x ns * a a oe Ry THE tere Founded 1889 by Henry A. Pilsbry. Continued by H. Burrington Baker. Editor-in-Chief: R. Tucker Abbott NAUTILUS Vol. 89 No. 1 A quarterly devoted to malacology and the interests of conchologists @ ~ EDITORIAL COMMITTEE CONSULTING EDITORS Dr. Arthur H. Clarke, Jr. Department of Mollusks National Museum of Canada Ottawa, Ontario, Canada K1A-OM8 Dr. William J. Clench Curator Emeritus Museum of Comparative Zoology Cambridge, Mass. 02138 Dr. William K. Emerson Department of Living Invertebrates The American Museum of Natural History New York, New York 10024 Mr. Morris K. Jacobson Department of Living Invertebrates The American Museum of Natural History New York, New York 10024 Dr. Auréle La Rocque Department of Geology The Ohio State University Columbus, Ohio 43210 Dr. James H. McLean Los Angeles County Museum of Natural History 900 Exposition Boulevard Los Angeles, California 90007 Dr. Arthur S. Merrill Biological Laboratory National Marine Fisheries Service Oxford, Maryland 21654 Dr. R. Tucker Abbott Delaware Museum of Natural History Box 3937, Greenville, Delaware 19807 Mrs. Horace B. Baker Business and Subscription Manager 11 Chelten Road Havertown, Pennsylvania 19083 Second Class Postage paid at Wilmington, Delaware Dr. Donald R. Moore Division of Marine Geology School of Marine and Atmospheric Science 10 Rickenbacker Causeway Miami, Florida 33149 Dr. Joseph Rosewater Division of Mollusks U. S. National Museum Washington, D.C. 20560 Dr. G. Alan Solem Department of Invertebrates Field Museum of Natural History Chicago, Illinois 60605 Dr. David H. Stansbery Museum of Zoology The Ohio State University Columbus, Ohio 43210 Dr. Ruth D. Turner Department of Mollusks Museum of Comparative Zoology Cambridge, Mass. 02138 Dr. Gilbert L. Voss Division of Biology School of Marine and Atmospheric Science 10 Rickenbacker Causeway Miami, Florida 33149 EDITORS Dr. Charles B. Wurtz 3220 Penn Street Philadelphia, Pennsylvania 19129 OFFICE OF PUBLICATION Delaware Museum of Natural History Kennett Pike, Route 52 Box 3937, Greenville, Delaware 19807 Subscription Price: $7.00 (see inside back cover) THE NAUTILUS Volume 89, number 1 — January 31, 1975 CONTENTS Leslie Hubricht Four New Species of Land Snails from the Eastern (Uliana! SHEMES. <5. ad's © Bato tO.o-0 5.0.0 GEORG Uicuel OF Coo Ene net atta a ee ne 1 ~ James W. Eckblad itnevAsian’ Clam) Corbicula, in the Upper Mississippi River................+...+..++s+.... 4 Sheila A. Herrmann and Willard N. Harman Population Studies on Helisoma anceps (Menke) (Gastirarsackns 1Aleraavd siChYs))) 6's-as 3:0 9 arab’ doe O OlO Sa ae een ne eon ne te mt can DPSS R. Tucker Abbott ObitnanyaCi ohne uimeyaburchin (S94 — 01974) eee oe ee eee 4 12 David W. Behrens Use of Disposable Beverage Containers by the Bmestiwetere Olam G0 7010 Cameo mene re cree ae ee Rae er ey epi oe 13 W. D. Russell-Hunter and Robert F. McMahon An Anomolous Sex-Ratio in the Sublittoral Marine Snail, Lacuna vincta Turton, from near Woods Hole Emile A. Malek Biomphalaria havanensis (Pfeiffer) from Grenada, West Indies James A. Kushlan Population Changes of the Apple Snail, Pomacea BOLO SOM Hew so Ubherne vere ladesaatars «<5 sso eect sia aalctinc cis wie cuca acini one 21 M. A. Rokitka and C. F. Herreid, II Position of Epiphragms in the Land Snail, Otala LAcECOM VIG ey,) meme ee Re etree eke: erties sche Rosen een Acie MAN, col Bent eRe Me 23 Publications Received STATEMENT OF OWNERSHIP, MANAGEMENT AND CIRCULATION (Re- quired by) Act of October 23, 1962: Section 4396. Title 39. United States Code, and postal regulation 132-622. 1 Title of publication: THE NAUTILUS. 2 Date of filing, September 25, 1974. st Frequency of issue: Quarterly (4 per year). 4 Location of known office of publication: Delaware Museum of Natural History, Kennett Pike, Box 3937, Greenville, De. 19807. Location of the Headquarters or General Business Offices of the Publishers: Delaware Museum of Natural History, Kennett Pike, Box 3937, Greenville, De. 19807. 6. Names and addresses of publisher, editor, and managing editor: Publisher, Mrs. Horace Burrington Baker, 11 Chelten Rd. Havertown, Pa. 19083. Editor, R. Tucker Abbott, Delaware Museum of Natural History, Box 3937, Greenville, De. 19807. Managing o editor, none. 7/ Owner: Mrs. Horace Burrington Baker, 11 Chelten Rd., Havertown, Pa. 19803. 8 Known bondholders, mortagages, and other security holders owning or holding 1 percent or more of total amount of bonds, mortgages or other securities: none. 9. Extent and Nature of Circulation: Average Single 12 Mos. Issue A. Total No. Copies Printed (Net Press Run) 1,000 1,000 B. Paid Circulation 1. Sales through dealers and carriers, street vendors and counter sales none none 2. Mail subscriptions 648 650 C. Total Paid Circulation 648 650 D. Free Distribution (including samples) by mail carrier or other means 14 14 E. Total Distribution (Sum of C & D) 662 664 iF Office use, left-over, unaccounted and back start subscription copies 338 336 G. Total (Sum of E & F)-should equal net Press run shown in A 1,000 1,000 | certify that the statements made by me above are correct and complete. (signed) R. Tucker Abbott, Editor PUBLICATIONS RECEIVED Porter, Hugh J. 1974. The North Carolina Ma- ine and Estuarine Mollusca - An Atlas of Occurrence. Univ. of North Carolina, Insti- tute of Marine Sciences, Morehead City. 351 pp., paperback. A checklist with many new records for the mollusks of 176 families. Useful bibliography. Coomans, H. E. 1974. Infe and Malacological Works of Hendrick Elingsz van Rigersma (1835-1877). Bijdragen tot de Dierkunde, vol. 44, no. 2, pp. 116-214. Worked on Dutch West Indies mollusks. Abbott, R. Tucker, Oct. 1974. American Sea- shells, second edition. The Marine Mollusks of the Atlantic and Pacific Coasts of North America. Van Nostrand Reinhold Co., N.Y. 663 pp., 24 new colored plates, about 3000 text illus. Includes about 6500 species and subspecies. $49.50. ll Salvini-Plawen, L. V. and R. Tucker Abbott, Nov. 1974. Phylum Mollusca. Vol. 3 of Grzi- mek’s Animal Life Encyclopedia. Van Nos- trand Reinhold, N.Y. 225 pp. 47 colored plates, numerous text figures. A survey of the structure, biology and systematics of the 390 families of land, freshwater and marine mol- lusks. Remainder of this volume, pp. 226-540, deals with Bryozoa, Brachiopoda, echinoderms and tunicates. ; Ross, Arnold and William K. Emerson, Nov. 1974. Wonders of Barnacles. Dodd, Mead and Co., N.Y. 78 pp., text illus. a well-done intro- duction to the barnacles for the general pub- lic. $4.95. Saul, Mary. Oct. 1974. Shells. Country Life, London. 192 pp., 32 colored pls., numerous text illus. An excellent ethnological account of man’s use of shells. About $9.00. Vol. 89 (1) THE NAUTILUS FOUR NEW SPECIES OF LAND SNAILS FROM THE EASTERN UNITED STATES Leslie Hubricht 4026 35th Street Meridian, Mississippi 39301 ABSTRACT Mesodon orestes Hubricht (Polygyridae) from Waterrock Knob, Haywood Co., North Carolina; Paravitrea mira Hubricht (Zonitidae) from near Council, Buchanan Co., Virgima; Paravitrea toma Hubricht (Zonitidae) from near Maysville, Madison Co., Alabama; and Helicodiscus lirellus Hubricht (En- dodontidae) from near Lexington, Rockbridge Co., Virginia are described as new. The taxonomic value of the teeth in Helicodiscus is discussed. Mesodon orestes new species Figs. 1-3 Description: Shell imperforate, depressed, conoid-globose, thin, dull, pale olive-brown; sutures deeply impressed; whorls 5, rather convex, the last rounded but with the periphery above the middle; base convex, excavated in the umbilical region, constricted behind the lip; aperture oblique, lunate, lip broadly reflected, thickened, white, appressed over the umbilicus; a small perietal tooth sometimes present; nuclear whorl with fine radial striae, becoming gradually stronger, body whorl with distinct but low rib striae; second to fourth whorls with fine irregularly placed pits; body whorl with numerous distinct spiral engraved lines; epidermis distinctly wrinkled radially between the striae. Height 10.5 mm., diameter 17.7 mm., whorls 5.0 Holotype. Height 11.4 mm., diameter 18.3 mm., whorls 5.3 Paratype. Height 9.4 mm., diameter 14.7 mm., whorls 5.0 Paratype. Instribution: North Carolina: (type locality) Haywood Co.: 6200 ft., Waterrock Knob, Blue Ridge Parkway, holotype 232583, and paratype 232582 Univ. of Michigan Mus. Zool.; other paratypes 40465, collection of the author. Remarks: Mesodon orestes resembles M. wheatleyi (Bland) most closely, but differs in having distinct spiral engraved lines, rather than short hairs. From M. ferrissi (Pilsbry) it differs in being smaller, in having more spirally engraved lines, in having pits rather than papillae, and in having the epidermis distinctly wrinkled between the striae. Paravitrea mira new species Figs. 4-6 Description: Shell large for the genus, subhyaline, glossy, pale amber colored, 8.5 whorls; umbilicate, the umbilicus funnel-shaped, contained about 6 to 6.5 times in the diameter of the shell; spire low dome shaped, sutures moderately impressed, whorls somewhat flat- tened, base somewhat flattened, excavated around the umbilicus; last whorl slowly ex- panding behind the lip; lip thin, aperture oblique, lunate; in the last whorl there are usually two rows of rather large teeth, in im- mature shells there are 3 teeth in each row, in adults the inner tooth is intermittently absent; sculpture of irregularly spaced radial grooves above, becoming obsolete below. Height 3.9 mm., diameter 6.3 mm., umbilicus diameter 1.0 mm., umbilicus diameter one whorl in 0.5 mm., 8.5 whorls. Holotype. Distribution: Virginia: (type locality) Buchanan Co.: ravine, 2.5 miles west-southwest of Council, holotype 232584, and paratypes 232585 UMMZ., other paratypes 42109, collection of the author; low ground near creek, 2.2 miles southwest of Vansant. Dickenson Co.: ravine, 2 miles southeast of Birchleaf. Kentucky: Pike Co.: wooded hillside, 1.7 miles west of Meta. Remarks: Paravitrea mira is related to P. reecei Morrison and P. tridens Pilsbry. It dif- fers from both in its larger size, P. tridens is toothless in the adult. Immature shells might be mistaken for P. reecei but the teeth are smaller in that species. 2 THE NAUTILUS Paravitrea toma new species Figs. 7-9 Description: Shell small, pale amber, subhyaline, glossy; spire low dome-shaped, sutures shallow, sculpture of numerous irregularly spaced radial grooves, distinct above but becoming weaker below; periphery somewhat flattened in immature shells, becoming more rounded at maturity; umbilicus deep and well-like, exhibiting all the whorls, contained over 5 times in the diameter of the shell; base flattened and excavated around the umbilicus; whorls slowly expanding, last whorl expanding more rapidly; aperture lunate, oblique; lip thin, simple; teeth absent at all stages of growth. Penis very large, top-shaped, lower ths rather thin walled, upper part thick walled; epiphalis joining at base of upper chamber, about as long as the penis, enlarging slowly distally to an abruptly rounded end; duct at- tached to epiphalis a little before the end; penial retractor muscle attached below the sum- mit. Height 2.6 mm., diameter 4.8 mm., umbilicus diameter 0.9 mm., 6.5 whorls. Holotype. Distribution: Alabama: (type locality) Madison Co.: base of Sharp Mtn., near Sneeds Spring, Sharps Cove, northeast of Maysville; holotype 232586, and paratype 232587 UMMZ., other paratypes 29664, collection of the author; near Aladdin Cave, 7 miles northeast of Maysville. Jackson Co.: limestone hillside, 1.7 miles northeast of Princeton. Remarks: Parawtrea toma is most closely related to P. seradens Hubricht, differing in the complete absence of teeth at all stages of growth. It also resembles P. conecuhensis (Clapp) in size and shape but that species has pairs of teeth in its immature stages. Helicodiscus lirellus new species Figs. 10-12 Description: shell discoidal or nearly so; whorls 4.5 to 5, pale greenish yellow, dull, sub- translucent; umbilicus wide and shallow, showing all of the whorls, occupying about 45% of the diameter of the shell; whorls somewhat flattened, slowly increasing, sutures deep, impressed; sculp- tured with coarse growth wrinkles and very fine, January 31, 1975 Vol. 89 (1) spiral threads, 15 to 18 on the body whorl; aperture lunate, the peristome thin; within the aperture there are 2 pairs of teeth on the outer and basal walls, these teeth radially elongate, and distinctly separated; alternating with these are 2 teeth on the parietal wall, the parietal teeth in front of the teeth on the outer and basal walls; these teeth are present at all stages of growth, the back set being absorbed as a new set is added near the aperture. Height 1.8 mm., diameter 4.4 mm., umbilicus diameter 1.9 mm., aperture height 1.4 mm., aperture width 1.3 mm., 5 whorls. Holotype. Distribution: Virginia: (type locality) Rock- bridge Co.: burrowing in shale rubble at base of hill, opposite Denmark Store, 10 miles north- west of Lexington, holotype 232588, and paratypes 232589 UMMZ., other paratypes 42020, collection of the author. Remarks: Helicodiscus lirellus is closely related to H. multidens Hubricht and H. diadema Grimm. From the former it differs in having fewer and finer lirae and in having somewhat smaller teeth. From H. diadema it differs in not having hairs on the lirae and in the smaller teeth. In a recent book by Bequaert & Miller (1973, p. 86.) Helicodiscus triodus Hubricht, H. multidens Hubricht, H. diadema Grimm, and H. saludensis (Morrison) were placed in the synonomy of H. parallelus (Say), apparently without examining specimens or carefully reading the descriptions, as these four species are probably the most distinctive in the genus. Over the years I have collected over 700 lots of H. parallelus and I have found it to be a very uniform species which does not intergrade with any of the recently described species. I have never seen the slightest trace of parietal teeth in it, which is a characteristic of all four of the species listed above. They also _ place Helicodiscus singleyanus inermis H. B. Baker in the synonomy of H. singleyanus (Pilsbry). The difference in shell sculpture by which these two forms were originally differentiated is a poor character, but differences in size and shape are sufficient to warrant their recognition as dis- tinct species. H. mermis is distinctly smaller than H. singleyanus and the sutures are not as deeply impressed. H. jacksoni is smaller than H. Vol. 89 (1) THE NAUTILUS FIGS. 1-3. Mesodon orestes Hubricht, holotype. FIGS. 4-6. Paravitrea mira Hubricht, holotype. FIGS. 7-9. Paravitrea toma Hubricht, holotype. FIGS. 10-12. Helicodiscus lirellus Hubricht, holotype. Photographs provided through the courtesy of Dr. John B. Burch, University of Michigan. Museum of Zool ey, ww 1 THE NAUTILUS inermis and the umbilicus is larger. These three species are easily separated when their dif- ferences are understood, but these differences are hard to describe. They also recommend that the subgenus Hebetodiscus H. B. Baker be raised to the status of a genus. In my opinion it may not be able to survive as a subgenus. There are intermediate species: H. apex (C. B. Adams), H. roundyi (Morrison, H. aldrichianus (Clapp), and H. tridens (Morrison). But more important is the probability that it is polyphyletic, that its species are the culmination of different lines of shell degeneration. On page 85 they make the following statement concerning H. parallelus (Say), H. fimbriatus Wetherby, H. salmonaceus W. G. Binney, and H. eigenmanni Pilsbry: “These four species share a disk-like shell, with flattened THE ASIAN CLAM CORBICULA IN THE UPPER MISSISSIPPI RIVER James W. Eckblad Department of Biology Luther College Decorah, Iowa 52101 Since its introduction to North America in 1938 the Asian clam, Corbicula manilensis, has expanded its range from the Columbia River, south to Baja California, and east to Florida. In the Mississippi River system it has spread from Louisiana and Mississippi north to the upper Ohio River (Stein, 1962; Burch, 1972). In a recent review of this clams’ distribution and ecology (Sinclair, 1971) it was thought that its range still excluded the upper Mississippi River, i.e. above Cairo, Illinois. Studies during the summer of 1974 revealed the presence of Corbicula manilensis in an ef- fluent channel of a power generating plant at Lansing, Allamakee Co., northeast Iowa. The heated water of the effluent channel runs for about half a mile before emptying into the Mississippi River about 660 river miles above Cairo, Illinois. A few shells have also been col- lected along the Iowa side of the Mississippi River just downstream from the entrance of the effluent channel. January 31, 1975 Vol. 89 (1) upper surface, a sculpture of spaced spiral threads, a broad umbilicus, and occasional small internal teeth in the last whorl. The presence and number of these teeth vary, however, sometimes within one population; as the teeth are often resorbed by the snail and their material redeposited later, they provide no reliable specific characters.” While in immature shells the set of teeth nearest the aperture may be incompletely developed, in mature shells teeth-transfers cease and the teeth become stable. With mature specimens the teeth are very good characters for the recognition of species. LITERATURE CITED Bequaert, Joseph C. & Walter B. Miller. 1973. The Mollusks of the Arid Southwest, with an Arizona check list. University of Arizona Press. Tucson, Arizona. 1-xvi, 1-271. There appeared to be a very aggregated distribution of this clam along the bottom of the effluent channel. In some places they were not present, while at other sites their population densities were over 200 per square meter. From preliminary studies on the size-frequency distribution of this clam it appears that there were some clams at least two-years old. During June of 1974 it was noted that clams had a wet weight of either from two to five grams (presumably last years veliger larvae) or from 11 to 22 grams (presumably at least two-years old). Studies are currently being conducted on the growth and survival of different size clams living within enclosures in the effluent channel and in the main channel of the Mississippi River. LITERATURE CITED Burch, J. B. 1972. Freshwater Sphaeriacean clams (Mollusca: Pelecypoda) of North Amer- ica. Biota of freshwater ecosystems identifica- tion manual no. 3, Environmental Protection Agency, Washington, D.C., 31 p. Sinclair, R. M. 1971. Annotated bibliography on the exotic bivalve Corbicula in North America, 1900-1971. Sterkiana 43: 11-18. Stein, Carol B. 1962. An extension of the known range of the Asiatic Clam, Corbicula fluminea (Muller) in the Ohio and Mississippi Rivers. Ohio Journ. Sci., 62(6): 326-327, 2 figs. Vol. 89 (1) THE NAUTILUS POPULATION STUDIES ON HELISOMA ANCEPS (MENKE) (GASTROPODA: PLANORBIDAE) Sheila A. Herrmann and Willard N. Harman Bio Control Biology Department Packaging Department New York State University Adolph Coors Company College at Oneonta, N.Y. 13820 Golden, Colorado 80401 ABSTRACT A population of Helisoma anceps (Menke) (Gastropoda: Planorbidae) was studied for 17 months near Cooperstown, Otsego Co., New York, in a small lake (Moe Pond) on the lands of the SUNY Oneonta Biological Field Station. Height-width and height-weight regression lines are illustrated. A size-frequency histogram represents the weekly data collected on reproduction, growth and mortality of the popwation. Helisoma anceps began ovipositing in late May and ceased late July. The species exhibited one cohort, hatching during June and July. Biomass and density data are given. Growth rate data show slower in- creases in weight uith maturity and slower growth when temperatures were lower in the fall. There was an inverse relationship between total egg produc- tion and eggs oviposited per egg mass with population density. High mortality in these populations was attributed in part to physical stresses such as dessication of immatures, and freezing of the habitat during the winter months, and, in part, to predation. INTRODUCTION In 1971 studies on the characteristics of a population of Helisoma anceps (Menke) (Gastropoda: Pulmonata: Planorbidae) were un- dertaken in Moe Pond. This small eutrophic lake drains into Otsego Lake, Otsego Co., New York, the headwaters of the Susquehanna River, and is a part of the properties of the New York State University College at Oneonta Biological Field Station at Cooperstown. Moe Pond has an effective width of 330 m, and an effective length of 750 m. Its greatest depth is 3.7 m. Most aquatic macrophytes grow from the eulittoral areas to water only 12 cm in depth. The sample area, located on the southwest side of the lake, includes water 0-10 cm deep in a 60 m long strip adjacent to the shore. Sub- strate in the area is mostly channery, silt and sand derived from Devonian shales and glacial deposits. A 1-4 mm thick layer of silt and auf- wuchs covers the rocks. Submergent Eleocharis (needlerush) and Chara (stonewort) grow in pat- ches on the silt, and Carex (sedge) is emergent at the shoreline. The terrestrial area adjacent to the collection site is an old field. Onoclea (sensitive fern) rhizomes and roots form a low bank which projects into the water along one half of the area. The remainder of the bank supports grasses and common weeds. Important invertebrate associates include the pulmonate limpet Ferrissia parrallela Haldeman and several common orders of aquatic insects. Also present is the scud, Hyallela aztecta and the leeches, Helobdella stagnalis (L.) and Placobdella sp. The water level is highest in the spring, but recedes quite rapidly after May exposing 0.1-0.4 m of inorganic and organic substrate. Due to its small size and protection from the wind, waves rarely attain a height greater than 5 cm. Ice covered the water from late December 1970 to late April 1971. METHODS For designation of sample sites, uniform in- tervals were marked along a one-meter-wide area that was parallel to the shoreline. This 6 THE NAUTILUS transect was 60 m long and divided into 20 three meter sample plots. Numbers generated from a computer random number program (APL) determined which plots were to be sampled at the various collection dates. . Five 462 em locations along the transect were sampled once a week. It was impossible to take valid samples after ice formed because the water was frozen very close to, or against, the substrate in the collection area. To facilitate collecting, a square metal frame, 21.5 cm on one side and 11 cm high, was placed in the water at depths from 0.10 cm. Also used for sampling were four 21.5 cm rods placed 21.5 em apart to form a square. This method proved more satisfactory because the sample area was not shaded by the high sides of the metal frame. All stones inside the frame, or rods, were picked up and inspected visually for snails and their eggs. The total number of snails and eges for each sample was noted. When there were high densities of immature snails present in populations found on silt and fine gravel substrates, those materials were scooped up and placed in a beaker filled with water so that they could be inspected with a 2.5X hand lens. When vegetation was dense enough to obscure inorganic substrates, 115 cm” out of the plot was removed and returned to the laboratory. Snails were collected from the vegetation using a dissecting microscope. Each sample contained 0 to 27 snails which is similar to the 3 to 20 individuals per sample that satisfactorily represents the density of snail populations as stated by Hairston et al., (1958). Height-diameter data were collected and analyzed using the methods of Sokal and Rohlf (1969) to show annual changes in the shell mor- phology. The resulting regression lines are illustrated in figure 1 and expressed as the H:D ratio for the species (Clampitt, 1970; Wurtz, 1949). A vernier caliper was used to measure the snails to the nearest 0.1 mm. The diameter of H. anceps is the length of a straight line from the outermost part of the outer lip, to the op- posite extreme edge; the height is that of the largest whorl (Harman and Berg, 1971). Snails found inside the transect were returned to the January 31, 1975 Vol. 89 (1) 15 Ss height in mm H:D RATIO .542 5 diameter in mm 10 15 Fig.] Height-diameter regression. Helisoma anceps. Moe Pond 1971. water as soon as they were measured to assure minimal disturbance of the populations. To represent weekly changes in numbers and growth of the populations during the sample period, a size-frequency histogram was used (fig. 2) (Hunter, 196la, b; Duncan, 1959). All of the snails were classed in the following size ranges by diameter measurements: 0.5-1.4 mm = 1 mm, 1.5-2.4 mm = 2 mm, etc. up to 14.5-15.4 mm = 15 mm. The diameters are shown on the ordinate and the number of snails in each size class is represented by the width of the vertical line. The data from each collection date represent the average of five samples that is specified by a vertical line from the abscissa. Row E above the histogram indicates the num- ber of snails in all the size classes at the respective sample date. Because the numbers of eggs and numbers of eggs per mass oviposited is important in ascer- taining mortality and natality rates for each population, and in determining if the populations react in a density-dependent fashion, these data are given in conjunction with the histogram (fig. 2). Each egg mass was counted, as were the numbers of eggs in each mass. The state of development; prelarval (0.2 mm), larval (0.4-0.5 mm) and possession of a protoconch (0.8 mm) were noted. Since prelar- val (newly laid) eggs observed at week X would Vol. 89 (1) also be present at week X+1 (because develop- ment took 2-3 weeks), those eggs which included young with protoconchs (before hatching) at week X+1 were not included in the total count of eggs for that week. The numbers in row A, above the histogram, represent the relative number of eggs collected on each sample date. The percentages were found by using 100% to represent the maximum number of eggs ever collected during any one sampling period during the year. Row B includes a series of circles with the darkened areas illustrating the data in row A. Row C shows the average number of eggs for each sample date and Row D the average number of eggs per mass. The per- centage of survival of eggs was computed from data representing the differences in averages of eggs per mass between prelarval and protoconch stages of development. Size-weight regressions (Sokol and Rohlf, 1969) were used to obtain biomass and growth rate statistics because during routine sampling only the dimensions of the organisms were recorded. It was necessary to use this technique 100% 38% 57% 94% 19% 7% THE NAUTILUS 7 to keep disturbances in the sample area at a minimum (Eckblad, 197la). Sixty H. anceps were collected for size-weight (wet weight of shell and soft parts) measurements from areas adjacent to the transect. Analysis of each regression line indicated three slopes that were evident at various periods during development. Therefore three equations were computed for the best fit (fig. 3). A semi-log graph was used with weight in grams as the ordinate on the log scale and snail diameter in mm as the abscissa. In calculating biomass, the total weight was determined by adding the weight of each class obtained from the diameter-weight regression line (fig. 3). Density was determined by count- ing the total number of snails per sample. In figure 4 the left vertical scale illustrates the total number of snails per Im? and the right vertical scale represents the total biomass in grams for that area. The growth rate (r) reflects changes in weight (w) of a cohort as it develops over a time in- terval (t). The equation used to calculate these growth rates is r = (log W,-log W,) = t O08 9G@® ®O000 O00 0 OO 106 40 61 102 20 29 =©20 16 23 20 SCALE |) INDIVIDUAL o SNAIL DIA. IN MM MAY JUNE JULY AUG SEPT OCT Fig.2 Size-frequency histogram Helisoma anceps Moe Pond 1971. 8 THE NAUTILUS (Eckblad, 1971b). From the size-frequency histogram two cohorts were chosen and traced from 0.5 mm to 12 mm. The size class of each cohort on each sample date was determined and then its weight ascertained from the size-weight regression line. Water samples were analyzed for pH using a Beckman pH meter (Model no. 1009). The Alsterberg modification of the Winkler method was followed for determining values of dissolved oxygen in ppm. Total alkalinity in ppm as CaCO, was ascertained by titration with 0.02N H.SO, using methyl orange as the indicator. A nomograph was used to calculate CO, ppm (Moore, 1939). Air and water temperatures were recorded on each sample date. Maximum-minimum _ ther- mometers left in the water for 24 hr. periods were used to determine diurnal temperature fluctuations. RESULTS Temperature measurements for Moe Pond, taken between 9 and 11 am., fluctuated greatly. The pond warmed form 5 to 21°C in less than one month. Oxygen values fluctuated between 3.8 and 8.2 ppm. The pH values were highest in June and September, (8.2-8.7). The lowest readings (7.3) were in August, 1971. Alkalinity followed pH in its basic changes; the highest values (38-40 ppm) being present in June, and lowest (19 ppm) recorded at the same times as the low pH values. The life cycle of Helisoma anceps is illustrated graphically in figure 2. Eggs between 1 and 3 days old were found June 1, 1971. Oviposition by snails 8.5-12.4 mm in diameter continued until the first of July, but the rate steadily decreased after June first. Helisoma anceps oviposited the largest number (x = 73 per sample) of eggs in June when snail density was low (less than 1 per meter at each sample date) and declined to zero in two weeks as snail numbers increased (0.6-6.7 per m? ). No eggs were produced after July. During the reproductive periods the population exhibited a weekly variation in the average nummer of eggs per mass. Maximum numbers of eggs per mass occurred (x = 29) the first week of the reproductive period (fig. January 31, 1975 Vol. 89 (1) 2). After this the number of eggs per mass averaged slightly less (x = 23-16) until the end of the reproductive season. When egg laying ceased (July 14) the population decreased, but some adults persisted until May 1972. In May and June 1971 the ovipositing adults grew 1 to 4 mm in diameter. They reached about 11 mm in diameter in July at which time growth slowed appreciably. One cohort (distinct groups hatching at dif- ferent times the same summer) was _ present from the end of June, 1971 to the end of Sep- tember when its members attained sizes ranging from 9.5 to 10.4 mm in diameter. There was no late summer cohort to supplement the June cohort so its individuals must have sur- vived the winter in order to maintain the population. Two adults were found on June 21, 1971 that exhibited three varices, indicating a life span extending over three winters. Survival rates in 1971 were 0.1% from egg to adult and 10% from newly hatched young to adult. Regression lines computed from _ the Height:Diameter data in figure 1 illustrate morphological differences in the shells during growth. The shells of young specimens exhibit H:D ratios somewhat greater than 1:1. Older shells appear more flattened with H:D ratios of about 1:2. Diameter-weight coordinates and regression lines (fig. 3) of H. anceps have a steep slope initially which levels off slowly when intermediate sizes are reached. The larger sizes result in the gentlest slope. This indicates that the larger snails gain less weight per unit diameter increase than the smaller gastropods. Biomass and population density for H. anceps are shown in fig. 4. The biomass was large (x = 9.0 g/m’) in June, July, and August. The population density was greatest (x = 180/m?) in July when the greatest number of immature snails was present. Biomass averaged 6.9 g/m? and density = 70/m* between April and October, 1971. Figure 5 indicates the changes in growth rate which occurred during five months in 1971. The growth rates are highest in June and July and gradually decline to near zero in October and November. Weekly fluctuations are evident, but it is evident that as the snails grow larger they increase in size at a slower rate. Vol. 89 (1) 0.1 0.0) a = £ a £ = = ° 3 0.001 logY= 39X+4 diameter in mm 0.0001 2 4 6 8 10 12 Fig.3 Diameter-weight regression. Helisoma anceps. DISCUSSION Freshwater pulmonate life cycles vary greatly but in the temperate zone annual life cycles are most common (Hunter 196la, b, Boycott 1936). Within this type of life cycle several patterns have been observed (Dewitt, 1955; Hunter, 196la, b; Duncan, 1959; McGraw, 1959; Geldiay, 1956; Burkey, 1971; Gillespie, 1969). The mature members of the population may produce one, two or three cohorts or continuously produce throughout their reproductive period (Burkey, 1971; Walton and Jones, 1926). If there is more than one cohort, the first may be replaced or supplemented by the succeeding cohorts (Hun- ter, 19%6la). Some individuals produced in one summer may grow and mature before over- wintering; others may attain near maximum THE NAUTILUS 9 280 — biomass —- density 240 12 _, 200 0s = g a =" a 160) 8 = oe © @ = 120 62 FL n 80 4 Fig. 4 Biomass-density Helisoma anceps Moe Pond 197] r - growth rate J J A S (@) N Fig. 5 Growth rate. Helisoma anceps Moe Pond 1971 sizes and mature after overwintering; or spend the winter as small immature individuals which grow the following spring before reaching maturity. Many species of larger pulmonates have biennial life cycles (Berrie, 1965). A true biennial lives for two years, reproducing the 10 THE NAUTILUS second. The H. anceps population at Moe Pond was of this type. There was one cohort which hatched in June 1970, maturing in May 1971. The adults which produced this cohort survived until late sum- mer. Some individuals survive the second win- ter and reproduce again the following year. Evidence of this was the presence of varices, lines on the shell that reflect several months of slow winter growth. Two individuals were ob- served in June, 1971 which had survived a third winter. Variation in initiation of oviposition, develop- ment of eggs, and fecundity of adults are related to physical and biotic factors. Other authors (Dewitt, 1954; Eisenberg, 1970) have ob- served differences in reproductive responses of gastropods due to these following environmental stimuli; temperature, population density, and nutrient availability. At Moe Pond the water temperature was 14-15°C (10:00 am.) when H. anceps egg masses were first observed (May 22, 1971). If a specific increase in temperature was necessary to stimulate oviposition, then an in- crease of less than 14-15°C was adequate. The total number of eggs produced by a snail during its reproductive period in this study ap- peared to be correlated more closely with population density than any other factor. This agrees with Eisenberg’s (1970) conclusions on Lymnaea elodes. Egg production was _ highest when population densities were low. The fewest eggs were laid when the snails were very abun- dant or when they had reached the end of their reproductive period. The numbers of eggs per mass also directly correlated with population density. As shown in figure 2, eggs per mass were greatest when population density was lowest, and eggs per mass fewest when population density was at its greatest. Frank (1968) suggested that there is a selec- tion for early maturing snails in populations when individuals reach adult stages long before they die. Populations reproduce faster, therefore generation time decreases the earlier maturity occurs. In the populations studied, the ob- servation that the most productive adults were not the oldest and largest snails, but the snails which had been mature for approximately a month, supports his hypothesis. January 31, 1975 _ Vol. 89 (1) Two causes of mortality were apparent, physical stresses and predation. A small per- centage (less than 1%) of overwintering adults, which did not succumb to these factors prob- ably died of old age. The organisms observed in this study were not obviously influenced by the chemical parameters measured. The data collected were within the ranges given by Harman and Berg (1971) for central New York where these chemical parameters were considered to be unlimiting. The presence of ice effects the distribution of snails. In Moe Pond the transect area was frozen solid, including several cm of substrate, most of the winter and therefore uninhabitable. Cheatum (1934) noted that some snails migrate to deeper water during periods of ice cover, some species of Helisoma burrow in the substrate (Clampitt, 1972), while others have been seen crawling on the underside of the ice (Harman, unpublished). The population considered in this study had a density (less than 1/m?) during the winter period. Despite this, the population density in- creased considerably in the spring because of the high fecundity of adult snails. Therefore, the high percentage of winter mortality is com- pensated for, and does not influence, the population density the following year (Kisen- berg, 1966, 1970). Fluctuating water levels in June and July of- ten exposed a strip of substrate 5 to 10 cm wide along the shore within short period. Since egg masses required 1 to 2.5 weeks to develop, those oviposited in the shallowest areas were of- ten exposed to the air. After hatching, the young snails migrated to eulittoral areas. They often crawled completely from the water, were stranded and died. The littoral substrates at Moe Pond are hetero- geneous, supplying food to snails and providing cover from predators. The leech, Helobdella stag- nalis was abundant in the study area. The num- ber of leeches fluctuated directly with the snail population or lagged behind by one or two weeks. Helobdella stagnalis extracts the fluids from snails, eventually sucking in all the soft parts (Mann, 1955). Murdoch (1971) concluded that the more prey there are, the more predators, so a constant percentage of animals is usually Vol. 89 (1) removed from the population. However, if a particular size class is decimated, predators may play a role in population density regulation (Brockelman, 1969). Predators observed in this study appeared to contribute substantially to snail mortality when population densities were high. LITERATURE CITED Berrie, A. D. 1965. On the life cycle of Lym- nea stagnalis (L.) in the west of Scotland. Proc. Malac. Soc. London, 36: 286-295. Boycott, A. E. 1936. The habitats of freshwater molluses in Britain. J. Anim. Ecol. 5: 116- 186. Brockelman, W. Y. 1969. An analysis of dens- ity effects and predation in Bufo americanus tadpoles. Ecology, 50: 632-643. Burkey, A. J. 1971. Biomass turnover, respira- tion, and interpopulation variation in the stream limpet Ferrissia rivularis (Say). Ecol. Mongr., 41: 235-251. Cheatum, FE. P. 1934. Limnological investigations on respiration, annual migratory cycle, and other related phenomena in freshwater pul- monate snails. Amer. Microsc. Soc. Trans., 53: 348-407. Clampitt, P. T. 1970. Comparative ecology of the snails Physa gyrina and Physa integra (Basommatophora: Physidae). Malacologia, 10: 113-151. Clampitt, P. T. 1972. Seasonal migrations and other movements in Douglas Lake Pulmonate snails Malacol. Rev., 5: 1-12. Dewitt, R. M. 1954. Reproduction, embryonic development, and growth in the pond snail Physa gyrina Say. Amer. Microsc. Soc. Trans., 73: 125-187. Dewitt, R. M. 1955. The ecology and life his- tory of the pond snail Physa gyrina. Ecology, 36: 40-44. Duncan, C. J. 1959. The life cycle and ecology of the freshwater snail Physa fontinalis (L.). J. Anim. Ecol., 28: 97-117. Eckblad, J. W. 1971a. Weight-length regression models for three aquatic gastropod popula- tions. Amer. Mid. Natur., 85: 271-274. Eckblad, J. W. 1971b. Population studies of three aquatic gastropod populations in an intermit- tent backwater. Ph.D. Thesis, Cornell Univer- sity. Eisenberg, R. M. 1966. The regulation of den- THE NAUTILUS 11 sity in a natural population of the pond snail Lymnaea elodes. Ecology, 47: 889-906. Eisenberg, R. M. 1970. The role of food in the regulation of the pond snail Lymnaea elodes. Ecology, 51: 680-684. Frank, P. W. 1968. Life histories and commu- ity stability. Ecology, 49: 355-356. Geldiay, R. 1956. Studies on local populations of the freshwater limpet Ancylus fluviatilus Muller. J. Anim. Ecol., 25: 389-402. Gillespie, D. M. 1969. Population studies of four species of molluscs in the Madison River Yellowstone National Park. Limnol. and Oceanog., 14: 101. . Hairston, N. G., F. E. Smith, and L. B. Slobod- kin 1960. Community structure, population control and competition. Amer. Naturalist, 94: 421-425. Harman, W. N. and C. O. Berg 1971. The fresh- water snails of central New York with il- lustrated keys to the genera and_ species. Search: Cornell Univ. Agr. Exp. Sta., Ent. Ithaca. 1: 1-67. Hunter, W. Russell 196la. Life cycles of four freshwater snails in limited populations in Loch Lomond, with a discussion of inter- specific variation. Proc. Zool. Soc. London, 137: 135-171. Hunter, W. Russell 1961b. Annual variations in growth and density in natural populations of freshwater snails in the west of Scotland. Proc. Zool Soc. London, 136: 219-253. Mann, K. H. 1955. The ecology of the British freshwater leeches. J. Anim. Ecol. 24: 98-118. McCraw, B. M. 1959. The ecology of the snail Lymnaea humilis Say. Trans. Amer. Microsc. Soc. 78: 101-121. Moore, E. W. 1939. Graphic determination of carbon dioxide and the three forms of alka- linity. Jour. Amer. Water Works Assn., 31: 51-66. Murdoch, W. W. 1971. The development re- sponse of predators to changes in prey den- sity. Ecology, 52: 132-137. Sokal, R. R. and F. J. Rohlf 1969. Biometry. Freeman, San Francisco. p. 404-493. Walton, C. L. and W. N. Jones 1926. Further observations on the life history of Limnaea truncatula. Parasitology, 18: 144-147. Wurtz, ©. B. 1949. Physa heterostropha (Say). Nautilus, 63: 2-7. 