactiniids or taxa having characteristics similar to Entactiniidae are treated here. They comprise 17 genera and 72 species and subspecies, of which 13 genera and 66 species and subspecies are new. Bisphaera, Radiobisphaera, Plenoentactinia, Apophysisphaera, Retentactinia, Retisphaera, Spongosphaera, Duodecimentactiniaand Multientactinia belong to the Family Entactiniidae. Apophysiactinia, Magnisphaera, Magnentactinia, and Intracorpus, are of uncertain taxonomic position. Entactiniid genera of this fauna are tentatively classified into two subfamilies: (1) Entactiniinae, which has a latticed shell(s) and lacks apophyses, and (2) Retentactiniinae n. subfam., characterized by a spongy shell and possessing apophyses. Taxa belonging to subfamily Entactiniinae plus taxa having characteristics similar to Entactiniidae, and subfamily Retentactiniinae are described respectively in this paper and in a second paper in this volume (Won 1997).

Two cystidicolid nematodes, Ctenascarophis lesteri n. sp. and Prospinitectus exiguus n. sp., are described from the skipjack tuna, Katsuwonus pelamis, from Fiji, New Caledonia, Marquesas Islands, New Zealand, Papua New Guinea, and Puerto Rico. The former species differs from Ctenascarophis gastricus, the only other member of the genus, by having comb rows extending farther posterior than two-thirds the body length, to the anus in the female; it also has differently distributed spines on each comb, with a maximum of 32 rather than 8. The male has 7 rows of precloacal longitudinal crests; 3 pairs of precloacal, 1 pair adanal, and 6 pairs postcloacal papillae; and a spicule ratio of 1:3.4-1:5.0. The latter species differs from Prospinitectus mollis, the only other species in the genus, by being less than one-half as long, 3.5-5.9 mm long; with a proportionally longer esophagus; fewer spines per spine ring, a maximum of 49 compared with 100; deirids that lack spinules; males with an unornamented precloacal cuticle as well as a different number and distribution of caudal papillae, 2 precloacal and 7 postcloacal; and a smaller spicule ratio, 1:4 rather than 1:5-1:7.

Heliconema brooksi n. sp. is described from the shrimp eel, Ophichthus gomesi, in Mississippi Sound. This species is distinguished from other members of the genus by possessing in the male 40 or more tessellated longitudinal ridges, a spicule ratio averaging 1:10.6, 4 precloacal papillae, and 6 postcloacal papillae. Females have a protruding vulvular flap. Both sexes have a prominent sclerotized cardium. Heliconema brooksi is morphologically most closely related to Heliconema heliconema. A juvenile worm from the white shrimp, Penaeus setiferus, in the same locality may be the infective stage.

Emended diagnoses encompassing forms described herein are proposed for the family Palaeoscenidiidae and the subfamily Palaeoscenidiinae. Diagnosis of the family Entactiniidae is emended to include only forms with latticed or spongy shells developed around a central spicule. This emendment permits mutual exclusivity of forms of the Palaeoscenidiidae and the Entactiniidae. Five genera of Palaeoscenidiinae are distinguished by skeletal ray arrangement. One of these, Palaeoscenidium, was illustrated previously in the literature. It is here emended to include only skeletons with four apical and four basal rays. Palaeoscenidium bicorne is reassigned to Palaeoephippium, n. gen. New genera are erected for 1) five-rayed spicules with one apical ray and four basal rays-Palaeopyramidium; 2) six-rayed spicules with two apical rays and four basal rays-Palaeoephippium; 3) six-rayed spicules with three apical rays and three basal rays-Palaeotripus; and 4) ten-rayed spicules with two apical rays and eight basal rays-Palaeodecaradium. Twenty-three new species belonging to the subfamily Palaeoscenidiinae and two new species of the family Entactiniidae are described. The Palaeoscenidiinae are shown to have given rise polyphyletically to the Entactiniidae.

