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The Glaucomyidae and the Solenidae are generally included in the suborder Solenacea, but the systematic position of the Glaucomyidae has always been doubtful. The habit and structure ofGlauconome rugosaare here described and compared with those of the Solenidae as exhibited in the first place by the speciesPharella acuminata. The systematic position of the genera comprising the family Glaucomyidae is discussed. The structure and mode of growth of the external, opisthodetic ligament is described and it is shown that the form and growth of the shell (which includes the ligament) in the Bivalvia can be represented satisfactorily only when the two valves together with the ligament are considered as a unit. Fusion of the mantle margins ventrally and the formation of the long, united siphons involves the inner marginal folds together with the inner surfaces of the middle folds. In association with the mode of life, the foot is poorly developed and the pedal gape restricted to the anterior end. The ctenidia are capable of dealing rapidly with water containing large amounts of sediment, while the ciliation of the frontal surfaces of the filaments and the currents on them are similar to those ofPetricola pholadiformis. The style sac and mid-gut are combined. Also included in the family Glaucomyidae is the genusTanysiphonand shells ofTanysiphon rivaliswere examined. The ligament of this species is short and, unlike that ofGlauconome rugosa, extends obliquely across the hinge-plate posterior to the poorly developed cardinal teeth. The relationships betweenGlauconomeandTanysiphonare discussed and it is concluded that the latter genus is closely allied toLutrariaand should be transferred to the Mactridae. Features, which unfortunately could not be verified, but which probably characterize the animal ofTanysiphonand would indicate it to be a member of the Mactridae, are listed. Of the three subfamilies previously considered as comprising the Solenidae only the Soleninae remain. The habits and general structure of the available genera now included in the Solenidae are described: in particular Pharella acuminata (in greatest detail);Siliqua patula(preserved specimens);Cultellus lacteusandC. subellipticus(shells only);Phaxus pellucidus;Solen marginatus;Ensis siliqua,E. arcuatusandE. ensis. In all members of the Solenidae the mantle/shell is elongated posterior to the demarcation line and in the more specialized genera this is accompanied by a marked reduction in depth. The external, opisthodetic ligament is composed of anteriorly and posteriorly secreted fusion layer and outer and inner layers of the primary ligament. A fourth pallial aperture is present inSiliqua,Cultellus(probably),PhaxusandEnsisand in these genera the inner marginal folds anterior to the fourth pallial aperture are joined by cuticular fusion. Posterior to the fourth pallial aperture there is complete tissue fusion of the mantle margins. This involves the inner folds only inSiliquaand the inner folds together with the inner surfaces of the middle folds inPhaxusandEnsis. InPharellaandSolen, tissue fusion is of this latter type along the entire ventral margin. In all genera the inner surface of the middle fold is involved in the formation of the siphons. The ctenidia range from flat and homorhabdic (Phaxus)to plicate and heterorhabdic and adjacent tracts of long and short cilia are present on the frontal surfaces of some (Phaxus) or all of the lamellae. The style sac and midgut are always separate. The most significant feature of the Solenidae is the posterior elongation of the mantle/shell, and the effect of this on pallial attachment and the position of the adductor muscles is discussed. InPhaxus, SolenandEnsisthe primitive ventro-dorsal axis of the anterior adductor muscle is orientated antero-posteriorly. As a result, pallial attachment extends from the posterior end of the elongated adductor anteriorly to the anterior end of the functional ligament. The systematic position of the family Glaucomyidae (now represented by the single genus,Glauconome) is discussed. It is concluded that the Glaucomyidae are venerid bivalves specialized for life deep below the surface of the substrate. The mobility which characterizes the Veneridae has been lost, the animal living permanently embedded in the substrate and maintaining contact with the surface by way of the long siphons. The Glaucomyidae should be included with the Veneridae and Petricolidae in the Veneracea and not with the Solenidae in the Solenacea.

The work described in the following pages was carried out in the Department of Zoology of the University of Edinburgh and at the Marine Laboratory, Plymouth. It is my pleasant task to thank the British Association for the use of their table at Plymouth, and the staffs of the Plymouth Laboratory and of the Department of Zoology at Edinburgh for help and advice; in particular, I would thank Professor J. H. Ashworth, F.R.S., under whose direction the work was carried out, for his continued aid and interest at every stage.The animal which was used throughout the investigation was the common razor shellfish or spoutfish of our coasts, Ensis siliqua (Schumacher). The specimens studied at Edinburgh were obtained from a sandy bay at Port Seton, about ten miles below Edinburgh on the Firth of Forth; at Plymouth they were got from the east bank of the Salcombe Estuary. At both places razor shellfish were abundant at the low-water mark of spring tides, and at both Ensis siliqua was the sole species obtained.For histological purposes small- whole animals, which were very rare, and small pieces of tissue were fixed in Bouin's fluid, in E. Allen's chromic Bouin with urea, or in corrosive sublimate and acetic mixture, and sections, cut 8 μ and 12 μ thick, were stained with Heidenhain's iron alum hæmatoxylin or in Delafield's hæmatoxylin and counter-stained with eosin.