12 THE NAUTILUS OBITUARY JOHN QUINCY BURCH (1894-1974) R. Tucker Abbott Delaware Museum of Natural History Greenville, Delaware 19807 The name of Burch is a hallmark in the twentieth century history of Pacific Coast malacology. Patriarch of this clan was the world-known shell and book dealer, mollusk researcher, and editor, John Q. Burch. “John Q.”, as he was familiarly called by thousands of his friends around the world, was born on June 20, 1894, in Chillicothe, Livingston County, Missouri, and died on August 7, 1974, at the age of 80, at Seal Beach, California. His family moved to El] Paso, Texas, in the 1900’s, where he met and later married Rose FIG. 1. taken um 194 2. John @. Burch in a formal portrait January 31, 1975 Vol. 89 (1) Adams. John Q. was the youngest in his El Paso High School class, and excelled in football and won the gold medal for debating. He received his law degree in 1915 at the Univer- sity of California, after attending Texas Univer- sity at Austin for three years. After serving as an aviator in World War I, he was a salesman for a law book firm in California from 1918 to 1944, and was also briefly associated with Rose in the Nogales Seed Merchant Co. in Arizona in 1922. John Q.’s first interest in shells was obtained from his son, Thomas Adams Burch, who in 1940-41 was President of the Conchological Club of Southern California. John Q. became the next president, and one of the originators and the editor of the monumental Minutes of the Con- chological Club of Southern California. The en- tire family soon became very active in collec- ting and dredging for shells, including his daughter-in-law Beatrice Burch. In 1944 he AN FIG. 2. John Q. Burch on Christmas Day, 1966, on his son’s boat, Janthina V, at Cholla Bay, California. Vol. 89 (1) began a long and successful career as a dealer in shell books and specimen shells. He became a life member of the American Malacological Union in 1959, and belonged to many other conchological and scientific societies. One of his greatest contributions was the voluminous “Minutes” that he composed, typed and mimeographed. They not only included valuable contributions by people such as A. G. Smith, Myra Keen, A. M. Strong, and George Willett, but during the war years, especially, kept everyone informed of conchological hap- penings around the world. He contributed several hundred articles himself. These are listed in the Index to the Minutes prepared by A. G. Smith (Minutes 169, 199, 200). The 200th USE OF DISPOSABLE BEVERAGE CON- TAINERS BY THE FRESHWATER CLAM, CORBICULA David W. Behrens Pacific Gas and Electric Company Department of Engineering Research San Ramon, California 94583 Utilization of disposable beverage containers by fishes has been reported by Kottcamp and Moyle (1972), but to the author’s knowledge their use by invertebrate animals has not been reported. Living specimens of the introduced Asiatic freshwater clam, Corbicula manilensis (Philippi, 1844) were found in surprising abundance in discarded disposable beverage containers, during the 1972-1973 dewatering of the Delta-Mendota Canal in central California. The beverage con- tainers were examined by biologists from the Department of Ichthyology, California Academy of Sciences, while conducting a survey of the fish in the canal. Examination of beverage con- tainers was conducted with the hope of gathering data to compare to the Kottcamp and Moyle (1972) paper which reported the use of cans by fishes in neighboring waters. Of the more than 50 cans and_ bottles examined, all contained clams with ap- proximately 80% totally full. The absence of available space is most likely the reason that no fish were found occupying the containers. THE NAUTILUS 13 and last number was issued in June 1960. John Q. was an affable and always helpful gentleman. Few shell dealers ever attained his reputation for honesty and constant attempt to give the best locality data possible. Museum and private collections throughout the world are the richer for the many splendid samples of mollusk material dredged off Redondo Beach, California, and elsewhere. This is a_ lasting monument to a beloved conchologist who will be remembered for centuries to come. A longer biography, including a list of his 37 articles on mollusks, was published by his daughter-in-law, Beatrice, in The Tubulata, Vol. 4, no. 1, pp. 7-12, in January 1971. In approximately 20% of the containers that were opened for closer examination, some of the clams were seen to be as much as twice the size of the original opening of the container, in- dicating substantial growth during occupancy of the container. None of the clams seemed to be in any way affected by their occupancy in the containers. In the Delta-Mendota Canal huge beds of Corbicula were built up on the inside radius of the turns and behind obstructions such as check structures and sunken automobiles. The means by which the containers became filled with clams is probably hydrolics and _ voluntary movement. Sedimentation and clam transport in the canal were seen to be quite dramatic as abandoned cars hauled out of the canal were found to be filled to the windows with mud and clams. Upon opening a locked fishing tackle box recovered at the bottom of the canal, live clams were found inside. Other invertebrate species found to be living in the containers were the brackish water crab, Rhithropanopeus harrisii, tubificid worm, Bran- chyura sowerbii, and isopod, Gnorimosphaeroma lutea. LITERATURE CITED Kottcamp, Glenn M., and Moyle, Peter B., 1972. Use of disposable beverage cans by fish in the San Joaquin Valley. Trans. Amer. Fish. Soc., 101(3): 566. 14 THE NAUTILUS January 31, 1975 Vol. 89 (1) AN ANOMOLOUS SEX-RATIO IN THE SUBLITTORAL MARINE SNAIL, LACUNA VINCTA TURTON, FROM NEAR WOODS HOLE ' W. D. Russell-Hunter Department of Biology Syracuse University Syracuse, New York 13210 Robert F. McMahon Department of Biology University of Texas at Arlington Arlington, Texas 76019 and Marine Biological Laboratory Woods Hole, Mass. 02543 ABSTRACT Sampling of a natural population of Lacuna vincta Turton near Woods Hole, Massachusetts, over the summers of 1968-1973 showed significant differences be- tween the sexes in mortality. By early July, after the principal reproductive period, all the larger snails in the population are male. This anomolous dimor- phism is discussed in relation to the more usual pattern of large females sur- viving longer, and to alternative hypotheses regarding the bioenergetics of reproduction. Among the most common small snails living in the lower intertidal and shallow sublittoral of the temperate Atlantic and Pacific coasts is the mesogastropod prosobranch, Lacuna vincta Tur- ton. Generally placed in the Stirps or Super- family Littorinacea, the genus Lacuna shares many features of reproductive and somatic physiology with the more aquatic littorinids such as Littorina obtusata L. Like most mesogastropods Lacuna vincta has separate sexes. During several summers (1968-1973) we have been collecting Lacuna vincta around Woods Hole, Massachusetts, for use in respiratory studies (McMahon and_ Russell- Hunter, 1973), and in comparative studies of egg-production bioenergetics (see Russell-Hunter, 1970, pages 179-181). The majority of our collec- tions have been made on a boulder-beach below the lighthouse at Nobska Point (41° 30°54’N; 70° 39'20”W). It has become obvious to us that, as regards the survivorship of larger (over- wintered) snails, each year in late spring and early summer, there is a great disparity be- tween the sexes. Proportionately more females die, so that by early July all the larger snails in the population are male. Our most detailed sampling was done in 1969 and 1973, and Figure 1 presents a summary of the data for a Supported by a research grant from the National Science Foundation, grant #GB-36757, to Dr. W. D. Russell-Hunter. these years as the successive stages of a single generation. It can be seen that the sex ratio of males: females changes from about 50:50 (from November through March) to about 60:40 in May and to about 70:30 by the end of June. By mid-July, the only survivors of the generation (now 11-14 months old) are male. This has been true for all six summers observed. Egg-laying has been observed in the field population from March through early June. Comparison of size distributions for the earlier samples (Figure 1) shows the females as having grown somewhat more rapidly than the males. Further, if we allow for appropriate adult growth rates through the spring and summer months, it is clear that the mortality rates in June and July are higher for larger snails than they are for smaller, in addition to being higher for females than for males. All of our sex determinations were made on freshly-collected living samples before shell- measurement and fixation, and we used the presence or absence of the penis (which in Lacuna is relatively large and prominent) in our determinations. We are very unlikely to have overestimated the number of males. In such gonochoristic prosobranchs, —_un- derestimation of the number of males in a population is much more likely due to regressive changes in penial structures which can occur either naturally in some sexual cycles Vol. 89 (1) (Jenner and Chamberlain, 1955; Jenner, 1956), or in certain abnormalities of host reproductive physiology induced by parasitic infections (Rothschild, 1936). It is also worth noting that the greater survivorship of males in the field is not paralleled in the laboratory. Paired snails used in our laboratory assessments of fecundity showed no differential survival between the sexes after reproduction ended. Lastly, extensive collecting of other species in and around the population site for Lacuna enables us to say with some degree of certainty that the changing sex ratios in the natural population are the result not of any differential migration to an- 9.0 THE NAUTILUS 15 other habitat but of real differential mortality. In almost all other cases where differences in mortality between the sexes have been reported in snails, these differences operate in favor of females: in other words, as each cohort ages, the proportion of larger female snails increases. Pelseneer (1926) noted such female proportions in populations could rise to 63% in Rissoa par- va, 80% in Bithynia leach, and 60% in Nassarius reticulatus. In his classic study of life-cycle in JLuttorina littorea, Moore (1937) found the percentage of females to rise to 76.9% in a population at Trevol, near Plymouth, England, U. K. SAMPLE PERCENTAGES SHELL LENGTH in mm + CA fo) fo} o co} +0 (OX, d 3.0 Q sem s2 39 34 29 27 26 28 32 0 ° 0% 2.0 CO 48% 48 61 66 7 73 Unk: Te 68 100 100 100% 1.0 30 | 29 a) 16 19 Bey (27/ 3 7 10 16 JUNE NOV. MAR. MAY “ JUNE i s JULY — FIG. 1.: Changes in size and sex distribution in relation to survivorship in a natural population of Lacuna vincta Turton. Sets of histograms show size distributions in samples of Lacuna from Nobska Point, near Woods Hole, Massachusetts, presented as the successive stages of a single generation (although the data are derived from two summers, 1969 and 1973); note that the horizontal axis is only a continuous scale of time after (ie., to the right of) June 11. Except for one histogram of spat on the extreme left, each histogram shows the shell sizes and relative numbers for females on the left and those for males on the right. To facilitate comparisons, the first eleven of the histograms indicate the percentage of the total sample (both sexes) in each class interval of shell size. The actual sample numbers fell from 126 (Nov. 11) to 14 (July 7); difficulty of collection reflecting mortality. The last two histograms (for July 10 and July 16) are arbitrarily not plotted as percentages since they represznt the very small samples, 4 and 7 respectively, of the longest-lived male members of the generation. The two lines of numbers below the histograms of adult snail samples represent the relative percentages of females and males: the changing sex ratios of the generation. 16 THE NAUTILUS The pattern of differential survivorship which we have found in Lacuna vincta, with a generation (or combined cohorts) coming to con- sist entirely of large males, is unusual and biologically anomolous. In general, the usual patterns with disproportionately more large females surviving are clearly of adaptive value in any situation of competition for food or other limiting resource. This is so _ largely because (in most snails which have been in- vestigated) a single successful copulation can provide for a long subsequent period of fertile egg-production. In the opinion of one of us (W.D.R-H.), these patterns, and the two more widely distributed phenomena of protandry in hermaphrodites and of sexual dimorphism with large females, are inextricably linked to the greater bioenergetic cost of ‘femaleness” (especially in egg-production) implicit in much of our earlier work on molluscs (Apley, Russell- Hunter and Avolizi, 1967; McMahon, 1974; Russell-Hunter, 1970; Russell-Hunter, Apley and Banner, 1971; Russell-Hunter, Apley and Hun- ter, 1972). On the other hand, some other theoretical biologists concerned with the evolution and genetics of sexual dimorphism (such as Scudo, 1973) emphasize the advantages of having larger numbers of smaller, more mobile, males. These two adaptive hypotheses are not necessarily mutually exclusive, and some combination of them could account for the evolution of the more common patterns of dif- ferential mortality of the sexes (with females surviving). The opposite disparity, with large males surviving preferentially which we have found in Lacuna, is anomolous and remains enigmatic. ACKNOWLEDGMENTS We are grateful to several colleagues for help in collecting — John L. Banner III, Martyn L. Apley and Jay Shiro Tashiro — and to Sandra K. Belanger and Perry Russell-Hunter for help in preparing this manuscript. January 31, 1975 Vol. 89 (1) LITERATURE CITED Apley, M. L., W. D. Russell-Hunter and R. J. Avolizi, 1967. Annual reproductive turnover in the saltmarsh pulmonate snail, Melampus bidentatus. Biol. Bull., 133: 455-456. Jenner, C. E. 1956. The timing of reproductive cessation in geographically separated pop- ulations of Nassarius obsoletus. Biol. Bull, 111: 292. Jenner, C. E. and N. A. Chamberlain. 1955. Seasonal resorption and restoration of the copulatory organ in the mud snail, Nassa obsoleta. Biol. Bull., 109: 347. McMahon, R. F. 1974. Growth, reproduction, and bioenergetic variation in three natural populations of a freshwater limpet, Laevapex fuscus (Morelet). Proc. Malacol. Soc. London, 41: in press. McMahon, R. F. and W. D. Russell-Hunter, 1973. Respiratory adaptability in relation to vertical zonation in littoral and sublittoral snails. Biol. Bull., 145: 44’. Moore, H. B. 1937. The biology of Littorina littorea. Part I. Growth of the shell and tis- sues, spawning, length of life and mortality. J. Mar. Biol. Assoc. U.K., 21: 721-742. Pelseneer, P. 1926. La proportion relative des sexes chez les animaux et particuliérement chez les mollusques. Mém. Acad. R. Belg. Cl. Sci. (Series 2), 8: 1-258. Rothschild, M. 1936. Gigantism and variation in Peringia ulvae Pennant 1777, caused by in- fection with larval trematodes. J. Mar. Biol. Assoc. U.K., 20: 537-546. Russell-Hunter, W. D. 1970. Aquatic Pro- ductivity. The Macmillan Company, New York, pp. v-xill, 1-306. Russell-Hunter, W. D., M. L. Apley and J. L. Banner III. 1971. Preliminary studies on brain implants and sex change in Crepidula fornicata (L.) Biol. Bull., 141: 400. Russell-Hunter, W. D., M. L. Apley and R. D. Hunter, 1972. Early life-history of Melampus and significance of semilunar synchrony. Biol. Bull., 143: 623-656. Scudo, F. M. 1973. The evolution of sexual di- morphism in plants and animals. Bull. Zool., 40: 1-23. Vol. 89 (1) THE NAUTILUS 17 BIOMPHALARIA HAVANENSIS (PFEIFFER) FROM GRENADA, WEST INDIES’ Emile A. Malek Department of Tropical Medicine Tulane University Medical Center New Orleans, Louisiana 70112 ABSTRACT The freshwater planornd snail, Biomphalaria havanensis (Pfeiffer), 1s' record- ed from three localities on Grenada Island, Lesser Antilles. The shell and genitalia are described and illustrated. Live snails were exposed to both the St. Lucian and Puerto Rican strains of Schistosoma mansoni but none became in- fected, although control infections of B. glabrata were 85% successful. Grenada snails identified by E. A. Smith in 1895 as Planorbis terverianus Orbigny and by C. S. Richards in 1973 as B. straminea (Dunker) are havanensis. Not much has been written on the molluscan fauna of the West Indies island of Grenada. The only record I could find is a report by E. A. Smith (1895), on a very few land and fresh- water shells. One of these was identified by Smith as Planorbis terverianus (Orbigny). There has been interest in the last decade in the freshwater planorbid species of the West Indies because of the medical importance of some of them. Many of these species have in the past been placed under the genera Planorbis, Tropicorbis and Australorbis. 1 am abiding with the decision of the International Commission on Zoological Nomenclature (Opinion 735, 1965) in giving precedence to Biomphalaria. In 1965, I made a survey of some Caribbean islands including Grenada to determine the ac- tual and potential hosts of Schistosoma man- som, and the endemicity or non-endemicity of the disease schistosomiasis on these islands. The biomphalarid material I collected on Grenada were Biomphalaria havanensis (Pfeiffer, 1839) as indicated in this present paper. The field- collected adult snails were found to be non- susceptible to S. mansom. In view of a recent finding (Richards, 1973) that juvenile biom- phalarids, identified by him as Biomphalaria straminea from one of my collection sites on 1 This investigation was supported by a Research Career Award number K6-AI-18, 424, and by reseach grant num- ber 1 R22, AI-11645, from the U.S. Public Health Service national Institute of Allergy and Infectious Diseases. Grenada, are susceptible to infection with S. mansoni, a clarification of the identity and morphology of these snails is of significance. A report on some other freshwater and land snails GRENADA CARIBBEAN SEA Grenada O Scale 1:100,000 —_— 1 2 3 miles $B Collection Sites of Biomphalaria havanensis 61° 45° FIG. 1. Map of Grenada showing collection sites of Biomphalaria havanensis. Shaded area indicates the central highlands. 18 THE NAUTILUS from Grenada will appear in a forthcoming paper. Grenada of the Lesser Antilles, lies about 90 miles north of ‘Trinidad and the South American coast in the Caribbean Sea (Fig. 1). The terrain is mountainous, but gentler slopes occur on the eastern and southwestern coasts. The high mountains extend almost longitudinally in the center, and from these mountains arise streams in all directions to- wards the sea. Rainfall varies considerably and is as low as 40 inches per ani.um on the dry southwest coast, and exceeds 150 inches in the central highlands. The dry season occurs from January to May aad the wet season from June to December with Novemker as the wettest month. Temperatures are relatively constant, fluctuating between 78 and 90° F during the day, and between 65 and 75°F at night. HABITATS During this partial survey PBiomphalana havanensis was located in three sites: 1. Grand Etang Lake: This lake is perched 1740 feet above sea level in a volcanic crater, and is over two miles in circumference. It is larger than two other lakes, Antoine and Levera in the north of the island. Red soil is characteristic of the area of Grand Etang Lake; there is not much in the way of aquatic vegetation, but sedges and bank vegetation are common. The snails were found in shallow, quiet waters along the bank. 2. Stream arising from Grand Etang Lake: The snails were located at about one to one and a half miles from the lake. The stream is narrow, about six feet in width, but is deep. 3. Creek in the vicinity of Paradise, in the east central part of the island: A large number of snails were collected from this site. The creek is about four feet in width and only about one to two feet in depth. The snails were found on many decaying leaves on the mud bot- tom. DESCRIPTION The descriptions below are specimens of B. havanensis. Shell (Fig. 2): The diameter of the shell in my material does not exceed 8 mm, nor the height 2 mm. In these specimens the shell has of Grenada January 31, 1975 Vol. 89 (1) Imm ‘al FIG. 2. Shell of B. havanensis from Grenada, in right (upper, umbilical), left (lower, spire) and apertural view. The right and left sides of the shell, as indicated here, are in relation to the living animal. up to 45 whorls increasing moderately in diameter; they are rounded and are separated by moderate sutures. In some specimens the whorls look bluntly subangular. The right (up- per or umbilical) side is shallow with a central notch which may be deep in some specimens especially the large ones. The left (lower or spire) side is broadly and shallowly concave. The aperture is heart-shaped and is deflected to the left, especially in adult specimens. The peristome is thin and continuous. The shell is encrusted with black deposits in the population from the creek near Paradise, while these deposits are reddish to pink in the populations from the other two sites. Animal: Twenty snails were dissected for morphological details of the animal. The ex- terior of the animal is pale gray. The mantle is studded with distinct rounded or elongated black or gray spots, more numerous in the population from creek near Paradise than in the other two populations. In the pallial cavity, there is no renal ridge on the ventral surface of the kidney. However, the dorsal mantle ridge and rectal ridge are both present and are quite distinct. The teeth of a radular half raw on either side of the central tooth are: 7 or 8 laterals, 1-2 intermediates, and, from the 10th tooth on, 9-11 marginals. The mesocone on the lateral teeth is dagger-like, triangular and is sharp and pointed. In the genitalia (Fig. 3) the ovotestis has several diverticula, arranged in transverse raws of two or three, predominantly unbranched and are club-shaped. The seminal Vol. 89 (1) FIG. 3. Dissected genitalia of B. havanensis from Grenada. al.g., albwmen gland; h.d., her- maphroditic duct; mu.g., muciparous gland; ovd., oviduct; ovt., ovotestis; pre., preputium; pro.g., prostate gland; sp.d., sperm duct; s.¥.s., seminal receptacle sac; s.v., seminal vesicle; ut., uterus; va., vagina; v.d., vas deferens; V.s., vergic sac. vesicles are finger-like. The prostate has as an average 16 short and branched tubules. The spermathecal sac is club-shaped, and its c-ict is short, about half the length of the sac. The vagina to the right of the spermathecal duct has a poorly developed vaginal pouch when compared to that in certain other species. In specimens measuring 5 to 7.5 mm in shell diameter and 1.8 to 2 mm in height, the female genital tract averaged 6.4 mm. The length ratio (calculated from average measurements of 20 genitalia) of female tract (=1), that is, from the point of bifurcation of hermaphroditic duct to female genital opening, to: oviduct, 0.40; penial complex, 0.38; hermaphroditic duct, 0.40; prostate, 0.38; spermathecal duct and sac, 0.15. The preputium, 1.45 mm, is longer than the vergic sac which is 1.0 mm. SUSCEPTIBILITY TO SCHISTOSOMA MANSONI Experiments were carried out to test the susceptibility of B. havanensis from Grenada to THE NAUTILUS 19 infection with two strains of S. mansoni, one from Puerto Rico and the other from St. Lucia. The snails were exposed individually to about 10 miracidia of the schistosome. The exposure temperature and the maintainance temperature after the exposure was 24 to 25 C. For the Puerto Rican strain of S. mansoni the following snails were exposed: 65 snails measuring 5.5 to 7.5 mm in diameter from Grand Etang Lake, and 79 snails measuring 5 to 8 mm in diameter from creek near Paradise. For the St. Lucian strain 182 snails measuring 6 to 7.5 mm in diameter from creek near Paradise were ex- posed to the miracidia. No B. havanensis became infected when observed starting a month after exposure, while up to 85% of B. glabrata from Puerto Rico exposed in each case as controls became infected and released cer- carlae. DISCUSSION My survey did not cover the entire island, but Biomphalaria havanensis is apparently widely distributed judging by finding it in three localities during this partial survey. Moreover, Smith (1895) reported his Planorbis tervernnus from a small ditch near St. George’s, in the southwestern part. In the morphological part of this in- vestigation criteria established by the author (1969) for the differentiation of biomphalarid species of the neotropics are followed in this present paper for the identification of the biom- phalarid material from Grenada. These criteria are shell characteristics, shape of mesocone on the radular lateral teeth and, more importantly, characteristics of the genitalia, in particular characteristics of the prostate gland and vagina, the length ratio of preputium to vergic sac, and the length ratio of the female genital tract to oviduct, to penial complex, to hermaphroditic duct, to spermathecal duct and sac and to prostate. On the basis of these characteristics and ratios as described above in this paper the Grenada biomphalarid is B. havanensis (Pfeif- fer). The. hermaphroditic duct in the Grenada material is, however, slightly shorter than that in the typical B. havanensis. I regard Smith’s (1895) Planorbis terverianus Orbigny a synonym. The type locality of havanensis Pfeif- fer, 1839, and terverianus Orbigny 1841, is 20 THE NAUTILUS Havana, Cuba. The snails from the volcanic lake (Grand Etang Lake), those from the stream arising from the lake, and those from the creek near Paradise agree anatomically and in shell characteristics. However, those from the first two habitats have a lightly pigmented mantle. This is only an ecological difference and does not warrant their separation taxonomically. In his recent short research note on the susceptibility of the Grenada specimens to in- fection with S. mansoni Richards (1973) iden- tified his specimens as Biomphalaria straminea (Dunker). They were collected for him by Dr. F. F. Ferguson of Puerto Rico. On the basis of my study the snails from Grenada are definitely not B. straminea because of the following reasons: 1. The vagina does not have transverse folds on the right of the spermatheca which give it a corrugate appearance, something which is characteristic of B. straminea. Moreover, a vaginal pouch is present, although small, while it is absent in B. straminea. 2. The length ratio of preputium to vergic sac is different. The vergic sac is either equal to, or longer than preputium in B. straminea, whereas it is shor- ter than preputium in the Grenada material, that is, B. havanensis. 3. The length ratios of female genital tract to other parts of the genitalia are different. For example, in my Venezuelan material of B. straminea (Malek, 1969) the ratios are: female tract (=1) to penial complex, 0.50; to hermaphroditic duct, 0.52; to spermathecal duct and sac, 0.25; to prostate, 0.40. In the Grenada B. havanensis the same ratios are as follows: 0.38; 0.40; 0.15 and 0.38. Baker (1945), page 500, lists Tropicorbis gund- lachi (Dunker) from the nearby island of Trinidad. Apparently on the basis of the shell Baker synonymized 7. gundlachi with T. stramineus. His figures 33-35 show that his snail, that is, 7. gundlachi from Trinidad, is January 31, 1975 Vol. 89 (1) probably also B. havanensis, but this conclusion should await anatomical studies. As to the host capacity of the Grenada biom- phalarids my results agree with those of Rich- ards (1973), that adult snails are not susceptible to infection with Schistosoma mansoni. It is of interest, though, that Richards found that juvenile snails are susceptible to infection with the same blood fluke. It should be noted that schistosomiasis is not endemic on this West In- dies island. During my stay on the island I checked with public health officials, and examined some hospital records and confirmed the truth of this contention. With human population movements, however, there is the possibility of introduction of the disease from some neighboring islands where the disease is endemic because of the existence on Grenada of susceptible snail intermediate hosts. ACKNOWLEDGMENTS Thanks are due Mrs. Linda Gibson Stoner for the shell illustrations, and the Research Laboratory of the U.S.P.H.S. Hospital in New Orleans for many facilities. LITERATURE CITED Baker, F. C. 1945. The Molluscan Family Plan- orbidae. Univ. Illinois Press, Urbana, 540 p. Malek, E. A. 1969. Studies on “tropicorbid” snails (Biomphalaria: Planorbidae) from the Caribbean and Gulf of Mexico areas, includ- ing the southern United States. Malacologia, 7: 183-209. Richards, C. S. 1973. A potential intermediate host of Schistosoma mansoni in Grenada. Jour. Parasitol., 59: 111. Smith, E. A. 1895. Report on the land and freshwater shells collected by Mr. Herbert A. Smith at St. Vincent, Grenada, and other neighbouring islands. Proc. Malacol. Soc., 1(7): 300-322. Vol. 89 (1) THE NAUTILUS POPULATION CHANGES OF THE APPLE SNAIL, POMACEA PALUDOSA. IN THE SOUTHERN EVERGLADES James A. Kushlan U.S. National Park Service Everglades National Park, Homestead, Florida 33030 ABSTRACT A six-year program of monthly sampling of aquatic animals in the southern Everglades, Florida, provided information on population changes of Pomacea paludosa in relation to two water regimes — fluctuating water levels with seasonal drought and continuously high water levels. Higher population levels were attained under more permanent water conditions. However the average size of snails was smaller indicating increased juvenile recruitment. Larger snails apparently survived drought better than did smaller snails. The apple snail, Pomacea paludosa (Say), oc- curs in the extreme southeastern United States in southern Alabama, southern Georgia and throughout the Florida peninsula. It is especially common in the freshwater wetlands of southern Florida where it forms an im- portant intermediate link in the aquatic food chain. The endangered Everglade kite (Rostrhamus sociabilis) is almost completely dependent on the snail for food (Strieglitz and Thomson 1967). The limpkin (Aramus guarauna) feeds heavily on Pomacea (Harper 1936, 1941; Cottam 1941), and the snail forms an important part of the diet of more euryphagous avian predators such as the boat-tailed grackle (Cassidix mexicanus) (Snyder and Snyder 1969) and the white ibis (Hudocimus albus) (Kushlan in prep.). Young alligators (Alligator mississip- piensis), snapping turtles (Chelydra serpentina) and other aquatic predators also consume this snail. Despite its ecological importance and recent reduction in numbers due to habitat alteration (Heard 1970, U.S. Department Interior 1973:120), little is known about the ecology of this species. It is most active at night and is capable of aestivation by burrowing in the mud when marshes begin to dry. Survival during such periods is evidenced by the appearance of egg clusters soon after water levels rise. Sur- vival through drought is of critical importance in the marshes of the southern Everglades which typically experience a seasonal fluc- tuation of water level and are usually without surface water during the latter part of the dry season. In some years which do not follow the typical pattern, water remains above ground level throughout the year. A program of quantitative sampling of aquatic organisms from 1966 through 1972 provided information on the abundance and size distribution of Pomacea in the southern Everglades of Everglades National Park. The purpose of this paper is to describe changes in the population of Pomacea paludosa over the 6- year study period especially in relation to population differences between years of typically fluctuating water conditions and years of extended high water levels. In as far as seasonal fluctuation or stable high water con- ditions are representative of snail habitats in other areas of southern Florida, implications can be drawn concerning the role of water levels in other parts of the snail’s range. METHODS Data discussed in this paper were collected as part of a more extensive program to monitor populations of aquatic organisms in the southern Everglades conducted by the U.S. Geological Survey for the U.S. National Park Service. Samples were taken with ten 4.5-m° pull-up traps described by Higer and Kolipinski (1967). Traps were located in sawgrass marsh (Cladium jamaicense) and mixed-marsh prairie composed of several species of herbaceous plants (Eleocharis cellulosa, Rynchospora tracyi). Traps 22 THE NAUTILUS were generally used on two consecutive nights each month. These samples generated monthly averages for the number of snails per square meter, the wet weight biomass (including shell) of snails per square meter, and the average weight per snail. In order to take into con- sideration any seasonal changes in snail population, an average value of each parameter was calculated for each hydrologic year which runs from the beginning of the rainy season in June to the end of the dry season the following May. RESULTS AND DISCUSSION Fig. 1 shows how water level fluctuated in the southern Everglades from 1966 through 1972. The typical water level pattern charac- terized by low water levels during the dry season, occurred in the hydrologic years of 1966-67, 1967-68, 1970-71 and 1971-72. From 1968 to 1970 water levels were continuously high. Fig. 1 also shows the average abundance, biomass and size of snails each year. The data from the hydrologic years of 1968-69, 1969-70 and 1970-71 reflect changes in the snail population coincident with prolonged high water. It is apparent that both abundance and biomass increased during the high water and then declined when the typical pattern was re- established after 1971. The average size of snail decreased during the high water period probably due to higher production and survival of young snails. Average size increased during 1971-72 suggesting that larger snails survived the dry period of 1970-71 better than did smaller snails and perhaps that juvenile recruit- ment declined. In general, the results suggest that higher population levels are attained under more per- manent water conditions in contrast to con- ditions in which surface water reaches low levels in the dry season. Apparently there is a differential survival of large snails through dry periods, and greater juvenile recruitment in constantly high water. As a result, the average size of snails is greater under conditions of fluctuating water levels. It is not unlikely that these general relations hold in ecologically similar areas elsewhere in southern Florida. For example canal-edge marsh- January 31, 1975 Vol. 89 (1) es, water impoundment marshes, and lake- edge marshes may have higher populations than the Everglades. It is not surprising therefore that these are preferred foraging habitats of the Everglade kite, limpkin and grackle. Limpkins and white ibis also feed on snails throughout the Everglades especially when water levels are low. However canal-edge habitats, such as those observed by Snyder and Snyder (1969), probably » o Lind o meters above MSL = w ABUNDANCE snails / m2 BIOMASS AVERAGE SIZE gm /snail 1966-67 1967-68 1968-69 1969-70 1970-71 1971-72 year FIG. 1. Changes in water level and in the abun- dance, biomass and average size of snails in the southern Everglades from 1966 to 1972. Vol. 89 (1) combine high snail densities with availability to avain predators. ACKNOWLEDGMENTS The sampling was carried out under the direction of A. L. Higer and M. C. Kolipinski of the U.S. Geological Survey under contract to the U.S. National Park Service. LITERATURE CITED Cottam, C. 1941. Supplementary notes on the food of the limpkin. Nautilus, 55: 125-128. Harper, F. 1936. The distribution of the limpkin and its staple food Pomacea. Nautilus, 51: 37-40. Harper, F. 1941. Further notes on the food of the limpkin. Nautilus, 55: 3-4. Heard, W. H. 1970. American Malacological Union symposium rare and endangered mol- lusks. 3. Eastern freshwater mollusks (II). ready THE NAUTILUS 23 The south Atlantic and Gulf drainage. Mal- acologia, 10: 23-31. Higer, A. L. and M. C. Kolipinski. 1967. Pull-up trap: A quantitative device for sampling shal- low water animals. Ecology, 48: 1008-1009. Snyder, N. F. R. and H. A. Snyder. 1969. A comparative study of mollusc predation by limpkins, Everglade kites, and _ boat-tailed grackles. Living Bird, 8: 177-223. Stieglitz, W. O. and R. L. Thomson. 1967. Status and life history of the Everglade kite in the United States. Fish and Wildl. Serv., Bur. of Sport Fisheries and Wildl., Special Sci. Rep.-Wildl. No. 109. 21pp. U.S. Department of the Interior. 1973. Threat- ened wildlife of the United States. Bur. of Sport Fisheries and Wildl. Resource Publ. 114. POSITION OF EPIPHRAGMS IN THE LAND SNAIL OTALA LACTEA (MULLER) M. A. Rokitka and C. F. Herreid II Department of Physiology State University of New York at Buffalo Buffalo, New York 14214 ABSTRACT Dormant land snails (Otala lactea Miiller) were X-rayed to determine the position of the membranes (emphragms) secreted across the shell aperture. Measurements of the distance between the mantle and the aperture rim (peristome) were made. Spacing between multiple epiphragms was determined. Data on epiphragm spacing and arrangement suggested that the extent of retraction of the snail body into the shell is not related to the total number of epiphragms secreted by a snail. As the number of epiphragms increases, the distance between the mantle and the emphragm closest to it decreases. Similarly, the mean distance between successive epiphragms decreases as the total number of epiphragms increases. INTRODUCTION The formation of multiple epiphragms by land snails is generally interpreted as a response to conditions which threaten dormant snails. Grassé (1968) views the production of more than one epiphragm as a reaction to the persistence of drought. Cooke et al (1895) report that multiple epiphragms are laid down as the length of hibernation increases. Cadart (1955) proposes that with each retraction of the snail body into its shell, a new “veil” is produced. A number of recent studies have been made to assess the functional role of the epiphragm as a barrier to water loss (Machin, 1967, 1968; Schmidt-Nielsen, 1971). The studies described here represent an attempt to identify the man- ner in which epiphragms are laid down, ie., their position relative to the snail body and 24 THE NAUTILUS FIG. 1. Typical contact print from a radiograph of a dormant snail. The four small arrows in- dicate the position of four calcified epiphragms; the larger arrow points to the mantle. aperture. It is hoped that this information can be used to design a compartmentalized model of the snail shell, body and epiphragms. The model would enable one to account for water exchange between the snail and its environment. MATERIALS AND METHODS Adult Otala lactea (Miiller) were imported from Morocco. The dormant snails were placed on sheets of Kodak No-Screen Medical X-ray film at a target-to-sample distance of 85-90 cm. They were oriented so that the outermost epiphragm was approximately perpendicular to the plane of the film. A Universal X-ray Products dental unit with no added filtration operating at 60 kV was set to provide 12 mAs- exposures. This particular setting provided an image of the shell, mantle and epiphragms; the number of epiphragms for each dormant snail was “read” from the X-ray images (Fig. 1). Estimates of maximum spacing between suc- cessive epiphragms were obtained by placing a fine wire (Marked off at 1 mm intervals) along the upper curvature of the X-ray image of the January 31, 1975 Vol. 89 (1) Outermost Epiphragm FIG. 2. Schematic representation of epiphragm spacing as a function of the total number of epiphragms. The seven views (coded A-G) correspond to “model” snails with 1-7 epiphragms. The numbers in parentheses in- dicate the total number of epiphragms in a given view. shells. Distances were measured to the nearest 0.5 mm. Films were viewed under a dissecting microscope (X7). RESULTS The analysis of X-ray images of 112 dormant snails showed that as the number of epiphragms per snail increases, the distance be- tween the mantle and the epiphragm closest to it decreases (Table 1, Fig. 2). The table also in- dicates that the distance between the mantle and the outermost epiphragm (the one closest to the aperture) remains virtually unchanged as the number of epiphragms per snail increases. Calculation of the mean distance between suc- cessive epiphragms revealed a general decrease Vol. 89 (1) THE NAUTILUS 25 TABLE 1. Measurement of Epiphragm-Mantle Distances. Total number of N Mean distance between Mean distance between epiphragms mantle and closest mantle and epiphragm epiphragm (mm)* nearest aperture (mm)* 1 36 Oe = ES 198-22 1:5 2 27 Bil Se 14! Il Se. ILS 3 25 8.9 = 0.9 ly se 18 4 17 84 + 14 iy = 127 5 4 12 = 34 140 = 36 6 2 i) se IY 21.5 = 15 7 1 2.0 + 0.0 10h 0010 es SH TABLE 2 — Mean Distances between Successive Epiphragms (mm)* EPIPHRAGM ae eae Co Sp Ee INTERVAL roy Ponce |isisoe | sits |2aso2| veso04 | a5ets mantle) @ (aed ean the mantle) MEAN DISTANCE BETWEEN 3.4 31 7 3.2 17 ALL EPIPHRAGMS + *X+ SE + Calculated as the distance between the first and last epiphragms divided by the number of intervening spaces. in the length of the space between epiphragms DISCUSSION as the total number of epiphragms increases There are no documented reports of the (Table 2, Fig. 2). This tendency can be expected analysis of spacing and/or arrangement of solely on the basis of the limited space made multiple epiphragms within the shells of land available by the confines of the rigid shell. snails. This study raises the possibility that a 26 THE NAUTILUS number of variables, either environmental or physiological or both, may influence the number and positioning of epiphragms. An earlier investigation (Rokitka and Herreid, in preparation) showed that O. lactea form calcified epiphragms that vary in extent of calcification and in thickness. Furthermore, as the length of dormancy increases, epiphragm formation continues so that the epiphragms closest to the body may be formed days or weeks after the first epiphragms were laid down. This implies that the dormant snail periodically arouses, moves to within 2 to 4 mm of the last epiphragm and forms a new epiphragm only to retreat to its original dor- mant position. The close packing of the last epiphragms in a series is a necessary con- sequence of the limited space available to the snail if dormancy is prolonged. The purpose of epiphragm formation is unknown. Epiphragms could serve as barriers to water loss during dormancy, and obviously multiple epiphragms are more effective than single ones. However, recent evidence suggests that the mantle rather than the epiphragm is the primary barrier to water loss (Machin, 1968, 1972). Epiphragms could serve as barriers to parasite invasion during dormancy as well. Alternatively, epiphragms may be merely tem- porary storage sites for mineral products. Changes in electrolyte composition of body fluids accompany or precede dormancy in many species. Changes in Mg/Ca ratio are well documented in mammalian hibernation where dormant animals have depressed blood calcium levels (Riedesel, 1960). In species such as the little brown bat the blood calcium level even varies with the depth of hibernation. Is_ it possible that multiple epiphragms are formed as January 31, 1975 Vol. 89 (1) hemolymph calcium levels are lowered for prolonged dormancy in snails? Finally, it is noteworthy that snails arousing from dormancy usually eat their old epiphragms and presumably conserve calcium supplies. ACKNOWLEDGMENTS We wish to thank Dr. A. K. Bruce of SUNYAB for providing X-ray equipment and for recommending radiographic techniques. We also are grateful to I. Weinstein for gathering data on epiphragm spacing. LITERATURE CITED Cadart, J. 1955. Les Escargots. Paul Lechevalier Editions, Paris. Cooke, A. H., Shipley, A. E. & Reed, F. R. C., 1895, Molluscs and Brachiopods, in Cambridge Natural History, Edited by S. F. Harmer & A. E. Shipley, Macmillan, London, 3: 1-535. Grassé, P. -P. 1968. Traité de Zoologie; anato- mie, systématique, biologie - Vol. V, Masson, Paris. Machin, J. 1967. Structural adaptation for re- ducing water-loss in three species of ter- restrial snail. J. Zool., Lond., 152: 55-65. Machin, J. 1968. The permeability of the epi- phragm of terrestrial snails to water vapor. Biol. Bull., 134: 87-95. Machin, J. 1972. Water exchange in the mantle of a terrestrial snail during periods of re- duced evaporative loss. J. exp. Biol., 57: 103- AISLE Riedesel, M. L. 1960. The internal environment during hibernation. Bull. Mus. Comp. Zool. Harvard Coll., 124: 421-435. Schmidt-Nielsen, K., Taylor, C. R. & Shkolnik, A. 1971. Desert snails: problems of heat, wa- ter and food. J. exp. Biol., 55: 385-398. INFORMATION FOR SUBSCRIBERS The annual subscription rate for The Nautilus is $7.00 for individuals and $12.00 for institutions (domestic or foreign). Subscriptions may begin in January. Send check or money order to “The Nautilus” to Mrs. Horace B. Baker, Business Manager, 11 Chelten Road, Havertown, Pa. 19083. Back issues from volume 72 to date are obtainable from the Business Manager. Volumes 1 through 71 (if available) may be obtained in reprint or original form from Kraus Reprint Co., Route 100, Millwood, New York 10546. Advertising rates may be obtained from the Business Manager or Editor. 