A new method for preparation of sponge spicules for microscopy utilizes membrane filters for separation of spicules from cleaning fluids. The membranes with adherent spicules are cleared during mounting on microscope slides for direct analysis by light microscopy. The basic filtration procedure is also used to produce preparations for scanning electron microscopy. The main advantages of this procedure over a variety of traditional methods include preclusion of spicule loss during cleaning and significant reduction of procedure-introduced variation. The technique described offers promise for quantitative analysis of spicule complements. Incentive to develop a standardized procedure for spicule preparation stems from several problems noted in publications of both veteran and neophyte sponge taxonomists. Most prevalent is a general absence of detailed reporting of methods employed in spicule examinations. The result is a disturbing lack of certainty in taxonomic identifications, deriving partly from real differences in the specimens themselves, but also is an artifact of the methods of spicule preparation and analysis. The most commonly reported problems are the rare occurrence or absence of a spicule type and differences in size of spicules from specimens that otherwise appear to belong to the same species. We surveyed 123 primary taxonomic papers on Porifera published during the last 40 years3. Although the sample is biased by both ease of access and language of publication (untranslated Eastern languages were excluded), it does include all of the important contemporary treatments: 75% (n = 92) of these papers include no mention of the method of skeletal preparation; 19% (n = 24) include a short mention of, or reference to, a technique; and only 6% (n = 7) provide a description of methods in sufficient detail to enable duplication. Potential investigators looking to these publications of methods to use in identification, and, more importantly, seeking an authoritative format for preparation of taxonomic publications, are provided with little or no guidance. A detailed set of standard procedures for (1) making spicule preparations, (2) examining them microscopically, and (3) carrying out and reporting quantitative statistical analyses on the data generated has not been formally proposed or tested. Our purpose is to put forward a basic procedure for producing permanent spicule preparations. This procedure is new, requires minimal speSupported by a Natural Sciences and Engineering Research Council of Canada Operating Grant

Capillaria schmidti n. sp. was described from the intestine of a marine fish, Raja radiata. It was distinguished from other congeneric species by a spiny spicular sheath, mainly by a shorter spicule (0.08-0.092 mm long), 4 pairs of caudal papillae (1 pair in sublateral lobe and 3 pairs precloacal sessile) in male, a pair of papillae at the distal end of the tail of female and globular vulvar appendage. During a survey of nematode parasites, several male and female specimens of the genus Capil- laria Zeder, 1800, were recovered from the in- testine of the marine fish, Raja radiata, collected from the South Coast of the Indian Ocean, India. Of the several fishes dissected, every host har- bored mature nematode parasites. A detailed study of these worms revealed that they do not conform to any known species of the genus and appear to constitute a new species, and hence are reported as such.

Two species of Cyrnea are reported from 706 wild turkeys (Meleagris gallopavo) from 25 localities in 9 southeastern states. Cyrnea (Cyrnea) neeli sp. n. in birds from Alabama and Florida is differentiated primarily by distal processes of the left spicule and spicule lengths. Specimens from wild turkeys previously reported as C. eurycerca are identified as C. coloni. The configuration of caudal papillae of C. colini is redescribed. Neither species occurred in birds from montainous regions, and C. neeli sp. n. was restricted to Florida and southern Alabama. Poults less than 1-month old were not infected. Infections peaked in early fall and then declined rapidly.

Diplotriaena darnaudii sp. n. is described from 13 specimens collected from the thoracic air sacs of a D'Arnaud's barbet (Trachyphonus darnaudii) originating in the Lake Baringo area of Kenya and which died in captivity in Canada. In morphology it is similar to D. bargusinica Skrjabin 1917, D. campanae Anderson 1959, D. dollfusi Anderson 1959, and D. epsilon Johnston and Mawson 1940, but can be separated from these species by combinations of trident size and spicule size and morphology.

Ackertia globulosa sp. n. (Nematoda: Filarioidea) is described from the pulmonary arteries of the striped mouse, Lemniscomys striatus striatus (L.), in Kenya. Distinguishing features are the small size of the adults; the short left spicule and arrangement of the caudal papillae (3 pairs preanal, 4 pairs postanal) of the male; small projecting lobes on the tail of the females; and 10 to 12 refractile globules in the microfilarial sheath. The microfilariae are found in the skin, mostly of the ear. The probable intermediate host is a hard tick, Haemaphysalis leachi.

The worm is distinguished by the presence of both unequal spicules and a gubernaculum in the male and also the elongated nipplelike tip of the right spicule. P. gombensis was found to be a common parasite within a troop of feral chimpanzees living in Gombe National Park, Tanzania.

On the basis of morphological characteristics of adult and microfilarial stages, Wuchereria kalimantani sp. n. (Nematoda: Filarioidea) is described. The parasites were recovered from the inguinal lymph nodes and testes of silvered leaf monkeys (Presbytis cristatus) from a rubber estate, Banjar Regency, South Kalimantan (Borneo), Indonesia. Adult males are characterized by having more than 24 caudal papillae, a left spicule with a simple lamina, four pairs of sessile caudal papillae, a blunt tail, a mean overall length of 41 mm, and sheathed microfilariae with a nude tail tip; accordingly, the parasite is placed in the genus Wuchereria. This is the second species of Wuchereria described on the basis of both adult and embryonic forms, and is the first such species that has been found to infect primates naturally.