Faecal streptococci in mollusks were detected according to the MPN methodology (Azide Dextrose broth followed by Ethyl Violet Azide broth) and the Pour Plate (PP) technique on two agarized media (KF agar and m-Enterococcus agar). Samples of the bivalve mollusks Donax trunculus, Ensis siliqua and Chamelea gallina were collected in different marine areas and examined. Results showed that the various media and techniques yielded different faecal streptococci counts. The MPN procedure almost always gave lower titres than those recovered according to the PP technique. Accompanying and competitive bacterial flora, more abundant in the highest volumes examined according to this procedure, may explain these lower counts. m-Enterococcus agar generally gave lower yields than KF agar, but it was also more selective for faecal streptococci than the latter medium. Notwithstanding the partitioning of the examined samples, the findings may suggest that different shellfish species may differentially concentrate and/or retain microorganisms present in the environment.

1. 1. Electrophoretic variants of phosphoglucose isomerase (E.C. 5.3.1.9) have been studied in six species of bivalve molluscs. 2. 2. Two phenotypes were observed in Ostrea edulis , three in Mytilus edulis , four in Crassostrea angulata , six in Ensis ensis , eleven in Tapes decussatus and twenty-five in Pecten maximus . 3. 3. The enzyme is inferred to be a dimer encoded at a single polymorphic locus in all species. There are two alleles at this locus in O. edulis and in M. edulis , four in C. angulata , three in E. ensis , five in T. decussatus and nine in P. maximus . 4. 4. The occurrence of enzyme polymorphisms in bivalve molluscs is discussed briefly.

The inhabitants of the lower regions of the Purari Delta traditionally live on a subsistence basis and obtain most of their animal protein from the fish of the delta. The mangrove crab Scylla serrata (Forskal) is the most important crustacean, and large numbers found in some parts of the delta resulted in a commercial venture being started in 1978 (Haines and Stevens, this volume). Carid prawns, particularly the large freshwater prawn Macrobrachium rosenbergii (De Man), and juvenile penaeid prawns are also caught, and can form up to 20% by weight of the traditional subsistence catch. The adult penaeid prawns form the basis of a commercial fishery in the Gulf of Papua, with the annual catch varying between 800 and 1100 tonnes tail weight (Gwyther, this volume). This fishery, which incorporates an annual lobster trawl fishery, is a valuable resource to Papua New Guinea, being second only to the tuna fishery. The banana prawn, Penaeus merguiensis (De Man) is the dominant species and constitutes 50 – 60% of the total catch. Metapenaeus demani (Roux), M. ensis (De Haan) and M. eboracensis (Dall), collectively known as endeavour prawns, form 15 – 20%; and tiger prawns (P. monodon (Fabricus) and P. semisulcatus (De Haan)) form 10 –15% of the catch.

1. 1. Reduction in oxygen content of the water affected the rhythmic closure of lamellibranchs in three different ways according to species: (a) It had no detectable effect (Cardium, Ensis, etc.). (b) It increased the periodic closures immediately (Ostrea, Venus). (c) It increased the periodic closures after some time delay (Glycemeris). 2. 2. CdCl2 and KCl could affect the periodicity of closure. 3. 3. The periodic closures may be a respiratory adaptation.

[Abstract] We report current genetic variation of populations of the razor shell Ensis directus (Conrad 1843) (Mollusca: Bivalvia: Pharidae) in native (North American) and introduced (European) ranges using nuclear and mitochondrial sequence-based markers. We expected less variation within the introduced range, especially considering the frequent mass mortality events observed in Europe since the species was recorded for the first time in 1978. However, we found higher variation in Europe. The possible significance of temporal fluctuations of genetic variation, limited effect of random genetic drift, and multiple introductions are discussed. Interestingly, the multiple-introduction hypothesis contrasts with the gradual colonisation of European coastal waters but is supported by trained clustering analysis and by the intensity of transatlantic shipping. Genetic and morphometric evidence strongly supports that examined individuals from a supposed E. directus population from Newfoundland (Canada) belong to a separate species. This new Ensis is formally described here and named E. terranovensis n.sp.