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U it y vl y Y ne ‘ huts! ae APRIL 1975 THE NAUTILUS Vol. 89 A quarterly devoted to malacology and the interests of conchologists SS Founded 1889 by Henry A. Pilsbry. Continued by H. Burrington Baker. Editor-in-Chief: R. Tucker Abbott EDITORIAL COMMITTEE : CONSULTING EDITORS Dr. Arthur H. Clarke, Jr. Department of Mollusks National Museum of Canada Ottawa, Ontario, Canada K1A-OM8 Dr. William J. Clench Curator Emeritus Museum of Comparative Zoology Cambridge, Mass. 02138 Dr. William K. Emerson Department of Living Invertebrates The American Museum of Natural History New York, New York 10024 Mr. Morris K. Jacobson Department of Living Invertebrates The American Museum of Natural History New York, New York 10024 Dr. Auréle La Rocque Department of Geology The Ohio State University Columbus, Ohio 43210 Dr. James H. McLean Los Angeles County Museum of Natural History 900 Exposition Boulevard Los Angeles, California 90007 Dr. Arthur S. Merrill Biological Laboratory National Marine Fisheries Service Oxford, Maryland 21654 EDITOR-IN-CHIEF Dr. R. Tucker Abbott Delaware Museum of Natural History Box 3937, Greenville, Delaware 19807 Mrs. Horace B. Baker Business and Subscription Manager 11 Chelten Road Havertown, Pennsylvania 19083 Second Class Postage paid at Wilmington, Delaware Dr. Donald R. Moore Division of Marine Geology School of Marine and Atmospheric Science 10 Rickenbacker Causeway Miami, Florida 33149 Dr. Joseph Rosewater Division of Mollusks U. S. National Museum Washington, D.C. 20560 Dr. G. Alan Solem Department of Invertebrates Field Museum of Natural History Chicago, Illinois 60605 Dr. David H. Stansbery Museum of Zoology The Ohio State University Columbus, Ohio 43210 Dr. Ruth D. Turner Department of Mollusks Museum of Comparative Zoology Cambridge, Mass. 02138 Dr. Gilbert L. Voss Division of Biology School of Marine and Atmospheric Science 10 Rickenbacker Causeway Miami, Florida 33149 Dr. Charles B. Wurtz 3220 Penn Street Philadelphia, Pennsylvania 19129 OFFICE OF PUBLICATION Delaware Museum of Natural History Kennett Pike, Route 52 Box 3937, Greenville, Delaware 19807 Subscription Price: $7.00 (see inside back cover) — THE NAUTILUS Volume 89, number 2 — April 1975 CONTENTS M. A. Rokitka and C. F. Herreid, II Formation of Epiphragms by the Land Snail Otala lactea (Miller) lnderavarioussEnvironmentals Conditions: 4+ 40 ss.soe bees ae cso aeees ade oo. Gee see 27 Victor L. A. Yoloye The Validity of the Subgenus Senilaa Gray, 1842 (Bivalvia: Arcidae)....................... 33 Eva Pip Scalaniionmysinetheseondasnallymngeaustagnalsy. .....04ne4.45 0556500080 een oe ee eee ae 36 Thomas R. Hester and T. C. Hill, Jr. Eating Land Snails in Prehistoric Southern Texas: Ethnohistoric and Xe RINE tala Data meee Nene ct ae reer Sen cate seis digo ah Sk oandoare eeu Geass a eee F. Wayne Grimm A Review of Succinea wilsoni, a Coastal Marsh Snail of BASTIEN OLUNMATNICI Cam etme eT areca ee hes Mon emer nee Co ee eS oe a eked 2 oy haere 39 Carl C. Christensen and Walter B. Miller Genital Anatomy and Physiology of the Snails, Berendtia Crosse and Fischer and Spartocentrum Dall (Stylommatophora: Bulimulidae)......................... 43 Branley A. Branson Radiodiscus hubrichti (Pulmonata: Endodontidae) New Species from the Olyimypai ceRentnsnlayaWashingtonaere, ees seca aise eet Se yore Mmiene mye cei) ole ans aunterele Dow, Eales 47 R. N. Kilburn The Rediscovery of Morum praeclarwm Melvill (Cassidae)................002 000. ee eens 49 R. N. Kilburn Substitute Name for Conus orbignyi aratus Kilburn, Nom. Preoce.........................-50 James E. Joy and Laidley E. McCoy Comparisons of Shell Dimensions and Viscera Mass Weights in Convene, meanness (Riaillijon, Ws). ocbasoandovcnegacudcuseubocdsouususus obo aE So ooC ul Morris K. Jacobson ives atenialgotesomes CubanmHelicimidsemen, laser. anor + aoeier cieiniei ere cae seen a De: Thomas J. Horst and Robert R. Costa Seasonal Migration and Density Patterns of the Fresh Water Snail, AAOOD, UU. 3 5. 55.6. 6i6s0 ale 66.3%. scone 8 OTS ee AD Ce ee ee ee ree 8 W. C. Fallaw Size Distribution of the Bivalve, Mulinia lateralis, (Mactridae) and ldnenay ILevell or Some leigmesne Sachets .s45c00¢nncobsecseuvcnecuadaouncoudcubuE 60 C. O. van Regteren Altena Notes on Land Slugs, No. 22: A Catalogue of the Genus Lytopelte (Limacidae) and AM NOLCRONM UMA OLOnensisa (Nlbenal) asec 5 <4 < sas ble seies sciee cine ae bic laa cc clsteesensmietia a ara 62 Notices Jot Meeting of WS:ME and) -AUMLU., June 22-26, 1975... 226.52. ane e oeaeeeee 63 ill A priceless book for anyone who loves the sea and its Shells m@ ‘Froma basic explana- tion of tides and waves, to a pan- oramic coverage of all the well- known sea creatures, Mrs. Sheets has given the new student of biology and oceans an interesting and entertaining account.’’—from the foreword by R. Tucker Abbott. Illustrated with 130 photographs, 113 of them in full color. 7” x 10”. THE FASCINATING WORLD OF THE SEA Circling the Globe for the Wild Seashell by ELVA D. SHEETS $14.95, now at your bookstore, or send check or money order to CROWN PUBLISHERS, 419 Park Ave. South, New York, N.Y. 10016 oun EDITOR-IN-CHIEF R. Tucker Abbott duPont Chair of Malacology, Delaware Museum of Natural History american malacologists a national register of living professional and amateur conchologists $12.50 plus biographies of 500 great, as well as little-known, American malacologists of the past American Malacologists P.O. Box 4208 Greenville, DE 19807 Vol. 89 (2) THE NAUTILUS 27 FORMATION OF EPIPHRAGMS BY THE LAND SNAIL OTALA LACTEA (MULLER) UNDER VARIOUS ENVIRONMENTAL CONDITIONS M. A. Rokitka and C. F. Herreid II Department of Biology State University of New York at Buffalo Buffalo, New York 14214 ABSTRACT The production of epiphragms by land snails is related to the environmental conditions under which the snails are maintained. Active Otala lactea (Miiller) are more likely to become dormant and form epiphragms at low relative humidities and low temperatures than they are at high relative humidities and high temperatures. The transparent epiphragms which are laid down during the early phases of exposure to experimental conditions are gradually replaced by calcified epiphragms. Multiple calcified emphragms are secreted with increasing Frequency as exposures to “drying conditions” increase in duration. X-ray studies of dormant populations of snails lend further support to the suggestion that the total number of epiphragms secreted by a snail depends on the length of the period during which it has been dormant. INTRODUCTION Land snails retire into their shells and remain dormant for varying lengths of time (Comfort, 1957). Survival during prolonged periods of dormancy (lasting for months and even for years at a time) is made possible by reductions in water loss and metabolism during these periods of inactivity (Grassé, 1968). The mantle collar (the only exposed tissue of a withdrawn snail) has been credited with regulating water exchange between snails and their environment during dormancy (Machin, 1972). In addition, the membranes (epiphragms) which are often secreted across the aperture of the shells of inactive snails reduce water loss below that observed for snails without epiphragms (Machin, 1967; Herreid, unpublished observations). The factors which bring about secretion of an epiphragm have not yet been clearly identified. Field data on epiphragm production is limit- ed; the only experimental work (other than that presented here) has been that of Bonavita (1961, 1964) who observed epiphragm form- ation as a function of various ambient temper- atures and relative humidities. The present study evaluates the influence of ambient temperature and relative humidity on epiphragm formation by Otala lactea (Miiller) and identifies the conditions under which several epiphragms are formed by the same snail. MATERIALS AND METHODS Adult Otala lactea (Miiller) were imported from Morocco in the dormant condition. They were aroused from dormancy by placement in a humid atmosphere; snails which aroused over- night became the subjects for the studies described below. The influence of relative humidity and tem- perature on epiphragm formation was studied by placing aroused snails in controlled relative humidity chambers which were kept in a con- stant temperature unit. Appropriate relative humidities were achieved by the use of anhydrous calcium chloride (12% RH), a solution of potassium hydroxide (58% RH), or a saturated potassium sulfate solution (98% RH); (Solomon, 1951; Winston & Bates, 1960). Both 24-hr and 5-day exposures were arranged at each of the experimental temperatures. Lengthened exposures to various environmental conditions were designed to determine the extent of multiple epiphragm formation. The number of epiphragms formed by a given snail was determined by the sequential removal of its 28 THE NAUTILUS epiphragms at the end of the exposure period. The analysis of epiphragm number in populations of snails that were dormant since their arrival from Morrocco was accomplished via a radiographic technique. Groups of dor- mant snails were X-rayed using Kodak No- Sereen Medical X-ray film and 12 maAs- exposures to irradiation provided by a Univer- sal X-ray Products dential unit. Two different populations of snails were X-rayed. One group spent 6-9 months in the laboratory following collection from the field during the summer of 1970. A second group was X-rayed 8-10 wk following arrival in the laboratory; this group was collected during the winter of 1970-71. RESULTS Aroused snails form epiphragms soon after ex- posure to “drying conditions.” Approximately 40% of the snails studied formed epiphragms PERCENT OF SNAILS WITH EPIPHRAGMS } a nN a fe) So. 2 oe TIME (days) PERCENT OF SNAILS WITH EPIPHRAGMS @-12% RH X— 58% RH 50) O- 98% RH VAG EN fo) 4 2 si 4 TIME (days) uw FIG. 1. Epiphragm production under controlled environmental conditions. N=32 at each tem- perature and relative humidity. April 30, 1975 Vol. 89 (2) within the first 24 hr of exposure to either 12 or 58% RH at 31.5°C (Table 1). There was a progressive increase in the percentage of snails that formed epiphragms through time. However, even at the end of the experiment a few snails still had not formed epiphragms. It should also be noted that the transparent epiphragms formed during the first 24 hr of ex- posure were replaced by calcified epiphragms; this tendency persisted for the duration of the study. No apparent difference in the incidence of epiphragm formation occurred at the two relative humidities. In addition, there appears to be no difference in the ratio of calcified to transparent epiphragms at the two humidities. To examine epiphragm formation in more detail, snails were observed over a 5-day period at 12, 58 and 98% RH at temperatures ranging from 10-40 C. In these experiments epiphragm formation was higher at 12 and 58% RH than at 98% RH (Fig. 1). This trend, aside from being poorly defined, was complicated by oc- casional arousals and returns to dormancy that took place during the 5 days. In spite of this handicap, the trend toward decreased epiphragm production with increased temperature is clear. Linear regression analysis of the data obtained after the first 24 hr of each exposure shows a well-defined relationship between temperature and the occurrence of epiphragm production (Fig. 2). A second set of experiments wherein only a 24hr exposure was arranged, produced results that confirmed those obtained after the first 24 hr of the 5-day series. In both cases, epiphragm formation is most frequent among snails kept at 12 or 58% RH and least frequent among those kept at 98% RH (independent of ambient temperature). The low incidence of epiphragm formation at the upper temperature limit in Fig. 2 is partially due to the deaths of large numbers of snails at that temperature. During the course of many experiments, some snails were observed to form several epiphragms. In order to examine the possibility that multiple epiphragm formation is a function of the length of dormancy, the following ex- periment was set up. Groups of snails wére kept at 12% RH and 25°C for up to 7 wk. It was found that epiphragm formation does in- , Vol. 89 (2) = 00 + fo) @ [e) Oo (e) PERCENT OF SNAILS WITH EPIPHRAGMS ip”) fe} [o} 10 20 FIG. 2. Epiphragm formation as a function of ambient temperature. The correlation coefficient and regression line equation for the relative humidities studied are: crease as dormancy is prolonged (Table 2). This clearly indicates that the snail periodically lays down new epiphragms as dormancy progresses. Table 3 is a summary of epiphragm for- mation at two different temperatures and two relative humidities. It shows that at 25°C the fraction of the population that formed multiple epiphragms at 12% RH is similar to that record- ed at 58% RH. The same table also reveals no significant difference in the appearance of single and multiple epiphragms at 12 and 58% RH at an elevated temperature of 31.5°C. There is, however, a marked shift toward maintaining a single epiphragm instead of constructing ad- ditional epiphragms at the higher of the two temperatures. A comparison of Tables 1 and 2 will also show that the general rate of epiphragm formation was much higher at 25°C than at 31.5°C. Analysis of epiphragm formation for longer periods using an X-ray technique indicates that epiphragm formation continues throughout dor- mancy. Snails which were dormant for 8-10 wk showed a higher frequency of single epiphragms than did the snails which were dormant for 6-9 months. The frequency distribution of the two populations were similar. Most of the snails had single epiphragms, followed progressively by THE NAUTILUS 29 30 40 TEMPERATURE (°C) 12%RH: r=0.878, y=96.60 - 1.912; 58% RH: r=0.953, y= 104.11 - 1.762; 98% RH: r=0.928, y=65.01 - 1.342. lower percentages of snails with 2, 3, 4, 5, 6 and 7 epiphragms. DISCUSSION The periods of heat and drought which charac- terize Moroccan summers make the creation of a favorable microclimate a virtual necessity for O. lactea, land snails which abound in the areas surrounding Rabat and Casablanca. Retirement into a shell which is “sealed” by means of one or more epiphragms presumably creates a niche which favors survival during periods of stress. If a significant function of an epiphragm is the prevention or reduction of water loss from a dormant snail, then one would expect epiphragm formation to occur in anticipation of, or in response to the onset of conditions which would increase water loss. As expected, epiphragm formation by O. lactea occured with the highest frequency at low relative humidities (Figs. 1 and 2). There appears to be some threshold humidity above which epiphragm for- mation rarely occurs and below which epiphragm formation is almost a certainty. Ob- servation of epiphragm formation at a larger number of experimental relative humidities would test this suspicion. 0) TI NAUTILUS April 30, 1975 Vol. 89 (2) TABLE 1. Epiphragm formation at different relative humidities. (Ty = 31.5°C) Length of exposure Percent snails with epiphragms (days) at 12% RH at 58% RH 1 42.9 (23.2) 36.2 (29.2) 2 70.6 (52.9) 62.7 (57.2) 3 77.1 (63.4) 74.2 (65.7) 4 78.8 (66.1) 80.0 (71.0) 5 81.8 (69.3) 83.5 (72.5) 6 81.4 (68.9) 87.5 (73.5) 7 81.6 (68.9) 89.5 (74.4) 8 83.2 (69.3) 91.5 (75.5) 9 84.5 (70.5) 91.5 (75.9) 10 85.7 (71.7) 91.5 (75.9) 16 87.5 (73.5) 87.5 (73.5) 23 91.4 (76.8) 97.0 (78.6) (N.B.)- Numbers in parentheses represent percent calcified epiphragms. *N at 12% RH = 228 on day 0 and 216 by day 23; at 58% RH, N = 202 on day 0 and 196 by day 23. Differences are due to deaths. TABLE 2. Epiphragm production over a 7-week period. (RH = 12%; Ts = 25°C. time N* percent snails with a percent snails with (days) single epiphragm multiple epiphragms 1 15 100 0 4 22 95 5 tl 29 86 14 14 29 66 34 Pal 61 43 57 49 200 52 48 * All of the snails produced epiphragms, either calcified or transparent or both. The effect of ambient temperature on epiphragm production is a _ surprising one. Larger numbers of snails laid down epiphragms at low temperatures than at high ones (Figs. 1 and 2). Since higher ambient temperatures favor increased water loss from dormant snails, one would expect that epiphragms would be produced by snails kept at high temperatures. Observation to the contrary either reinforces the notion that epiphragms are not particularly important as barriers to water loss or suggests that mobilization of materials required for the construction of an epiphragm is more difficult at high temperatures. Prolonged exposure to a constant ambient temperature and relative humidity results in epiphragm formation by increasing numbers of snails as the length of the exposure period in- creases. Similarly, the total number of epiphragms secreted by a dormant snail in- creases as the duration of dormancy increases. It appears that the laying down of a single epiphragm is followed by the retraction of the dormant snail into its shell. During extended periods of dormancy, periodic arousals ac- companied by the laying down of additional Vol. 89 (2) THE NAUTILUS 31 TABLE 3. Formation of single and multiple epiphragms under different ambient conditions. Relative Humidity 12% 58% Temp single multiple single multiple (°C) 43% 57% 53% 47% 25.0 (N=61) (N=61) (N = 267) (N= 267) single multiple single multiple 88% 12% 87% 13% BileD (N=185) (N= 185) (N=179) (N=179) The percentages are based on the fraction of the appropriate population that formed either single or multiple epiphragms. Exposures at 25.0°C lasted 21 days; those at 31.5°C lasted 23 days. epiphragms may take place. The purpose of these arousals (which cannot be observed since they do not involve rupture of the original epiphragm) is not clear. They may represent an attempt to more effectively conserve a water supply which is gradually reduced throughout the course of dormancy. The reinforcement of a single epiphragm by additional epiphragms may provide a more effective barrier to water loss and would thus prolong dormancy. Horne (1973) proposed that the chambers between epiphragms may reduce evaporation by decreasing air circu- lation within the spaces created by multiple epiphragms. Alternatively, multiple epiphragm secretion can be viewed as a physiological event which enables the snail to remain dormant for a longer period. If the release of calcium and other inorganic materials from the hemolymph has an effect on the neuromuscular excitability of the snail, then release of additional material for the construction of several epiphragms should theoretically provide for a more profound state of dormancy. Both of the above considerations are discussed in greater length in a companion paper (Rokitka & Herreid, in preparation). Finally, the observation that fecal matter is often found in the compartments created by multiple epiphragms leads one to suspect that periodic arousals occur as metabolic wastes accumulate. Spontaneous arousal during periods of hiber- nation and torpor are common among mam- malian species. Mrosovsky (1971) reviews accounts of periodic arousal. He evaluates the metabolic end-product theory which explains spontaneous arousal on the basis of a need to re-establish normal homeostatic levels of 70 N=95 (dormant for 8-10 weeks) 60 50 40 30 N= 401 (dormant for 6-9 months) PERCENT OF TOTAL POPULATION { 2 3 4 5 6 ile TOTAL NUMBER OF EPIPHRAGMS FIG. 3. Differences in the total number of epiphragms secreted by snails which were dor- mant for different lengths of time. 32 THE NAUTILUS metabolic waste products. While a number of investigators are pursuing the arousal pheno- menon, none has advanced a theory to explain the function of spontaneous arousal that could arousal that could replace the currently-held metabolic end-product theory. Epiphragm formation has been observed in the laboratory during periods that do not coin- cide with Moroccan summers and under con- ditions which do not simulate the climatic variables to which snails are exposed in the field: this raises an interesting point. It is highly probable that epiphragm formation is not merely a function of the environmental con- ditions to which snails are exposed. It is far more likely that the availability of internal organic and inorganic reserves dictates whether or not an epiphragm can be laid down. The concentrations of epiphragm components may quite possibly vary with season. If this is the case, then snails exposed to experimental con- ditions during the summer will not react in the same way as snails exposed to identical con- ditions during the winter. Kostyuk (1968) reports “a substantial increase in calcium concen- tration during spring” in the hemolymph of Helix pomatia. Hyman (1967) reviews reports of increases of calcium in the midgut gland and nephridium during the summer and a decline of calcium during hibernation. These seasonal variations, while not the subject of this report, must be acknowledged as yet another variable which influences epiphragm production. Land snails other than O. lactea form epiphragms in response to dessicating con- ditions. Bonavita (1965) made this suggestion while noting that epiphragm production did not occur in a humid atmosphere. The ecological significance of epiphragm production in habitats which differed in dampness was considered by Cameron (1970) who studied three species of land snail. Bonavita (1961, 1964) drew a parallel between geographic distribution of several species of land snail and the incidence of epiphragm formation under various sets of ex- perimental conditions. The findings of these in- vestigators, coupled with the information presented here, constitute evidence for an association between the incidence of epiphragms and the environmental conditions under which they are formed. April 30, 1975 Vol. 89 (2) ACKNOWLEDGMENTS We are grateful to D. Adler, R. Ham and A. Harris for their contributions to this study. LITERATURE CITED Bonavita, A. 1965. Conditions determinant la production de l’épiphragme chez les Gastero- podes Heélicellinés. C. R. Acad. Sc. Paris., 260: 4093-4094. Bonavita, D. 1961. Conditions de la production de l’épiphragme chez quelques Mollusques Hélicides. C. R. Acad. Se. Paris., 253: 3101- 3102. Bonavita, D. 1964. Conditions écologiques de la formation de l’épiphragme chez quelques Heél- icides de Provence. Vie et Milieu., 15: .721- 755. Cameron, R. A. D. 1970. The survival, weight- loss and behaviour of three species of land snail in conditions of low humidity. J. Zool., Lond., 106: 143-157. Comfort, A. 1957. The duration of life in mol- luses. Proc. Malac. Soc. Lond., 32: 219-241. Grassé, P.-P. 1968 Traite de Zoologie; anatomie, systematique, biologie - Vol. V., Masson, Paris. Horne, F. R. 1973. The utilization of foodstuffs and urea production by a land snail during estivation. Biol. Bull., 144: 321-330. Hyman, L. H. 1967. The Invertebrates - Vol. VI - Mollusca I., McGraw-Hill Book Co., New York. Kostyuk, P. G. 1968. Ionic background of activ- ity in giant neurons of molluscs, in Neuro- biology of Invertebrates, Edited by J. Salanki, Plenum Publ. Corp., New York. Machin, J. 1967. Structural adaptation for re- ducing water-loss in three species of ter- restrial snail. J. Zool., Lond., 152: 55-65. Machin, J. 1972. Water exchange in the mantle of a terrestrial snail during periods of re- duced evaporative loss. J. Exp. Biol. 57: 103- 111. Mrosovsky, N. 1971. Hibernation and the Hypo- thalamus. Appleton-Century-Crofts, New York. Solomon, M. E. 1951. Control of humidity with potassium hydroxide, sulphuric acid, or other solutions. Bull. Ent. Res., 42: 543-559. Winston, P. W. & Bates, D. H. 1960. Saturated solutions for the control of humidity in biolo- gical research. Ecol., 41: 232-237. Vol. 89 (2) THE NAUTILUS 33 THE VALIDITY OF THE SUBGENUS SENILIA GRAY, 1842 (BIVALVIA: ARCIDAE) Victor L. A. Yoloye School of Biological Sciences, University of Lagos Lagos, Nigeria ABSTRACT The erection of the subgenus Senilia Gray, 1842, was based on five con- chological characters, viz. a high trigonal form, an extremely prosogyrate beak and umbo, an oblique break in dentition beneath the wmbo, a massive shell with smooth periostracum, and a small number of ribs. Anadara senilis, the only species of the subgenus, shares its internal anatomical features and the first four of these conchological characters with typical members of the subgenus Ana- dara sensu stricto. The possession of a small number of ribs is here considered in- adequate for continued recogmtion of Senilia as a valid subgenus and the species is here referred to the well-established subgenus Anadara sensu stricto, although the latter is predated by Senilia Gray, 1842. INTRODUCTION Anadara senilis, an endemic West African species, was first described as Arca senilis by Linnaeus in 1758. In 1842, Gray erected the genus Senilia (a genus without species) charac- terized by a large and massive shell with a smooth periostracum. By subsequent designation of Gray in 1847, Arca senilis became the type for the genus. Thiele (1935) classified A. senilis in section Senilia of the subgenus Arca sensu stricto. Nicklés (1950), Buchanan (1954), Yonge (1955) and Longhurst (1958), following Thiele (op. cit.) referred to the species as Arca (Senilia) senilis. Reinhart (1935) assigned the West African bloody cockle to the subgenus Senilia of the genus Anadara. Because of the wide acceptance of Reinhart’s classification of the family Ar- cidae, the West African bloody cockle has sub- sequently been cited as Anadara (Senilia) senilis. According to Gray (1842), Thiele (1935) and Reinhart (1935), the subgenus Senilia is charac- terized by the following: (a) a high trigonal form (b) an extremely prosogyrate (Cardita-like) beak and umbo (c) an oblique break in dentition beneath the umbo (d) a massive shell with a smooth periostracum, and (e) a small number of ribs. The creation of the subgenus by Gray in 1842 was based solely on one conchological character, viz. the possession of a heavy shell with a smooth periostracum. Reinhart (1935) and Thiele (1935) similarly classified the species in the subgenus Senilia on the basis of shell characters. Since it has long been recognized that a classification based upon shell characters alone may lead to erroneous phylogenetic con- clusions, the anatomy of the species was com- pared with that of representatives of the subgenus Anadara sensu stricto (Yoloye, 1969). Such detailed comparison was considered necessary in order to resolve the prevailing con- troversy over the validity of the subgenus Senilia (Iredale, 1913; Reinhart, 1935). REFERENCE 1&2. Ghana Lagoons © 100 200 300 400 500 fee SES a MILES FIG. 1. Map of West localities sampled. Africa showing the 34 THE NAUTILUS MATERIALS AND METHODS The specimens used in this work were collect- ed from the following four areas along the coast of West Africa (Figure 1): Bunce River estuary in Sierra-Leone; Princess-town lagoon in Ghana; Kuramo Waters near Lagos, Nigeria; and An- doni Flats in the Niger Delta. The anatomy was studied in dissections as well as in serial sections of specimens fixed in Bouin’s fluid, embedded in paraffin wax and stained in Erhlich’s haematoxylin. RESULTS AND CONCLUSIONS The present work (see Yoloye, 1969 for details) shows that the final form of the shell FIG. 2. Anadara lagoon near Lagos, Nigeria) (upper figure) and Quadrate and trigonal specimens of senilis from tidal lagoon (Kuramo non-tidal lagoon (Princess-town lagoon in Ghana) (lower figure). Note also the highly prosogyrate beak of the latter. (Photos courtesy of Joseph Rosewater). April 30, 1975 Vol. 89 (2) of the West African bloody cockle is greatly in- fluenced by environmental conditions. Specimens collected from tidal waters such as the Kuramo lagoon and the Andoni Flats of the Niger Delta have a quadrate outline (Figure 2A), while specimens from non-tidal lagoons such as the Princess-town lagoon in Ghana have a high trigonal outline (Figure 2B). In addition, only shells of populations of Anadara senilis from non-tidal lagoons have extremely prosogyrate umbones. The two morphotypes, however, grade into one another in localities where en- vironmental conditions are variable. They, therefore, belong to the same species (Nicol, 1964, personal communication). In view of the fact that all populations of A. senilis do not have high trigonal forms or ex- tremely prosogyrate umbones, these two features cannot be regarded as diagnostic nor should they be cited as valid criteria for the creation of the subgenus Senilia. A comparison of the shells of Anadara senilis with those of members of the subgenus Anadara s. s. shows that an oblique break in dentition below the umbo is found also in Anadara granosa (see Purchon, 1956, fig. 2; 1958, fig. 3) and Anadara antiquata, the type species of the subgenus (see Grassé, fig. 1735). Similarly, many species in the subgenus Anadara s.s. have massive shells with smooth periostracum. It seems, therefore, that of the five conchological characters upon which the erection of the subgenus Senilia is based, only the possession of relatively few and wide ribs (9-15) is peculiar to Anadara senilis, the only species in the subgenus. Functional anatomical study shows also that the internal anatomy of Anadara senilis is not fundamentally different from that of Anadara granosa, A. bisenensis and A. trapezia which are regarded as typical members of the subgenus Anadara s. s. (Reinhart, 1935; Heath, 1941). The structure and ciliary currents of the ctenidia and labial palps of Anadara senilis are both essentially as described for A. granosa (Purchon, 1956), A. trapezia (Sullivan, 1960), A. anomala, A. cuneata and A. antiquata (Lim, 1966). In Anadara granosa, however, there is an anteriorly directed current at the ventral edges of the gills (Purchon, 1956). This current is Vol. 89 (2) posteriorly directed in A. senilis, A. antiquata, A. anomala and A. cuneata (Lim, 1966). The ciliary currents on the labial palps of A. senilis and A. granosa differ from those of the three species of Anadara s. s. described by Lim (1966) in that the currents in the transverse grooves are rejectory and do not run into the lateral oral groove. The structure of the stomach, ‘kidneys’, heart and sense organs of A. senilis are also closely comparable with those of A. granosa and A. bisenensis (Heath, 1941; Sullivan, 1960). In Anadara senilis, the rectum runs through the ventricle. An identical situation occurs in Anadara trapezia (Sullivan, 1960). In A. bisenen- sis (Heath, 1941), however, the rectum is ventral to the ventricle. It, therefore, seems that the relationship between the rectum and the ven- tricle is variable in the subgenus Anadara s. s. and A. senilis falls within the range of variation. In view of the facts that most of the significant conchological characters as well as the internal anatomy of Anadara senilis is identical with that of members of the subgenus Anadara s. s., it is here suggested that the possession of a small number of ribs alone does not justify the erection of a separate subgenus for Anadara senilis. This character should be of specific significance only (see also Reinhart, 1935, p. 9). The species should thus be placed with other species in the subgenus Anadara sensu stricto. Senilia Gray, 1842 predates and should nor- mally have priority over Anadara Gray, 1847. The popular acceptance of Reinhart’s (1935) classification as well as the subsequent established usage of Anadara in the literature suggest that the rule of priority should be waived in favor of Anadara in this case. LITERATURE CITED Buchanan, J. B. 1954. Marine molluscs of the Gold Coast West Africa. Journal of the West African Science Association 1(1): 30-45. THE NAUTILUS 35 Grassé, P. P. 1948. Traité de Zoologie, Paris, vol. 5. Heath, H. 1941. The anatomy of the Pelecypod family Arcidae. Trans. Am. Phil. Soc. 31: 287-319. Iredale, T. 1913. Proc. Malac. Soc. Lond. 10: p. 301. From Reinhart, P. 1935, Classification of the Pelecypod Family Arcidae. Bull. Mus. Mist. Nat. Belg. 11(13): 1-67. Lim, C. F. 1966. A comparative study of the cil- iary feeding mechanisms of Anadara species from different habitats. Biol. Bull. Mar. biol. Lab. Woods Hole. 130: 106-117. Longhurst, A. R. 1958. An ecological survey of the West African Marine Benthos. Colonial Office Fish. Publs. No. 11, 102 pp. Nicklés, M. 1950. Manuels Quest-Africain. Mol- lusques Testaces marins de la Cote occiden- tale d’ Afrique. Owen, G. 1959. The ligament and digestive sys- tem in the Taxodont bivalves. Proc. Malac. Soc. Lond. 33: 215-224. Purchon, R. D. 1956. The biology of ’Krang’, the Malayan Edible Cockle. Proc. Sci. Soc. Malaya, 2: 61-68. Purchon, R. D. 1956. The stomach in the Fili- branchia and Pseudolamellibranchia. Proc. Zool. Soc. Lond. 129: 27-60. Purchon, R. D. 1958. Phylogeny in the Lamelli- branchiata. Proc. Centinary and Biocentinary Congr. Biol. Singapore, 69-82. Reinhart, P. W. 1935. Classification of the Pe- lecypod Family Arcidae. Bull. Mus. roy. Hist. nat. Belg. 11(13): 1-67. Sullivan, G. E. 1960. Functional morphology, microanatomy and histology of the ‘Sidney Cockle’ Anadara trapezia (Deshayes). Austr. Jour. Zool. 9: 219-257. Thiele, J. 1935. Handbuch de systematischen Weichtierkunde. Dritter Teil. Class Bivalvia. Jena. Yoloye, V. L. A. 1969. On the biology of the West African ‘Bloody Cockle’, Anadara (Sen- ilia) senilis Linne’. Unpublished Ph. D. Disser- tation, University of Ibadan, Ibadan, Nigeria. Yonge, C. M. 1935. A note on Arca (Senilia) senilis Lamarck. Proc. Malac. Soc. London, 31: 202-208. 36 THE NAUTILUS April 30, 1975 Vol. 89 (2) SCALARIFORMY IN THE POND SNAIL, LYMNAEA STAGNALIS Eva Pip Department of Botany University of Manitoba Winnipeg, Manitoba R3T 2N2 ABSTRACT A brief review and a new report of scalariformy in Lymnaea stagnalis (Linné) are presented. Theories dealing with the cause of phenotypic uncoiling m gastropods are reviewed. Very little is known about the occurrence of scalariformy in Lymnaea stagnalis (L.), although this species is common throughout much of its circumboreal range (F. C. Baker, 1928) and has been extensively studied. The scarcity of reports regarding this phenomenon in L. stagnalis would seem to indicate that its incidence is very rare. F. C. Baker (1911) noted that the Lymnaeidae are subject to scalariformy and reported having seen an undetermined number of specimens of L. stagnalis exhibiting this anomaly from Spoon- bill Slough, Deuel County, South Dakota. Huben- dick (1951) provided a line drawing of a scalariform L. stagnalis but the locality was not given. Working with material from the U.S.S.R., Zhadin (1952) commented that scalariformy oc- curs very rarely among the Lymnaeidae but cited no examples. A photograph of a_ scalariform specimen of L. stagnalis was provided by Pip and Paulishyn (1970). This specimen was collected at Jackson’s Lake, 3 km southeast of Sidney, Manitoba, in August, 1970. The substrate in this area was sand, with an abundance of vegetation. The authors reported that all other individuals examined from this locality were apparently nor- mal. Subsequently Jackiewicz (1972) figured a specimen that had been collected at Debinie near Poznanie in Poland in 1928. Clarke (1973) noted the presence of one scalariform specimen among the 141 lots of L. stagnalis examined from the Canadian Interior Basin; it was collected from a farm pond 6 miles southwest of Abernethy, Saskatchewan. The remainder of the lot from this locality was apparently normal. Another specimen (Fig. 1) was collected in Katharine Lake, Riding Mountain National Park, Manitoba in August, 1974 by Dr. John M. Stewart. The bot- tom in this area was sand and gravel, with patch- es of Potamogeton, Myriophyllum and Chara. Again, other individuals of L. stagnalis examined from this locality were apparently normal. The three available figures (Pip and Paulishyn, 1970; Jackiewicz, 1972 and Fig. 1 below) show an abrupt onset of the anomaly in initially non- scalar shells. The rate of forward progression of coiling along the shell axis has apparently been altered, resulting in subsequent disjunction of the whorls and progressive “uncoiling” of the shell. The cause of scalariformy is unclear (Pip and Paulishyn, 1970). F. C. Baker (1911) postulated that such deformity may be due to disease, ac- cident or parasitism. Jackiewicz (1972) cited evidence of mechanical injury in the shell that she figured; no external evidence of injury is FIG. 1. Dorsal, ventral and lateral views of a scalariform L. stagnalis L. collected in Katharine Lake, Riding Mountain National Park, Manitoba, in August, 1974. Scale is in mm. Vol. 89 (2) apparent in the two Manitoban specimens. The theories dealing with uncoiling in gastropods have been briefly reviewed by Jackiewicz (1972). According to Boettger (1944 in Jackiewicz, 1972), phenotypic uncoiling may be caused by foreign bodies which interfere with the sub- sequent construction of the shell. According to Rotarides and Schesch (1951 im Jackiewicz, 1972), uncoiling and even breakage of the axis may be due to mechanical injury. Geyer (1929 in Jackiewicz, 1972) has suggested that un- coiling may be due to injury of the axis; he has noted the occurrence of this phenomenon in mollusca associated with the algal stoneworts of the Characeae. LITERATURE CITED Baker, F. C. 1911. The Lymnaeidae of North and Middle America. Chicago Acad. Sci. Spec. Pub. No. 3, 539 pp. THE NAUTILUS 37 Baker, F. C. 1928. The Fresh Water Mollusca of Wisconsin. Part I. Wis. Geol. Nat. Hist. Sur- vey Bull. 70, 507 pp. Clarke, A. H. 1973. The freshwater molluscs of the Canadian Interior Basin. Malacologia 13: 1-2: 509 pp. Hubendick, B. 1951. Recent Lymnaeidae. Kungl Svenska Vetens. Handl., Fjairde Serien 3: 1: 223 pp. Jackiewicz, M. 1972. Anormalnosci w budowie skorupki niekt6rych mieezakow wodnych. Przeglad Zoologiczny 16: 1: 95-98. (in Polish). Pip, E. and W. F. Paulishyn 1970. Unusual fresh water mollusk collected. Hawaiian Shell News ie isle @, Zhadin, V. I. 1952. Mollusks of Fresh and Brack- ish Waters of the USSR. Keys Fauna USSR. No. 46. Acad. Sci. USSR. (Eng. Trans. Isr. Prog. Trans., Jerusalem, 1965). 368 pp. EATING LAND SNAILS IN PREHISTORIC SOUTHERN TEXAS: ETHNOHISTORIC AND EXPERIMENTAL DATA Thomas R. Hester The University of Texas at San Antonio Division of Social Sciences San Antonio, Texas 78285 In a previous issue of this journal, Clark (1973) presented a brief review of problems surrounding the occurrence of land snails (Rab- dotus sp.) in Texas archaeological sites. Clark and T. C. Hill, Jr. Crystal City, Texas outlined four hypotheses which might explain the large concentrations of these snails in prehistoric occupation sites. In his first hypothesis, which is of particular interest to us, 38 THE NAUTILUS he postulated that “snails were intentionally collected as a source of protein in the diet.” He later noted the lack of empirical data sup- portive of this hypothesis, particularly the ab- sence of ethnographic accounts of Indian con- sumption of land snails. On this latter account, we should like to point out that at least one ethnohistoric report exists which clearly in- dicates that Indian groups in southern Texas did, in fact, consider the land snail as a food resource. Cabeza de Vaca, a captive of the Mariame peoples in south central or southern Texas ca. 1529, has provided a detailed discussion of Mariame subsistence patterns. Quoting from Bishop’s (1933:95) version of Cabeza de Vaca’s narrative: “Then at the end of May we shall go to eat the prickly pear, and snails for garnishing, the best food of all the year’. Another analysis of the Cabeza de Vaca narrative by Krieger (1956) also mentions the eating of snails by the Mariames: “Nothing else was eaten during this season (summer) except large numbers of snails.” Archaeological explorations which we have conducted in southern Texas prehistoric camp- sites have revealed large quantities of land snails in the midden deposits. In particular, we have noted distinct clusters of large, adult Rab- dotus schiedeanus specimens at several sites. They appear to have been sorted or selected ac- cording to size, the largest specimens naturally preferred. (Hester and Hill 1974). None of the shells in these clusters has been broken open or perforated, and we must assume that the snail was extracted by some other means. There is no evidence of the shells having been burned or charred, and no charcoal was associated with the concentrations. Recent experiments by Hill indicate that if snail shells are dropped into boiling water, for a very few minutes, the snail will partially extrude from the shell aperture and can easily be extracted using a mesquite thorn. The shell is not damaged by the boiling, April 30, 1975 Vol. 89 (2) and in fact, Hill could detect only very minor color change. It seems highly likely that the boiling technique could have been used in prehistoric southern Texas for snail extraction; this is particularly true of the late prehistoric sites which have yielded the large clusters of snails, as the late prehistoric peoples had ceramic vessels. In summary, we believe that the ac- cumulations of snail shells found in southern Texas archaeological sites result from human agencies. Southern Texas was occupied in prehistoric times by small groups of hunters and gatherers, known collectively as “Coahuiltecans.” We have noted = an ethnohistoric account of the eating of snails among the Mariames, linked by Newcomb (1961) to the Coahuiltecan linguistic stock. Ar- chaeological excavations in the area have revealed sizable concentrations of Rabdotus snails within sites, and we presume these snails to have been collected as a food resource. The shells in these clusters are not broken or per- forated, but experimental data indicate the snails could have been easily extracted (without damage to the shells) by boiling the shells in water for a short period. LITERATURE CITED Bishop, Morris 1933. The Odyssey of Cabeza de Vaca. The Century Co., New York and Lon- don. Clark, John W., Jr. 1973. The Problem of the Land Snail Genus Rabdotus in Texas Archeo- logical Sites. The Nautilus. 