Tetrapetalonema (T.) saimiri sp. n., a filarial nematode from the subcutaneous tissues of squirrel monkeys (Saimiri sciureus) from central Colombia, is described. Within the subgenus, the small size of this worm (females 19-25 mm long) readily distinguishes it from several of the other species in which the minimum length exceeds 40 mm. Tetrapetalonema saimiri can be separated further from nearly all the other small species (T. dunni, T. barbascalensis, T. parvum, and T. obtusa) by its lack of annular body swellings, its low spicular ratio, the location of the vulva near the midportion of the esophagus, the shape and length of the tail in the female, and in details of spicular structure. Tetrapetalonema saimiri closely resembles T. panamensis, but is separated from T. panamensis by the salient buccal region, the acute flexure of the female tail, the shorter right spicule, and the configuration of the vagina of the former species. The microfilaria of T. saimiri is distinguished from that of all other known species of the subgenus by its consistent attitude (loose helical coil or closed C-shape) in 2% aqueous formalin preparations (Knott's technique). During an investigation of the filarial para- sites of Neotropical primates in Colombia, a distinctive microfilaria, easily recognized by its helical attitude in wet, 2% aqueous for- malin concentrates of blood (Knott's tech- nique), was observed in squirrel monkeys (Saimiri sciureus). Of 42 monkeys examined from Barbascal, Meta, 30 were infected with this microfilaria. Only one of 10 Saimiri sci

Ascarops talpa sp. n. (Nematoda: Spirocercidae) is described from the small intestine of the Formosan mole, Talpa micrura insularis, from Taiwan. It is most similar to A. kutassi (Shul'ts, 1927) and A. tuvensis Sulimov, 1961. Ascarops kutassi differs by having a smaller ratio of left to right spicule length (1:4 vs. 1:5.5), no caudal alae, by its preanal papillae that are not equidistant from one another, and in its area rugosa which extends 1.25 mm anterior to the anus. Ascarops tuvensis differs by having a smaller ratio of left to right spicule length (1:3.8 vs. 1:5.5), by its preanal papillae that are not equidistant from one another, and in its area rugosa which covers only the ventral tip of the tail.

A new species of nematode, Capillaria procyonis, is described from the esophageal epithelium of the raccoon in southern Louisiana. This species is distinguished from other similar mammalian capillarids found in this location by the terminal location of the anus and more posterior postion of the vulva in the female. In the male there is a much longer cirrus and spicule and a unique bursalike expansion of the posterior extremity. The systematics and biological implications of the new species are discussed in relation to similar forms from carnivorous and insectivorous mammals.

Baylis described six lip-like plates surrounding the mouth, but did not illustrate them. Our en face preparation (Fig. 1) revealed six well developed lips, each with a papilla at its base. Surrounding these are four large papillae and the amphids. Each spicule has a wide fin, bearing longitudinal striations near the distal end, and a short spur is present very near the tip. These structures were not clearly described in the original description of the species.

Specimens from Thoimomys bottae bottae are larger than those described by Hall, 1916, from Thomomys fossor in Colorado, the males measuring 28 to 30 mm in length, and the females 28 to 33 mm. In Hall's specimens, which were probably immature, the anterior portion of the body exceeded the posterior portion in length, but in my mature specimens the posterior portion equals or exceeds the anterior portion in length. The specimens agree in the bilobed end of the male body, the bell-shaped, spiny, spicular sheath, and the length of the spicule (about 1.5 mm long in my specimens). The spicule flares slightly a short distance behind the tip. The cloacal tube is about 2.5 mm long, and is joined by the spicular tube near the middle of its length. The ejaculatory duct joins the vas deferens at about the middle of the length of the posterior portion of the body. In the female the vulva is not situated on a prominence, and the ovejector is from 1.1 to 2 mm long, gradually widening into the uterus. The anus is subterminal. The eggs, not seen by Hall, are relatively broad, measuring 64 to 68 microns by 35 to 38 microns.

Spinitectus beaveri sp. n. from the stomach of Albula vulpes is described. In the male, the maximum length is 6 mm, the esophagus is approximately 30% of the body length, the spicule ratio is 1:2.5 to 3.0, and there are 4 pre- and 5 postcloacal papillae. In the female, the maximum length is 7 mm, the esophagus is approximately 27% of the body length, and approximately 38% of the body length is posterior to the vulva. The species most closely resembles S. carolini Holl, 1928, from which it differs by having 10 to 16 rather than 25 to 35 cuticular spines per transverse row and a complex rather than a plain distal portion of the left spicule.