The incidence of shell damage due to dredging was studied in the bivalve Ensis siliqua off Lagos, on the south coast of Portugal. Three tow durations (1, 3 and 5 min) and 2 tooth lengths (30 and 40 cm) were investigated. Both factors affected the proportion of damaged individuals. The increase of tooth length results in lower proportions of damaged razor clams. An increase in tow duration increased total numbers caught but also increased the proportion of damaged clams. It is suggested that dredges with 40 cm teeth and tows of 1 min duration should be used in this fishery, although experiments should be undertaken in order to evaluate the environmental and ecological impact of dredges.

This paper deals with a collection of epigean and hypogean water mites from the Hormozgan and Sistan va Baluchestan prov-inces in southern Iran. One new genus, Haloaxonopsis, is described, characterized by the presence of so-called wheel-likeacetabula, a unique character so far known only in marine mites of the family Pontarachnidae. One new subgenus, Halolimne- sia, and fourteen new species are described: Hydrachna sistanica, Nilotonia hormozgana, Torrenticola asadiae, T. hormozgan- ensis, Monatractides martini, Neoatractides calidus, Limnesia diversipes, Atractides hormozganus, Javalbia persica, Axonopsis gloeeri, A. interstitialis, A. hyporheica, Haloaxonopsis salina and Albia hyporheica. The first descriptions of thefemale are given for Neumania cf. maharashtris Cook, 1967 and Arrenurus bharatensis Cook, 1967. The following species arereported for the first time in Iran: Hydrachna cf. vaillanti K. Viets 1951, H. globosa lacerata Lundblad, 1969, Diplodontus sil- vestrii (Daday, 1898), Hygrobates hamatus K. Viets, 1935, Atractides biscutatus Cook, 1967 and Arrenurus bharatensis Cook,1967. The zoogeographical and ecological characteristics of the water mite fauna of southern Iran are discussed. The fauna ofSE Iran is of Oriental character, and no typical Palaearctic species were found. Our study shows that this fauna is not transitional, suggesting a rather ‘sharp’ boundary between the Palaearctic and Oriental regions in southern Iran.

Two “conventional” antibody preparations directedn against fractions of soluble macromolecules from shells of the recent bivalve Ensis ensis were allowed to react with shell fragments of a large variety of invertebrates, mainly molluscs. Use was made of a special adaptation of the Enzyme-Linked ImmunoSorbent Assay (ELISA). One antibody preparation, aE1, reacted with a broad variety of taxa, including representatives of nonmolluscan phyla, while the other, aE3, only recognized determinants in taxa closely related to Ensis . Reactions with fossils were obtained with both antisera. By incubation of antibody solutions with etched shell powders of non- Ensis shells more specific preparations were obtained that gave more meaningful systematic results. In an artificial diagenesis experiment carried out with shell fragments of Mercenaria mercenaria the degradation of individual determinants of the soluble matrix could be followed with monoclonal antibodies. These data are related with the amino acid racemization profile. In the light of the available information the possible significance of immunology for organic geochemical research is discussed.

Miscalcthus sileelesis ANDERSS. var. coudelcsatus HACK, collected at Misaki and Inatori, and M. ti, ectorius (STEUD.) HACK. collected in Gifu and Shiga Pref. were found to be diploid, the chromosome number observed being 1c='19, 2n=38. With regard to M. tiinctorius. TAKIZAWA had previously found tetraploid and hexaploid plants Therefore, the discovery of diploid implies the establishment of a complete polyploid series. Moreover, M. tinctorius seems to be different in geographical distribution with polyploidy. It was observed in M. sin;ensis, Ie=19, 2 Ie=38, the same chromosome number as TAKIZAWA'S result. But in the present experiment, aneuploid was not observed which TAKIZAWA had found.

The commercial penaeid prawns of northern Australia have been surveyed by electrophoretic techniques to determine the extent of geographic differentiation throughout their ranges in Australian waters. Genetic differences were detected among widely separated populations of P. latisulcatus and M. endeavouri, but P. esculentus, M. ensis, P, semisulcarus and P. merguiensis showed no evidence of genetic differentiation. In both P. latisulcatus and M.endeavouri the most marked differences were detected between the samples from the Gulf of Carpentaria and Western Australia. The measures of genetic divergence between these two regions are Φ* = 0.127 for P. latisulatus and 0.214 for M. endeavouri.