87(1): 24. Hester, Thomas R. and T. C. Hill, Jr. 1974. The Archaeology of Late Prehistoric and Proto- historic Peoples in Southern Texas. Manu- script submitted for publication. Krieger, Alex D. 1956. Food Habits of the Texas Coastal Indians in the Early Sixteenth Cen- tury. Bull. Texas Archeological Soc. 26: 47-58. Newcomb, W. W., Jr. 1961. The Indians of Texas. University of Texas Press, Austin. Vol. 89 (2) THE NAUTILUS 39 A REVIEW OF SUCCINEA WILSONI A COASTAL MARSH SNAIL OF EASTERN NORTH AMERICA F. Wayne Grimm Design and Display Division (National Museums of Canada) 39 McArthur Rd. Vanier, Ontario, Canada ABSTRACT Succinea wilsoni Lea, 1864, a variable coastal marsh succineid, is re-described and compared briefly with closely related species. Along with its genitalia, its unde range of shell variation is discussed and figured. Succinea bayardi Vanat- ta, 1914, Succinea pronophobus Pilsbry, 1948, Succinea crisfieldi Jackson, 1958, Succinea aurea of authors, not of Lea, and Succinea pyrites Hubricht, 1960, are here considered synonyms of Succinea wilsoni. Succinea wilsoni Lea, 1864 Succinea wilsonii Lea, 1864, Proceedings of the Academy of Natural Sciences of Philadelphia 16: 109. Journal of the Academy of Natural Sciences of Philadelphia 2(6): 177, pl. 24 fig. 105 (TYPE-LOCALITY near Darien, Geor- gia). Succinea wilsoni Lea, Pilsbry, 1948, Land Mol- lusca of North America (north of Mexico) 2(2): 823-824, p. 824 fig. 445a (type), b (St. Simon’s Island, Georgia). Succinea bayardi Vanatta, 1914, Proceedings of the Academy of Natural Sciences of Phila- delphia 66: 222, figs. 1-3 (TYPE-LOCALITY Indian River, “Kensington”, Prince Edward Island). Pilsbry, 1948, Land Mollusca of North America (north of Mexico) 2(2): 814-815, 818, p. 814 fig. 440, p. 818 fig. 442 G, g, gl. Succinea pronophobus Pilsbry, 1948, Land Mol- lusea of North America (north of Mexico) 2(2): 809-810, p. 810 fig. 437a (TYPE-LO- CALITY Wilmington, North Carolina). Succinea aurea “Lea”, of authors, not of Lea. Succinea aurea “Lea”, in part, Pilsbry, 1948, Land Mollusca of North America (north of Mexico) 2(2): 814-815, 818, p. 818 fig. 441 A, B, fig. 442 E, F. Succinea pyrites Hubricht, 1960, Nautilus 73(3): 113 ( To replace preceding TYPE-LOCALITY Cape May, New Jersey). Succinea avara “Say”, in part, Pilsbry, 1948, Land Mollusca of North America (north of Mexico) 2(2): 818 fig. 442A, a, fig. 445 d (Sea Isle City, New Jersey). Not of Say. Succinea crisfieldi Jackson, 1958, Maryland Naturalist 28(1-4): 17 (TYPE-LOCALITY Crisfield, Somerset County, Maryland). Description — The shells of mature examples are glossy, smooth, with fine growth lines and occasional fine spiral sculpture, ovate, ranging from short-ventricose to elongate-attenuate; spire acute and tapering, sometimes slightly truncated. The shell color varies, ranging from translucent greenish yellow, through amber, to pale, slightly calcareous orange-yellow. Usually the apices are salmon red, though sometimes they are light pinkish-orange or yellow. The columella is thin, slightly curved to straight, and translucent white. The aperture is oblique and ranges between two-thirds and four-fifths the length of the shell. The suture is moderately impressed, and there are 2.5 to 3.5 whorls. Often, much of the shell is covered with dirt, especially in young examples. Specimens from dry habitats are cleanest. When alive, the animal has a dull, trans- lucent, whitish grey body, flecked on the sides with black, with darker tentacles and a pale sole. The base color of preserved examples is cream, marked with black. Beneath, and around the pneumostome, the mantle is shaded with grey. The edge of the mantle is pale whitish, streaked with conspicuous zones of black which 10 THE NAUTILUS April 30, 1975 Vol. 89 (2) \\ FIG. 1. Succinea wilsoni Lea, shells and genitalia. Aja NMC 64819 Chatham Co., Georgia. B,b NMC 64823 Cape May Co., New Jersey. (topotype of S. pyrites Hubricht). C,e NMC 64818 New Hanover Co., North Carolina. (topotype of S. pronophobus Pilsbry). Dd NMC 64844 Sussex Co., Delaware. E,e NMC 64826 Talbot Co., Maryland. F,£ NMC 63389 Prince Co., Prince Edward Island. (adult topotype of S. bayardi Vanatta). G,g NMC 64817 Somerset Co., Maryland. (topotype of S. crisfieldi Jackson). H,h NMC 69090 St. George’s Distr., Newfoundland. I,i NMC 64824 Charles Co., Maryland. Vol. 89 (2) coalesce to form large black patches. Over the lung, the mantle is shaded or blotched with dark-grey, and elongate black blotches lie parallel to the kidney, which is yellow or green. Behind the kidney, and over the hepatopan- creas, the mantle often bears scattered, irregular, rounded black spots. Genitalia of mature specimens — The _her- maphrodite duct is lightly pigmented with black, crimped, and varies in thickness with the sexual activity of the animal. The seminal vesicle (talon) is variable in size (sometimes quite large), club-shaped, with a median groove FIG. 2. Map showing range of Succinea wilsoni Lea. Closed circle: specimens dissected; solid square: records accepted. THE NAUTILUS 41 which divides it into unequal sections. It is lightly pigmented with black. At its base is the slightly rounded, small fecundation pouch. The albumen gland is granular, yellow, truncated, and variable in size. The prostate gland is large and located in the middle of the genital mass. It is yrounded-truncate and moderately to heavily pigmented with black. Rarely, it is free of pigment. The vas deferens is short, sheathed, and enters the penis behind the apical ex- pansion. The thinly sheathed penis is long, slen- der, and expanded at the apical end (the “epiphallus”). Usually the apical expansion emerges as a conspicuous terminal loop, but sometimes it is sheathed. The small _penial retractor, which is connected to the penis loosely at the base of the loop, also connects to the apex of the sheath. When fully contracted it is short and_ spindle-shaped, and when relaxed it is long and slender. The spermatheca is large, thin, and globose with a small muscle attached. Sometimes the posterior half of the slender, long, uniform spermathecal duct is stip- pled with black, and other times it is free of pigment. The atrium and the vagina are very short, and the free oviduct is curved, and often strongly folded immediately behind the in- sertion of the spermathecal duct. A long muscle is attached to the atrial region. Measurements (in mm.) — Length of Width of Length Width Aperture aperture 9.67 5.90 6.00 3.50 Chatham Co., Ga. 12.00 683 7.33 4.83 Cape May Co., NJ. 11.00 633 7.67 4.83 Wilmington, N.C. Similar species: Succinea urbana Hubricht, 1961, has nearly identical but smaller genitalia. It matures at half the size of S. wilsoni. The shell of S. urbana is much more calcareous than that of S. wilsoni. S. wilsoni frequents salt marshes and fresh estuarine marshes, and S. urbana lives upon exposed, calcareous ground, often quite far from the sea. Succinea concordialis Gould, 1848 (= Suc- cinea unicolor Tryon, 1866) has very similar genitalia but the prostate is unpigmented. It matures and lays eggs when smaller than S. wilsoni, its shell is more rotund, the nuclear whorl is smaller, and the animal is not halophile. 12 THE NAUTILUS All other species which resemble Succinea wilsont have very different genitalia. Specimens dissected: All are in the collection of the Mollusc Unit, National Museum of Natural Science, National Museums of Canada, and were collected by the author unless other- wise stated. GEORGIA: Chatham Co., roadside 2 miles west of Savannah Beach (Leslie Hubricht, coll.). NORTH CAROLINA: New Hanover Co., saltmarsh 2 miles northwest of Wilmington (Hubricht) — topotypes of S. pronophobus Pilsbry. VIRGINIA: Accomack, Northampton, and Mathews Co. MARYLAND: Baltimore City, Baltimore, Harford, Anne Arun- del, Calvert, Charles, St. Mary’s, Kent, Queen Anne’s, Talbot, Dorchester, Wicomico, Somerset (many localities including foot of North 7th St., Crisfield, — topotypes of S. crisfieldi Jackson. DELAWARE: Sussex, Kent, Newcastle Cos; many stations. NEW JERSEY: Cape May, Cape May Co. — topotypes of S. pyrites Hubricht. NEW BRUNSWICK: Charlotte Co., saltmarsh, S.E. edge of St. Andrews (F. W. Schueler and M. Hynenick, coll.). PRINCE EDWARD ISLAND: Prince Co., saltmarsh, Indian River, west side of Hwy. 106, — topotypes of S. bayar- di Vanatta. The town of Kensington is not on the Indian River and has no saltmarshes, but it is the nearest town to the type-locality. NEWFOUNDLAND: St. George’s District, trans- itional fresh-salt marsh, branch of Grand Codroy River at crossroad 0.5 mile southeast of Upper Ferry. Records accepted: GEORGIA: Near Darien (TYPE-LOCALITY), holotype examined; St. Simon’s Island (Pilsbry, 1948, figured); Chatham Co. (Hubricht, 1964, Sterkiana 16: 5-10). SOUTH CAROLINA: Charleston Co. (Hubricht, 1971, Sterkiana 41: 41-44). NORTH CAROLINA: New Hanover Co., Wilmington (Pilsbry, 1948, type- locality for S. pronophobus; Hubricht, 1970, Sterkiana 39: 11-15); also Beaufort, Bertie, Brunswick, Chowan, Craven, Dare, Hyde, On- slow, Pamlico Co. (Hubricht, 1970, loc. cit., listed as pronophobus, Beaufort Co., listed as wilson). VIRGINIA: King George and Nan- semond Cos. (Hubricht, 1971, Sterkiana 42: 41- 45). NEW JERSEY: Cape May and Sea Isle City (Pilsbry, 1948, cited, as S. aurea and S. avara; Hubricht, 1960, Nautilus 73(3): 113). April 30, 1975 Vol. 89 (2) MAINE: Knox Co., Seal Island (N: W. Lermond, Del. Mus. Nat. Hist. no. 96886. Discussion — Succinea wilson is an ex- tremely variable species which appears in several distinct forms. It occurs in scattered colonies throughout its known range, and it may be distributed by birds, by storms, and by tides. Its variation does not appear to be geographic, for many forms may be found within a few miles of each other. Usually each colony is fairly uniform, and the extreme forms are connected by intermediate colonies, not by individuals within the same colony. Such variation is characteristic of species which are distributed adventitiously, because each colony may have originated with one or a few chance arrivals. Justifiably, Swecinea wilsom has masqueraded under a number of names for quite a long period of time. Fortunately, variation in the genitalia is slight. Small dif- ferences in the proportions of the organs are caused by differences in the reproductive cycle or contraction of the organs. As a rule, Succinea wilson is an eurytopic halophile marsh-dweller which occurs most frequently in the freshest zone of saltmarshes. Although it usually occupies estuarine marshes, it has been found in a shaded fresh water swamp which supports Physa, Lymnaea, and Pisidium, as well as in saline marshes a few hundred yards from the ocean. Usually specimens may be found on shaded soil at the bases of sedges and reeds, or on bare soil in full sunlight. In the Chesapeake-Delaware Bay region, where thousands of specimens were ob- served and collected over a period of ap- proximately ten years, the appearance of the shells seemed to be correlated partially with the habitat occupied by the snails. The form which climbs reeds in comparatively fresh marsh- es is thin and elongate with a short spire and a large aperture. This form was called Suc- cinea pronophobus by Pilsbry (1948, loc. cit.). Gradually, colony-by-colony, this form grades in- to one which has a higher spire, a smaller aperture, and a more calcareous shell, and which occupies bare, calcareous, saline ground. Examples of this form have been called Suc- cinea crisfieldi by Jackson (1958, loc. cit.), and Succinea wilsoni by Lea (1864) and Hubricht (1964, 1971, cited). A more rotund form which Vol. 89 (2) occupies saline ground was named Succinea pyrites by Hubricht (1960). Suecinea bayardi Vanatta (1914, cited) was described from im- mature specimens. Colonies of thin examples may be found on the ground in marshes and swamps which vary greatly in salinity and ex- posure, but are low in lime. Depauperate exam- ples have been found on dry waste ground near salt marshes, climbing driftwood and vegetation. The Canadian colonies may have originated with migrating birds. Many marshes were visited in Newfoundland, Prince Edward Island, New Brunswick, and Nova Scotia and only the three colonies reported upon here were found. ACKNOWLEDGEMENTS I am grateful to Leshe Hubricht, R. Tucker Abbott and F. W. Schueler for providing specimens for examination and to Ralph W. Jackson of Cambridge, Maryland, for graciously allowing me to examine his private collection. LITERATURE CITED Hubricht, Leslie 1960. Succinea aurea Lea and S. pyrites, new. The Nautilus 73(3): 113. THE NAUTILUS 43 Hubricht, Leslie 1961. Eight new species of land snails from the southern United States. The Nautilus 75(1): 21-32, 75(2): 60-63. Hubricht, Leslie 1963. Some Succineidae, with a new species. The Nautilus 76(4): 135-138. Hubricht, Leslie 1964. The land snails of Geor- gia. Sterkiana 16: 5-10. Hubricht, Leslie 1970. The land snails of North Carolina. Sterkiana 39: 11-15. Hubricht, Leslie 1971. The land snails of South Carolina. Sterkiana 41: 41-44. Hubricht, Leslie 1971. The land snails of Vir- ginia. Sterkiana 42: 41-45. Jackson, Ralph W. 1958. Maryland Naturalist 28(1-4): 17. Lea, Isaac 1864. Description of six new species of Succinea of the United States. Proceedings of the Academy of Natural Sciences of Phila- delphia 16: 109-111. Pilsbry, H. A. 1948. Land Mollusca of North America (north of Mexico) 2(2): 809-824. Academy of Natural Sciences of Philadelphia, Monographs 3. Vanatta, E. G. 1914. Land and_ fresh-water shells from eastern Canada. Proceedings of the Academy of Natural Sciences of Philadelphia 66: 222-226. GENITAL ANATOMY AND PHYLOGENY OF THE SNAILS, BERENDTIA CROSSE AND FISCHER AND SPARTOCENTRUM DALL (STYLOMMATOPHORA: BULIMULIDAE) Carl C. Christensen and Walter B. Miller Department of Biological Sciences, University of Arizona Tucson, Arizona 85721 ABSTRACT The genital anatomy of Berendtia taylori (Pfeiffer) and Spartocentrum van- duzeei (Hanna) are described. Based on anatomical and conchological evidence it is proposed that Spartocentrum, previously considered a subgenus of Coelocen- trum Crosse and Fischer, be accorded full generic status and that Spartocentrum and Berendtia be transferred from the Urocoptidae to the Bulimulidae. INTRODUCTION Berendtia Crosse and Fischer, 1869, and Spar- tocentrum Dall, 1895, are two genera of land snails which inhabit the peninsula of Baja California, Mexico, and certain nearby islands. Berendtia is a monotypic genus found in the Sierra de la Giganta of the central region of Baja California. Spartocentrum includes several species in the central and southern parts of the peninsula, with additional species occurring on islands in the Gulf of California. It has been considered a geographically isolated subgenus of 14 THE NAUTILUS Coelocentrum Crosse and Fischer, 1872, a taxon otherwise limited to Central America and southern Mexico. Berendtia and Spartocentrum have previously been assigned to the family Urocoptidae, subfamily Eucalodiinae; no other representatives of this family are known to oc- cur in Baja California. Aspects of the anatomy of Berendtia have been studied previously. Binney and Bland (1869) and Crosse and Fischer (1870) described and figured the jaw and radula of Berendtia taylori (Pfeiffer, 1861). Fischer and Crosse (1872, 1873) also discussed these structures, as well as the reproductive and nervous systems. Un- fortunately the description of the genitalia was incomplete and did not include figures. There are no anatomical studies of any species of Spartocentrum in the literature. Knowledge of the structure of the genitalia is 10mm to FIG. 1. Genitalia of Berendtia taylori (Pfeiffer, 1861). La Purisima Canyon, 4.8 km northeast of San Isidro, Baja California Sur. FIG. 2. Genitalia of Spartocentrum vanduzeei (Hanna, 1923). Juncalito, Baja California Sur. FIG. 3. Same, showing enlargement of anterior genitalia. FIG. 4. Genitalia of Rabdotus inscendens (W. G. April 30, 1975 Vol. 89 (2) often indispensable in systematic studies of land pulmonates. In the absence of critical data in this area, the systematic position of these taxa has been determined primarily on the basis of shell characters, which have been in- terpreted as indicating Urocoptid affinities. We have recently collected living representatives of both Berendtia and Spartocentrum and conclude from study of the genitalia and from reevaluation of the conchological data that these snails have been improperly assigned to the Urocoptidae and are instead members of the Bulimulidae. Description of genitalia Berendtia taylor (Pfeiffer, 1861). Fig. 1. Penis with muscular sheath enclosing vas deferens and cylindrical lower portion of penis; penis above sheath swollen, extending partly Binney, 1861). 2.7 km northwest of Valle Per- dido, Baja California Sur. Abbreviations: ag albumen gland; ee epiphallic caecum; ep epiphallus; hd hermaphroditic duct; pe penis; pr penial retractor muscle; ps penial sheath; sd spermathecal duct; so spermoviduct; sp spermatheca; vd vas deferens. Vol. 89 (2) over lower end of epiphallus; epiphallus cylin- drical, continuous with epiphallic caecum, their junction marked by entrance of vas deferens; distal end of epiphallic caecum bearing in- sertion of penial retractor muscle; vagina short; spermatheca globose or ovate, its duct un- branched, with a slight swelling halfway along its length in some specimens; albumen gland curved, the convoluted hermaphroditic duct en- tering at its base; ovotestis embedded in digestive gland. Approximate length of struc- tures (in mm): penis 5.5; epiphallus 6.0; epiphallic caecum 19.0; spermathecal duct 33.0; spermoviduct 31.0 mm. Spartocentrum vanduzeei (Hanna, 1923). Figs. 2, Be General description as above. Length of penis 3.5; epiphallus 3.5; epiphallic caecum 7.0; sper- mathecal duct 33.0; spermoviduct 28.0 mm. Rabdotus inscendens (W. G. Binney, 1861). Fig. 4. General description as above. Length of penis 7.0; epiphallus 13.5; epiphallic caecum 8.5; sper- mathecal duct 42.0; spermoviduct 30.0 mm. Discussion As can be seen from the above description and figures, the genitalia of Berendtia and Spartocentrum are nearly identical to those of the bulimulid genus Rabdotus Albers, 1850. The most important similarities concern the male reproductive organs. In all three genera a sheath encloses the vas deferens and lower por- tion of the penis, the penis above the sheath appears swollen, and the epiphallus is con- tinuous with a long epiphallic caecum which bears the penial retractor muscle at its distal end. As yet only the gross morphology of these organs has been studied. Of particular interest for future work is the structure of the penis. The enlarged upper region of it, above the penial sheath, may correspond to the complex of penial diverticula reported by Van Mol (1971, 1972) in Bulimulus (s. s.) and Naesiotus, bulimulid snails from the West Indies and Galapagos Islands, respectively. The genitalia of several genera of Eucalodiinae have been described and figured; those of Hucalodium Crosse and Fischer, 1868, by THE NAUTILUS 45 Fischer and Crosse (1873), Strebel and Pfeffer (1880, cited in Pilsbry, 1903), and Thompson (1963); of Coelocentrum (s. s.) Crosse and Fischer, 1872, by Strebel and Pfeffer (op. cit.); of Anisospira Strebel and Pfeffer, 1880, by Pilsbry (1903) and Thompson (1968); and of Dissotroms Bartsch, 1906, by Thompson (op. cit.). Comparison of these accounts with the data given above for Berendtia and Spar- tocentrum shows that these two taxa are unlike the Eucalodiinae in their genital structure. Once again, the male genitalia are of primary im- portance. Unlike Berendtia and Spartocentrum, the Eucalodiinae have a relatively short penis which receives the insertion of the penial retractor muscle directly on the penis itself or on a short penial diverticulum. There is no FIG. 5. Berendtia taylori (Pfeiffer, 1861). San Javier, Baja California Sur. Length 50.6 mm. FIG. 6. Spartocentrum vanduzeei (Hanna, 1923). 1.6 km south of Chuenque, Baja California Sur. Length 24.1 mm. FIG. 7. Rab- dotus ramentosus (Cooper, 1891). Hills 5.1 km northeast of Santa Catarina, Baja California Sur. Length 23.6 mm. 16 THE NAUTILUS epiphallic caecum and the penis lacks a sheath. We believe that the genitalia indicate a close relationship of Berendtia and Spartocentrum to Rabdotus, in the family Bulimulidae, and con- flict with the present assignment of these genera to the family Urocoptidae. A reexamination of the conchological features of Berendtia and Spartocentrum shows that these characters are consistent with the proposed close relationship to Rabdotus. The sculpture of the nuclear whorls consists of ver- tical riblets, as in Rabdotus. While the shells of these two genera (figs. 5, 6) are more slender and elongated than those of most species of Rabdotus, they are similar to those of the subgenus Plicolumna Cooper, 1895, such as R. (P.) ramentosus (Cooper, 1891) (fig. 7). Berendtia and Spartocentrum resemble many Urocoptids in their ribbed sculpture and elongated outline, yet differ from them in im- portant features. Most eucalodiine Urocoptids lose the initial whorls of the shell and close the resulting break with a calcareous plug. Berend- tia and Spartocentrum retain these whorls throughout life. The Rabdotus-like ribbed sculp- ture of the first embryonic whorls is also unlike that found in the Eucalodiinae. Pilsbry (1903), recognizing these distinctions, termed Spartocentrum an “aberrant” subgenus of Coelocentrum. Hanna (1923) predicted that it would eventually be given full generic status. Berendtia has long been recognized as a distinct genus. CONCLUSION Based on the anatomical and conchological evidence discussed above, we propose that Spar- tocentrum be accorded generic status and that it and Berendtia be transferred to the Bulimulidae. Rabdotus has speciated extensively in Baja California; in view of the fact that no other closely related Bulimulids occur in Baja California or in adjacent regions of mainland Mexico, this group is the probable ancestor of these two unusual genera, which are autochthonous to Baja California. At present in- sufficient information is available to determine which subdivision of Rabdotus is most closely related to Berendtia and Spartocentrum. A\l- though similar in form to members of the sub- genus Plicolumna, Berendtia and Spartocentrum April 30, 1975 Vol. 89 (2) do not seem to be descended from that group, as they lack the keeled nuclear whorls which distinguish that subgenus from other Rabdotus. ACKNOWLEDGEMENTS We wish to thank Mrs. Margaret M. Vescovi, who prepared the illustrations which accompany this report. LITERATURE CITED Binney, W. G. and T. Bland 1869. Land and fresh water shells of North America. Part 1. Pulmonata Geophila. Smithson. Mise. Collect. 8(3) (194); i-xil + 1-316. Crosse, H. and P. Fischer 1869. Diagnoses mol- luscorum novorum reipublicae Mexicanae. Jour. Conchyliol. 17: 190-192. Crosse, H. and P. Fischer 1870. Etude sur la machoire et l’armature linguale des Cylindrel- lidae et de quelques voisins sous le rapport conchyliologique. J. Conchyliol. 18: 5-27, pl. 3-5. Dall, W. H. 1895. Synopsis of the subdivisions of Holospira and some related genera. The Nautilis 9: 50-51. Fischer, P. and H. Crosse 1870-1878. Etudes sur les mollusques terrestres et fluviatiles du Mexique et du Guatemala. Mission scientifi- que au Mexique et dans l’Amerique Centrale. Recherches zoologiques. Pt. 7. Paris. 1: 1-702, pl. 1-31. [section on Berendtia: 1872, 1873; section on Hucalodium: 1873] Hanna, G. D. 1923. Expedition of the California Academy of Sciences to the Gulf of California in 1921: land and freshwater mollusks. Proc. Calif. Acad. Sci. (4) 12: 483-527, pl. 7-11. Pilsbry, H. A. 1903. Manual of Conchology (2) 15: i-vil + 1-323, pl. 1-65. Strebel, H. and G. Pfeffer 1880. Beitrag zur Kenntnis der Fauna mexikanischer Land- und Siusswasser-Conchylien. Pt. 4. Hamburg. 112 p., 15 pl. [not seen] Thompson, F. G. 1963. New land snails from El Salvador. Proc. Biol. Soc. Wash. 76: 19-82. Thompson, F. G. 1968. Some Mexican land snails of the family Urocoptidae. Bull. Fla. State Mus. Biol. Ser. 12: 125-183. Van Mol, J. -J. 1971. Notes anatomiques sur les Bulimulidae (Mollusques, Gasteropodes, Pul- mones). Ann. Soc. R. Zool. Belg. 101: 183-226. Van Mol, J. -J. 1972. Au sujet d’une nouvelle et remarquable espece de Bulimulidae des Iles Galapagos. Bull. Inst. R. Sci. Nat. Belg. Biol. 48(11): 1-7. 7 Vol. 89 (2) THE NAUTILUS 47 RADIODISCUS HUBRICHTI (PULMONATA: ENDODONTIDAE) NEW SPECIES FROM THE OLYMPIC PENINSULA, WASHINGTON! Branley A. Branson Department of Biological Sciences Eastern Kentucky University Richmond, Kentucky 40475 Henderson (1929, 1936), in his rather ex- tensive collecting, failed to disclose the presence of Radiodiscus in the state of Washington, as have all subsequent collectors. The generic name was proposed by Pilsbry and Ferriss (1906) to include a small number of small to minute en- dodontid snails that ranged from western Oregon to Arizona southward to Terre del Fuego in South America; R. millecostatus, from the Huachuca Mountains of Arizona, was presented as the genotype. The _ principal distinguishing feature of the genus are the em- bryonic whorls which are minutely engraved with spiral sculpture, whereas the remainder of the shell is radially costulate. H. B. Baker’s (1930) discovery of a new species, R. abietum, in Idaho extended the range of the genus to that state. Pilsbry (1948) summarized the published information on the two U.S. species, and Brunson and _ Russell (1967) reported the last-named species from 10 Montana localities, and that is essentially the present state of knowledge of the genus as far as North American species are concerned. This paper extends that knowledge somewhat, and describes a new species, named in honor of my old friend, Leslie Hubricht, who has spent nearly his entire adult life in the study of terrestrial gastropods. Radiodiscus hubrichti new species Figs. la, b, ¢ Description of holotype (U.S. National Museum, USNM 709470): the palehorn colored, nearly transparent shell is minute, 1.59 mm in diameter, 0.87 mm in height, with three whorls; the last whorl is slightly more than two times ‘ Supported in part by a Sigma Xi-RESA travel grant, and in part by Eastern Kentucky University Faculty grants 422-61 and 42-38. wider than the next to the last (0.52mm/0.25mm), and the wide-open umbilicus, exhibiting all volutions to the apex, measures 0.51 mm and goes into the shell diameter three times; the umbilicus is paralleled by a series of minute, spiral sculptures. The spire is slightly everted, its whorls being separated by a moderately channelled suture; first one and one-half whorls marked by minute spiral sculp- ture, the rest being radially costulate; the costae are rather widely-spaced and extend for only about two-thirds the way on to the base, which is otherwise slightly granular in ap- pearance. The aperture is oblique, and _ slightly descending. The animal is dead white with the exception of a small black blotch over the lung, FIG. 1. Radiodiscus hubrichti, new species. a, apical view; b, apertural view; e, umbilical view. Scale line equals 1 mm. 8 THE NAUTILUS and the foot is very narrow and pigmentless. The following measurements were secured from the several paratypes. Locality 1: old glacial valley of Sams River, Kloochman Rock Quadrangle, S 34, R 10 W, T 24 N, Olympic Peninsula, Washington. Beneath the canopy of a bigleaf maple in piles of leaf litter and licorice ferns. 7 July 1969. Eastern Kentucky University (EKU 10904). Locality 2: Mount Storm King, 4,000 feet mean sea level, Joyce Quadrangle, R 8 W, T 29 N, Olympic National Park, Washington, in litter of buckthrone and western hemlock. 5 July 1969. Chicago Field Museum of Natural History (FMNH_ 175456). Locality 3: three miles up trail from Hoh Rain Forest ranger station, Mount Tom Quadrangle, S 4, R W, T 27 N, 960 feet mean sea level, in bigleaf maple litter, Olympic National Park, Washington. 11 July 1969. Delaware Museum of Natural History (DMNH 75901). Locality 4: Type Locality: Spruce Mountain Quadrangle, northwest corner of S 30, R 12 W, T 27 N, 400 feet mean sea level, in bigleaf maple litter, Olympic National Park, Washington. 12 July 1969. Holotype and three additional specimens (EKU 10847 and 10954). Locality 5: mouth of Duckabush River, U.S. Highway 101, Olympic Peninsula, Washington. 18 July 1969. (EKU 10949). Locality 6: ten miles southwest of Sequim on Palo Alto Road, Tyler Peak Quadrangle, S 30, R 3 W, T 29 N, 1106 feet mean sea level, in red alder and fern litter, Olympic Peninsula, Washington. 15 July 1969. One specimen (EKU 10953). Locality 7: La Poel Point, Lake Cresecent Quadrangle, S 32, R 9 W, T 30 N, 580 feet mean sea level, in salal litter, Olympic National Locality Diameter Height Umbilicus Width ] 1.6 mm 0.50 mm 2 1.5 0.90 0.50 3 1.5 0.70 0.60 4 12 0.46 4 ile7f 0.70 5 1.39 0.79 0.31 5 1.26 0.70 0.35 4 1.50 0.98 0.36 6 1.60 0.91 0.42 7 1.68 0.95 0.47 7 1.60 0.96 0.47 April 30, 1975 Vol. 89 (2) Park, Washington. 12 July 1969. Two specimens (EKU 10952). REMARKS Radiodiscus hubrichti appears to be most closely related to R. millecostatus, from which it differs in being pale-horn-colored rather than chestnut-brown, in having a pale first whorl rather than a bluish white one, in being somewhat smaller, and in having fewer whorls, less deeply channelled sutures. Also, the animal is much paler, and the lung is not mottled. The new species differs from R. abietwm in being much smaller, in having a nearly trans- parent epidermis rather than an opaque one, in color (R. abietum is light chocolate-brown), in having fewer whorls, in having 1% em- bryonic whorls rather than 2 to 2%, and in having a much larger umbilicus. LITERATURE CITED Baker, H. B. 19380. New and problematic west American land snails. The Nautilus 43: 121- 128. Brunson, R. B. and R. H. Russell 1967. Radio- discus new to molluscan fauna of Montana. The Nautilus 81: 18-22. Henderson, J. 1929. Non-marine Mollusca of Oregon and Washington. Univ. Colo. Stud. 17: 45-190. Henderson, J. 1936. The non-marine Mollusca of Oregon and Washington — supplement. Univ. Colo. Stud. 23: 251-280. Pilsbry, H. A. 1948. Land Mollusca of North America (north of Mexico). Acad. Nat. Sci. Phila. Mongr. 3(11)2: 521-1113. Pilsbry, H. A. and J. H. Ferriss 1906. Mollusca of the southwestern states. II. Proc. Acad. Nat. Scr. Phila. 1906: 123-176. Whorls Width Last Whorl Width Spire 344 23/, 35 2” 31/5 2% 0.46 0.75 2% 0.38 0.70 3 0.43 0.86 3 0.50 0.84 oe 0.50 0.93 25% 0.43 0.89 Vol. 89 (2) THE NAUTILUS 49 THE REDISCOVERY OF MORUM PRAECLARUM MELVILL (CASSIDAE) R. N. Kilburn Natal Museum, Pietermaritzburg, South Africa ABSTRACT The previously unlocalized Morum (Cancellomorum) praeclarum Melvill, 1919, inhabits Natal/Zululand waters at depths of 27-250 fathoms. Reasons are given for believing that the holotype was orginally dredged in 250 fathoms off Port Shepstone, Natal, by the Cape Government trawler, the ss. Pieter Faure, in 1901; this is accordingly designated as type locality for the species. Morum praeclarum Melvill, 1919, was based on a solitary specimen, without locality data, purchased by the describer from the MacAn- drew collection. The holotype, now in the National Museum of Wales, Cardiff, U.K. (Dance & Emerson, 1967), has remained supposed- ly unique to this day, and the species unlocalized. Melvill’s figure and description are good, and the shape of the species, notably the constricted nature of the aperture, is quite characteristic, so that recognition presents no problem. In recent years several specimens, clearly repre- senting the “lost” praeclarum, have been taken from the stomachs of fishes caught in Natal/Zululand waters. Moreover the series in the collection of the South African Museum (Cape Town) that was recorded by Sowerby (1903) and Barnard (1963) as the Sino-Japanese Morum macandreun (Sowerby, 1888), is also clearly conspecific. From the latter it is possible to muster a sufficient body of circumstantial evidence not only to indicate with a high degree of probability the origin of the holotype of M. praeclarum, but even to reconstruct details of the type locality. In 1900-1901 the Cape Government conducted a survey of the continental shelf off Natal and Zululand, using the trawler s.s. Pieter Faure; many of the larger Mollusca obtained were sent to G. B. Sowerby (3rd) for identification and recording. Of these, a certain number (including some types) was retained by him and _ ap- parently sold. Now, according to Dance (1966: 216) James J. MacAndrew built up his collec- tion almost entirely by the purchase of shells from dealers, notably Messrs. Sowerby and Fulton. That his purchases included Pieter Faure specimens is proved by a reference in Dautzenberg (1929: 407) to the author having obtained from the MacAndrew collection a syn- type of Nassaria [ = Hindsia] gracilis Sowerby, 1902, one of the species described from Pieter Faure material. Among the specimens retained by Sowerby was at least one specimen of the spe- cies that was recorded by him as Oniscia macan- dreun (teste Barnard, 1963). It is here contended that this in all probability was the shell that Melvill later described as praeclarum. This can- not now be proven (unless MacAndrew’s corres- pondence, if extent, contains some clue), but the alternative is to suppose that no less than two specimens of this striking mollusc were in circu- lation at about the same time, and that the sec- ond not only remained unrecognized by its FIG. 1. Morum praeclarum. Left, 15 miles off Mvoti River, 56 fathoms. South African Museum coll, ex ss. Pieter Faure. 363 X 24,2 mm. Right, off Durban in 160 fathoms, Natal Museum coll., leg. R. Cruickshank. 36,6 X 24,6 mm. 50 THE NAUTILUS owner, but has subsequently completely disap- peared. Simple application of Occam’s Razor is sufficient to resolve the issue. The material of Morum praeclarum retained by Sowerby came from 11 miles off Port Shep- stone, bearing N.W. by W., at a depth of 250 fathoms. (This was one of the few hauls made off the continental shelf, and one of the last of the survey, which dates it as March or April 1901, fide Barnard, 1964). This is here formally designated as the type locality of the species. Melvill’s original description of the general form and Barnard’s detailed description of sculptural and other details should be read in conjunction. M. praeclarum is known from off Neill (O‘Neil) Peak (28° 40’ S.) in Zululand south to the type locality (30° 44’ S.), in 27-250 fathoms. Barnard showed that the Cape St. Blaize locality cited by Sowerby was almost cer- tainly due to a mutilated label. The chief references to the species are as follows: Morum (Cancellomorum) praeclarum Melvill Morum praeclarum Melvill, 1919: 69. Oniscia macandrewr (non Sowerby, 1888); Sow- erby, 1903: 229. Lambidium macandrewi (non Oniscia m. Sower- by, 1888); Barnard, 1963: 15. ACKNOWLEDGEMENTS I am indebted to the Director and Mr. B. F. SUBSTITUTE NAME FOR CONUS ORBIGNYI ARATUS KILBURN, NOM. PREOCC. R. N. Kilburn Natal Museum, Loop Street Pietermaritzburg, South Africa. Dr. Harald A. Rehder has kindly pointed out that Conus orbignyi aratus Kilburn, 1973 (Ann. Natal Mus. 21 (3): 575), proposed for the April 30, 1975 Vol. 89 (2) Kensley of the South African Museum for the loan of their set of Morum praeclarum. LITERATURE CITED Barnard, Keppel Harcourt 1963. Contributions to the knowledge of South African marine Mollusca. Part III. Gastropoda: Prosobranchi- ata: Taenioglossa. Ann. S. Afr. Mus. 47(1): 1- 199. Barnard, Keppel Harcourt 1964. The work of the ss. Pieter Faure in Natal waters, with spe- cial reference to the Crustacea and Mollusca; with descriptions of new species of Mollusca from Natal. Ann. Natal Mus. 16: 9-29. Dance, S. Peter 1966. Shell collecting, an illus- trated history. 7-344 pp + 35 pl. London: Faber & Faber. Dance, S. Peter & Emerson, William K. 1967. Notes on Morum dennisoni (Reeve) and re- lated species. Veliger 10(2): 91-98. Dautzenberg, Philippe 1929. Contribution a l’etude de la fauna de Madagascar. Mollusca Il. Mollusea marine testacea. Fauna Col. France 3: 321-636. Melvill, James Cosmo 1919. Description of Mo- rum praeclarum, sp. noy., with remarks on the recent species of the genus. Proc. Malac. Soc. London 13(3-4): 69-72. Sowerby, George Brettingham 1903. Mollusca of South Africa. Mar. Invest. South Africa 2: 213-232, pls. 3-5. suleate southeast African subspecies of the lirate Japanese Conus orbignyi orbigny Audouin, 1831, is a junior homonym of Conus aratus Gabb, 1873. The substitute trivial name Conus orbigny elokismenos (“scratched in furrows”) is here proposed in its stead. Dr. R. Tucker Abbott informs me (in. litt.) that specimens collected by A. Crosnier from off northwest Madagascar (310 to 428 meters) and by C. P. Fernandes from 400 meters, in mud, off Inhaca, Mozambique, have the charac- ter of both typical orbignyi and elokismenos. Vol. 89 (2) THE NAUTILUS 51 COMPARISONS OF SHELL DIMENSIONS AND VISCERA MASS WEIGHTS IN CORBICULA MANILENSIS (PHILIPPI, 1844) James E. Joy and Laidley E. McCoy Department of Biological Sciences Marshall University Huntington, West Virginia 25701 ABSTRACT Relationships of shell weight, size and wet and dry viscera weights were com- puted for Corbicula manilensis. The highest coefficient of correlation was record- ed for shell length vs. width (0.9993) and the lowest for shell width vs. viscera dry weight (0.8755). Regression analyses were calculated for each of 10 shell and viscera comparisons. INTRODUCTION The present paper is an attempt to determine whether data relating to selected length—weight relationships of Corbicula would be useful in determining the biomass of natural or cultivated populations of the Asiatic clam. While this paper constitutes only the second report of Corbicwa from West Virginia, random collecting in the southwestern portion of the state indicates that Corbicula is well-established here.’ MATERIALS AND METHODS Seventy-two Corbicula manilensis individuals were randomly collected from a riffle area in Mud River, Cabell County, W. Va. (Military grid 901 546, U. S. Geological Survey Map, Bar- boursville Quadrangle, W. Va. — _ Ohio, N3822.5—W8215—7.5) on 10 October, 1973. The collection area was characterized by gravel of a wide range in size overlying a mixture of sand and silt. At the time of collection the riffle area measured 12 M wide and 30 M long. A rake was used to turn the gravel and the clams were collected by hand, placed in a con- tainer, and immediately transported to the laboratory. Each C. manilensis individual was measured for length, the greatest distance 1 Editor’s note: Live specimens of the Asian clam, Cor- bicula, are now being sold by a Florida wholesale aquatic nursery under the name of the “Dwarf Clam”, and they have been found for sale in retail fish hobby stores in New Jersey. This will probably speed the distribution of the clam throughout its maximum possible range in the United States and eventually the remaining Americas—R. T. Ab- bott. measured on a line perpendicular to a line form- ing a right angle with the hinge site, and width, the greatest shell dimension from the right to left valve. A razor blade was then in- serted between the valves to sever the anterior and posterior adductor muscles (Pennak, 1953). The visceral mass was removed from each clam, blotted dry on a paper towel, weighed and recorded as wet weight. The wet weight samples were then placed in an oven to dry at 80°C. After a 12-24 hour period the samples were removed from the oven, weighed and recorded as dry weight. Shells were blotted and allowed to dry thoroughly at room temperature before weighing. All weights were recorded to the nearest ten-thousandths of a gram on a Bosch S2000 balance. Viscera wet weights and_ shell weights were recorded on the same day the clams were collected. RESULTS AND DISCUSSION Coefficients of correlation were calculated for ten different relationships pertaining to shell size and weight, and viscera weight of Corbicula manilensis (Table 1). The highest coefficient of correlation (0.9993) was recorded for length vs. width and the lowest (0.8755) for width vs. vis- cera dry weight. High r-values represented in Table 1 were anticipated since an r-value of 0.98 for width vs. viscera dry weight was recorded by Rinne (1974) for Corbicula from Arizona. High r-values give investigators the advantage of quickly and accurately determining various parameters of living Corbicula individuals by measuring only their shell length or width. It 2 THE NAUTILUS April 30, 1975 Vol. 89 (2) 3.0 Fig 1 35 . Fig 2 3.0 ee < = - x ¥ ae Fas < = 2.0 . v Se a= vy s f- ate 2.0 r i x z ae =z : . - . z = 2 © 5 = a & a z f/f = 2 - we = = “uw = y Of 15 2 “= _ = “fl e - = oe _ = 1.0 3 |Le = xz . = = 1.0 w = 0 wo =-0. 