Capillaria colubra sp. n. is described from the oviducts of the southern black racer, Coluber constrictor priapus, from southern Louisiana. It is distinguished from the closely related Capillaria heterodontis by its larger size, transverse striations on the spicule and spicule sheath, and a more elaborate caudal bursalike expansion and two ventral papillae in the male. It is smaller and has a lower ratio of anterior to posterior body regions than Capillaria longispicula. It differs from other snake capillarids in its greater size, higher ratio of anterior to posterior body regions, larger eggs, and more elaborate male caudal bursalike expansion. This is the first capillarid reported from the oviducts of a vertebrate host. Several species of Capillaria have been reported from snakes in South and Middle America (Teixiera de Freitas and Lent, 1935; Aravjo and Gandra, 1943; Caballero and Cerecero, 1944; Yamaguti, 1961). However, Capillaria heterodontis Harwood, 1932, is apparently the only species described from a snake endemic to the United States. Between 1967 and 1969 17 specimens of Capillaria were removed from the oviducts of three southern black racers collected near New Orleans, Louisiana. These specimens represent a new species. Capillarids were removed from the oviducts, fixed in glacial acetic acid, stored in a mixture of alcohol, formalin, and glycerin, and studied in glycerin mounts after evaporation of the alcohol at room temperature. Drawings were made with the aid of a camera lucida. In the following description measurements are in millimeters unless otherwise noted. Capillaria colubra sp. n. (Figs. 1-6) Definition: Trichuridae Railliet, 1915; Capillariinae Railliet, 1915; Capillaria Zeder, 1800. Body diameter increasing from anterior to about the posterior three-fourths. Body very slender, threadlike. Cuticle smooth. Two lateral bacillary bands. Mouth small, porelike. Esophagus consisting of a single chain of stichocytes, some cells darker than others and containing granules, alternating with lighter cells devoid of granules. Anterior region shorter than posterior region of body in male and female. Female slightly longer than male. Received for publication 10 October 1969. * Supported in part by a Predoctoral Fellowship, 5-F01-GM-38,070, awarded by National Institute of General Medical Sciences, NIH, Public Health Service. Male (9 specimens): 19.56 to 26.40 (21.83) long, 68 to 78 /L (72) maximum width. Anterior region of body 5.54 to 6.90 (5.96) long, with muscular pharynx 304 to 552 /L (425) long, followed by 40 to 59 (45) stichocytes. Posterior egion of body 13.84 to 19.50 (15.88) long. Ratio of anterior to posterior region 1:2.4 to 1:2.9 (1:2.7). Ratio of anterior region to total length 1:3.4 to 1:3.9 (1:3.7). Posterior extremity bears ventrally a small bursalike expansion and 2 small papillae. Body terminates in short blunt tail dorsally. Cloaca 3.31 to 3.70 (3.45) in length. Anus subterminal, surrounded by bursa. Spicule 2.22 to 2.96 (2.59) long, 12 to 17 /u (14) at maximum width, transversely striated, with blunt tip. Spicule sheath long, transversely striated, 18 to 26 / (22) at maximum width. Female (8 specimens): 29.15 to 36.46 (31.99) long, 77 to 100 ,u (87) at maximum width. Anterior region of body with muscular pharynx 276 to 684 /, (490) long, followed by 40 to 52 (48) stichocytes. Posterior region 24.51 to 30.29 (25.71) long. Ratio of anterior to posterior regions 1:3.4 to 1:4.9 (1:4.1). Ratio of anterior to total length 1:4.4 to 1:5.9 (1:5.1). Vulva 100 to 150 A (130) posterior to last stichocyte, anterior and posterior lips slightly salient. Anus subterminal. Posterior extremity slightly rounded and blunt, caudal papillae absent. Eggs unembryonated, 61 to 70 / (65) in length, 28 to 31 ,/ (30) in width. Holotype male: USNM Helm. Coll. No. 70563. Allotype female: USNM Helm. Coll. No. 70564. Paratypes: USNM Helm. Coll. No. 70565. Host: Coluber constrictor priapus Dunn and Wood, 1939. Location: Posterior region of oviducts; anterior end threaded into the mucosa, posterior region free in the lumen. Locality: Covington, Louisiana, USA 30?30' N, 90010' W. DISCUSSION The capillarids of cold-blooded vertebrates were thoroughly reviewed by Teixiera de Freitas and Lent (1935). In addition, Yama