A somewhat novel but nonetheless important predator-prey relationship was described by Turner (1955) and Schneider (1982): the naticid gastropod Polinices duplicatus commonly captures the solenid bivalve Ensis directus by attacking its foot rather than by drilling through its shell. From a paleoecologic or taphonomic standpoint, the most significant result is numerous dead in-situ individuals of E. directus, the valves of which remain pristine. In other instances the valves are retained partly within the burrow but project above the substrate surface, reflecting a futile attempt by the clams to escape. Frequently clams burrow widely through the sediment in various attempts at flight, some successful and others not. Such behavior evidently is widespread among morphologically and ecologically equivalent mollusk species (e.g., Colbath, 1985, p. 858), and was observed recently on tidal flats near Inchon, Korea. These tidal flats, which are generally similar to ones described by Lee et al. (1985), are replete with epibenthic and endobenthic mollusks. Among them is the razor clam Solen strictus, ecologically equivalent to Ensis directus, and the gastropod Euspira fortunei, which is equivalent to Polinices duplicatus. Populations of S. strictus FIGURE I-Burrows and in-situ live individuals of the solenid bivalve Solen strictus in muddy sediments of a macrotidal flat near Inchon, Korea. These well-maintained domiciles are lined with a smooth, thick layer of mucus-impregnated sediment; basal enlargements represent dilations of the foot. Escape burrows are considerably more irregular and ephemeral; yet, all burrows are arcuate, as governed by the longitudinal curvature of the animal itself.

The relationship between sediment type and the distribution of the commercial prawn species of the western Gulf of Carpentaria was examined. The distribution of sediments was described on the basis of the mud content while the spatial distributions of the adult populations of all the commercial species were described from the results of trawl surveys. The main species caught were the tiger prawns Penaeus esculentus and P. semisulcatus, the endeavour prawns Metapenaeus endeavouri and M. ensis, and king prawns P. latisulcatus and P. longistylus, the banana prawn P. merguiensis, and the coral prawn Solenocera australiana. The individual species were caught in varying depth ranges and, in order to assess the influence of sediment type on the spatial distributions, a stepwise multiple regression analysis was carried out in which variation due to depth was considered before that due to percentage mud. Although depth generally accounted for most of the variation in catch-per-unit-effort (CPUE), percentage mud was also found to be a significant factor for all species except P. Merguiensis. Three species, P. semisulcatus, M. ensis and S. australiana, showed a preference for sediments with a high mud content while the abundances of P. esculentus, M. endeavouri and P. latisulcatus were each negatively correlated with percentage mud. P. longistylus showed a strong depth-mud interaction, being largely found on sediments of 40-60% mud in depths of 40-50 m. P. merguiensis was found in depths 75% mud) whereas those of P. esculentus were associated with coarser sediments (50-75% mud).

The new species Heterodermia sitchensis is describedfrom British Columbia, Canada, where it is apparently a rare epiphyte restricted to sheltered localities at low elevations along the highly oceanic outer coast. Zeorin and atranorin are its primary phenolic constituents. Particularly interesting are the sterile, but sorediate, apothecial structures of this species. Heterodermia sitch- ensis is possibly a vicariad of the fertile H. podocarpa (BIl.) Awas. One of the lichenologically most interesting, and yet least explored, parts of North America is the coastal margin of the Pacific Northwest. Here an annual precipitation often exceeding 3000 mm combines, even at boreal latitudes, with a high de- gree of thermal oceanity to support many endemic lichen species (Ahti 1977). Recent intensive studies on the west coast of Vancouver Island, Canada, have turned up the present new species, Hetero- dermia sitchensis.

The 'Elepaio (Chasiempis sandwichensis) exhibits great vari- ation in plumage color on the Island of Hawai'i. Analysis of specimens from localities throughout the island reveals that the variation is geographically based, and that three subspecies can be distinguished: C. s. bryani, a pale form found at high elevation on the southwestern slopes of Mauna Kea; C. s. ridgwayi, a dark form found in wet windward forests; and C. s. sandwich- ensis, an intermediate form found in forests of the Kona region. Several zones of primary intergradation and one of possibly secondary intergradation occur, but appear to be narrow. The forms C. s. sclateri of Kaua'i and C. s. gayi of O'ahu exhibit no similar intra-island variation. Variation among the Hawai'i subspecies probably evolved in response to local variation in rainfall, and follows the predictions of Gloger's Rule, but the selective forces involved are obscure. The 'Elepaio (Chasiempis sandwichensis) is a monarchine flycatcher that comprises a genus endemic to the Hawaiian Islands. 'Elepaios occur on Kaua'i, O'ahu, and Ha- wai'i, but are enigmatically absent from oth- er seemingly suitable islands. Great plum