0.6618 --) y =-0.0167+ x AS y=-3.0908+2.8188 x y 771.1866 +1,0332 x 1.0 2.0 2.0 40 6.0 0.5 15 2.5 SHELL WIDTH (CM) SHELL WEIGHT (GM) VISCERA WET WEIGHT (GM) 3.5 52 : ¥v : 2.0 a 8 ae = = secevelel ini =x = g Pai a Macs & z - ik 2 : : oe 15 2 y =) "1 ¢ Phd Ae Fe rm « cA = = = “ y 71.1463 41.5110 x z y "3.0071 + 4.1871 x w 05 y =-0.3012+ 0.2409 x 2.0 4.0 6.0 05 5 25 SHECU EUG Hiia (Gi) VISCERA WET WEIGHT (GM) 01 03 05 VISCERA DRY WEIGHT (GM) Fig 9 6.0 Fig 8 Vy 6.0 2.0 F = : x ; = Hh 2 4 ues 6 © 40 nes © 40 cube te _ oe by ». . = 5 2 go O80 iS 6 5 ¥ 3 iE 3 ro >, = rrr} = > > = o - -~ > 10 z = > = 210 2.0 w” w“ — = / z= y =-0.1687+ 0.2592 x y =-0.0455+0.3546 x y =-0,0413+0.0851 x ww 0.1 0.3 0.5 0.5 15 25 0.1 0.3 0.5 VISCERA DRY WEIGHT (GM) VISCERA WET WEIGHT (GM) VISCERA DRY WEIGHT (GM) FIGS. 1—10. Scatter diagrams depicting various relationships between shell dimensions, weight, and wet and dry viscera weights of Corbicula manilensis. Each point represents a single individual. The regression analysis equation is included in the lower right corner of each figure. ' » Vol. 89 (2) _ 2.0 Fig 10 : S fo : ls = ote o a - 3 1,0 = 3 - . = * = a y=-0.0195+0,2273x « a as : =) > 0.1 0.5 0.3 VISCERA DRY WEIGHT (GM) TABLE 1. Coefficients of correlation for various parameters concerning shell size and weaght, and viscera weight of Corbicula manilensis. r-value Length vs. Width 0.9993 Length vs. Shell Weight 0.9607 Length vs. Viscera Wet Weight 0.9407 Length vs. Viscera Dry Weight 0.9143 Width vs. Shell Weight 0.9599 Width vs. Viscera Wet Weight 0.9370 Width vs. Viscera Dry Weight 0.8755 Shell Weight vs. Viscera Wet Weight 0.9811 Shell Weight vs. Viscera Dry Weight 0.9779 Viscera Wet Weight vs. Viscera Dry Weight 0.9325 should be emphasized that present data was based on clams, taken from a riffle area during the autumn. While seasonal differences in visceral weight will conceivably occur because of changes in available food, depth of collection apparently did not influence data of the present study since Rinne (1974) noted that an “Analysis of variance showed non-significant differences between numbers, sizes, and biomasses relative to depth”. THE NAUTILUS 53 Regression analyses were calculated for each of the ten shell and viscera comparisons upon which r-values were computed (Figs. 1—10). When plotted against a linear regression curve, individual clams exhibit an amazingly direct relationship between shell length and width (Fig. 1). The same strict relationship is also evident, when plotting shell length vs. weight (Fig. 2), shell width vs. weight (Fig. 5), and wet and dry viscera weights (Fig. 10). In the remaining six figures, larger clams, when plot- ted against the regression curve, tend to fall below the curve, suggesting that the parameter on the axis increased at a greater rate than the parameter on the ordinate. For example, once Corbicula attained a shell length of 2.3 em the rate of increase in wet weight became greater than the rate of increase in shell length. Prior to a length of 2.3 cm, the reverse was true (Fig. 3). The same pattern was evident when viscera weight was compared with shell weight. Viscera weight in larger clams in- creased at a greater rate than shell weight (Figs. 8 & 9). This was not altogether unique, however, since Kabayashi and Watable (1959) found that the rate of shell deposition in pearl oysters decreased with age. Another interesting facet concerning weight of C. manilensis was that dry viscera weight increased at a greater rate than wet visceral weight, resulting in proportionally higher dry weights in larger clams (Table 2, Fig. 10). Moreover, higher r- values in viscera wet weight than viscera dry weight indicate noncombustable mineral uptake varied more per individual than water content (Table 1). Additional work (unpublished) in our laboratory by Mr. John Dingess has indicated TABLE 2. Dry weight expressed as a proportion of wet weight relative to shell length. No. Corbicula Mean dry wt. expressed as a percentage Shell length (cm) in sample of mean wet wt. > 2.50 9 23.23 2.01 — 2.50 34 20.29 1.51 — 2.00 11 LEST 1.01 — 1.50 15 16.71 < IH 3 9.27 54 THE NAUTILUS that comparisons of shell dimensions of Lamp- silis radiata luteola (Lamarck, 1819) are not correlated as closely as those of Corbicula. For example, shell length vs. width in L. r. luteola has an r-value of 0.6907 for males and 0.6757 for females, both considerably below the calculated 0.9993 for Corbicula. LITERATURE CITED Kobayashi, S. and N. Watable 1959. “The Study April 30, 1975 Vol. 89 (2) of Pearls.” Gihodo Press, Tokyo. (Not seen; vide, Wilbur, K. M. and C. M. Yonge. 1964. Physiology of Mollusca. Academic Press, New York and London). Pennak, P. W. 1953. Fresh Water Invertebrates of the United States. The Ronald Press Co., New York. Rinne, J. N. 1974. The introduced Asiatic clam (Corbicula), in central Arizona reservoirs. The Nautilus 88(2): 56-61. TYPE MATERIAL OF SOME CUBAN HELICINIDS Morris K. Jacobson Associate in Malacology The American Museum of Natural History Central Park West at 79th St. New York, N.Y. 10024 During a recent inspection of the Antillean land shells in the Newcomb Collection of Recent Mollusks, Department of Geological Sciences, Cornell University, assembled by Dr. Wesley Newcomb (1811-1892) and_ presently stored in the building formerly occupied by the Paleontological Research Institute at 109 Dear- born Place, Ithaca, New York, the writer located some type material of Cuban helicinids which should be called to the attention of in- terested students. The locality of all the lots consists solely of the word “Cuba” but Newcomb added “ex auct.” to the labels, thereby verifying their status as syntypes. In several revisions of the Cuban helicinids, Clench & Jacobson (1968, 1970, 1971) and Boss & Jacob- son (1973) designated lectotypic specimens from material in the collection of the Museum of Comparative Zoology in Harvard University. In three cases, as noted below, these authors were unable to locate some typological material. The availability of the Newcomb Collection now per- mits the selection of additional types. Other data cited below add to our knowledge of some poorly known taxa, mainly specimens of species described by Poey. There is presumably more such material in the Museo Poey in Havana, and a report that a catalog of this material may soon appear in print is very welcome. The Newcomb Collection was described by ' Nol. 89 (2) Clarke (1960), to whom the author of this report is obligated for having called his at- tention to the Cuban shells in the Collection. I am much indebted to the kindness of Dr. John W. Wells, Professor Emeritus of Cornell University, who provided me with every facility to examine the Newcomb Collection. Dr. William K. Emerson of the American Museum of Natural History discussed certain problems with me and checked the manuscript. The list of these types follows: nodae Arango, Helicina. 1862: Jour. de Con- chyl. 10: 409 [non Sowerby, 1866] (Guane [Pinar del Rio)). Newcomb Coll. 24076, 4 cotypes. Syn. of Troschelviana (Cubaviana) rubromarginata (Gundlach, 1858). NOTE: Clench & Jacobson (1971: 426) selected as lectotype MCZ 73781 ex Arango. politula Poey, Helicina. 1852: Memorias sobre historia natural isla de Cuba 1: 113 (Santa Cruz en tierra de D. Francisco Adolfo Sauvalle [Pinar del Rio?]. Newcomb Coll. 24207, 4 cotypes. Syn. of Troschelviana (Cubaviana) pyramidalis (Sowerby, 1842). NOTE: Clench & Jacobson (1971: 424) supposed that the type was in the Museo Poey, not seen. proxima Gundlach MS Pfeiffer, Helicina. 1858: Malak. Blatt. 5: 49 (Buena Vista, Orien- te). Newcomb Coll. 24188, 2 cotypes. Syn. of Aleadia (Penisoltia) minima (Orbigny, 1842). NOTE: Type previously reported as destroyed (Boss & Jacobson, 1973:338). rubella Wright MS Pfeiffer, Helicina. 1864: Malak Blatt. 11: 107 /non Green, 1833] (Cayos de San Felipe [Pinar del Rio]). Newcomb Coll. 24117, 4 cotypes. Syn. of Troschelviana (T) erythraea (Sowerby, 1866). NOTE: Clench & Jacobson (1971: 418) selected as lectotype MCZ 73779 ex Wright. stellata Velasquez MS Poey, Helicina. 1851: Memorias sobre historia natural isla de Cuba 1: 117 (Sierra de Casas, [sic] Isla de Pinos). Newcomb Coll. 24212, 5 cotypes. Is Priotrochatella stellata (Poey). NOTE: Type reported as “not seen” by Clench & Jacobson (1970: 70). Poey erroneously transposed the THE NAUTILUS 55 names Sierra de Casas and Sierra de Caballos (Clapp, 1918: 48). subglobulosa Poey, Helicina. 1851: Memorias sobre historia natural isla de Cuba 1: 115, pl. 12, figs. 17-21 (Trinidad [Oriente]). Newcomb Coll. 24140, 3 cotypes. subunguiculata Poey, Helicina. 1857: Memorias sobre historia natural isla de Cuba 2: 34 (Sierra de Guane [Pinar del Rio]). Newcomb Coll. 24214, 4 cotypes. Is Viana regina subunguiculata (Poey). NOTE: Clench & Jacobson selected as lectotype MCZ 73672 ex Poey. suturalis Gundlach MS, Pfeiffer, Helicina bellula. 1860: Malak. Blatt. 6: 80 (La Cubana, Yateras, Guantanamo, Oriente). Newcomb Coll. 23955, 5 cotypes. Syn. of Alcadia (Idesa) spec- tabilis (Pfeiffer, 1858). NOTE: Boss & Jacobson (1973: pl. 6, figs. 7-9) figured MCZ 74029 ex Anthony ex Gundlach. LITERATURE CITED Boss, Kenneth J. and Morris K. Jacobson 1973. Monograph of the genus Alcadia in Cuba. ibid. 145(7): 311-357, 6 pls., 2 figs., 3 maps. Clapp, W. F. 1918. A new Priotrochatella from the Isle of Pines, Cuba. The Nautilus 32(2): 47-51, pl. 4. Clarke, Arthur H. Jr. 1960. Catalogue and II- lustrations of Mollusks Described by Wesley Newcomb, with a Biographical Resume. Bull. Amer. Paleont. 41(188): 135-160, pl. 17. Clench, William J. and Morris K. Jacobson 1968. Monograph of the Cuban Genus Viana (Mol- lusca: Archaeogastropoda, Helicinidae). Brev- iora, Harvard Univ., No. 298, 25 pp., 4 pls., 5 maps. Clench, William J. and M. K. Jacobson 1970. The genus Priotrochatella of the Isle of Pines and Jamaica. Occ. Pap. Mollusca, Har- vard Univ., 3(39): 61-80, pls. 17-20, 1 map. Clench, William J. and M. K. Jacobson 1971. A monograph of the genera Calidviana, Us- tronia, Troschelviana, and Semitrochatella in Cuba. Bull. Mus. Comp. Zool., Harvard Univ., 141(7): 403-463, 8 pls., 3 figs. 56 THE NAUTILUS April 30, 1975 SEASONAL MIGRATION AND DENSITY PATTERNS OF THE FRESH WATER SNAIL AMNICOLA LIMOSA Thomas J. Horst! and Robert R. Costa? Department of Biological Sciences State University of New York, College at Brockport, New York 14420 ABSTRACT The life cycle and dispersion of the freshwater snail Amnicola limosa (Say) were studied unth interest in seasonal migraton patterns. It was initially hypothesized that seasonal migration between shallow and deep water would be adaptive for snails living in temperate lakes with seasonally fluctuating benthic environments. The thickness of ice would preclude them from shallow water im winter. During summer months snails would be concentrated in shallow water. This pattern of seasonal migration was supported by studies of a small lake in western New York. Migration was found to be associated with changes in water temperature at the sediment interface and variation in the hydrophyte community. The life cycle was found to have two periods of high mortality. One occurred in newly-hatched snails and the second in post reproductive adults. Vol. 89 (2) INTRODUCTION Cheatum (1934) suggested a_ seasonal migration pattern for pulmonate gastropods in Douglas Lake, Michigan. He concluded that this migration to shallow water during spring and to deep water during fall was in response to the changes in water temperature. Seasonal migration between shallow and deep water probably would be adaptive for the fresh- water prosobranch snail, Amnicola limosa (Say) (Hydrobiidae) living in temperate lakes with seasonally fluctuating benthic environments. The thickness of ice would preclude them from shallow water in winter and thereby con- centrate them in deeper water. Ice on McCargo Lake reached a maximum thickness of one meter for the 1969-1970 winter. During summer months snails would be concentrated in shallow water. This is where aquatic macrophytes and the algal community associated with them would be located. Shallow water was defined as the area from shore to a depth of 1.0 meter. Deep water was ‘ Present address: Environmental Division, Stone and Webster Engineering Corp., P. O. Box 2325, Boston, Mass. 02107. 2 Present address: Director of Biology 175 Science Center, Clarkson College of Technology, Potsdam, New York 13676. defined as the area from 1.5 to 2.0 meters deep. A mid-water station was also sampled which was located at depths between the other two stations (1.0 to 1.5 m). Migration was defined as a change between successive months in the proportion of the population in either deep or shallow water. MATERIALS AND METHODS The study area, McCargo Lake, is located on the Fancher Campus of the State University of New York College at Brockport in western New York. The lake has a surface area of 3.2 hec- tares, a maximum depth of 5.75 m. and a mean depth of 2.6 m. The average Secchi reading for 1970 was 1.4 m. Rooted vegetation extends to a depth of about one meter (Horst 1971). The lake was partitioned into seventeen tran- sects each oriented from shore to a depth of 2.0 m. Previous work indicated the gastropod com- munity in McCargo Lake was restricted to depths of 2.0 meters or less (Horst and Costa 1971). Three stations which were sampled in duplicate were designated along each transect. Transects were sampled one per week. The order of sampling the transects was such that at monthly intervals a north, south, east and west facing location were involved. Differences in population density had been previously Vol. 89 (2) recognized at the north and south facing tran- sects (Horst and Costa 1971). Monthly estimates served to integrate these differences within the lake and therefore, preferable for detection of migration patterns. Macrobenthos were sampled with a fifteen centimeter square Ekman dredge. Snails were removed from dredge samples using the techniques of Duncan (1959). A least squares analysis of variance (ANOVA) was performed with a square root transformation of count data to provide a statistical basis for conclu- sions. The benthic environment at each station was characterized by determinations of water and sediment temperatures, dissolved oxygen con- centration and percent organic matter in the sediments. Water samples were collected at the mud-water interface at each station. Dissolved oxygen was determined by the azide modification of the Winkler method. Percent organic matter in the sediments was estimated by weight loss upon ignition at 600°C. Randomized complete block ANOVA’s were performed to test for differences in each of these variables at the three locations. Time in 100 SHALLOW WATER 75 PERC ENT FIG. 1. The density of Amnicola limosa April to December 1970; averaged over all depths in McCargo Lake. THE NAUTILUS 57 months was used as a blocking factor in the analyses to remove seasonal fluctuations. RESULTS Significant differences in Ammnicola density were detected between months (p< 0.007) and between depths (p< 0.014). The depth by month interaction was also. significant (p< 0.0002) indicating the depth pattern was dependent upon the month. Further analysis was performed using the least significant difference test (LSD), and significant differences (p = 0.05) in the popula- tion density were detected for all successive months from June to October. During spring and early summer (April to June) and the fall to ear- ly winter (October to December) there were no detectable differences in the population (Fig. 1). LSD analysis of depth showed no significant difference between shallow and mid-depth; or between mid and deep water. The proportion of the population in shallow and deep water was therefore, compared for analysis of seasonal migration due to the significant difference (p = 0.05) detected by this analysis. Gaz: lation April to December, 1970; McCargo Lake. The percentage of the Amnicola popu- in the shallow and deep water «areas, 58 THE NAUTILUS Proportions of the population found at shallow water and deep water stations varied throughout the year (Fig. 2), For example, August samples had the greatest proportion of any month in shallow water (68%) and the smallest proportion of any month in deep water (2%). December samples demonstrated a reverse pattern with 64% of the population in deep water and 17% in shallow water. The ANOVA’s of environmental variables detected no significant differences in dissolved oxygen, sediment organic matter, water and sediment temperatures at the three depth areas. The mean dissolved oxygen concentration was 7.1 ppm. Sediments had an average of 30.4% organic matter. The greatest range in water temperature between depths was 2.8°C, which was detected during summer stratification. A typical seasonal fluctuation in sediment and water temperature was recognized with a win- ter minimum of 1.0°C (January) and a summer maximum of 25°C in August. DISCUSSION The Amnicola population for any month at any depth is dependent upon the population the previous month (birth, death, immigration and emigration). It is assumed that immigration and emigration take place only between depths. This is a reasonable assumption, as the population was found to be concentrated at depths of 2.0 m. and less in the lake (Horst and Costa, 1971). Any movement at the same depth will not alter the population at that depth. Any change in the population averaged over the three depths (Fig. 1) is therefore, dependent upon only birth and death in the population. Birth to the population will be a factor only during egg-hatching months and can be ignored at other times. Post (1971) reported the first Amnicola eggs in McCargo Lake on June 23 and the last ones on August 25, 1970. They reached a maximum density of 40 eggs per 100 em? of artificial substrate on July 7. Eggs were observed only to a depth of 1.0 m. which corresponds to stations in shallow water. A lag period between observation of eggs and young in the population should reflect the development time of eggs. Berry (1943) reported a development time of ten days at about 24°C. The first increase in the population was_ be- April 30, 1975 Vol. 89 (2) tween July and August during which time water temperature was above 25°C. Another increase in population density between August and Sep- tember reflected hatching of later eggs. Thus it appears the increase in population density be- tween July and September is the result of eggs hatching. Two periods of high mortality have been suggested during gastropod life cycles. One period of high mortality occurs following the hatching of eggs (DeWitt 1955, Hunter 1961). The reduced population density observed be- tween September and October is interpreted as a reflection of this mortality. Another period of reduced density in this study occurred between June and July. Eggs were first detected in late June which suggests from June to July there was no birth and post- reproductive adults were dying. DeWit (1955) reported high mortality for post-reproductive adult pulmonate snails. Analysis of mean shell size at the three depths by month also supports this contention (Horst 1971). The maximum mean for shell size (3.3 mm) occurred in July in shallow water and the minimum shell size (1.1 mm) was observed at the same depth in August. It therefore ap- pears that the large adults in July samples have either died or moved to deeper water. The rather high mean shell sizes (2.0 mm) in deeper water stations during August and Sep- tember suggests those snails which hatch late in the summer do not reach maturity by the next breeding season and overwinter the second time (Horst, 1971). Houp (1970) has reported a lag in growth of the late hatch of Plewrocera acuta. Migration took place from deep water to shallow water from June to August (Fig. 2), although some of the increase in density was a result of birth to the population in shallow water (Fig. 1). From September to December a reverse migration pattern, from shallow to deep water, took place. Migration to shallow water in June followed an increase in water temperature during April and May. Movement to deeper water in Sep- tember also corresponded to a change in water temperature. Water temperature could have stimulated the response as suggested by Cheatum (1934). Vol. 89 (2) Growth of the hydrophyte community began during April and continued into September. Migration to shallow water followed the spring growth of aquatic plants. Fall migration took place about the end of the growing season for the plants. Aquatic vascular plants support rich algal communities upon which Amnicola feed (Berry, 1943). These plants also provide a_ three- dimensional environment as compared to the two dimensional nature of the substrate in deeper water. This increase in space can be significant as these plants provide the substrate upon which the snails feed and lay their eggs. Since Post (1971) observed eggs only in shallow water this area may serve as a nursery area for Amnicola limosa. LITERATURE CITED Berry, E. G. 1943. The Amnicolidae of Michigan: distribution, ecology and taxonomy. Mus. Zool., Univ. Michigan Misc. Publ. 57: 1-68. Cheatum, E. P. 1934. Limnological investigations on respiration, annual migratory cycle and other related phenomenon in freshwater pul- monate snails. Trans. Amer. Micros. Soc. 53: 348-407. DeWit, W. F. 1955. The life cycle and some bio- THE NAUTILUS INDO-PACIFIC MOLLUSCA MONOGRAPHS OF THE MARINE MOLLUSKS OF THE WORLD WITH EMPHASIS ON THOSE OF THE TROPICAL WESTERN PACIFIC AND INDIAN OCEANS The most technical and most beautifully illustrated journal now being published on Recent and Tertiary marine mollusks. Over 20 professional malacologists are currently contributing. Edited by R. Tucker Abbott. Among the groups treated are Strombidae, Cassidae, Tridacnidae, Tur- ridae, Littorinidae, Phasianellidae, Patellidae, Harpidae, and soon to come, Mitridae. Issued to date in looseleaf form with three sturdy, perm- anent binders — 1300 pages, 997 plates (43 in full color). Limited number of complete sets left, $105.90 U.S. (foreign: $108.00), postage paid. Any numbers of extra binders available at $6.00. Published by The Delaware Museum of Natural History, Box 3937, Greenville, Delaware 19807 U.S.A. 59 logical details of the freshwater snail Physa fontinalis (L). Basteria 19: 35-73. DeWitt, R. M. 1955. The ecology and life his- tory of the pond snail Physa gyrina. Ecology 36: 40-44. Duncan, C. J. 1959. The life cycle and ecology of the freshwater snail Physa fontinalis (L). Jour. Anim. Ecol. 28: 97-117. Horst, T. J. 1971. Ecology of Ammnicola limosa and selected gastropod species of McCargo Lake. M. S. Thesis. State University of New York, Brockport. 151p. Horst, T. J. and R. R. Costa. 1971. Distribution patterns of five selected gastropod species from McCargo Lake. The Nautilus 85(2): 38- 43. Houp, K. H. 1970. Population dynamics of Pleurocera acuta in a central Kentucky lime- stone stream. Amer. Midl. Nat. 83(1): 81-88. Hunter, R. W. 1961. Annual variations in growth and density in natural populations of fresh- water snails in the west of Scotland. Proc. Zool. Soc. London 136: 219-253. Post, D. R. 1971. The Ecology of the Aufwuchs community of McCargo Lake. M. S. Thesis. State University of New York, Brockport. 122 p. 60 THE NAUTILUS April 30, 1975 Vol. 89 (2) SIZE DISTRIBUTION OF THE BIVALVE MULINIA LATERALIS (MACTRIDAE) AND ENERGY LEVEL OF SOME PLEISTOCENE SEDIMENTS W. C. Fallaw Department of Geology, Furman University Greenville, South Carolina 29613 ABSTRACT The size distribution of the clam Mulinia lateralis in Pleistocene sediments from North Carolina is closely related to the energy level of the depositing medium as measured by sand percentage of the sediment. The strata which were sampled show little or no evidence of a high energy paleoenvironment when examined in the field, but the effect on the fossil populations is obvious in the detailed analysis. INTRODUCTION The clam Mulinia lateralis (Say) is the most abundant megafossil in the Pleistocene Neuse Formation (Fallaw and Wheeler, 1969) in southeastern North Carolina. It is a shallow burrower, common in modern lagoons and estuaries (Stanley, 1970). The sediments of the formation are mostly fine-grained and very fine-grained quartz sands, with varying amounts of silt and clay. They were deposited in shallow bays and estuaries and in the shallow shelf en- vironment. There is a significant variation in the size of M. lateralis in different beds of the formation, even in those beds which appear to be very similar in texture when examined in the field. The relationship between size of the clam and its enclosing sediments was investigated by analyzing six samples in detail. Two samples were obtained from each of these localities: Alliance and Flanner Beach, North Carolina, described by Fallaw and Wheeler (1969), and the Waccamaw Brick Company outcrop near Myrtle Beach, South Carolina, described by DuBar (1971). The length (maximum dimension) of fifty valves from each locality was measured by a micrometer to 0.01 mm. The sand _per- centage of the clastic portion of the samples was determined by dissolving carbonates in hydrochloric acid, rinsing, dispersing with dilute Calgonite solution, and pouring the sediment through a 0.062 mm _ screen which retained sand-size particles. Sorting was calculated ac- cording to the formula of Folk and Ward (1957), that is, oO Jn = 12h Peg = Rs i Sarerainnn IEG The striking thing resulting from this study is that differences in energy level of the depositing medium had a major effect on the size dis- tribution of the fossil populations, but little ef- fect on the sediments themselves as far as major structural and textural properties are concerned. The sand percentage in the six sam- ples ranged only from 83% to 94%, the remaining material being silt and clay. There is little structural evidence of transportation in those beds which were sampled. No cross- bedding, unconformities, or ripple marks were observed. The sand was mostly in the very fine- grain and fine grain classes, less than one per- cent being in the greater-than-coarse-grain classes (Wentworth scale). There is enough silt, clay and organic matter in the sediments to give them an olive gray or greenish-gray ap- pearance. Indeed, the first impression on looking at the deposits is that they formed in a quiet, low energy environment. The shells show little evidence of transportation, broken and abraded ones being rare, and some clams (not Mulinia) were found with both valves still together. "Vol. 89 (2) Figure 1 shows several parameters of the length distribution of Mulima populations plot- ted against sand percentage, a crude measure of the energy level of the environment of deposition. For the parameters minimum length, mean length, and maximum length, the three relatively low sand samples fall into one field and the three high sand samples fall into a distinctly different field. For minimum length, the valves in the high sand field are at least 30% longer, for the mean length parameter, the valves in the high sand field are at least 19% longer, and for the maximum length, they are at least 9% longer. Another interesting result of the analysis is that sorting, shown by “S” on the graph, is not closely related to energy level, even though high energy levels tend to produce good sorting in the shallow marine environment. Investigators of age and size distributions of fossil populations should be aware that even in studies of materials that show little evidence of THE NAUTILUS 61 transportation, the energy level can have a significant effect on the populations. ACKNOWLEDGMENTS I wish to acknowledge the assistance of Linda Heatwole who compiled much of the data for this study. LITERATURE CITED DuBar, J. R. 1971. Neogene stratigraphy of the lower Coastal Plain of the Carolinas. Atlantic Coastal Plain Geol. Assoc., 12th Ann. Field Conf. 128 p. Fallaw, Wallace and W. H. Wheeler 1969. Ma- rine fossiliferous Pleistocene deposits in south- eastern North Carolina. Southeastern Geology 10(1): 35-54. Folk, R. L. and W. C. Ward 1957. Brazos River bar—a study in the significance of grain size parameters. Jour. Sed. Petrology 27(1): 3-26. Stanley, S. M. 1970. Relation of shell form to life habits of the Bivalvia (Mollusca). Geol. Soc. America Mem. 125, 296 p. 6 1 8 9 10 I 12 VALVE LENGTH Ho) Th 23) 4 SS SORTING Jae {NAS mm LESS 20 FIG. 1. Graph showing relationships of Mulinia valve length distribution parameters and sand per- centage. “S” denotes sorting values. Other points are for areas labeled. 62 THE NAUTILUS April 30, 1975 Vol. 89 (2) NOTES ON LAND SLUGS, 22': A CATALOGUE OF THE GENUS LYTOPELTE (LIMACIDAE) AND A NOTE ON L. KANDAHARENSIS (ALTENA) C. O. van Regteren Altena Rijksmuseum van Natuurlijke Historie Leiden, Netherlands I am indebted to Mrs. Dochita Lupu for calling my attention to the fact that Deroceras kandaharensis Altena (1970) belongs to the genus Lytopelte. The generic transfer means that this species should be called Lytopelte kan- daharensis (Altena). Kandahar, Afghanistan, the type locality, is more than 500 km. south of the area from which Lytopelte maculata (Koch & Heynemann) is known, and also more than 500 km. south- west of the localities from which L. boettgeri Rosen and L. transcaspia Rosen were reported. All of these differ from L. kandaharensis in having the keel on the whole dorsum and in color. Only L. maculata has been dissected. It differs also in penial structure. They all belong to Lytopelte s. str. Since the keel in L. kan- daharensis extends over at most half the dor- sum, it must be placed in the subgenus Tiolytopelte. The nearest geographic represen- tatives of this subgenus are L. caucasica Simroth and L. grusina Simroth. Both of them lack the white line on the dorsum and_ they have a collateral protuberance on the penis that is lacking in L. kandaharensis. The species with the most similar penis structure is L. moldavica Grossu & Lupu from Romania, but it has a longer oviduct that is sharply reflected, and the calcareous plate on the penis stimulator differs in shape from the “dunce’s cap” found in L. kandaharensis. This latter structure is more similar to the calcareous plate found in L. caucasica. The following list of named taxa in Lytopelte is thought to be complete. After each listing, the correct genus and subgenus reference is listed in brackets. ‘ Notes on land slugs, 21: On a new species of Deroceras from the island of Kéa. Basteria, 37: 89-91, fig. 1(1973). Genus Lytopelte O. Boettger, 1886 G. Radde, Die Fauna und Flora des sud-west- lichen Caspi-Gebietes, p. 266 (as section of Amalia Moquin-Tandon); O. Boettger, 1886, Jahrb. d. malak. Ges., 13: 241. Monotype. - Amalia (Lytopelte) longicollis Boettger, 1886. Proposed subgeneric names are: Platytoxon Simroth, 1886. Jahrb. d. malak. Ges., 13: 311, 316 (subgenus of Agrmolimax Morch). Monotype: Agriolimax (Platytoxon) maculatus (Koch & Heynemann, 1874). = /Lytopelte s. str.] A synonym of Lytopelte s. s. Liolytopelte Simroth, 1901. Nacktschneck. russ. Reiches, p. 174 (subgenus of Lytopelte). In- cluded species were: Lytopelte caucasica Sim- roth, 1901 and L. grusina Simroth, 1901. Type species: Lytopelte caucasica Simroth, 1901 by subsequent designation of Hesse, 1926. = [Lytopelte (Liolytopelte)] Tropidolytopelte Simroth, 1901. Nacktschneck. russ. Reiches, p. 174 (subgenus of Lytopelte). Syntypes: “Lytopelte maculata Koch et Hey- nemann nebst deniibrigen von Bottger und Rosen beschriebenen Arten.” = (/Lytopelte s. str.] Proposed species names are: boettgeri Rosen, 1892, Lytopelte. Nachrichtsbl. d. malak. Ges., 24: 124-Suluklu [at the south- eastern corner of the Caspian Sea.] = /Lyto- pelte s. str.] burescht H. Wagner, 1934, Agriolimax (Hydro- limax). Mitt. k. naturw Inst. Sofia, 7: 55, figs. 7-9. Near entrance cave Medenik near Plakalnitza, vicinity of Vratza, Bulgaria (see also: Urbanski & Wiktor, 1967, Bull. Soc. Am. Sea. Lettr. Poznan, (D), 8: 62, figs. 6A-G). = /[Lytopelte (Liolytopelte)] caucasica Simroth, 1901, Lytopelte. Nackt- schneck. russ. Reiches, p. 171, pl. 17, figs. 5-14, maps 6,7. “Lagodechi, in einem linken ' Vol. 89 (2) Nebenthale des Alasan” [southern slope of Kaukasus]. — caucasica Simroth, 1901, Lyto- pelte (Liolytopelte). Tbidem: 174. = [Lytopelte (Liolytopelte)] caucasica armenia Akramovski, Lytopelte. Dokl. Ak. nauk Armyansk. SSR, 8: 37, figs. 1-3 Gnishik, Armenian SSR. = /Lytopelte (Lio- lytopelte)] grusina Simroth, 1901, Lytopelte. Nacktschneck. russ. Reiches, p. 173, pl. 17, figs. 15-21, maps 6,7. Tiflis. grusina Simroth, 1901, Lytopelte (Liolytopelte). Ibidem: 174 = /Lytopelte (Liolytopelte)] herculana Grossu, 1964, Lytopelte. An. Univ. Bucuresti (Biol.), 13: 84, figs. la-c. Baile Her- culane and Baia de Arama, Romania. - /Lyto- pelte (Liolytopelte)] kandaharensis Altena, 1970, Deroceras. Field- jana, Zoology, 51(15): 175, figs. la-e. Baba Wali near Kandahar, 1425 m., Afghanistan. - [Lytopelte (Liolytopelte)] longicollis O. Boettger, 1886, Agriolimax (Lyto- pelte). In: G. Radde, Die Fauna und Flora des stidwestlichen Caspi-Gebietes, p. 266, pl. 2, figs. la-Lenkoran. = /Lytopelte s. str.] lotrensis Grossu, 1970, Lytopelte. Proc. malac. Soc. London, 39(2-3): 108, figs. 3a-f- Lotru THE NAUTILUS 63 river valley, 550 m., Romania. = /Lytopelte (Liolytopelte)] maculata Koch & Heynemann, 1874, Amalia. Jahrb. d. malak. Ges., 1: 152, pl. 6, fig. 5. Tschupanata, Samarkand and Chodschaduk in Turkestan (see also: Simroth, 1886, Jahrb. d. malak. Ges., 13: 341, pl. 10, figs. 104). - [Lyto- pelte s. str.] moldavica Grossu & Lupu, 1961, Lytopelte (Liolytopelte). Arch. Moll., 90: 28, figs. 1, 2. In the neighborhood of Suecava, Moldava, Romania. - /Lytopelte (Liolytopelte)] occidentalis Grossu & Lupu, 1966, Lytopelte. Trav. Mus. Hist. nat. “Grigore Antipa”, 6: 25, figs. 1-3. Stina de Vale, eastern Carpathian Mountains, Romania.-/Lytopelte (Liolytopelte)] olteniana Grossu, 1964, Lytopelte. An. Univ. Bucuresti (Biol.), 13: 86, figs. 2a-c. “Vallée du Lucavit, commune de Vaideeni (rayon de Horezu, région d’Argesh)”, Romania. - /Lyto- pelte (Liolytopelte)] suboceidentalis Grossu & Grossu, 1965, Lyto- pelte (Liolytopelte). Arch. Moll., 94: 51, figs. 1-4. Mountains of Retezat, 1000-1800 m., Ro- mania. = /Lytopelte (Liolytopelte)] transcaspia Rosen, 1892, Lytopelte. Nachrichtsbl. d. malak. Ges., 24: 123. Germab [in Kopeh Dagh]. = /Lytopelte s. str.] NOTICE The eighth annual meeting of the Western Society of Malacologists and the forty-first an- nual meeting of the American Malacological Union will be held jointly from June 22-26 1975, at San Diego State University, San Diego, California. The program will include contributed papers, symposia, exhibits, and study workshops on molluscan subjects. Inquiries about the meeting should be made no later than May 10 and should be directed to: Mr. Clifton Martin, Secretary (WSM), 324 Ken- nedy Lane, Oceanside, Calif. 92054. Applications for membership in the W. S. M. should be sent to Mr. Bertram C. Draper, Treasurer, 8511 Bleriot Ave., Los Angeles, Calif. 90045. Dues: regular membership - $5.00, ad- ditional family members - $1.00 a piece, student membership - $2.00. Regular and student mem- bers will receive the published proceedings of the meeting. 1975 U0W 9 PAPERBACK! ONLY $4.95 A national register of living professional malacologists and amateur conchologists TO 1973-74 Cross-indexed by residences, AMERICAN faa MALACOLOGISTS sisibojoorjew UR oueLA HSCEI LK emer ONLY $2.00 : anaan Edited by R. Tucker Abbott : ee wmencan malacologists An indispensable desk companion for all mollusk research workers, = shell exchangers and historians. american malacologists Hundreds of new malacological registrants Recent (1975) address changes Recent deaths 2 Additional biographies of deceased malacologists amencan malacologists amencan malacologists amencan malacologists amencan malacologists american mMalacologists 3 Typical comments: nalacologists “T refer to it almost every day” (Harvard Malacologist) “A very useful reference” (Tulane University Historian) “It’s a great help when exchanging (private sheller) am it) soap Make personal check or money order to “American Malacologists” Box 4208, Greenville, De. 19807 american malacologists INFORMATION FOR SUBSCRIBERS The annual subscription rate for The Nautilus is $7.00 for individuals and $12.00 for institutions (domestic or foreign). Subscriptions may begin in January. Send check or money order to “The Nautilus” to Mrs. Horace B. 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This is particularly true of mollusks used in physiological, medical, parasitological, ecological, and experimental projects. The Delaware .Museum of Natural History has extensive, modern facilities and equipment for the housing and curating of voucher specimens. Mater- ial should be accompanied by the identification, locality data and its bibliographic reference. There is no charge for this permanent curating service, and catalog numbers, if desired, will be sent to authors prior to publication. Wee 1h AR ah Aa by ue by Rint a () —— > JULY 1975. THE NAUTILUS Vol. 89 No. 3 A quarterly devoted to malacology and the interests of conchologists Founded 1889 by Henry A. Pilsbry. Continued by H. Burrington Baker. 4 Faitor-in-Chief: R, Tucker Abbott EDITORIAL COMMITTEE CONSULTING EDITORS Dr. Arthur H. Clarke, Jr. Department of Mollusks National Museum of Canada Ottawa, Ontario, Canada K1A-OM8 Dr. William J. Clench Curator Emeritus Museum of Comparative Zoology Cambridge, Mass. 02138 Dr. William K. Emerson Department of Living Invertebrates The American Museum of Natural History New York, New York 10024 Mr. Morris K. Jacobson Department of Living Invertebrates The American Museum of Natural History New York, New York 10024 Dr. Auréle La Rocque Department of Geology The Ohio State University Columbus, Ohio 43210 Dr. James H. McLean Los Angeles County Museum of Natural History 900 Exposition Boulevard Los Angeles, California 90007 Dr. Arthur S. Merrill Biological Laboratory National Marine Fisheries Service Oxford, Maryland 21654 EDITOR-IN-CHIEF Dr. R. Tucker Abbott Delaware Museum of Natural History Box 3937, Greenville, Delaware 19807 Mrs. Horace B. Baker Business and Subscription Manager 11 Chelten Road Havertown, Pennsylvania 19083 Second Class Postage paid at Wilmington, Delaware Dr. Donald R. Moore Division of Marine Geology School of Marine and Atmospheric Science 10 Rickenbacker Causeway Miami, Florida 33149 Dr. Joseph Rosewater Division of Mollusks U.S. National Museum Washington, D.C. 20560 Dr. G. Alan Solem Department of Invertebrates Field Museum of Natural History Chicago, Illinois 60605 Dr. David H. Stansbery Museum of Zoology The Ohio State University Columbus, Ohio 43210 Dr. Ruth D. Turner Department of Mollusks Museum of Comparative Zoology Cambridge, Mass. 02138 Dr. Gilbert L. Voss Division of Biology School of Marine and Atmospheric Science 10 Rickenbacker Causeway Miami, Florida 33149 Dr. Charles B. Wurtz 3220 Penn Street Philadelphia, Pennsylvania 19129 OFFICE OF PUBLICATION Delaware Museum of Natural History Kennett Pike, Route 52 Box 3937, Greenville, Delaware 19807 Subscription Price: $7.00 (see inside back cover) THE NAUTILUS Volume 89, number 3 — July 1975 CONTENTS William P. Hammer and Royal Bruce Brunson Fluoride Accumulation in the Land Snail, Oreohelix subrudis, PROMIMAV ESL VON amen nnn = cy eg Dee S. Dundee, Marie Tizzard and Michael Traub Ageregative Behavior in Veronicellid Slugs.................. Wayne Leathem and Don Maurer Northern Range Extension of the Bivalve, Paramya-subovata Supe Ltanillvas My aces ME eo nin mtrads mites wf ands ee edie es Wayne Leathem and Don Maurer The Distribution and Ecology of Common Marine and Estuarine ° Gastropodsiim! the Delaware Bay Area ..................... Harald A. Rehder Corrections to Recent Papers on New Species of Volutocorbis MFROMMOOUEMM AIT COmMIEINE rian hvac on duke ack ose Sees eee Alan Solem Polygyriscus virginianus (Burch, 1947), a Helicodiscid Land Snail (Pulmonenas Ilene oCKe).5,6enanccensnenegeanos sands ee Joseph Rosewater The Marine Commensal Gastropod, Caledomella montrouzieri (Prosobranchia: Hipponicacea) in Thailand ..............¢-.. Mark C. MacNamara and Willard N. Harman Further Studies of the Mollusca of the Otsego Lake Area...... Melbourne R. Carriker Radular Anomaly in Urosalpinx cinerea (Gastropoda: Muricidae) Gale G. Sphon Marseniopsis sharonae (Willett, 1939), Comb. Nov............. Douglas G. Smith The Identity of Planorbula jenksii (H. F. Carpenter) .......... Obituary: Daniel Downey Steger (1906-1975)................... Sa sSaceiae atte eel assupege da eee 65 Pee OMe A MUS Boles Are cic 136 79 5 CPDL A POA Dhar Ono ero denice O:b'0 ¢ 86 98 Vol. 89 (3) THE NAUTILUS 65 FLUORIDE ACCUMULATION IN THE LAND SNAIL OREOHELLX SUBRUDIS FROM WESTERN MONTANA William P. Hammer and Royal Bruce Brunson Department of Zoology, University of Montana Missoula, Montana 59801 ABSTRACT Land snails of the species Oreohelix subrudis (“Pfeiffer” Reeve, 1854) were collected and analyzed for their fluoride content. The snails were collected within a region in western Montana that is known to be contaminated with gaseous and particulate fluoride emissions from an aluminum reduction plant. Analyses of the specimens revealed that fluoride accumulation had occurred within the shells and to a lesser degree in the body tisswes of the snails. Fluoride levels 9-12 times control levels were observed in shells of snails collect- ed nearest the aluminum plant, whereas fluoride levels 2-3 times control levels were observed in shells of snails collected eleven air-miles from the aluminum plant. On August 15, 1955, the Anaconda Company formerly dedicated a new aluminum reduction plant at Columbia Falls, Montana. The plant uses the Vertical Stud Soderberg Pot system for reducing alumina to pure aluminum. During this electrolytic process, sodium fluoride (NaF) and aluminum fluoride (AIF3) are released as airborne particulate waste, and hydrogen fluoride (HF) and carbon tetrafluoride (CF,) are released as gaseous waste. NaF, AIF;, and HF are accumulated by and cause injury to plants. The work of Carlson and Dewey (1971) and Carlson (1973) documented fluoride air pollution over nearly 214,000 acres of private and public lands in the vicinity of the aluminum reduction plant. Carlson (Op. cit.) reported elevated fluoride content and fluoride-induced necrosis on some of the vegetation which he studied. Dewey (1972) observed elevated fluoride levels in both herbivorous and carnivorous insects, whereas Gordon (1972) observed abnormalities of the bones and teeth of cattle and deer which had fed on fluoridated vegetation. Figure 1 (from Carlson, 1972) shows the ex- tent of fluoride pollution for August, 1971. Ten ppm fluoride or less was accepted by Carlson as the level which could be expected to occur in unpolluted vegetation in this region. Inasmuch as fluoride accumulates in plants and is carried through the food chain to her- bivores and carnivores, the authors postulated that the herbivorous land snail, Oreohelix subrudis (“Pfeiffer” Reeve, 1854), might also have accumulated large amounts of fluoride af- ter it had fed on polluted vegetation. According to Pilsbry (1939, 0. 