Retracted cirrus (spicule sheath) lined by short stout spines; length of spinous part of cloaca, 0.116-0.128; width, 0.012-0.014. Distance from anus to spicule pouch, or point of entrance of spicule, 0.165-0.204; spicule length, base to tip, 0.179-0.363; width, 0.0043-0.0072; ejaculatory duct, length, 0.36-0.46; width, 0.026-0.033; total length of cloaca, 0.38-0.46; width, 0.023-0.027. Cirrus usually not everted. Body, blunt posteriorly, ending in two knob-like enlargements bearing a transparent bursal membrane (Fig. 1-3). The ratio of esophagus length to body length was approximately 1 :2.4-1 :3.6. The structural plan (Fig. 7) was similar to Trichuris. The seminal vesicle proceeded posteriorly beside the narrow intestine. Near the last fourth of the body the seminal vesicle enlarged to become the muscular ejaculatory duct which opened into the proximal end of the thick walled cloaca. The cloaca was lined by a thin cuticular membrane continuous with the external cuticle. These structures were best seen when the male was placed in glycerin and viewed from the side. The spicule pouch entered the mid region of the cloaca and its lining fused with the cloacal lining. The spicule, tightly enclosed by the spicule pouch, was difficult to distinguish. However, critical focusing at different levels under oil immersion revealed the spicule as a translucent rod whose proximal part arose as a continuation of the retractor fiber at the base of the spicule pouch (Fig. 8). Measurement of the spicule length was made from this point to the rounded tip. The retractor fiber passed anteriorly and was fused to the body wall. Along its anterior length it received large muscle fibers from the body musculature (Fig. 9).

From a study of the distribution of trichostrongylids in the small intestine of the sheep Tetley (1937) concluded that their particular location was determined by the rate of response of incoming larvae to conditions within the alimentary canal and that, following taking up their station, virile subsequent stages of the parasites migrated to an inappreciable degree. It was further concluded that parasites were able to survive in a wider range of area and physiological condition of the small intestine than they actually invaded.

As previously remarked by the writer in Part I of this study the worms of the genus Capillaria Zeder, 1800, do not show a marked degree of host specificity. Further evidence in favor of this view is afforded by the fact that C. americana n. sp., described in this paper, has been found in four different species of rodents. C. muris-sylvatici (Diesing, 1851) evidently also occurs in a variety of rodent hosts. Elton, Ford, and Baker (1931) in a study of the parasites of various rodent populations in England failed to find this worm in Microtus although these workers found it in other rodents. Conversely, the writer has found it only in material from Microtus in North America although large collections of parasites from a considerable number of different native rodents have been available for study. It seems probable that food habits are the chief factor determining the acquisition of infections with this species by rodents. Description or discussion of five species of Capillaria from North American mammals follows: Capillaria muris-sylvatici (Diesing, 1851) (Plate II, Figs. 10-13) Worms of this species were recovered from the small intestine of the vole, Microtus p. pennsylvanicus, examined at Madison, Wisconsin. No previous record from this host nor from any North American host has been found in a search of the literature. Since the worms show some features not recorded by other workers, a description of this material seems warranted. Description: Lateral bacillary lines visible. Mouth simple. Cuticle striated transversely. Female: 13.4 to 15.1 mm long; maximum width in posterior region 70 to 75 t. Termination of esophagus 3 mm from anterior end. Vulva just posterior to termination of esophagus, 3 to 3.2 mm from anterior end, with cuticular vulvar flap projecting from region of anterior labium. A discoid cuticular projection is located anterior to vulvar flap at level of esophageal termination. Vulva divides body 1: 3.5 to 1: 3.7. Ova 47 to 60 . long by 24 to 26 . wide; inner shell bends to form collar at each end; outer shell smooth. Anus slightly subterminal. Male: 9.1 to 10.8 mm long; maximum width 45 to 47 j. Termination of esophagus 2.7 to 2.9 mm from anterior end. Lateral caudal alae present, about 70 . long. Spicule 204 to 225 & long by 11 to 13 . wide. Spicule sheath without spines or transverse striations. Everted spicule sheath divided into four portions: Distal portion delicate, membranous, usually wrinkled; subdistal portion bulblike, muscular; proximal portion bulblike with rugose markings on lateral aspect; proximal and subdistal portions joined by short wrinkled tubular projection of proximal bulb. Cuticular bursa supported by pair of bifid papillae. Cloaca subterminal. Termination of esophagus divides body about 1:2.7.