Two razor clam populations from two shores in North Wales were identified on morphological grounds as Ensis siliqua (L.) and E. ensis (L.). Ensis siliqua occurs in fine sand on the exposed south-westerly facing shore of Newborough beach, whilst E. ensis inhabits the coarser sediment of Penmon beach, a sheltered north-easterly facing shore in the Menai Strait. At Penmon smaller E. ensis ( 100 mm) occurred almost subtidally at extreme low water springs. No small E. siliqua (

The present paper was prompted by the discovery of an interesting addition to the veliid fauna of the salt marshes in southernmost peninsular Florida. This proved to be the species originally described as Microvelia turmatis by Drake and Harris (1933) from British Honduras. It was transferred by them later (1936) to Xiphovelia Lundblad, 1933, a genus whose type and only species was collected in Sumatra. Further study of the Florida material discloses that turmalis Drake and Harris is generically distinct from Xiphovelia ensis Lundblad, and it is here made the type of the new genus Husseyella. Husseyella belongs to the subfamily Microveliinae, which is characterized as follows: Ocelli absent. Tarsal formula 1, 2, 2; all claws pre-apical. Apical segment of middle tarsi not deeply cleft, and without plumose hairs arising from the base of such cleft. Hemelytra, when present, with four closed cells, not divided into distinct corium and membrane.

Introduction The Miocene and Pliocene faunas of the West Indies and Central America should be compared only with European faunas that lived under essentially similar conditions. These American faunas, with the exception of a supplementary Mexican fauna, are almost purely tropical, according to the distribution of their living genera. The Miocene and Pliocene faunas of the Mediterranean region and the Miocene faunas of Aquitaine, which most closely resemble these American faunas, include the following temperate genera: 2 Mytilus ( Mytilus ), Astarte, Cardium ( Cerastoderma ), Macoma ( Macoma ), Solen ( Sole9n ), Ensis, Saxicava, and Aporrhais . None of these genera are in any of the West Indian Tertiary or living shallow-water faunas. All except Aporrhais are common in the Tertiary and living faunas of the Atlantic coast of the United States. Aporrhais has not been found in the Tertiary faunas of the Atlantic States, but is living in temperate waters on both sides of the Atlantic. Although . . .

Specimens of eight species of marine pelecypods, Crassostrea virginica, C. gigas, Mytilus edulis, Modiolus demissus, Ensis directus, Mya arenaria, Mercenaria mercenaria, and Tapes philippinarum, were individually challenged with 150 Himasthla quissetensis cercariae in order to study their susceptibility and reactions. Quantitative recovery rates are given. Metacercariae were found encysted in various tissues of all of the pelecypods except C. virginica and C. gigas. In C. virginica few metacercariae were found in blood vessel lumina. Except in T. philippinarum, when metacercariae were found in tissues, they were enveloped by a non-cellular, parasite-secreted inner cyst wall. In T. philippinarum, only those metacercariae found in the testes were enveloped by such a wall. In addition to the inner wall, an outer wall, comprised of host leucocytes and either myofibers or connective tissue fibers, surrounded encysted metacercariae in most instances. The fibrous constituent of the outer wall appeared to be dependent on the type of fibers available in the immediate proximity, while the leucocytes are believed to be attracted by the inner wall. Encysted metacercariae were found on the gill and mantle surfaces of C. virginica and C. gigas and on the palps of M. edulis. These are believed to be inactivated, and thus prevented from invading the molluscs, by some host-elaborated substance. Adults of the echinostomatid trematode Himasthla quissetensis (Miller and Northrup) were originally described by Stunkard (1937) from gulls, Larus argentatus Pontoppidan, which were experimentally infected with metacercariae in molluscs which had been exposed to Cercaria quissetensis Miller & Northrup, 1926, a larval trematode of the mud snail, Nassarius obsoletus Say, collected at Woods Hole, Massachusetts. In one abstract (Stunkard, 1934) and two papers (Stunkard, 1937, 1938), Stunkard reported the life cycle of this parasite. In these papers he recorded that seven species of marine molluscs, Mya arenaria L., Modiolus modiolus L., Mytilus edulis L., Cumingia tellinoides Conrad, Aequipecten irradians L., Ensis directus Conrad, and Crepidula fornicata L., were compatible second intermediate hosts into which the cercariae penetrated and encysted. He reported encystment in the mantle, gills, and foot of these molluscs. Uzmann (1951) reported that the soft clam, Mya arenaria, is an important second intermediate host of H. quissetensis in nature since he found 43 to 100% of the samples of this clam from Merrimac Bay, Plum Island Sound, and Annisquam River, Massachusetts, and 90% of 50 specimens of this clam from St. Andrews, New Brunswick, Canada, to harbor metacercariae of this trematode. During a recent survey of the parasites of Nassarius obsoletus in Narragansett