490-491), two- banded O. subrudis shells are widely spread in Montana, and a high, beehive-like form has been recorded in Glacier National Park, in the Mission Range, and near Flathead Lake. O. subrudis has been collected extensively in and around western Montana by the authors. Control levels of fluoride for the snails were established by analyzing shells from the authors’ collection and from several collection sites in western Montana. Four collection sites were established near the aluminum plant in order to determine the extent of fluoride ac- cumulation in the snails. Shells which were collected empty were rinsed under running tap water (unfluoridated) and scrubbed with a brush to remove particles of soil before being air-dried 72 hours at 32°C in a forced draft drying oven. After drying the shells were ground to a fine powder in a mortar with a pestle. Living snails were placed in boiling tap water for 90 seconds to kill and loosen the bodies from the shells. These shells also were rinsed and scrubbed with a brush un- der running tap water, whereas the bodies were 66 THE NAUTILUS AAC <> WEE FALLS/S/ FIG. 1. Isopols of fluoride pollution at Columbia Falls, Montana, August, 1971. Values represent mean ppm fluoride in the vegetation. placed on paper toweling to blot dry. At this time the body was separated into a portion consisting of the head, foot, and proximal por- tion of the visceral mass and a remaining por- tion consisting primarily of the midgut gland (“liver”) and the ovotestis. These shells and body portions also were air dried at 32°C and ground as previously described. Mature (4 1/2 whorls) shells from the study area weigh approximately 0.8 gram; therefore, one shell is adequate material for the standard 0.500 gram sample. Approximately five snails were needed to make up a 0.500 gram sample of the head, foot, and lower visceral mass. Ap- proximately ten snails were needed for an adequate sample of the liver portion. The determination of fluoride content in snail shells and body tissues was done the same ex: cept where noted in the following procedure: Standard 0.500 gram portions of each sample were weighed into nickle crucibles. Body tissue samples, only, were supplemented with 0.050 gram of low fluorine calcium oxide. All samples were then slurried with distilled water and then charred in an infrared oven. After being charred, the samples were ashed for ap- proximately 16 hours at 600°C in a muffle fur- July 17, 1975 Vol. 89 (3) FIG. 2. Location of snail collection sites and the mean fluoride content of the shells of snails collected at these sites relative to Carlson’s 1971 isopols of fluoride pollution. nace and then cooled in a desiccator. Each sam- ple subsequently was moistened with distilled water. To dissolve the moistened ash, 2 ml of 30 percent perchloric acid were added to the ash of the body samples, whereas 2 ml of 19 percent hydrochloric acid were added to the ash of the shell samples. The dissolved samples were then brought to 100 ml volume by adding TISAB (from Orion Research) diluted 50 percent by distilled water. Fluoride activity was deter- mined using an Orion lonalyzer and Orion fluoride and reference electrodes. Levels of fluoride in the control shells ranged from 2 ppm to 8 ppm with a mean of 5 ppm on the basis of 22 analyses. Six samples of shells from collection site WH-1 contained from 84 ppm to 127 ppm with a mean of 107 ppm. The bodies of the WH-1 snails contained an average of 38 ppm. Eleven shells from collection site WH-2 contained from 58 ppm to 90 ppm with a mean of 76 ppm. The bodies of the WH- 2 snails averaged 31 ppm. Thirteen samples of shells from site WH-3 contained from 9 ppm to 19 ppm with a mean of 14 ppm. The body tissues of the WH-3 snails contained an average of 16 ppm. The ten shell-samples which were analyzed from collection site WH-4 cantained from 13 ppm to 21 ppm with a mean of 16 ppm. The body tissues of these snails averaged Vol. 89 (3) THE NAUTILUS 67 TABLE 1 Head, foot, and lower WHlg 40 viscera from WH1a-d: WHIlh 35 Controls: Sample No. Pom WH1li 41 a Midgut gland-ovotestis Anguispira, St. Regis portion from WH1la-d: WHI 37 i ., Mont., WH53a (shell h ; ‘ ‘ : aes one WH53b Sie : WH-2. Collection site approximately 1 mile N. of the WH5ia (shell) 9 WH57b ” 6 WH57c (whole bodies) 5 Anguispira, Yellow Bay State Park, Lake Co., Mont., June, 1973: Oreoheliz, Troy, Lincoln WH58a (shell) 7 Co., Mont., June, 1973: WH58b”’ 5 WH58ce ” i WH5&d ==” 5 WH58e =” 8 Oreohelix, Noxon, San- M156a (shell) 4 ders Co., Mont. T25N, M156b Oo” 4 R32W, sec. 10, May, 1956: Oreohelix, Yellow Bay, IM114, 47a (shell) 5 Mont., T24N, R19W, IM114, 47b ” 3 sec. 3, Lake Co., Sep- IM115. 47a 4 tember, 1947: IM115. 47b 5 Oreohelix, Swan Mtns., IM120, 47 (shell) 2 T28N, R19W, sec. 35, Flathead Co., Mont., July, 1947: Oreohelix, Moose Creek —_IM379, 47a (shell) il Canyon, Jackson IM379, 47b ” 3 Hole, Wyo., 1947: Oreoheliz, Mission IM106, 48 (shell) 4 Canyon, T18N, R18N, sec. 7, Lake Co., Mont., May, 1948: Oreohelix subrudis, IM172, 48 (shell) 4 Saphire Range, Missou- la, Mont., May, 1948: Oreohelix, Woods Bay, IM190, 48a (shell) 5 T20N, R19W, sec. 21, IM190, 485” 4 Lake Co., Mont., June, 1948: WH-1. Collection site approximately 1/2 mile N. E. of the aluminum plant in the S. W. 1/4 of sec. 35, T31N, R20W, Flathead Co., Mont. Collection made in April, 1973: Sample Ppm No. Flu- oride Mature shells: WHila 9 WHIlb 118 WHic 127 WHid 104 Half-grown shells: WHle 114 WHif 84 aluminum plant in the N. E. 1/4 sec. 34, T31N, R20W, Flathead Co., Mont. Collection made in April, 1973: Sample Ppm No. Flu- oride Mature shells found WH2a 83 empty: WH2b 90 WH2e 86 Mature shells: WH2d 67 WH2e 68 WH2f 71 WH2g 61 WH2h 58 WH2i 81 Half-grown shells: WH2j 87 WH2k 82 3mm to 6 mm dia. shells: WH2l 143 Head, foot, and lower WH2m 32 viscera from WH2d-f WH2n 32 and WH2g-i, respective- ly: Midgut gland-ovotestis WH2o0 29 portion from WH2d-1: WH-3. Collection site approximately 3 miles N.N.W. of the aluminum plant in the S.E. 1/4 of sec. 21, T31N, R20W, Flathead Co., Mont. Collection made in April, 1973: Sample Ppm No. Flu- oride Mature shells found WH23a 18 empty: WH3b 16 WH3c 14 WH3d 9 Mature shells: WH3e 17 WH3f 13 WH38¢g 13 WH3h 18 WH3i 13 WH3j 14 WH3k 16 WH3l 19 WH3m 14 Head, foot. and lower WH3n 20 viscera from WH28e-g, WH3o0 14 WH3h-j, and WH3k-m, WH3p 15 respectively: 68 THE NAUTILUS Midgut gland-ovotestis WH3q 18 portion from WH3e-m: WH-4. Collection site located at West Glacier, Flathead Co., Mont., near the abandoned bridge across the Middle Fork of the Flathead River. The collection was made in June, 1973: Sample Ppm No. Flu- oride Mature shells: WH4a 17 WH4b 13 WH4c 16 WH4d 17 WH4e 16 WH4f 17 WH4g 13 WH4h 15 WH4i 20 Whole bodies from WH4j 11 WH4aii: 11 ppm fluoride. The results of the chemical analyses appear in Table I. Figure 2 shows the locations of the collection sites WH-1, 2, 3 and 4 and the mean fluoride content of the shells from these sites in relation to Carlson’s 1971 isopols of fluoride pollution. O. subrudis is an herbivore and has been ob- served during the course of this investigation to feed on fallen leaves of Populus tremulordes, P. trichocarpa, Betula papyrifera, Acer glabrum, and Physocarpus malvaceous. Both fresh and partially decayed leaves were eaten. Anguwispira kochi occidentalis (Von Martens, 1882), a land mollusc incidentally studied, is also an_her- bivore and has been observed feeding on the above mentioned plants and, also, on the green foliage of Asarum caudatum. It is probable that O. subrudis accumulates that fluoride which is in and on the vegetation on which it feeds. On the basis of the small number of samples analyzed there was no significant difference in the fluoride content of the midgut gland—ovotestis portion and that of the head, foot, and lower visceral mass. It is interesting to note that one sample con- sisting of shells 3 mm to 6 mm diameter con- tained 143 ppm fluoride (from collection site WH-2). No explanation is available for this July 17, 1975 Vol. 89 (3) phenomenon. However, the original shell is largely organic periostracum (Hyman, 1967, p. 606) and this material is easily eroded away and often absent from mature shells. Thus the latter consist almost entirely of calcium car- bonate (op. cit., p. 157). The variable ratio of shell-to-body fluoride content suggests separate accumulation rates and accumulation thresholds for shell and_ soft tissue. The authors gratefully acknowledge the assistance of Dr. Richard H. Russel, Univer- sity of Arizona, Department of Biology, for his identification of representative specimens. Dr. C. C. Gordon, University of Montana, Department of Botany, is thanked for supplying the laboratory space, equipment, and supplies used for the chemical analysis of the specimens. LITERATURE CITED Carlson, C. E., and J. E. Dewey. 1971. Environ- mental Pollution by Fluorides in Flathead National Forest and Glacier National Park. USDA, Forest Service, Missoula, Montana, 57 pp. Carlson, C. E. 1972. Monitoring Fluoride Pollu- tion in Flathead National Forest and Glacier National Park. USDA, Forest Service, Missou- la, Montana, 25 pp. Carlson, C. E. 1973. Fluoride Pollution in Mon- tana. Fluormde Quarterly Reports, 6(3): 127- 137. Dewey, Jerald E. 1972. Accumulation of Flu- orides by Insects Near an Emission Source in Western Montana. Environmental Entomology 2(2): 179-182. Gordon, C. C. 1972. 1970 Glacier National Park Study. University of Montana, Missoula, Montana. Hyman, Libbie Henrietta. 1967. The Inverte- brates, Volume VI, Mollusca I. McGraw-Hill Book Company, New York. Pilsbry, Henry A. 1939. Land Mollusca of North America (North of Mexico). The Academy of Natural Sciences of Philadelphia, Monographs 3h JOboll. Vol. 89 (3) THE NAUTILUS 69 AGGREGATIVE BEHAVIOR IN VERONICELLID SLUGS Dee S. Dundee, Marie Tizzard, Michael Traub Department of Biological Sciences Louisiana State University in New Orleans, 70122 ABSTRACT Aggregative behavior exhibited by veronicellid molluscs led us to suspect the action of one or more pheromones. Several series of experiments demonstrate that a pheromone exists, and is suspected to be a volatile compound. The identity of the pheromone is being sought through biochemical means at the present time. In collecting veronicellid slugs, it quickly becomes obvious that one cover object (board, stone, paper or such) hides many slugs whereas another, which appears to be equally suitable, has none. This repeated observation led us to suspect some type of pheromone as the basis for this aggregative behavior. Pheromones have been demonstrated to be used as guides to food (Bossert and Williams, 1963), guides to aggregative behavior in insects (Kaufman, 1966), possible guides to moisture in snakes (Dundee, 1968), guides for ant movements (Hangartner, 1970), guides to proper areas for oviposition (Norris, 1970) as well as for similar uses in various organisms. Wells and Buckley (1972) showed that the aquatic snail, Physa, follows trails which other Physa have laid down. Our premise was, then, that it might be that veronicellids use a similar mechanism resulting in aggregative behavior. The following experiments were designed to test this. MATERIALS Slugs: Two local, introduced - slugs, Veronicella ameghini (Gambetta) and Veronicella floridana (Leidy) were used because of their aggregative behavior in the field and because they are locally abundant and easily available for laboratory testing. Container and Discs: Circular plastic bowls, 25 cm in diameter with fitted lids were used. Into these was placed enough moist sterilized sand to cover the bottom. Circular discs of 5.5 em diameter were cut from masonite and placed in a circle on top of the sand so as not to touch the container and so that each was equidistant from the next. The discs were let- tered. This experimental design was patterned after that devised by H. A. Dundee (1968) for use with small snakes. The reason for keeping all materials circular in shape was for the pur- pose of eliminating angles which might provide attractive resting places for the slugs. These containers were kept on a lab table at room temperature. There was light from windows on one side. At intervals the containers were rotated and/or placed in a dark box so as to exclude light as a factor. Only during times when experiments were in progress were the slugs allowed in these containers: they were housed separately when not being used in ex- periments. Sand: Atter trying various substrates it was determined that substrate had no bearing on the aggregative behavior; the same results could be obtained using dirt, sand or paper as substrate. Sand was selected since it was easier to handle and could be easily autoclaved. The autoclaving was simply a precautionary measure in case the sand contained any extraneous influencing fac- tor. The reason for a substrate was to provide a means whereby the moisture could be retained for several days. METHODS AND DISCUSSION Each experiment was initiated by placing twenty slugs of one species in a container such as described above. They were placed in the center and left undisturbed for as long as necessary, usually about 72 hours. Table I presents a summary of the results. In Experimental Series I (Table I) slugs, given a selection of cover objects, almost always 70 THE NAUTILUS July 17, 1975 Vol. 89 (3) TABLE 1. Summary of experiments. Hach series was run separately with Veronicella ameghini and V. floridana. Experimental Series I Container Arrangement Animals (15 exps. with New sand. New discs. 2 in center each species) for each experiment II New container. New sand. 20 in center (2 exps. with Dises from E.S.I. used (those for each each species) where the aggregation had experiment occured) Ill (10 exps. with “Conditioned” sand from un- 20 in center each species) der dise where all had aggre- for each gated prior was placed under _ experiment disc F in new containers: (1) using “used” discs (2) using new discs IV (8 exps. with “Conditioned” sand and new 20 in center each species) discs used in new container. for each Conditioned sand placed on experiment top of dise F V (5 exps. with (1)‘‘Conditioned” sand put 20 in center each species) under B and E for each (2) “Conditioned” sand put experiment under B and on top of E all came to rest under the same object after a short period of time. This lent support to field observations which indicated aggregative behavior. Experimental Series II, consisting of two ex- periments with each species, substantiated the belief that the slugs do aggregate as a result of some chemical attractant. The use of one “used” disc (those under which aggregation occurred in previous experiments) and the resulting selec- tion of that disc by the slugs points out that some attractant had been left on that disc by slugs in the previous experiments. It also demonstrated that discs do become ‘“con- ditioned” and therefore new ones must be used In each experiment in order to make the ex- periment valid. Experimental Series III was designed as follows: new containers with new sand were used. Two types of experiments were done: (1) using all new discs except the one marked F; it was a disc from a previous experiment Usual Result By 48 hours most were under one dise. By 72 hours all were under it. 72 hours of “milling around” with most settling under F (the dises from ES.I. which had the aggregations under them—in this series they were labeled Hy) (1) Most under F when “used” dises were used. Some else- where. (2) All 20 under dise F in 24 hours with new discs General Observations Slime trails all over Discs do become “con- ditioned”; thus new ones are needed for each experiment (a)fewer slime trails than in E.S.I. (b) if “used” discs used, appearance of con- fusion (c)if new discs used, exp. more decisive In 48 hours all 20 had moved to sand adjacent to disc F. By week later all had scattered No slime trails under any discs. Trails on sand on dise F. (1) In 48 hours: 18 under B, 2 in center. In 72 hours: 4 on roof over B, 16 under B (1 exp. only—others similar) (2) In 72 hours: 1 on wall by B, 1 between A & B on wall, 18 on wall near E (1 exp. only— others similar) (1) tracks all over — including on E (2) tracks all over and one under which aggregation had occurred (2) using all new discs. In addition, in each of these types of experiments (5 of each type ex- periment was run for each species) “con- ditioned” sand (sand from under a disc where aggregation had occurred previously) was placed under disc F. In all experiments all slugs came to rest under dise F—no matter whether disc F was “used” or new; however, when disc F was a “used” one the time to aggregation was longer and the trails indicated more confusion. The next logical step was undertaken in Ex- perimental Series IV wherein the “conditioned” sand was placed on top of the disc instead of beneath it. The reasoning here was that perhaps they aggregated beneath the disc for some reason other than the presence of an attractant. It was expected, therefore, that, if our sup- position of an attractant was correct, they would not go under the disc but, rather, they should go on top of it. Sixteen such experiments were run (eight per species) and in each case in ri Vol. 89 (3) no longer than 48 hours all of the slugs had moved to the sand adjacent to the disc with the conditioned sand on top. No slime trails were found under any disc. Why the slugs did not go directly to the top of the disc cannot be ex- plained at this time. We suspect the reason is that the pheromone is volatile and elicits a response when in the air rather than when on the surface. Why the slugs selected the sand adjacent to the disc is also unexplainable at this time. The container was closed so it should not have been a matter of air currents; also the slugs were not always found in the same direction from the disc (this would have been expected had air currents been involved). Another significant factor to be noted in Ex- perimental Series IV is that the slugs scatter about the container (de-aggregate) within a week, sometimes regrouping elsewhere, sometimes not. In our “housing” containers they seem to leave the aggregation only rarely and then they usually return to it. This behavior in the Experimental Series IV led to the con- clusion that the attractant is one which is gradually inactivated. Experimental Series V was a perplexing one for which we do not yet have answers. It was conducted in two parts: (1) conditioned sand was placed under discs B and E. As Table I shows, all of the slugs went to disc B but even then not all of them went under it. None select- ed disc E although there were slime trails over it indicating that they had been there. The second phase of this series consisted of placing “conditioned” sand under disc B and on top of disc E. Five such experiments were run for each species and, while the numbers varied in the different experiments, the overall results were similar: at the end of the usual 72 hour period most (but not all) slugs were on the con- tainer wall near disc E with none under disc B. Two significant observations arise from these experiments: (1) again, it would appear that a volatile is involved and that it has much more influence on the slugs when out in the open as opposed to being beneath an object (2) one won- ders if the volatile is released only when suitable habitat is found. If it is released at all times it appears that mass confusion should result. The only difference in behavior between THE NAUTILUS 71 Veronicella ameghini and V. floridana in these experiments was that V. floridana seems to respond much more quickly and has the habit of digging at the site of the aggregation. CONCLUSIONS In view of the results of these preliminary experiments, it seems evident that the aggregative behavior exhibited in Veronicella ameghini and Veronicella floridana is mediated by a pheromone, unidentified at the present time. The pheromone appears to be of a volatile nature as evidenced by the fact that when placed on a disc, aggregation results above or around the disc but not upon it. However, when the pheromone is placed under a disc the aggregate forms beneath the disc thus in- dicating that perhaps the pheromone becomes trapped beneath the disc. The identity of the pheromone is being sought through biochemical means at the present time. The possible function of aggregation in these slugs lends itself to considerable speculation. In sexually reproducing organisms it is easy to see how aggregation may facilitate reproduction, in that it insures the presence of a mate. If this were not so, the slow movement of these slugs would prove a detriment to reproduction and survival of the species. This, then, presupposes the presence of pheromones in many of the other molluscs as well. Since these aggregates usually involve much contact between organisms, surface area exposed to the elements is effectively reduced and thus such attractants may function to aid in preven- tion of desiccation. This would be an adaptive advantage. Dainton (1954) found that a loss of 17% of slug body water resulted in inactivity and that slugs have to absorb moisture from a moist surface to replenish that lost in producing slime trails. Aggregation, therefore, may be a water conservation measure. LITERATURE CITED Bossert, W. H. and E. O. Witson 1963. The a- nalysis of olfactory communication among animals. Jour. Theoretical Biol. 5: 443-469. Dainton, B. H. 1954. The activity of slugs I. The induction of activity by changing temp- eratures. Jour. Exp. Biol. 31: 165-187. 72 THE NAUTILUS Dundee, H. A. 1968. Aggregative behavior in small snakes. Tulane Studies in Zool. and Botany 15(2): 41-58. Hangartner, W. 1970. Control of pheromone quantity in odor tracks of the ant, A. can- thomyops interjectus Mayr. Experientia 26(6): 664-65. Kaufman, T. 1966. Observations on some factors which influence aggregation by Blaps sulcata July 17, 1975 Vol. 89 (3) (Coleoptera: Tenedrionidae) in Israel. Ent. Soc. Amer. 59: 161-172. Norris, M. J. 1970. Aggregation response in ovi- positing female of the desert locust, with special reference to the chemical factor. Jowr. Insect Physiol. 16: 1493-1515. Wells, M. J. and S. K. L. Buckley 1972. Snails and Trails. Anim. Behavior 20: 345-355. NORTHERN RANGE EXTENSION OF THE BIVALVE, PARAMYA SUBOVATA (SUPERFAMILY MYACEA) Wayne Leathem and Don Maurer College of Marine Studies University of Delaware Lewes, Delaware 19958 The bivalve Paramya subovata (Conrad, 1845) was found (dead) in Indian River Bay, Delaware, at 38°36'30" north latitude and 75°6'35" west longitude. The sample was collected with a Petersen grab in muddy sand at a depth of approximately 18 m. Its range had previously been reported from North Carolina to the west coast of Florida (Morris, 1951). This constitutes a northern range extension of ap- proximately 820 km and crosses a major zoogeographic boundary (Cerame-Vivas, and Gray 1966). The specimen which is 1 em in length agrees with the description of Abbott (1974, p. 537, fig. 5989). Paramya subovata was reported by Jenner and McCrary (1970) as being a commensal bivalve, host specific with the echiuroid Thalassema hartmani. This commensal behavior takes on special interest since it is characteristic of another superfamily (Leptonacea). Also the occurrence of 7: hartmani has not been report- ed from Delaware, so this specimen of P. subovata could well be a subfossil. We would like to thank Dr. R. Tucker Abbott, who graciously checked the identification and en- couraged us to develop this account. LITERATURE CITED Abbott, R. T. 1974. American Seashells, Second Edition, Van Nostrand Reinhold Co., N.Y., 663 p. Jenner, C. E., and A. B. McCrary, 1970. Para- mya subovata, a commensal with the echi- uroid Thalassema hartmani. Ann. Rept. Amer. Mal. Union, 1969, 42 p. Morris, P. A. 1951. A field guide to the shells of our Atlantic and Gulf Coasts. Houghton Mifflin Co., Boston, p. 234. Cerame-Vivas, M. J. and I. E. Gray. 1966. The distribution pattern of benthic invertebrates of the continental shelf off North -Carolina. Ecology 47(2): 260-270. Vol. 89 (3) THE NAUTILUS 73 THE DISTRIBUTION AND ECOLOGY OF COMMON MARINE AND ESTUARINE GASTROPODS IN THE DELAWARE BAY AREA Wayne Leathem, and Don Maurer Marine Studies Center College of Marine Studies University of Delaware Lewes, Delaware 19958 INTRODUCTION Increased attention locally to pollution problems has intensified interest in benthic ecology. In order to deal with these problems, a number of taxonomic surveys were conducted in the Delaware Bay area (Kinner, et al., 1974; Leathem, et al., 1973; Maurer and Watling, 1973 a and b; Maurer, et al. 1974 a, b, and c; Watling and Maurer, 1972 a and b; Watling, et al., 1973; Watling, et al, 1974). This paper represents a synthesis of results from these and other surveys on the distribution and ecology of gastropods in the Delaware Bay region. Lowden (1965) provided an annotated checklist of the marine mollusks of Delaware Bay and New Jersey ocean beaches, while Wass, et al., (1972) provided a checklist of the biota of Chesapeake Bay. A guidebook for the Delaware Bay region fauna, which includes marine and estuarine mollusks, was prepared by Watling and Maurer (1973). METHODS Samples were collected from 1970 to the present with a variety of sampling gear: epibenthic dredge, Petersen bottom grabs (0.1 m?, 1/15 m?), Van Veen bottom grab (0.1 m7), and oyster dredge. Several areas which received intensive sampling both quantitatively and qualitatively are: a site 1 km off Cape Henlopen and South Bethany Beach, Delaware; a site 67 km east of Ocean City, Maryland; 26 transects across Delaware Bay from the capes to Woodland Beach; Cape Henlopen sand flat; Rehoboth, Indian River, and Little Assawoman Bays. All quantitative samples were sieved through a 1.0 mm mesh screen and the residual on the screen was preserved in 10% buffered formalin. Selected organisms from the ’ Contribution No. 97 qualitative (dredge) samples were preserved in a similar manner. Standard hydrographic data (temperature, salinity, and dissolved oxygen) were collected for many of the samples along with sediment aliquots. The sediment samples were dried and sieved to determine sediment particle size. RESULTS AND DISCUSSION The gastropods in this paper are grouped ac- cording to Carriker’s (1967) salinity distribution for organisms in estuaries to facilitate com- parison with other estuaries. This designation represents the most common distribution of the species rather than the exceptional or marginal occurrences. The distributions recorded in our studies agree with Carriker’s (1967) scheme in that the euryhaline marine group contained the largest number of species — 31 (67%), while the true estuarine and stenohaline species accounted for 8 (17%) and 7 (15%), respectively. There were no oligohaline species present in this study. TRUE ESTUARINE SPECIES (Salinity 5-30 %o) Intertidal Melanpus bidentatus is abundant at the marsh’s edge slightly above the high tide line where it is occasionally flooded, but is often more abundant slightly further from the water as reported by Allen (1954). This species hibernates and is generally absent from the marsh surface during the winter (Allen, 1954; Apley, 1970; Hauseman, 1973). Detracia floridana (Pfeiffer), also a member of the family Melampidae, is of- ten confused with M. bidentatus, has not been collected in our surveys. However, it may be expected, as it has been reported from Delaware by Abbott (1974, p. 332). Iyanassa ob- soleta occurs extensively on fine, silty sand 74 THE NAUTILUS flats in Delaware and Indian River Bays and in tributaries of salt water marshes. This species may, however, be incorrectly classified in the family Nassariidae (Abbott, personal communication) as it differs from other nassariids in having a crystalline style digestive rod (Jenner, 1956) and no caudal cirri; however, Fretter and Graham (1962) believe this is not a true style but a protostyle. Reproduc- tion and feeding studies of this gastropod have been reported by Scheltema (1961, 1964a and 1964b). Subtidal The prosobranch gastropod, Nassarius vibex, occurs abundantly in Indian River with scat- tered occurrences throughout Delaware Bay. It feeds as a scavenger and as a deposit feeder. Mitrella lunata, which Bird (1970) placed in his Macoma balthica community, has been found in the Cape Henlopen area living in association with Tubularia crocea and various algae where the salinity range is 29 % — 32 %. This species crawls on sunken logs and pilings throughout Delaware Bay and has also been collected extensively in Rehoboth Bay. This columbellid feeds mainly on soft algae (Abbott, 1968) and possibly ingests animal detritus as it clings to seaweeds. Bird (1970), Young and Rhoads (1971), and Russell-Hunter and Brown (1964) have classified it as a car- nivore, preying on small sessile invertebrates. Three species of the family Cerithiidae, Sezla adamsi, Cerithiopsis greeni, and the sinistral- shelled Triphora nigrocincta, are rather rare in this area; and, as yet, only their shells have been collected in our surveys. These species range from near shore to 74 m and feed mainly on detritus, diatoms, and sponges (Abbott, 1968; Bird, 1970). EURYHALINE MARINE SPECIES (Salinity 15-40 %) Intertidal The members of the family Littorinidae, Lit- torina saxatilis, L. obtusata, and L:. trrorata, are common. L. sazatilis and L. obtusata occur most commonly at or slightly above the high tide line grazing on algae among barnacles on rock jetties of the Harbor of Refuge (Delaware Bay) and Indian River Inlet. Another local July 17, 1975 Vol. 89 (3) species, L. littorea, also occurs on rocks at In- dian River. L. irrorata is particularly charac- teristic on grass in salt and brackish water marshes. The exposure times for Littorinidae as reported in Fretter and Graham (1962) are be- tween 5-65% for L. obtusata and L. littorea and 50-100% for L. saxatilis. Subtidal Most estuarine species are euryhaline (Carriker, 1967), although the acclimation of some of these to low estuarine salinities has been reported by Schlieper (1957). The most economically and _ ecologically significant euryhaline species (Hanks, 1953; Loosanoff, 1956; Carriker, 1951, 1955; Wells, 1959; Wood, 1968; Mackenzie, 1970; and Manzi, 1970) found in the Delaware Bay region are: the pyramidellids, Odostomia impressa, O. trifida, O. willisi, O. gibbosa, Turbonilla stricta, T. in- terrupta; the melongenids, Busycon canaliculatum, B. carica; the muricaceans, Urosalpinx cinera, Hupleura caudata; and the naticid, Polinices duplicatus. The majority of these occur in association with the local oyster communities as well as some southern oyster communities (Watling and Maurer, 1973; Wells, 1959, 1961). The ectoparasitic mode of existence of the pyramidellids was documented by several workers (Fretter and Graham, 1949; Loosanoff, 1956; Hopkins, 1956). Nevertheless, pyramidellids may not be species specific as previously thought by other workers (Allen, 1958; Scheltema, 1965). The abundance _ of pyramidellids in Rehoboth and Indian River Bays where certain “specific hosts” are absent confirms this. Busycon canalicwatum and B. carica have primarily been collected on bottoms of fine to medium sand near the mouth of Delaware Bay. Wells (1961) found that B carica occurred primarily on sand flats feeding on hard clams. Carriker (1951) observed the predation of Busycon on these and other bivalves. Maurer and Watling (1973 a) estimated an occurrence of 800 whelks per acre on the southern edge of Delaware's oyster beds; however, they were not considered as a limiting predator for that area. Polinices duplicatus also occurs sporadically near the mouth of Delaware Bay and like the Melogenidae, it is carnivorous on bivalves. A Vol 89 (3) detailed account of predation by _ these gastropods can be found in Ansell (1960, 1961). Probably the most economically important gastropods in our study area are the car- nivorous Muricidae, Urosalpinx cinera and Eupleura caudata. Allen (1963) and Carriker (1955) have summarized the research on their biology and control. Distribution of drills in the local rivers is spotty and unpredictable (Maurer and Watling, 1973a); however, local oystermen consider them to be a serious problem, especially on young spat in the planted beds. On the New Jersey side of Delaware Bay, drill predation is of even greater consequence to the oyster industry; so much so that the New Jersey Shellfish Commission periodically scrapes the oyster beds with a specially designed bore dredge to help reduce oyster mortality rates caused by these borers. Although the genera Anachis and M(itrella are closely related, Anachis occurs in a higher salinity range (27-35 %) than does Mitrella (18-32 %.). This was also reported by Bird (1970) and Wigley and Stinton (1973). Two species, Anachis avara and A. lafresneyi, are not abundant in our collections. We have, however, found numerous shells of these species together with Haminoea solitaria, Acteocina canaliculata, and Acteon punctostriatus. Scheltema (1968) reports that Anachis avara and A. lafresneyi prefer eel grass and firm sub- strata, respectively. Despite their preference for different substrata, they are often confused. These species have been redescribed by Scheltema (1968). The Epitoniidae are locally represented by Epitonium humphreysi and E. rupicola. They inhabit sandy bottom and are generally found in association with sea anemones upon which they feed (Abbott, 1968). Wass (1972) reported finding as many as 30 FE rupicola per square meter. We have collected a few scattered specimens; however, EF. rupicola may be found to be quite abundant as more research is done in Indian River. A few species found relatively infrequently living in the Delaware Bay region are Skeneop- sis planoris and Kurtziella cerina. S. planorbis are abundant in the summer on weeds below midtide level to 16 fathoms. Breeding occurs in THE NAUTILUS 75 the spring and summer with egg capsules being attached to filamentous algae (Fretter and Graham, 1962). Live specimens of Marginella roscida were collected on the New Jersey side of the ship channel in the vicinity of Brandy- wine Shoal and on the Delaware side in the Anchorage area which would agree with the description of Abbott (1968) of depth and sub- strate preference. Species of the genus, Crepidula (family Crepidulidae), are among the most abundant snails in the Delaware Bay region. The young slipper shells are fairly active in moving about; but as adults (2 years), normally remain at- tached for life. Crepidula plana, C. fornicata, and C. convexa are found most abundantly in salinity above 20 %. Since they are filter feeders and require a firm substratum to at- tach, they can provide serious competition for food and space (Mackenzie, 1970; Loosanoff and Engle, 1941). Unlike the oyster, however, Crepidula can do well on a variety of substrata such as the horseshoe crab (Limulus) and the whelks (Busycon). Franz (1970) has described the shell shape of C. convexa in relation of the substratum diversity. Maurer and Watling (1973 a) found C. plana and C. fornicata living on the same substrate, but in different clusters. C. for- mcata was the dominant organism in one sector of Greenwich Bay (Stickney and Stringer, 1957). A widespread species in the Delaware Bay region is Nassarius trivittatus. Though it is found most often subtidally, it may also occur intertidally (Scheltema, 1964b; Scheltema and Scheltema, 1965). In our surveys, this species was found in sediment types ranging from silt- sand to fine sand and at depths from 1 m in Indian River to 35 m at a site 67 km east of Ocean City, Maryland. STENOHALINE MARINE SPECIES (Salinity 25-40 %. ) Most of the stenohaline species such as Colus pygmaeus, Calyptraea centralis, and Margarites groenlandicus are found subtidally in the deeper, cooler waters offshore; however, species such as Lunatia heros, L. triseriata, and Natica clausa, although found more abundantly sub- tidally, occur intertidally on sand. When present intertidally, they usually occur in lagoons or tide pools. The above naticids are 76 THE NAUTILUS less resistant than Polinices duplicatus to higher temperatures and lower salinities (Russell-Hunter and Brown, 1964). Lunatia heros is the most abundant stenohaline species occurring from the mouth of Delaware Bay to the 120 km site. Colus pygmaeus is one of the main foods for cod fish and may be dredged offshore to 275 m. As many as 7 in 0.1 m? in a fine sand bottom were found; however, it has been collected live at only two stations. Margarites groenlandicus is also a source of food for the bottom-feeding fish. Our sampling areas have produced numerous shells of this species, but so far only three live specimens have been recorded. SUMMARY OF ECOLOGY In summary, there are approximately 46 com- mon species of marine and estuarine gastropods in the Delaware Bay region — the majority being euryhaline marine species. As_ stated previously, a few of the species listed below have scattered occurrences in either the true estuarine or stenohaline marine _ ranges. However, this grouping represents their most common occurrence. The following list contains a summary of the species. Salinities and other ecological in- formation in parentheses represent data from published literature, while those not in paren- theses represent our data. The substratum is classified by median size of sediment in mm: fine sand, 0.063-0.25; medium sand, 0.25-0.50; coarse sand, 0.50-2.00. Acteocina 35 ho ); vorous. * Acteon punctostriatus (C. B. Adams). Anachis avara (Say): Salinity (28-35 %); eu- ryhaline (on algae); carnivorous. Anachis lafresneyi (Fischer and Bernardi): Salinity (27-35 %); euryhaline; prefers firm substrata; carnivorous. Busycon canaliculatum (Linné): Salinity, 20- 35 %o; euryhaline; fine and medium sand; car- nivorous; spawning months, May through Sep- tember. canaliculata (Say): Salinity (18- euryhaline; silty-sand; burrower; carni- * Ecological information unavailable at the present time. July 17, 1975 Vol. 89 (3) Busycon carica (Gmelin): Salinity, 20-35 %; euryhaline; fine-medium sand; carnivorous. * Calyptraea centralis (Conrad). Cerithiopsis green (C. B. Adams): Salinity (28-32 %.); true estuarine; substrate, mud-fine sand; carnivorous. Colus pygmaeus (Gould): Salinity, 30-35 %; stenohaline; medium sand; scavenger; deep water (20-250 m). Crepdula convera (Say): Salinity, 15-32 % (18-35 %.); euryhaline; attached to solid sub- strate; suspension feeder. Crepidula fornicata (Linné): Salinity, 15- 32 % (19-35 %); euryhaline; attached to solid substrate; suspension feeder. Crepidula plana (Say): Salinity, 15-32 %. (25- 35 %); euryhaline; attached to solid substrate; suspension feeder. Epitonium humphreysi (Kiener): Salinity, 18- 32 %.; euryhaline; carnivorous. Epitonium rupicola (Kurtz): Salinity, 18- 32 %; euryhaline; carnivorous. Hupleura caudata (Say): Salinity, 18-32 %o; euryhaline; carnivorous. Haminoea solitaria (Say): Salinity (18-30%); euryhaline; sand, shallow waters. Tlyanassa obsoleta (Say): Salinity, 15-30 % (18-32 %); true estuarine; substrate, intertidal flats; spawning months, June through August. * Kurtziella cerina (Kurtz and Stimpson). Tattorina irrorata (Say): Brackish water; true estuarine; on marsh reeds. Littorina littorea (Linné): Intertidal, true estuarine; on rocks and clinging to sea weed; spawning months, June through August. Littorina obtusata (Linné): Salinity, 28- 35 %.; euryhaline marine; rock jetties near high tide, herbivorous. Tattorina sawxatilis (Olivi): Salinity, 28-35 %; euryhaline marine; rocks, jetties, and side of wharves near high tide line; herbivorous, ovo- viviparous. Lunatia heros (Say): Salinity, 25-35 %.; steno- haline; fine-medium sand, carnivorous. Margarites groenlandicus (Gmelin): Salinity, 30-35 %0; stenohaline; medium sand (10-210 m); herbivorous. Marginella roscida (Redfield): 32 %e; euryhaline; fine-silty sand. Melampus bidentatus (Say): Salinity, 10-25 % (11-30 %); true estuarine; intertidal salt marsh- Salinity, 20- Vol. 89 (3) es, most abundant above high tide line; spawn- ing months, late May through July. Mitrella lunata (Say): Salinity, 25-32 % (18- 32 x); true estuarine substrate, algae-hydroids, silty-sand. Nassarius trivittatus (Say): Salinity, 15-35 %; euryhaline; mostly on sandy bottoms. Nassarius vibex (Say): Salinity, 15-30 % (9- 32 %); true estuarine; substrate, sandy-mud. * Odostomia gibbosa (Busch). Odostomia impressa (Say): Salinity (11-35 %.); euryhaline, ectoparasitic on oysters and other bivalves. * Odostomia trifida (Totten). * QOdostomia willisi (Bartsch) (may be seminuda C. B. Adams). Polinices duplicatus (Say): Salinity, 23-33 %o (27-35 %o); euryhaline; carnivorous; fine-medium sand; spawning months, June through August. Seila adamsi (Lea): Salinity (25-30 %); true estuarine; substrate, mud-fine sand; herbivorous. Skeneopsis planorbis (Fabricius): Salinity (18- 35 %0); euryhaline; on weeds below mid-tide; spawning months, May through July. Triphora mgrocincta (C. B. Adams): Salinity (20-35 %o); true estuarine; substrate, mud-fine sand. Turbonlla interrupta (Totten): Salinity (25- 35 %0); euryhaline; fine sand. * Turbonilla stricta (Verrill). Urosalpinx cinera (Say): Salinity (11-35 %); euryhaline; oyster beds, carnivorous; spawning months, May through October. ACKNOWLEDGMENTS We wish to thank Dr. R. T. Abbott for his assistance and use of the Delaware Museum of Natural History’s collection in verifying our species, and we express our gratitude to Dr. Melbourne Carriker for reading the manuscript and providing constructive criticism. We also thank our colleagues, Jeff Tinsman and Peter Kinner for help in the collection of specimens and for assistance in identifications. LITERATURE CITED Abbott, R. T. 1968. Seashells of North America. A Golden Field Guide. Golden Press, N.Y., pp. 268. THE NAUTILUS 77 Abbott, R. T. 1974. American Seashells. Van Nostrand-Reinhold, N.Y., Second Ed., pp. 663. Allen, J. A. 1963. Ecology and functional mor- phology of mollusks. Oceanogr. Mar. Biol. Ann. Rev. 1: pp. 253-288. Harold Barnes, Ed. Ansell, A. D. 1960. Observations on predation of Venus striatula (Da Costa) by Natica alderi (Forbes). Proc. Malac. Soc. Lond. 34: 157-164. Ansell, A. D. 1961. Egg capsules of the dogfish (Scylliorhinus canicula Linn.) bored by Natica (Gastropoda, Prosobranchia). Proc. Malac. Soc. Lond. 34: 248-249. Apley, M. L. 1970. Field studies on life history, gonadal cycle, and reproductive periodicity in Melampus bidentatus (Pulmonata: Ellobii- dae). Malacologia 10(2): 381-397. Bird, S. O. 1970. Shallow marine and estuarine benthic molluscan communities from area of Beaufort, N.C. The Amer. Assoc. of Pet. Geol. Bull. 54: No. 9. Carriker, M. R. 1951. Observations on the pene- tration of tightly closing bivalves by Busycon and other predators. 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The marine molluscs of New Jersey and Delaware Bay, an annotated checklist. Proc. Phila. Shell. Club. 1(8-9): 5-61. Mackenzie, C. L. 1970. Causes of oyster spat mortality, conditions of oyster setting beds, and recommendations for oyster bed manage- ment. Proc. Nat. Shellfish. Assoc. 60: 59-67. Manzi, J. 1970. Combined effects of salinity and temperature on the feeding, reproductive, and survival rates of Hwpleura caudata (Say) and Urosalpinx cinera (Say) (Prosobranchia: Muricidae). Biol. Bull. 138(1): 35-46. Maurer, D., R. Biggs, W. Leathem, P. Kinner, W. Treasure, M. Otley, L. Watling, and V. Klemas. 1974 a. Effect of spoil disposal on benthic communities near the mouth of Dela- ware Bay. Report to Delaware River and Bay Authority. College of Marine Studies, 125 pp. Maurer, D., W. Leathem, P. Kinner, and L. Watling, 1974 b. Benthic organisms. In: Environmental Survey of Two Interim Dump- sites, Middle Atlantic Bight, EPA 903/9-74- 010a, 141 pp. Maurer, D., L. Watling, and G. Aprill. 1974 c. The distribution and ecology of common ma- rine and estuarine pelecypods in the Dela- ware Bay area. The Nautilus 88(2): 38-45. Maurer, D. and L. Watling. 1973 a. Studies on Little Science July 17, 1975 Vol. 89 (3) the oyster community of Delaware: The in- fluence of the estuarine environment on the associated fauna. Inter. Rev. ges. Hy- drobiol. 58(2): 161-201. Maurer, D. and L. Watling. 1973 b. The biology of the oyster community and its associated fauna in Delaware Bay. Delaware Bay Report Series, 6(D. F. Polis, Ed.). College of Marine Studies, University of Delaware, pp. 1-97. Russell-Hunter, W. D. and S. C. Brown. 1964. Phylum Mollusca. In: R. I. Smith (Ed.). Keys to Marine Invertebrates of the Woods Hole Region. Contrib. No. 11, Systematics Ecology Program, Marine Biol. Lab., Woods Hole: 129-152. Scheltema, A. H. 1965. Two gastropod hosts of the pyramidellid Odostomia bisuturalis. The Nautilus 79: 7-10. Scheltema, A. H. 1968. Redescriptions of Ana- chis avara (Say) and Anachis translirata (Ravenel) with notes on some related species (Prosobranchia, Columbellidae). Ches. Sci. 5(4): 161-166. Scheltema, R. S. 1961. Metamorphosis of the vel- iger larvae of Nassarius obsoletus. Biol. Bull. 120(1): 92-109. Scheltema, R. S. 1964a. Feeding habits and growth in the mud snail, Nassarius obsoletus. Ches Sci. 5(4): 161-166. Scheltema, R. S. 1964b. Reproduction of Nas- sarius trivittatus off the coast of Georgia. The Nautilus 78: 49-50. Scheltema, R. S. and A. H. Scheltema. 1965. Pelagic larvae of New England intertidal gastropods. III. Nassarius trivittatus. Hydro- biologia 25(3-4): 321-329. Schlieper, C. 1957. Comparative study of Aster- ias rubens and Mytilus edulis from the North Sea and the Western Baltic Sea. Ann. Biol. 61, Ser. 33: 117-127. Stickney, A. P. and L. D. Stringer. 1957. A study of the invertebrate bottom fauna of Greenwich Bay, Rhode Island. Ecology 38: 111-122. Watling, L., W. Leathem, P. Kinner, C. Wethe, and D. Maurer. 1974. An evaluation of sew- age dumping on the benthos off Delaware Bay. Mar. Poll. Bull. 5(3): 39-42. Watling, L., J. Lindsay, R. Smith, and D. Maurer. 1973. Isopods of the Delaware Bay area. Vol. 89 (3) Inter. Rev. ges. Hydrobiol. (in press). Watling, L. and D. Maurer. 1972 a. Marine shallow water amphipods of the Delaware Bay area, U.S.A. Crustaceana. Studies on Peracarida, Supplement 3: 251-266. Watling, L. and D. Maurer. 1972 b. Shallow water hydroids of the Delaware Bay region. Jour. Nat. Hist. 6: 643-649. Watling, L. and D. Maurer. 1973. Guide to the macroscopic estuarine and marine _inverte- brates of the Delaware Bay region. Delaware Bay Report Series, Volume 5 (D. F. Polis, Ed.). College of Marine Studies, University of Delaware, pp. 1-178. THE NAUTILUS 79 Wells, H. W. 1959. Notes on Odostomia im- pressa. The Nautilus 72(4): 140-144. Wells, H. W. 1961. The fauna of oyster beds, with special reference to the salinity factor. Ecol. Monogr. 31: 239-266. Wood, L. 1968. Physiological and _ ecological aspects of prey selection by the marine gas- tropod Urosalpinx cinera (Prosobranchia: Muricidae). Malacologia 6(3): 267-320. Young, D. K. and D. C. Rhoads. 1971. Animal- sediment relations in Cape Cod Bay, Massa- chusetts. I. A Transect Study. Marine Biology 11(8): 242-254. CORRECTIONS TO RECENT PAPERS ON NEW SPECIES OF VOLUTOCORBIS FROM SOUTH AFRICA Harald A. Rehder Smithsonian Institution Washington, D.C. 20560 Mr. Richard N. Kilburn of the Natal Museum in Pietermaritzburg has called my at- tention to some transpositions of data in the two papers on Volutocoris that I published in a recent issue of The Nautilus (vol. 88, no. 2, pp. 31, 32 and 33-37, April 1974). The locality data and catalogue number of the holotype of Volutocorbis semirugata Rehder and Weaver, 1974 (loc. cit., pp. 31-32) should read (on p. 32) as follows: Holotype: off Ilha Bazaruto, Mozambique, 180 fathoms; ex A. Visage; Natal Museum Moll. no. G769. Catalogue number for figs. 1 and 5 in the illustration on page 31 should be changed to read: Natal Museum Moll. G769. Similarly, the locality data and catalogue number of Paratype No. 2 of Volutocorbis kilburni Rehder (loc. cit., p. 36) should read: SE of the Bluff, Durban, in 120 fathoms; collect- ed by G. Scott, August 1972 [not Museum, Moll. No. 9939. It is obvious that the data for these two specimens were somehow inadvertently trans- posed. In a personal communication, Mr. Kilburn has informed me that he is doubtful of the Natal records given by me for Volutocorbis semirugata. The specimens recorded as coming from off Durban and the mouth of the Tugela River were probably brought up by fishermen trawling in waters further north, off southern Mozambique. The range of this species should, therefore, be given as off southern Mozambique. This correction of the locality data alters also the range for Volutocoris kilburni Rehder, which is now known to occur only off Durban, Natal. 1872]. Natal [Published July 17, 1975] 80 THE NAUTILUS July 17, 1975 Vol. 89 (3) POLYGYRISCUS VIRGINIANUS (BURCH, 1947) A HELICODISCID LAND SNAIL (PULMONATA: HELICODISCIDAE) Alan Solem Department of Zoology Field Museum of Natural History Chicago, Illinois 60605 ABSTRACT Dissection and scanning electron microscope studies of the Virgina land snail, Polygyriscus virginianus (Burch, 1947), show that this species, previously associated with either Polygyra or Helicodiscus, is related to Helicodiscus and Stenopylis. The family growp Helicodiscidae is redefined and differences from possibly related family wuts noted. INTRODUCTION Shortly after it was described as Polygyra virginiana P. R. Burch (1947), Pilsbry (1948: 1097-1098, fig. 584) proposed a new subgenus, Polygyriscus, and stated “This very peculiar snail is probably not nearly related to Polygyra, but is left in that family tem- porarily.” Solem (1957: 9) raised Polygyriscus to generic rank and placed it in the endodontid subfamily, Helicodiscinae. J. B. Burch (1962: 148, fig. 363) presented new figures and Hu- bricht (1972: 16-17), who had collected some living specimens, also suggested that it was re- lated to Helicodiscus on the basis of the spiral epidermal fringes seen on the juvenile and some adult shells. The only known locality for this species, near Radford, Virginia, was visited by the author in 1974, but only one dead fragment observed. Through the courtesy of Leslie Hubricht, it was possible to dissect and illustrate the anatomy (Field Museum of Natural History 173197) and to illustrate a shell (FMNH 173234) with periostracal fringes intact. I am indebted to Carole W. Christman for the drawings in Fig. 1 and to Elizabeth Liebman who prepared the drawings in Fig. 2 with support from Office of Endangered Species Contract No. 14-16-0008- 764. The scanning electron microscope photographs (Figs. 3-8) were taken in the course of cooperative research with the American Den- tal Association Research Institute. The assist- ance of John Lenke and George Najarian is gratefully acknowledged. The prints were prepared by Fred Huysmans. This is one of the rarest and most unusual North American land snails. Recommendations have been made to the Office of Endangered Species (OES) that Polygyriscus virginianus be declared an endangered species and _ given protection against both collecting and habitat disturbance. This paper, publication of which is supported by the Office of Endangered Species, was prepared as one result of contract work on potentially endangered species of Eastern North America. I am grateful to the OES staff, par- ticularly Mare Imlay, for their support and en- couragement. SHELL STRUCTURE AND FORM The presence of deciduous periostracal spiral fringes (Fig. 2 a) is characteristic of Helicodiscus (see Pilsbry, 1948: figs. 339, 341, 342, 344) and Stenopylis (see Solem, 1957: 11, fig. 4). In Polygyriscus there are remnants of 8 to 10 such spiral rows on the body whorl above the periphery. Those on the shell base usually are completely eroded. The fringes have a very characteristic “comb-like” pattern (Fig. 2 c) when viewed under high magnification. In Helicodiscus, s. s. and Stenopylis the rows are more numerous and lower, while in Helicodiscus (Hebetodiscus) the fringes are ab- sent. In pattern of whorl coiling and umbilical shape, Polygyriscus (Fig. 2 a, 6) is the same as both Helicodiscus and Stenopylis. The genera differ in apertural armature and lip edge characters. In Helicodiscus (see Pilsbry, 1948: 622-640) the lip is not reflected and simple, Vol. 89 (3) while there are usually pairs of tubercles deposited at intervals on the parietal and/or palatal walls (see Hubricht, 1975: 2-4). In Stenopylis the outer lip is thickened and reflect- ed, the parietal callus is raised and curved out- wards so that it forms a crescent narrowing the aperture, and there are an internal lamellar ex- tension on the parietal wall and a separate FIG. 1. Anatomy of Polygyriscus virginianus (P. R. Burch): a, dissected genitalia showing origins and insertions of structures; b, interior of penis showing verge (PV) and major pilasters (PP); ¢, pallial region. Scale lines equal 1 mm. Field Museum of Natural History no. 173197. Other abbreviations explained in text. THE NAUTILUS 81 parietal nodule (see Solem, 1957: 11, fig. 4 e). In Polygyriscus the last fraction of the body whorl is strongly deflected downwards (Fig. 2 c) and it is narrowed by the deflection. There is a strong inward growth of the basal margin (Fig. 2 b) and an equivalent invagination of the parietal wall that produces either a nodular ef- fect (Fig. 2c) or, in the case of actual parietal wall detachment (Pilsbry, 1948: 1098, fig. 584), this becomes a U-shaped margin. In addition to the apertural constriction, there are two barriers present: a transverse ridge just inside the basal lip that was first reported by Hubricht (1972), and a long barrier on the up- per palatal wall (Fig. 2 c) that is moderately recessed (Fig. 2 6). The pattern of apertural constriction is different from that seen in Stenopylis, and the barrier positions and shapes are very different from the patterns found in Helicodiscus. While the three genera share a common growth pattern and basic shell sculp- ture, they are quite distinct in apertural form and barrier details. GROSS ANATOMY All available data on the anatomy of Helicodiscus are summarized or repeated in Pilsbry (1948). Rather than presenting a formal description of the anatomy of Polygyriscus, | provide comparative remarks and emphasize the features in which they differ from the other major groups of endodontoid land snails. The pallial complex (Fig. 1 ¢) is exactly comparable to that of the Endodontidae, in having a weak rectal arm to the kidney (K) and a slightly reflected ureter (KD) that opens posteriorly. There is no differentiated urinary groove leading to the pneumostome. The heart (H), in- testine (I), hindgut (HG), unbranched principal pulmonary vein (HV), anus (A), and mantle collar (MC) are exactly as in Helicodiscus (Pilsbry, 1948: 628, fig. 340 6) and agree with the Endodontidae. The Punctidae and Charopidae differ in usually having a com- pletely closed secondary ureter and often a strongly bilobed kidney, while the Discidae have a very simple triangular kidney that does not reach the hindgut at any point and a complete secondary ureter. Differences in the genitalia are fundamental and obvious at first inspection. Both 82 THE NAUTILUS July 17, 1975 Vol. 89 (3) Helicodiscus (Pilsbry, 1948: 624, fig. 338) and Polygyriscus (Fig. 1 a) have a long, unbranched ovotestis (G) that occupies about one whorl in the upper digestive gland. In most Punctidae and Charopidae there are one or two main lobes to the ovotestis that lie pointing apicad. Each of them is split into several fingerlike subsidiary lobes. In larger species the number and orientation of these lobes can change, but the basic cluster pattern is preserved. In the Endodontidae the ovotestis contains many follicles strung in a line along a single duct, with the follicles angled apicad from the shell axis, rather than pointing directly apicad. In the Discidae, there are a number of multi- branched follicle bundles at spaced intervals along a duct. These bundles lie nearly per- pendicular to the shell axis. All of these families except the Endodontidae agree in having the prostate-uterus at least partly fused with a common lumen, while the Endodontidae have these ducts completely separate for their entire length. Family level differences in the terminal genitalia will be discussed elsewhere, since con- fusing patterns of convergent evolution make simple definitions impossible without first presenting considerable illustrative material. The several families do show distinct differences in this region, but surveys of these differences are beyond the scope of this paper. The talon in the Charopidae and Punctidae has a globose head on a short shaft; in the En- dodontidae it is an elongately oval expansion on a usually longer shaft; in the Discidae it is a tripartite complex structure (Pilsbry, 1948: 568, fig. 304, D) very similar externally at least to that found in the Succineidae; and in both Helicodiscus (Pilsbry, 1948: 624, figs. 338, A, C, D) and Polygyriscus (fig. 1 a) the talon (GT) is a very long, often recurved shaft with only a shghtly enlarged head. The hermaphroditic duct (GD), albumen gland (GG), carrefour (X), uterine area (UT) of the prostate-uterine tract, free oviduct (UV), vagina FIG. 2. Shell of Polygyriscus virginianus (P. R. Burch). Field Museum of Natural History no. 173234. Scale lines equal 2 mm. Vol. 89 (3) (V), spermatheca (S), atrium (Y), and prostate (not shown. in fig. 2) of Polygyriscus are as in Helicodiscus. Both Helicodiscus and Polygyriscus have a muscle, the epiphallic retractor (fig. 2 a, b, EM), that has no analog in the other en- dodontoid families. The presence of a well dif- ferentiated epiphallus (E) is a characteristic of the Helicodiscidae and most Charopidae, but this THE NAUTILUS 83 structure usually is absent in the Endodontidae, Discidae, and Punctidae. The penis retractor muscle (PR) originates from the diaphragm and inserts on the penis-epiphallus junction, as in many endodontoid taxa. The penis of Polygyriscus (fig. 2 a, P) is short, and internally (fig. 2 6) has an apical verge (PV) with subterminal epiphallic pore FIGS. 3—8. Radula of Polygyriscus virginianus (P. R. Burch). Field Museum of Natural History no. 173197. FIG. 3. Central (lower left) and early lateral teeth. 2550X FIG. 4. Central and first lateral tooth. 3950X. FIG. 5. Third lateral tooth on left side of radula. 6000X. FIG. 6. Early marginal teeth from right side of radula. 4325X. FIG. 7. Mid- marginal teeth from left side of radula. teeth from left side of radula. 2375 X. 4225 X. FIG. 8. Outer marginal 84 THE NAUTILUS (EP) and two high, irregular pilasters (PP) in the lower two-thirds of the chamber. This dif- fers markedly from the penis of Helicodiscus parallelus (Say, 1921) (see Pilsbry, 1948: 628, fig. 340, a), where the epiphallus opens through a small valve and there are glandular linings to the wall, but no pilasters present. Within the Charopidae and Endodontidae, differences of this magnitude are indicative of generic separation and these structural differences alone are sufficient to warrant separating Helicodiscus and Polygyriscus. RADULAR STRUCTURE The Punctidae have a radula in which there is no distinction between lateral and marginal teeth, but all the side teeth have a_ bicuspid structure with minute accessory cusps (Pilsbry, 1948: 642, fig. 349, d). The Charopidae basically have tricuspid centrals and laterals, although this situation is secondarily modified in many taxa. The Endodontidae have a tricuspid, large central, and bicuspid laterals (for example, see Solem 1973: figs. 5-8, 13-14). The Discidae agree in the bicuspid nature of the lateral teeth, but their structure differs from that found in the Endodontidae (Solem, unpublished). The radula of Helicodiscus (Pilsbry, 1948: 623, fig. 337, a, p. 624, fig. 338, B) has a minute, tricuspid central tooth, large tricuspid laterals, and multicuspid marginals. The only note on the radula of Stenopylis (Hedley, 1896: 221, fig. C) showed tricuspid lateral teeth and marginals. Hedley “failed to distinguish the dentition as clearly as I wished” and probably overlooked the minute central tooth. In addition, Hedley referred to the marginals as “serrated”, although they are drawn as tricuspid. The radula of Polygynscus (figs. 3-8) is of the helicodiscid type. The central tooth (lower left of fig. 3 and left third of fig. 4) has relatively large ectocones and a small mesocone. The basal plate is far longer than the cusps and the tooth itself is much smaller than the first lateral (fig. 4). Early laterals (figs. 3, 4) are tricuspid with the ectocone and endocone equal in size (fig. 4). The mesocone is long and tapering, with all three cusps elevated at about the same angle (fig. 3). By the third lateral, the endocone has become much larger than the ectocone (fig. 5). July 17, 1975 Vol. 89 (3) The fourth lateral (fig. 6) or first marginal tooth, depending on how they are defined, shows reduction in mesoconal size, a change in tooth angling, the beginning of endoconal split- ting, and an unusual sinuation to the anterior margin on the endoconal side (right side in figure). Seen from a different angle (fig. 7), the mid-marginal teeth show splitting of both ec- tocone and endocone, with continued reduction in mesoconal size and a change in angle of tooth elevation. Outermost marginal teeth (fig. 8) are short and broad, with the mesocone barely larger than the split side cusps and the ectocone greatly reduced in size. There are thus three or four lateral teeth and six or seven marginal teeth on each side of the central tooth. They are virtually identical in structure to the teeth of Helicodiscus. AFFINITIES OF POLYGYRISCUS Polygyriscus is clearly related to Helicodiscus on the basis of shell form, sculpture, and aper- tural features; pallial region organization; gross genitalia; and radular features. Polygyriscus differs from Helicodiscus in possessing two prominent barriers in the shell aperture, having the aperture narrowed, deflected, and often detached when adult; having a penial verge and two prominent pilasters; and in having a much shorter pallial region. The suggestions of Solem (1957) and Hubricht (1972) that Polygyriscus is not a polygyrid, but a helicodiscid land snail are confirmed by these dissections. The subfamily unit Helicodiscinae was credited to Pilsbry in a paper by H. B. Baker (1927: 226, 230). It was defined on the basis of kidney position, with Helicodiscus, Radiodiscus, and Chanomphalus included. Thiele (1931: 568- 569) and Pilsbry (1948: 622-640) excluded Radiodiscus and defined the subfamily on the basis of the ovotestis, shell coiling, and radula. On the basis of studies on Pacific Island and Austro-Zelandic endodontoid snails (Solem, un- published), I consider that Helicodiscus, Stenopylis, and Polygyriscus form a_ sharply defined family unit within the endodontoid complex. The questions of phyletic relationships to the other families and the exact divisions that will be recognized within other family units are beyond the scope of this paper. It is “Vol. 89 (8) desirable to offer the following emended charac- terization of the Helicodiscidae. Family Helicodiscidae Pilsbry, 1927 Shell under 5 mm in diameter, consisting of flatly coiled whorls, few in number, that do not increase rapidly in size. Umbilicus widely open, shallow. Sculpture of spiral ridges, usually deciduous, reduced in some taxa. Aperture nor- mally with barriers or nodules, sometimes deflected and/or thickened when adult. Pallial region with kidney reaching hindgut, a slight rectal extension, ureter opening next to hindgut at posterior of pallial cavity. Ovotestis a single lobe, talon very elongated and without ex- panded head. Prostate and uterus apparently united into a spermoviduct. Epiphallus large and with a separate retractor muscle. Penial retractor muscle originating from diaphragm. Penis with or without verge and_ pilasters. Radula with very small, tricuspid rachidian tooth, three or four tricuspid laterals, and several marginals that become — shortened, broadened, and multicuspid near the outer edge of the radula. The three genera included are Helicodiscus Morse, 1864 (plus the subgenus Hebetodiscus H. B. Baker, 1929 and the section Pseudiscus Morrison, 1942), Polygyriscus Pilsbry, 1948, and Stenopylis Fulton, 1914 (=Coarctatio Haas, 1945). I consider that Chanomphalus Strebel & Pfeffer, 1880 and Radiodiscus Pilsbry & Ferriss, 1906 belong to the charopid complex and are not related to Helicodiscus. Their exact af- finities are still uncertain. Helicodiscus is known from Jamaica, Cuba, Northern Mexico, and much of Eastern North America, with one species in the Columbia River drainage, but the genus is absent from California. Polygyriscus is restricted to a single locality in Virginia. Stenopylis has a wide and unusual distribution, extending from the Philip- pines and Indonesia to the Solomon Islands, Queensland, the MacDonnell and Krichauff mountains in Central Australia, and northern areas of Western Australia (Solem, 1957: 9-11 and unpublished). There is only one _ species, which has been described several times, most recently from Bach-Long-Vi or Nightingale Island in the Gulf of Tonkin (Saurin, 1960, as Microphyura nghtingali; see Solem, 1957 for THE NAUTILUS 85 earlier synonymy). It has not, to my knowledge, been collected on the Asian mainland. The family units of the endodontoid complex, which are classified in the superfamily Arionacea, are, in the order of their description, Punctidae Morse, 1864; Charopidae Hutton, 1884: Endodontidae Pilsbry, 1895; Helicodiscidae Pilsbry, 1927; and _ Discidae Thiele, 1931. While a total of 19 family level names have been proposed for members of this complex (Solem, In Press), probably all of these can be grouped into the above categories. The most obvious anatomical differences from the Helicodiscidae have been covered in the discussion of structures found in Polygyriscus. Shell differences are more subtle and will be reviewed elsewhere. LITERATURE CITED Baker, H. B. 1927. Minute Mexican Land Snails. Proc. Acad. Nat. Sci., Philadelphia 1927: 223-246, pls. 15-20. Burch, J. B. 1962. How to Know the Eastern Land Snails. Dubuque: Wm. C. Brown. 214 p., 519 figs. Burch, P. R. 1947. Polygyra virginiana, a New Species from Virginia. The Nautilus 61(2): 40-41, pl. 3. Hedley, C. 1896. Notes on Anatomical Char- acters. Mollusca. In Report on the Work of the Horn Scientific Expedition to Central Australia. Part II. Zoology: 220-226, figs. A-P. Hubricht, L. 1972. Two New North American Pulmonata: Paravitrea seradens and Philo- mycus sellatus. The Nautilus 86(1): 16-17, 1 fig. Hubricht, L. 1975. Four New Species of Land Snails from the Eastern United States. The Nautilus 89(1): 1-4, 12 figs. Pilsbry, H. A. 1948. Land Mollusca of North America (North of Mexico). Acad. Nat. Sci, Philadelphia, Monog. 3, 2(2): i-xlviil, 521-1113, figs. 282-585. Saurin, E. 1960. Mollusques terrestres de l’ile Bach Long Vi (Golfe du Tonkin). Jour. de Conchyl. 100(1): 3-9, 3 figs., pl. 1. Solem, A. 1957. Philippine Snails of the Family Endodontidae. Fieldiana: Zool. 41(1): 1-12, 4 figs. 86 THE NAUTILUS Solem, A. 1973. A New Genus and Two New Species of Land Snails from the Lau Archi- pelago of Fiji (Mollusca: Pulmonata: Endo- dontidae). The Veliger 16(1): 20-30, 3. pls., 6 figs., 1 table. Solem, A. In Press. Endodontoid Land Snails July 17, 1975 Vol. 89 (3) from Pacific Islands (Mollusca: Pulmonata: Sigurethra). Part I. Family Endodontidae. Spec. Pub. Zoology, Field Mus. Nat. Hist. Thiele, J. 1931. Handbuch des syst. Weicht., 2: 377-778, figs. 471-783. THE MARINE COMMENSAL GASTROPOD, CALEDONIELLA MONTROUZIERI (PROSOBRANCHIA: HIPPONICACEA) IN THAILAND Joseph Rosewater Department of Invertebrate Zoology National Museum of Natural History Washington, D.C. 20560 R. L. Caldwell, University of California, Berkeley, and H. Dingle, University of Iowa, deposited 9 specimens of the crustacean, Gonodactylus viridis Serene, 1954', in the collec- tion of Mollusks, each infested with two specimens of Caledoniella montrouzieri (Souver- bie) (Rosewater, 1969). Caldwell and Dingle, who collected the Gonodactylus in Phuket, Thailand, stated that about 25% of the stomatopods were infested (pers. comm.). In all cases the location of the snails was exactly as previously described: males were between the periopods near the ventral posterior end of the thorax, females between the 4th and 5th pleopods on the ventral posterior abdomen. The pleopods were liberally covered with the snails’ egg capsules. This discovery adds the following new in- formation to that summarized in my earlier * R. B. Manning identified the stomatopod. paper: the sexual dimorphism apparent in the male and female shells illustrated on plate 55 of that paper is confirmed, females being larger and helicoid, males are smaller and cap-shaped; there is strong position preference in the two sexes; an additional stomatopod species is in- fested in addition to the 3 known previously, G. chiragra, G. platysoma and G. smithu; a new country is recorded as domicile for C. mon- trouzieri, although Phuket, Thailand, is less than 500 miles from the Andaman Islands where it was previously collected. LITERATURE CITED Rosewater, Joseph. 1969. Gross Anatomy and Classification of Commensal Gastropod, Cal- edoniella montrouzieri (Souverbie, 1869). The Veliger 11: 345-350, plate 55, text figs. ” #Vol. 89 (3) THE NAUTILUS 87 FURTHER STUDIES OF THE MOLLUSCA OF THE OTSEGO LAKE AREA Mark C. MacNamara and Willard N. Harman Biology Department State University College at Oneonta Oneonta, New York 13820 ABSTRACT Five years of collecting have resulted in the completion of a survey of the molluscan fauna of the State University of New York, College at Oneonta, Biological Field Station at Cooperstown and adjacent Otsego Lake. Fifty-eight species representing nineteen families of freshwater and terrestrial mollusks oc- cur there. Several traditional techniques, in addition to the use of Tullgren drying funnels, pit can traps and the examination of the stomach contents of the terrestrial stage of the common newt, Notophthalmus viridescens, were wsed to amass the collections. The latter was the most effective method of obtaining small, terrestrial forms, while pit cans were extremely effective for the collec- tion of slugs. INTRODUCTION In 1967 an area for the establishment of a biological research station and laboratory was acquired a short distance north of Cooperstown, Otsego County, on the west shore of Otsego Lake. More than 149 hectares of mature second- growth hemlock-hardwood forest, old plantations of larch, spruce, and pine, and wet forested lowlands are included on the site as well as two ponds, a swamp and a senescent bog. The climate is of the humid-continental type with prevailing westerly winds. Precipitation is evenly distributed throughout the year and averages between 75 and 100 cm annually. The freeze-free season has an average length of 123 days with the warmest weather normally less than 32°C. The highest temperature ever record- ed (1854-1974) was 38°C. The parent rocks in this area were deposited as sands, silts, clays and carbonates in the Ap- palachian geosynclinal sea during the Lower and Middle Devonian Period. Although the local sandstones and shales are low in calcium and other elements important in metabolic processes, the north end of Otsego Lake and the greatest portion of its watershed lie on the Onondaga limestone formation and drain areas of older limestones to the north. Therefore, the lake is much more productive than the smaller, natural aquatic and terrestrial biotopes oc- curring locally. This report is a synthesis of data concerning the molluscan fauna of the station accumulated over the past 5 years as a result of several major studies and the ongoing research projects on Otsego Lake (Harman, 1970, 1971, 1974; Herrmann and Harman, 1975), studies on Moe Pond (Harman, 1972b; Katsigianis and Harman, 1973, Katsigianis and Harman, 1974; Herrmann and Harman, 1975a,1975b). New Pond (Har- man, 1973) the terrestrial sites (Butts, 1971) and accumulation of unpublished data from col- lections of undergraduate and graduate students involved in research. DESCRIPTION OF COLLECTION AREAS Otsego Lake lies in the glacially overdeepened headwaters of the Susquehanna River in Otsego County, New York (42°40'N — 70°00’W). It is oriented, with its main axis north to south, in a valley about 1.6 km in width and ap- proximately 13 km long. The basin is enclosed on the east and west by truncated slopes rising to the divide at the height of about 610 m. The northern end of the lake is bounded by the Richfield Springs Drumlin Field and on the south by an end moraine and outwash plain that dammed the valley and impounded the waters trapped in the basin. It is unique, being the only Finger Lake in the Susquehanna Drainage Basin. The morainic dam at the south end of the lake was formed when the ice lobe that deepened and widened about 13 km of the upper Susquehanna River to the present village 88 THE NAUTILUS of Cooperstown, stopped and then receded north- ward as melting exceeded southward flow. Ot- sego is a morphometrically oligotrophic, chemically eutrophic, lake. It exhibits typical temperature stratification in the summer and when it is ice-covered in the winter, with lim- nological characteristics as follows: Elevation 364 m, maximum length 13 km, maximum width 2.5 km, surface area 1,702 hectares, maximum depth 50 m, mean depth 25 m, average Secchi transparency 4.7 m, average pH 8.1, and average alkalinity as CaCO; 115 ppm (Harman, 1972a). Moe Pond is a shallow (3.7 m) eutrophic body of water with an effective width of 330 m and effective length of 750 m. The highly productive nature of the pond appears artificial in origin and is possibly related to 51,000 keg of pulverized limestone that was added to the pond water while it was being utilized for irrigation of a nearby golf course in 1966 and 1967 (Harman, 1972b). However, alkalinity remains low, varying between 19 and 40 ppm in 1971. The pH varies between 7.3 and 11.3, and Secchi transparency is normally less than 0.5 m. Most aquatic macrophytes grow along the shoreline in 0-12 ecm of water, probably because of shallow compensation points resulting from the chronically turbid water due to algal blooms. The substrate is mostly chan- nery, silt and sand derived from Devonian shales and glacial deposits (Herrmann and Har- man, 1975a, 1975b). New Pond is a small (ca. 0.5 hectares surface area, maximum depth 4 m) body of water with no natural outlet. Greatly fluctuating water levels annually increase the surface area and depth by greater than 100%. An abundance of aquatic macrophytes occur in the shallow water which maintains remarkably low populations of phytoplankters (Harman, 1972b). Although terrestrial mollusks have been collected from several sites on station lands, most were obtained from a poorly drained area of northern hardwood forest approximately 150 m east of Moe Pond at an elevation of about 396 m. The dominant trees are red maple (Acer rubrum) and sugar maple (A. saccharum) with lesser amounts of red oak (Quercus rubra), white ash (Fraxinus americana), and basswood (Tila americana). The subcanopy (1-10 cm July 17, 1975 Vol. 89 (3) diameter breast height) is composed of sugar maple, hemlock (Tsuga canadensis), and red maple. The shrubs are dominated by poison ivy (Rhus toxicodendron) but also include numerous ferns and herbaceous plants. The water-table is close to the surface with standing water in many depressions during the spring and fall. A layer of decomposing deciduous leaf litter is present throughout the year. The soils are acid shales and clays with a pH of about 5.3. METHODS Several techniques were utilized in order to collect aquatic mollusks. In shallow waters they were obtained with a common household sieve or picked by hand from the substrate with for- ceps. In Otsego Lake, collections were made at 51 stations around the shores in waters from 0 to 1 m in depth. Using diving equipment, col- lections were taken at 35 of these locations reaching a depth of 8 m. Six deeper dives (to 23 m) were made. Approximately 125 Ekman dredge samples were taken at various depths from the surface to the deepest points in the lake. At all aquatic collection areas the following data were recorded: alkalinity as CaCO3, pH, ppm of oxygen, ppm of carbon dioxide, surface temperature, effective width, ef- fective length (if applicable), depth, current wave action, particle size and character (organic or inorganic) of the substrate, air temperature, wind velocity, soil type, and elevation. Collection of terrestrial mollusks was done in several ways. For general survey work hand picking from the soil, decaying wood, under sticks, logs, bark, stones and in leaf litter or pit can traps (No. 2 cans buried with their open tops flush with the soil surface primarily for collection of various types of arthropods) were used. The latter were particularly effective for obtaining slugs. Collections were also made from leaf litter samples processed in a series of modified Tullgren type dry funnels (Edwards and Fletch- er, 1970). In this apparatus heat and lack of moisture force most invertebrates to move down through the litter until they finally drop into a collecting vial filled with 70% ethanol. For the purposes of this study a 25 watt electric light bulb placed over each sample served as the heat source. Samples were left in the funnels for “ Vol. 89 (3) three days. Only six pulmonate snails, all in the order Basommatophora, were collected by this method. By hand searching through the dried samples of litter, we were able to gather organisms that died before they reached the collecting vial. Several hundred fingernail clams (Sphaeriidae) were recovered in this way. The most effective method of amassing small terrestrial mollusks was by the examination of the stomach contents of the red eft, the terrestrial stage of the common newt, Notophthalmus viridescens. One hundred twenty efts were collected from the poorly drained area previously described in the months of June and July 1973. Each stomach was opened and examined with a 45x binocular dissecting microscope. Two hundred thirteen mollusks, representing 25 species, were obtained. Aquatic Mollusca were determined by the junior author. The terrestrial mollusks were identified by F. Wayne Grimm, Canadian National Museums, Vanier, Ontario. TABLE 1. List of mollusks collected in the vicimty of Otsego Lake, N.Y. OTSEGO LAKE Lampsilis radiata (Gmelin) Elliptio complanata (Lightfoot) Anodonta cataracta (Say) Anodontoides ferussacianus (Lea) Strophitus undulatus (Say) Alasmidonta undulata (Say) Pisidium compressum (Prime) Pisidium subtruncatum (Malm) Sphaerium sulcatum (Lamark) Lymnaea humilis (Say) Lymnaea palustris (Miller) Lymnaea emarginata (Say) Lymnaea columella (Say) Helisoma trivolvis (Say) Helisoma anceps (Menke) Helisoma campanulata (Say) Gyraulus parvus (Say) Promenetus exacuous (Say) Physa heterostropha (Say) Viviparus georgianus (Lea) Spirodon carinata (Bruguiére) Valvata tricarinata (Say) Valvata sincera (Say) Ammnicola limosa (Say) THE NAUTILUS 89 Amnicola lustrica (Pilsbry) MOE POND Helisoma anceps (Menke) Physa heterostropha (Say) Ferrissia paralella (Haldeman) NEW POND Lymnaea humilis (Say) Helisoma anceps (Menke) Gyraulus parvus (Say) Physa heterostropha (Say) NORTHERN HARDWOOD FORESTS Pisidium casertanum (Poli)* Aplexa hypnorum (Linnaeus)* Lymnaea humilis (Say)* Carychium exiguum (Say)* Gastrocopta pentodon (Say)* Vertigo bollesiana (Morse)* Succinea ovalis Say* Catinella vermeta (Say)* Anguispira alternata (Say)* Discus catskillensis (Pilsbry)* Iscus cronkhitei ((Newcomb)* Discus patulus (Deshayes)* Punctum minutissimum (Lea)* Nesovitrea binneyana (Morse)* Mesomphix inornatus (Say)* Huconulus chersinus polygyratus (Pilsbry)* Ventridens intertextus (Binney)* Zonitoides arboreus (Say)* Striatura milium (Morse)* Striatura exigua (Stimpson)* Stenotrema fraternum (Say)* Triodopsis dentifera (Binney) Triodopsis denotata (Ferrussac) Triodopsis tridentata (Say) Mesodon sayanus (Pilsbry)* Triodopsis albolabris (Say) Arion fasciatus (Nilsson) Deroceras laeve (Miller) Deroceras cf. agreste (Linnaeus) Philomycus flexuolaris (Raf.) Philomycus togatus (Gould) Pallifera dorsalis (Binney) DISCUSSION The species collected are listed in Table 1 ac- cording to the habitats in which they were found. The distribution of the aquatic Mollusca * ree mollusks removed from stomachs of N. viridescens. 9) THE NAUTILUS in field station biotopes correlates directly with the types of substrate that occur in these areas. Helisoma anceps is extremely abundant in Moe Pond which has silted, flat cobblestones oc- curring over much of the bottom. This is typical of the biotopes in central New York where this species is found. In New Pond, Gyraulus parvus occurs in submergent vegetation that completely fills the low waters in late summer. At those times silty banks rise slowly from the shores and support ephemerally large populations of Lymnaea humilus. These again are the usual habitats for the species con- cerned. Physa heterostropha is abundant in both locations, occurring in somewhat shallower water than H. anceps on inorganic and organic substrates. Aplexa hypnorum occurs in vernal ponds under deciduous forest trees as is typical. This is the first record of this species in the Susquehanna watershed in central New York (Harman and Berg, 1971). Since it is widely separated from population centers in the Finger Lakes region to the west, we assume that its origin is from New England where Aplexa is also commonly found. The high species richness in Otsego Lake compared to New and Moe Ponds can be at- tributed to several factors: 1. the presence of prosobranch snails and freshwater mussels. The lake is the source of the Susquehanna River which provides access for these water-dependent organisms. 2. the diversity of substrates present compared to both smaller bodies of water. It has been shown by Harman (1972a) that sub- strate diversity is directly correlated with species diversity of mollusks in central New York State. 3. the high alkalinity (ca 115 ppm in Otsego compared to 19-40 ppm) in Moe Pond and New Pond. Many authors have shown correlations between high alkalinity, reflecting available calcium, and a high species richness of mollusks. The list of terrestrial mollusks illustrates a greater species richness than we would expect to find on acid shales in the Northeast. We ac- count, for this by the apparent efficiency of Notophthalmus as a “collector” of small to minute mollusks easily overlooked in general surveys. July 17, 1975 Vol. 89 (3) LITERATURE CITED Butts, W. L., J. Raver and M. Wang. 1971. Sampling of anthropophilous mosquitoes. 2 pp. In 3rd Ann. Rept. (1970-71). SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta. Chichester, L. F. and L. L. Getz. 1973. The ter- restrial slugs of Northeastern America. Sterk- iana 51: 11-42. Edwards, C. A. and K. E. Fletcher. 1970. As- sessment of terrestrial invertebrate popula- tions, pp. 57-66. In J. Philpson (ed.) Methods of Study in Soil Ecology. UNESCO Paris. Harman, W. N. 1970. Aquatic biology studies, pp. 15-16 and app. pp. 1-142. In 2nd Ann. Rept. (1969-70) SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta. Harman, W. N. 1971. The mollusca of Otsego Lake, New York. The Nautilus 85: 70-71. Harman, W. N. 1972a. Benthic substrates: Their effect on freshwater Mollusca. Ecology 53: 271-277. Harman, W. N. 1972b. Aquatic biology studies, pp. 4-15. Im 4th Ann. Rept. (1971). SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta. Harman, W. N. 1973. Aquatic ecology studies, pp. 2-42. Im 5th Ann. Rept. (1972). SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta. Harman, W. N. 1974. Aquatic ecology studies. pp. 4-27 + map. In 6th Ann. Rept. (1973). SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta. Harman, W.N. and C. O. Berg. 1971. The fresh- water Gastropoda of central New York with illustrated keys to the genera of the species. Search: Cornell Univ. Agr. Exp. Sta., Hnto- mology, Ithaca, 1(4): 1-68. Herrmann, S. A. and W. N. Harman. 1975a. Population studies on Helisoma anceps (Menke) (Gastropoda: Pulmonata). The Nauti- lus 89: 5-11. Hermann, S. A. and W. N. Harman. 1975b. Studies on two populations of Physa hetero- stropha (Say) (Gastropoda: Pulmonata). Ohio Journal of Sci. 75: 85-95. Katsigianis, T. S. and W. N. Harman. 1973. Variation in the radular teeth of Helisoma anceps (Menke). The Nautilus 87: 5-7. Vol. 89 (3) THE NAUTILUS 91 RADULAR ANOMALY IN UROSALPINX CINEREA (GASTROPODA: MURICIDAE)! Melbourne R. Carriker Marine Studies Center College of Marine Studies University of Delaware Lewes, Delaware 19958 ABSTRACT A radular anomaly involving the total absence of the central cusp in the rachidian row of teeth throughout the length of the radula of an adult in- dividual Urosalpinx cinerea follyensis is reported. The remainder of the radula was normal. Although the anomaly may not have interfered with hole-boring, it probably was a disadvantage in feeding. The anomaly may have resulted from a mutation rather than from a physical or biological injury. INTRODUCTION Wu in studies of the radula of many species of snails in the family Muricidae found no anomalies, and considers radular deformities very rare in this family (Wu, 1965, 1968; per- sonal communication, 1974). In research on the proboscis of the shell-boring marine snails Urosalpinz cinerea (Say), U. cinerea follyensis Baker, and Huplewra caudata etterae Baker (Carriker, 1943, 1961, 1969; Carriker and Van Zandt, 1972a; Carriker et al., 1972; Carriker et al., 1974), we have examined many radulae and observed a radular anomaly in only one in- dividual of U. cinerea follyensis which I feel is worth reporting in view of the rarity of radular anomalies in the Muricidae, and the important use of radulae in gastropod identification. METHODS The individual of Urosalpinx cinerea follyen- sis in which the radular anomaly was discovered was collected with others of the same subspecies in Wachapreague, Virginia. Prior to dissection, snails were maintained for some weeks in my laboratory in rapidly flowing seawater (salinity 31-32°/00) with an excess of oysters and mussels for food. The snail with the radular anomaly was 40 mm in shell height, normal in external appearance, and _ actively boring and feeding on prey. ‘ University of Delaware College of Marine Studies Con- tribution No. 100. The radula was excised in seawater under a binocular microscope with iridectomy scissors and fine jeweller’s forceps. The subradular membrane was cut loose and slipped off the twin odontophoral cartilages (leaving the radular sac and muscles at each end of the membrane still attached), rinsed in distilled water, and dried on a plastic cover slip. The radular membrane was oriented so that trans- verse rows of teeth were slightly elevated and separated from each other. Anterior and posterior ends of the radula were next secured to the plastic cover slip with Duco cement. Af- ter the cement had hardened, a small portion of the cover slip supporting the radula was cut out with scissors and affixed to a scanning elec- tron microscope stub with double adhesive tape. Ends of the radula were then coated with silver paint to minimize charging in the microscope. The preparation was dried in an oven at 60°C ovenight, coated with carbon followed by gold in a vacuum evaporator, and studied and photographed in a scanning electron microscope at an accelerating voltage of 20 Kv. OBSERVATIONS In normal adult Urosalpinx cinerea follyensis ranging in shell height from 38 to 44 mm, the radula varies from approximately 9 to 12 mm in length and from 330 to 4304 in width, but radular dimensions vary widely among different individuals of the same shell height. 92 THE NAUTILUS The normal radula of an adult snail contains approximately 250 to 850 transverse rows of nearly colorless teeth (see also Carriker et al., 1972), and each transverse row consists of two slender scythe-shaped marginal teeth separated from a sturdy central rachidian tooth by in- termediate grooves (see Carriker et al., 1974, for details). The pattern of radular structure is thus rachiglossan, with the formula ar is ar Ib July 17, 1975 Vol. 89 (3) The rachidian tooth of a normal radula is quinquecuspid, and each of the five prominent cusps arises from a stout basal plate attached to the radular membrane. Unworn cusps in the forward part of the radular sac and atop the odontophore before they come into use in hole-boring, are sharp, slightly hooked, and curve posteriorly. Approximately four to six small denticles protrude posteriorly from the basal plate between the marginal and lateral cusps, Scanning electron micrographs. Fig. 1. Normal rachidian teeth. Width (side to side dimension) of base plate of each tooth (at anterior end) 115y. Fig. 2. Anomalous rachidian teeth. Width of base plate of each tooth 114. Fig. 3. Anomalous rachidian teeth pictured in fig. 2, higher magnification, dorsal view. In- terval between tips of two principal lateral cusps 50u. Fig. 4. Anomalous rachidian teeth pictured in fig. 3, higher magnification, side view. Interval between tips of lateral cusp 50. * Vol. 89 (3) and a prominent denticle extends between the bases of the central and lateral cusps (fig. 1). The anomalous radula was 10 mm long and 3504 wide, dimensions characteristic of rad- ulae of a snail 40 mm in shell height. The major difference between the anomalous radula and normal radulae was the complete absence throughout the length of the radula of the cen- tral rachidian cusp (fig. 2). The site of the cen- tral cusp was marked by a smooth convexly rounded prominence. The posterior edge of the prominence in some of the teeth when viewed from the top appeared obtusely angled in the transverse plane (fig. 3). In other teeth the edge was rounded or slightly notched. As seen from the side, the prominence appeared obtusely angled in the sagittal plane, with a slight up- turned nodular lip (fig. 4). Large denticles be- tween the central and lateral cusps were slightly misshaped, those on the animal’s right (teeth point posteriorly) conspicuously more so than those on the left. All other morphological features of the radula, including marginal teeth, intermediate grooves, and rachidian basal plates were normal and fell within the range of struc- tural variation characteristic of radulae in this subspecies. DISCUSSION Rachidian cusps, and especially the prominent central one, function in (a) scraping shell in the borehole during penetration of shell of prey, (b) and, synchronously with the lateral teeth, in biting off fragments of flesh during feeding (Carriker and Van Zandt, 1972a). Absence of the central cusp in the snail with the anomalous radula probably did not affect hole boring significantly as the accessory boring organ does most of the work of shell penetration (Carriker and Van Zandt, 1972b), but probably did decrease efficiency of feeding. As suggested by the fact that the snail grew to a normal size and shape, however, decrease in the rate of ingestion was probably minor. How the anomaly might have affected the rate of growth is not known. The anomaly may have resulted from (a) a highly localized permanent injury to the odon- toblasts which initiate secretion of the central rachidian cusps within the innermost end of the radular sac, or (b) from a mutation. It is THE NAUTILUS 93 unlikely, however, that an injury, limited to the few cells which produce the central rachidian cusp sheltered inside the radular sac in the cephalic hemocoel, could have resulted from an external blow or puncture. Nor is it likely that the anomaly might have resulted from localized infection, parasitism, or physiological malfunc- tioning. The highly specific anatomical nature of the anomaly suggests instead that it may have arisen as a mutation. Whether the change was neutral or only mildly deleterious is not known. Morphological and behavioral evidence would indicate that it could not have been beneficial (Carriker and Van Zandt, 1972a), and thus individuals possessing the anomaly would find themselves disadvantaged in the com- petition for food. The stability of radular features in gastropods has been recognized for a long time. Fretter and Graham (1962), for example, noted that the number and shape of radular teeth dif- fer from species to species, but remain fairly constant within one species. Abbott (1954) point- ed out that radulae are so distinctive in the various families, genera, and species of molluscs that they have been used as a fairly reliable criterion in identification. And Wu (1965) reported that the muricid radula appears to be constant within each species and can be used for diagnosis of species. With the exception of the anomaly reported in this paper, my ob- servations of species of Uvosalpinx and Eupleura support Wu's observations. However, this anatomical stability does not appear to exist in all gastropods. Wu (1972), for example, discovered that the most distinctive features in the freshwater polyploid series of Bulinus (Planorbidae) were deformities in teeth. He be- lieves these anomalies could be genetic in origin. At first glance, and not having examined the proboscis of both sexes, one might consider the anomaly reported here in Urosalpinx cinerea follyensis an example of sexual dimorphism. Nevertheless, although sexually dimorphic radulae have been reported in the muricid Drupella (Arakawa, 1957), the muricid Nassa (Maes, 1966), the buccinid Pisania and the ar- chaeogastropod Hiloa (Robertson, 1971), sexual radular dimorphism, in size or other anatomical features, has never been observed in individuals 94 THE NAUTILUS of U. cinerea follyensis ranging in shell height from 14 to 42 mm (Carriker and Van Zandt, 197 2a). ACKNOWLEDGMENTS Live specimens of Urosalpinx cinerea follyen- sis were supplied by Mr. Michael Castagna from Wachapreague, Virginia. Preliminary scan- ning electron microscopy was done with Dr. Virginia Peters on a JOEL JSM-U3 at the Woods Hole Oceanographic Institution (see fig. 1, 4), and final examination was made with Mrs. Takako Nagasi on a Cambridge Stereoscan Mark II in the Department of Geology, Univer- sity of Delaware (see fig. 2, 3). I am grateful to these persons for their generous help. Research was supported in part by Public Health Service Research Grant DE 01870 from the National Institute of Dental Research, and in part by a grant from the University of Delaware Research Foundation. LITERATURE CITED Abbott, R. T. 1974. American Seashells, second edition D. Van Nostrand. Reinhold, N.Y. 663 pp. Arakawa, K. Y. 1957. On the remarkable sexual dimorphism of the radula of Drupella. Venus 19: 206-214. Carriker, M. R. 1943. On the structure and function of the proboscis in the common oys- ter drill, Urosalpinx cinerea Say. Jour. Morph. 73: 441-506. Carriker M. R. 1961. Comparative functional morphology of boring mechanisms in gastro- pods. Amer. Zool. 1: 263-266. Carriker, M. R. 1969. Excavation of boreholes by the gastropod Urosalpinx: an analysis by light and scanning electron microscopy. Amer. Zool. 9: 917-933. ACADEMY MOLLUSK COLLECTION UP-DATED Through a generous four-year N.S.F. grant, the extensive and venerable mollusk collection at the Academy of Natural Sciences of Philadelphia has been cleaned and put into bet- ter curatorial shape, so that scientists and students may use these facilities to greater ad- July 17, 1975 Vol. 89 (3) Carriker, M. R. and Van Zandt, D. 1972a. Pred- atory behavior of a shell boring muricid gas- tropod. Chapter 5, in H. E. Winn and B. L. Olla, Ed., Behavior of Marine Animals: Cur- rent Perspectives in Research 1, Inverte- brates, Plenum Press, N.Y., pp. 157-244. Carriker, M. R. and Van Zandt, D. 1972b. Regeneration of the accessory bering organ of muricid gastropods after excision. Trans. Amer. Micros. Soc. 91: 455-466. Carriker, M. R., Person, P., Libbin, R., and Van Zandt, D. 1972. Regeneration of the proboscis of muricid gastropods after amputation, with emphasis on the radula and cartilage. Biol. Bull. 143: 317-331. Carriker, M. R., Schaadt, J. G., and Peters, V. 1974. Analysis by slow motion picture photo- graphy and scanning electron microscopy of radular function in Urosalpinx cinerea during shell penetration (Muricidae, Gastropoda). Mar. Biol. 25: 63-76. Fretter, V., and Graham, A. 1962. British Pro- sobranch Molluscs. Their Functional Anatomy and Ecology. Ray Society, London. Maes, V. O. 1966. Sexual dimorphism in the radula of the muricid genus Nassa. The Nautilus 79: 73-80. Robertson, R. 1971. Sexually dimorphic archaeo- gastropods and radulae. Amn. Rept. Am. Malacol. Union, 1970: 75-78. Wu, S. 1965. Studies of the radulae of Taiwan muricid gastropods. Bull. Inst. Zool., Acad- emia Simca 4: 95-106. Wu, S. 1968. On some radulae of the muricid gastropods. Venus 27: 89-94. Wu, S. 1972. Comparative studies on a_ poly- ploid series of the African snail genus Buli- nus (Basommatophora: Planorbidae). Malaco- logical Rev. 5: 95-164. vantage. Loans of specimens and _ books, photography of types, photocopying, and storage facilities for voucher specimens are being of- fered to qualified workers. For further details, see The Veliger, Vol. 17, no. 4, pp. 414-415 (1975) or write Dr. George M. Davis, Chairman, Dept. Malacology, Academy of Natural Sciences of Philadelphia, Philadelphia, Pa. 19103. el ~ Vol. 89 (3) THE NAUTILUS 95 MARSENIOPSIS SHARONAE (WILLETT, 1939) COMB. NOV. Gale G. Sphon Curatorial Assistant, Invertebrate Zoology Los Angeles County Museum of Natural History Los Angeles, California 90007 ABSTRACT The generic placement of Lamellaria sharoni Willett, 1939, is changed to Marseniopsis sharonae (Willett, 1939). In 1939 George Willett described Lamellaria sharon. from Anaheim Bay, Orange County, California. Later, J. Q. Burch (1946) emended the name to Lamellaria sharonae because Willett had named it for its discoverer, Ruby Sharon. Apparently neither Willett nor Burch was familiar with Bergh’s genus Marseniopsis (1886). However, Burch (1946) noted that Willett had not been pleased with his’ generic placement of the species, but rather than describe a new genus, he placed it in Lamellaria. This animal is unlike any of the other eastern Pacific species of Lamellaria. The shell structure is more analogous to that of Polinices or Natica while the other eastern Pacific species of Lamellaria are similar to that of Sinum. In the true lamellarians the mantle may or may not cover the entire shell and is either smooth or warty. In Marseniopsis sharonae the mantle covers the entire shell and is divided into six areas by low ridges that commence from a raised hexagon in the center of the dorsum. The ridges, flat sides, and flat dorsum give the animal the appearance of a hexadendron. These ridges are not found in any of the other eastern Pacific lamellarians. Marseniopsis sharonae apparently has a broad north-south distribution. The northern most record is one specimen from Bodega Harbor in Marin County, California. It is in the collection of the Los Angeles County Museum of Natural History. The species has also been found in Monterey Bay, Palos Verdes Peninsula (Los Angeles), Anaheim Bay (type locality), La Jolla, and throughout the Gulf of California. To date, the species has not been found further south than the gulf of California. However, collection records indicate that it is more common in the Gulf of California than in California proper. It would not be surprising to have the range ex- tended further south. As Bergh (1886) noted when he named the genus Marseniopsis, the features of the radula are mid-way between those of Marsenia and Onchidiopsis and not particulary close to the type genus of the family, Lamellaria. After their purchase of the Ruby Sharon collection, the Cates (1962) discovered paratypes of this species and distributed them widely among U.S. institutional collections. The holotype had been deposited by Willett in the Los Angeles County Museum of Natural History, Invertebrate Type Collection no. 1059. LITERATURE CITED Bergh, R. L. S. 1886. Report on the Marsenidae collected by the H.M.S. Challenger during the years 1873-1876. Voyage of H.M.S. Chal- lenger, Zoology 15: 1-24. 1 plt. Cate, J. and C. Cate. 1962. The types of Lamel- laria sharonae Willett, 1939 (Gastropoda). The Veliger 5(2): 91. Burch, J. Q. 1946. (No title). Minutes of the Conch. Club So. Calif. no. 57, p. 1. Montagu, G. 1815. An account of some new and rare British shells and animals. Trans. Linn. Soc. London 11(2): 179-204. plts. 12-14. Willett, G. 1939. Description of a new mollusk from California. The Nautilus 52(4): 123-124, pl. 9, figs. 1, la, and 1b. 96 THE NAUTILUS July 17, 1975 Vol. 89 (3) THE IDENTITY OF PLANORBULA JENKSII (H. F. CARPENTER) Douglas G. Smith Museum of Zoology, University of Massachusetts Amherst, Massachusetts 01002 ABSTRACT The freshwater pond snail, Planorbula jenksii, has been recently accepted by some authors as the “eastern” species of Planorbula in North America. A review of the literature however indicates that this acceptance is ultimately based on an interpretation by F. C. Baker of a published statement by Pilsbry (1934). Examinations of specimens of Planorbula from north eastern North America show no differences from mid-western P. armigera (Say). Specimens identified as P. jenksii are therefore considered to be P. armigera. Planorbula jenksii (Carpenter) has, within the last thirty years, come to be accepted by a few workers as the eastern North American representative of the genus. Recent investigation however, shows that the taxon “jenksi” is in- correct in its present application (see Clarke, 1973). Carpenter’s (1887) original description, a reprint from the Gentral Falls Visitor (Feb., 1871), was based upon a single broken specimen, apparently since lost, from a pool near “Ham- monds Pond,” Pawtucket, Rhode Island. The exact location in relation to “Hammonds Pond” has been unclear though Davis (1905: 117) referred to Stump Hill, a presently existing locality. In his description Carpenter did not FIG. 1. drawn from Davis (1905). Segmentina jenksii (Carpenter). Re- mention the lamellar projections within the aperture, a characteristic feature of Planorbula, nor had he saved the soft parts for anatomical study. On conchological grounds he placed “Senksii” in Planorbis. Immediately following the description of “jenksii,” he listed the sympatric Segmentina armigera (Say), now in Planorbula, as distinct from his nominate “jenksi”. Davis (Loc. Cit.) figured Carpenter’s type specimen (fig. 1) and noted two small palatal lamellae on the left side of the aperture and by these alone, placed the species in Segmentina. The original drawn figure depicted two views of the shell and although the specimen was damaged to a degree, enough of the apertural area remained to indicate an absence of lamellae on the opposite palatal side and on the parietal surface. These structures have been usually sufficiently strong in examined Planor- bula specimens to resist breakage. Johnson (1915) listed Segmentina jenksu only from its type locality and retained S. armigera for all other New England localities. Walker (1918: 100) kept the genus Planortns possibly because he overlooked the account of the type by Davis (1905). Then for about twenty years the taxon jenksii disappeared in the literature. Jacot (1923) listed S. armigera from Connecticut and Baker (1928) gave the geographical range of S. armigera as including New England. Pinney and Coker (1934) recognized Planorbula as the genus but retained armigera for the New York area and Clench and Russell (1938) listed P. ar- migera from New Hampshire. Then F. C. Baker Vol. 89 (3) (1942: 79) remarked on jenksii as having “recent- ly been shown to be a Planorbula by Pilsbry (no date). He then subsequently assigned all of his specimens from New Hampshire to jenksvi. The only published account on the Planor- bidae by Pilsbry (1934) in that period made no specific mention of jenksvi, however in Footnote 9, p. 54, he recognized a species “allied” to ar- migera as occurring in New York. Shortly after F. C. Baker’s (1942) account, Rapp and Rapp (1945) credited an identity of P jenksii to Pilsbry. The accompanying synonymy follows the sub- sequent use of P. jenksir: Planorbula jenksii (Carpenter), F. C. Baker (1945), as occurring in New England. Planorbula jenksii (Carpenter), Robertson and Blakeslee (1948), the eastern species of Planor- bula. Planorbula jenksii (Carpenter), Jacobson and Emerson (1971), from south eastern New York State. Planorbula jenksu (Carpenter), Harman and Berg (1971), from central New York State. Clarke (1973: 422) has established the range of P. genks as covering eastern North America. Examinations have been made of Planorbula specimens collected in areas lying within the species range. A total of 71 specimens have been inspected from three localities in Massachusetts: Hampshire Co., Northampton (23), So. Hadley (17) and Middlesex Co., Winchester (12), presumably near Baker's (1945) record for Medford; and one locality in Rhode Island: Providence Co., Central Falls (19). The Rhode Island collection is only one mile from Carpenter’s “type” locality for Planorbis jenksii, as the Stump Hill area in- dicated by Davis (1905: 117) has been modified to hold a sealed reservoir that is inaccessible. Six characters were analyzed for each collec- tion including shell diameter, aperture height, shell sculpturing, number of whorls, number of lamellae and their shape. Average values for each character were then determined for the collected lots and compared to the published descriptions of Planorbula armigera that ap- peared in Blatchley and Daniels (1903), Win- slow (1921: fig. 1), F. C. Baker (1928) and Clarke (1973). Comparisons were also made with THE NAUTILUS 97 descriptions of P. jenskii in Jacobson and Emer- son (1961) and Harman and Berg (1972). In all respects the collected specimens agreed with all of the published descriptions for both “species”. In reference to the above characters, none of the specimens resembled Carpenter’s description of Planorbis jenksii or the figure of Segmentina jenksu in Davis (1905). Due to the existence of only one specimen from a presumably well-surveyed area, it seems reasonable to assume that Planorbis jenksii represents an aberrant or pathological example of some other species. It is proposed therefore, that jenksii as described by Carpenter (1887) and as amended by Davis (1905) be considered a_ species inquirenda. Additionally I can find no dif- ference between eastern and mid-western specimens of P. armigera. LITERATURE CITED Baker, F. C. 1928. The freshwater Mollusca of Wisconsin. Part 1. Gastropoda. Wisconsin Geol. Nat. Hist. Surv. Bull. 70(1): 1-507. Baker, F. C. 1942. Land and freshwater Mol- lusea of New Hampshire. American Mid. Nat. 27(1): 74-85. Baker, F. C. 1945. The molluscan family Plan- orbidae. Univ. Ill. Press, Urbana. 530 pp. Blatchley, W. S. and L. E. Daniels. 1903. On some Mollusca known to occur in Indiana. 26th Ann. Report Indiana Geol. Surv. pp. 577-628. Carpenter, H. F. 1887. The shell-bearing Mol- lusea of Rhode Island. The Conchologist’s Exchange 2(1): 2-3. Clarke, A. H. 1973. The freshwater mollusca of the Canadian Interior Basin. Malacologia 13(1-2): 1-509. Clench, W. J. and H. D. Russell. 1938. The freshwater shells of New Hampshire (in) Biological survey of the Merrimack water- shed. New Hampshire Fish and Game Comm., Surv. Rep. No. 3: 201-206. Davis, C. A. 1905. Mollusca. The Apteryx 1(3): 117, Plate 9. Harman, W. N. and C. O. Berg. 1971. The fresh- water snails of central New York. New York State Agric. Exp. Sta., Search: Entomology 1(4): 1-68. 98 THE NAUTILUS Jacobson, M. K. and W. K. Emerson. 1971. Shells from Cape Cod to Cape May with special reference to the New York City area. Dover, New York. 152 pp. Jacot, A. P. 1923. On the freshwater shells of Monroe, Connecticut. The Nautilus 37: 28-31. Johnson, C. W. 1915. Fauna of New England. List of Mollusca. Occas. Papers Boston Soc. Nat. Hist. 8(13): 1-231. Pilsbry, H. A. 1934. Review of the Planorbidae of Florida, with notes on other members of the family. Proc. Acad. Nat. Sci. Phila. 86: 29-66. Pinney, M. E. and R. E. Coker. 1934. Terrestrial and freshwater gastropods of the Allegany State Park in New York State. The Nautilus 42(2): 55-60. Dan Steger (1906-1975) The many friends of Dan(iel) D(owney) Steger will be saddened to know of his sudden death on May 16, 1975, at age 68, at Tampa, Florida, of a heart attack. Dan was born August 1, 1906, in Fresno, California, and received his education in structural engineering in San Francisco. Early in his life he was active in the opera and was a choral director and symphony conductor. He was director of the Florida Boys Band at the Chicago World’s Fair in 1934. During World War II he served as company carpenter for the Army 5lst Engineers. He dredged from a shrimp trawler in Florida from 1952 to 1970, and developed an_ extensive knowledge of the microscopic marine mollusks of the Gulf of Mexico, particularly of Turridae. He was active in the St. Petersburg, Florida, Shell Club and the A.M.U. The bulk of his collection has been given to the Delaware Museum of Natural History. He is survived by his wife, also a keen conchologist, Barbara (“Bobby”) Steger. — R. Tucker Abbott. July 17, 1975 Vol. 89 (8) Rapp, W. F., Jr. and J. L. C. Rapp. 1945. Eco- logical notes on the Gastropoda of the Great Swamp (New Jersey). The Nautilus 58(4): 124-125. Robertson, I. C. and C. L. Blakeslee. 1948. The Mollusca of Niagara Frontier Region. Bull. Buffalo Soc. Nat. Sci. 19(3): 1-191. Walker, B. 1918. A synopsis of the classification of the freshwater Mollusca of North America, north of Mexico, and a catalogue of the more recently described species, with notes. Misc. Publ. Mus. Zool., Univ. Michigan 6: 1-213. Winslow, M. 1921. Mollusca of North Dakota. Occas. Papers Mus. Zool., Univ. Michigan 98: 1-18. FIG. 1. Dan Steger at age 62. INFORMATION FOR SUBSCRIBERS The annual subscription rate for The Nautilus is $7.00 for individuals and $12.00 for institutions (domestic or foreign). Subscriptions may begin in January. Send check or money order to “The Nautilus” to Mrs. Horace B. Baker, Business Manager, 11 Chelten Road, Havertown, Pa. 19083. Back issues from volume 72 to date are obtainable from the Business Manager. Volumes 1 through 71-(if available) may be obtained in reprint or original form from Kraus Reprint Co., Route 100, Millwood, New York 10546. Advertising rates may be obtained from the Business Manager or Editor. CONTRIBUTORS Manuscripts: Authors are requested to follow the recommendations of the Style Manual for Biological Journals, which may be purchased from the American Institute of Biological Sciences, 2000 ‘“P”’ Street, N.W. Washington, D.C. 20036. Manuscripts should be typewritten and doublespaced; original and one copy are required, to facilitate reviews. Tables, numbered in arabic, should be on separate pages, with the title at the top. Legends to photographs should be typed on separate sheets. Explanatory terms and symbols within a drawing should be neatly printed, or they may be pencilled in on a translucent overlay, so that the printer may set them in 8 pt. type. There is a charge of 50 cents per word for this extra service. All authors or their institutions will be charged 50 cents per line of tabular material and taxonomic keys. The publishers reserve the right, seldom exercised, to charge $32 per printed page. An abstract should accompany each paper. Reprints and covers are available at cost to authors. When proof is returned to authors, information about ordering reprints will be given. They are obtained from the Economy Printing Co., Inc., R. D. 3, Box 169, Easton, Maryland 21601. MOLLUSK VOUCHER SPECIMENS It is becoming increasingly important for future research purposes that an identified sampling of species mentioned in publications be deposited in a permanent, accessible museum specializing in mollusks. This is particularly true of mollusks used in physiological, medical, parasitological, ecological, and experimental projects. The Delaware Museum of Natural History has extensive, modern facilities and equipment for the housing and curating of voucher specimens. Mater- ial should be accompanied by the identification, locality data and its bibliographic reference. There is no charge for this permanent curating service, and catalog numbers, if desired, will be sent to authors prior to publication. ‘ f , : leh hy cal ; y ‘ } Php he ( Se et aoe <> -OCTOBER 1975 THE NAUTILUS Vol. 89 No. 4 A quarterly devoted to malacology and the interests of conchologists Founded 1889 by Henry A. Pilsbry. Continued by H. Burrington Baker. Editor-in-Chief: R. Tucker Abbott EDITORIAL COMMITTEE CONSULTING EDITORS Dr. Arthur H. Clarke, Jr. Department of Mollusks National Museum of Canada Ottawa, Ontario, Canada K1A-OM8 Dr. William J. Clench Curator Emeritus Museum of Comparative Zoology Cambridge, Mass, 02138 Dr. William K. Emerson Department of Living Invertebrates The American Museum of Natural History New York, New York 10024 Mr. Morris K. Jacobson Department of Living Invertebrates The American Museum of Natural History New York, New York 10024 Dr. Auréle La Rocque Department of Geology The Ohio State University Columbus, Ohio 43210 Dr. James H. McLean Los Angeles County Museum of Natural History 900 Exposition Boulevard Los Angeles, California 90007 Dr. Arthur S. Merrill Biological Laboratory National Marine Fisheries Service Oxford, Maryland 21654 EDITOR-IN-CHIEF Dr. R. Tucker Abbott Delaware Museum of Natural History Box 3937, Greenville, Delaware 19807 Mrs. Horace B. Baker Business and Subscription Manager 11 Chelten Road Havertown, Pennsylvania 19083 Second Class Postage paid at Wilmington, Delaware Dr. Donald R. Moore Division of Marine Geology School of Marine and Atmospheric Science 10 Rickenbacker Causeway Miami, Florida 33149 Dr. Joseph Rosewater Division of Mollusks U. S. National Museum Washington, D.C. 20560 Dr. G. Alan Solem Department of Invertebrates Field Museum of Natural History Chicago, Illinois 60605 Dr. David H. Stansbery Museum of Zoology The Ohio State University Columbus, Ohio 43210 Dr. Ruth D. Turner Department of Mollusks Museum of Comparative Zoology Cambridge, Mass. 02138 Dr. Gilbert L. Voss Division of Biology School of Marine and Atmospheric Science 10 Rickenbacker Causeway Miami, Florida 33149 Dr. Charles B. Wurtz 3220 Penn Street Philadelphia, Pennsylvania 19129 OFFICE OF PUBLICATION Delaware Museum of Natural History Kennett Pike, Route 52 Box 3937, Greenville, Delaware 19807 Subscription Price: $7.00 (see inside back cover) THE NAUTILUS Volume 89, number B — October 1975 CONTENTS Peter J. Krieger and Daniel F. Austin Liguus: The Boynton Beach Colony after Forty Years................0000. 97 Richard S. Houbrick Clavocerithium (Indocerithium) taeniatum, a Little-known padeeinusualy@erithiia from New Guinea ..)60... 60. o8. ewe eee ewe es 99 Morris K. Jacobson The Freshwater Prosobranch, Tarebia granifera, in Oriente, Cuba......... 106 C. David Rollo and W. G. Wellington Terrestrial Slugs in the Vicinity of Vancouver, British Columbia .......... 107 Arthur S. Merrill and Robert L. Edwards Observations on Mollusks from a Navigational Buoy with Special Emphasis on the Sea Scallop, Placopecten magellanicus..............000: 116 (see ott) 54-61) Hans Bertsch Distributional and Anatomical Observations of Berthella tupala (Opisthobranchia: Notaspidea) HOG KMTCVACW2e.cicis cee ne cae ttle © ole 98 Publications received ............ 105 JOIN THE AMERICAN MALACOLOGICAL UNION An International Scientific Society of the Americas for the Progress of Malacology Lend your support to the cause of molluscan studies, and, in turn, bene- fit from the annual meetings and important publications of the A.M.U., including its annual bulletin and its “How to Study and Collect Shells”. No other society, from coast to coast, offers such a beneficial blending of the interests of the professional malacologists and the devoted, amateur conchologists. Be a part of the collective voice of this active organization for the protection of our environment, the survival of our taxonomic in- stitutions, and the progress of new malacological investigations. A special benefit for new 1975-76 members — a free copy of AMERI- CAN MALACOLOGISTS and its 1975 SUPPLEMENT, listing the biog- raphies and molluscan activities of 1200 living American malacologists and giving historical accounts of 600 mollusk workers of the past. Send your check now for $8.50 (the annual dues are $7.00 and the registration fee for new members is $1.50). An additional family member is $1.00. New corresponding members (outside the Western Hemisphere) $10.00. Subscription to the Bulletin for nonmembers is $10.00 a year. American Malacological Unon (Mrs. Hollis Q. Boone, Recording Secretary) 3706 Rice Boulevard Houston, Texas 77005 - Vol. 89(4) THE NAUTILUS 97 LIGUUS: THE BOYNTON BEACH COLONY AFTER FORTY YEARS Peter J. Krieger and Daniel F. Austin Department of Biological Sciences Florida Atlantic University Boca Raton, Florida 33432 In 1970 a colony of Liguus fasciatus (Miiller) was found in Boynton Hammock, Boynton Beach, Florida. This colony was assumed to be natural (Craig, 1973) in spite of the northern limit having been reported as Yamato Ham- mock, Boca Raton, Florida (Pilsbry, 1912; 1946). Subsequent investigation indicates that some trees and the Liguus were planted in Boynton Hammock (Jones, pers. comm.). Approximately forty years ago, an experiment was begun which was terminated during the summer of 1974. During the 1930's, then active malacologists P. L. and T. L. McGinty planted trees including the present wild tamarind (Lysiloma bahamensis), and aboreal snails, Inguus fasciatus, including the color forms castaneozonatus, roseatus, septentrionalis, and testudineus in Boynton Hammock. The snails were taken from the Yamato Hammock, Upper Key Largo and elsewhere in Florida (Jones, per. comm.). Boynton Hammock, a remnant of a once extensive coastal hammock system is now a mere 800 yards long and 75-80 yards wide (Austin and Weise, 1973). The eastern border is the Atlantic Ocean with the western border form- ed by U.S. Highway A1A. The southern limit is a public beach and parking lot, while the northern border is a private residence. The recent construction of a condominium apart- ment building bisects the hammock removing 75-80 yards and presenting a barrier to migrations within the hammock. Casual observations from 1970 to late 1973 are exemplified by a total of 30 living in- dividuals at four sites by Austin indicating a well established population. Quantitative study from February 1974 to August 1974 revealed a population change from 51 individuals to zero. Counts were made by examination of mastic, paradise, and tamarind trees within a 60 X 60 meter plot located in a dense portion of the hammock north of the construction detailed above. TIiguus has many natural predators including the land hermit crab Coenobita clypeatus (Davidson, 1965), the carnivorous snail Huglan- dina rosea, the opossum, and rats (Pilsbry, 1946). Man, however, has been indicted as a fac- tor commonly limiting many organisms by over- collection and/or habitat destruction. Numerous shells of the carnivorous snail Euglandina rosea are strewn about the floor of Boynton Hammock. The presence of E. rosea suggests predation on Ligwus as other species of suitable prey are lacking. Liguus shells found in the leaf litter indicate predation by E. rosea and/or senescence as many display no shell damage. On the other hand, Liguus fragments are in evidence on the hammock floor as well as in the trees. These fragments range from those with punctures to those that have been shat- tered. The punctured shells match the dentition of the Florida mink; whereas, shattering may be due to opossums, racoons, and hermit crabs. The above potential predators have been ob- served or their spoor found in Boynton Ham- mock. Perhaps the most devastating influence on the hammock has been man. The present Boyn- ton Hammock is only a remnant bordered by the Atlantic Ocean, man-made structures, and TABLE I. Identification of dead Liguus fasciatus shells collected from Boynton Ham- mock between 1970 and 1975. Color Forms Individuals Percent castaneozonatus 48 17.27 elliottensis 4 1.44 luteus 2 0.72 ornatus 1 0.36 roseatus 179 64.39 septentrionalis 3 1.08 testudineus 1 1.44 unidentifiable, bleached msi 13.31 278 100.01 98 THE NAUTILUS has been bisected by construction. Tropical hammocks are prime real estate locations for the Florida “Gold Coast” developers; hence, the hammocks are disappearing. Furthermore, foot paths cross the hammock leading to a well used ocean beach and also afford access to the ham- mock by collectors. Heavy predation, habitat alteration, and over- collection are the factors to which the Boynton Beach Liguus colony succumbed after forty years. ACKNOWLEDGMENTS We are grateful for the account of work done by P. L. and T. L. McGinty in Boynton Ham- mock provided by Archie L. Jones, Coral Gables, Florida. October, 1975 Vol. 89(4) LITERATURE CITED Austin, D. F., and J. G. Weise. 1973. Annotated checklist of the Boynton Beach Hammock. Quart. Jour. Florida Acad. Sci. 35(2): 145-154. Craig, A. K. 1973. A new record for Liguus: the Boynton Beach colony. The Nautilus 87(3): 83-85. Davidson, T. 1965. Tree snails, gems of the Everglades. National Geographic. 129(3): 372-387. Pilsbry, H. A. 1912. A study of the variation and zoogeography of Liguus in Florida. Jour. Acad. Nat. Sci. Phila. 15(2): 429-470. Pilsbry, H. A. 1946. Monograph 3, Acad. Nat. Sci. Phila. 2(pt. 1): 37-102. REVIEW Galtsoff, Paul S. 1972. Bibliography of Oysters and other Marine Organisms Associated with Oyster Bottoms and Estuarine Ecology. vii + 857 pp. G. K. Hall and Co., 70 Lincoln St., Boston, Mass. 02111. $74.00. ISBN 0-8161- 0945-1. This is probably the most extensive bibliography ever published on edible and pearl oysters. It represents 43 years of compilation by one of the world’s experts on the biology of oysters, and contains 18,000 entries. 6,900 of these are author cards covering a period roughly from the 1860’s through 1964. The remaining entries, 11,000, are divided into numerous subjects from “ abundance” to “zinc”. There are, for instance, 224 references to pearls and pearl oysters, and 172 entries dealing with the taxonomy of oysters. The bibliography reflects the research in- terests of Dr. Galtsoff, and one will find very complete coverage in the fields of oil and in- dustrial waste pollution, biology of oysters, enemies of oysters, fishing laws, “Red Tides” and ostreiculture. There are many references to mussels, scallops and whelks, but these deal largely with papers having some relationship to the study of oysters. This enormous reference book weighs almost nine pounds and consists of folio-size pages of durable paper upon which have been photo- reproduced the actual cards, with notes, from Dr. Galtsoff’s bibliography. Fortunately it has a rugged hardback binding. Although costly, the book is an invaluable tool for any school or marine laboratory interested in bivalves, mariculture, estuarine studies or environmental protection. Let us hope that someone covers the period from 1965 to 1975 in the not too distant future. R. Tucker Abbott duPont Chair of Malacology Delaware Museum of Natural History . Vol. 89(4) THE NAUTILUS 99 CLA VOCERITHIUM (INDOCERITHIUM) TAENIATUM, A LITTLE-KNOWN AND UNUSUAL CERITHID FROM NEW GUINEA Richard S. Houbrick Smithsonian Oceanographic Sorting Center Washington, D.C. 20560 ABSTRACT New data on Cerithium taeniatum Quoy and Gaimard are presented. This species becomes the first Recent member referred to the genus Clavocerithium, subgenus Indocerithium. A new description, synonymy, discussion of types and nomenclature are given and scanning electron micrographs of the radula are presented. Comparison with fossil members of the subgenus Indocerithium is made. INTRODUCTION While working on a revision of the cerithiid genera Rhinoclawms, Proclava, Pseudovertagus and Cerithium of the Indo-Pacific region, I recently examined a series of specimens from the collections of the Academy of Natural Sciences of Philadelphia and the Australian Museum that, at first glance, appear to be variations of Rhinoclavis vertagus (Linnaeus, 1767). Close examination showed that these were indeed distinct from vertagus and con- stitute rare examples of an uncommon, little- known and unusual species described in 1834 by Quoy and Gaimard as Cerithium taeniatum, collected at Dorey Baai, Netherlands New Guinea (now known as West Irian, Indonesia) by the “Astrolabe” Expedition. Quoy and Gaimard noted the close resemblance between vertagus and taeniatum, remarked that their species was rare, and that they had not seen the animal. The description pointed out that taeniatum, in contrast to vertagus, has a more oblique, oval aperture, a shorter, less reflexed siphonal canal, and longitudinal riblets or plaits confined to the upper whorls. The overall yellow color and the orange banding were also stressed in the original description. Quoy and Gaimard’s figure (pl. 54, fig. 21) is an excellent representation but exaggerates the color pat- tern, Kiener’s (1841-42) figure of C. taeniatum (pl. 19, fig. 2) also is good, but indicates brown rather than orange bands. Sowerby’s (1855) figure (pl. 176, fig. 1) is evidently a copy of that in Quoy and Gaimard (1834). Both Kobelt (1898) and Tryon (1887) had little to say of this species and their figures also appear to be merely copies of Quoy and Gaimard. Aside from Cernohorsky (1972), who synonymized taeniatum with vertagus, no other modern writer has aluded to C. taeniatum. Cerithium taeniatum superficially resembles Rhinoclavis vertagus and other nomina in the genera Rhinoclavis Swainson, 1840 and Pseudovertagus Vignal, 1904. Both genera are characterized by relatively large shells and well-developed anterior canals that are reflexed sharply. Rhinoclavis differs from Pseudovertagus by the presence of a prominent median columellar plait (fig. 7). Cerithium taeniatum superficially looks like Rhinoclavis vertagus, the type-species of Rhinoclavis; however, it lacks the median columellar plait characteristic of Rhinoclavis and does not have the long, reflexed anterior canal prominent in the former genus and Pseudovertagus (fig. 8). Thus it cannot be placed into either group and it does not ap- pear to fit into any other closely related Recent cerithiid taxa, such as Proclava Thiele, 1931, or Ochetoclava Woodring, 1928. Rather than en- cumber the literature with another new generic name I have reviewed the numerous generic and subgeneric nomina proposed for fossil species of Cerithiuwm, sensu lato. The limits of these taxa often are confusing and they are ranked differently by various authors; however, I believe C. taeniatum should be referred to the genus Clavocerithium Cossmann, 1920. The type- 100 THE NAUTILUS species of Clavocerithium, C. lacazei (Vasseur, 1881), resembles C. taeniatum, but is an Eocene species described from the Lower Loire, France. Like taeniatum, it lacks a columellar plication, has a sinuous outer lip and differs mainly by the absence of axial riblets on the upper whorls. Wenz (1938) considered Clavocerithium a subgenus of Clava Martyn, 1784 [=Rhinoclavis Swainson, 1840], but the radula, anatomical and conchological characters of C. taeniatum are distinct enough to indicate that Clavocerithium is a good generic group. Clavocerithium taeniatum thus becomes the first October, 1975 Vol. 89(4) Recent species to be referred to this genus. Chavan (1952) assigned an Indonesian Tertiary species, Cerithium (Vertagus) jonkeri Martin, 1884, to the genus Clavocerithium but believed it differed enough to warrant a new subgenus that he named Indocerithium, designating Cerithium jonkeri as the type-species of the new taxon. Cerithium taeniatum is very closely related to jonkeri; consequently, I refer taeniatum to the subgenus Indocerithium Chavan, 1952. I have not found additional specimens in any museum collections in the United States but FIGS. 1-6, Clavocerithium (Indocerithium) taeniatum (Quoy and Gaimard): FIG. 1, specimens from Kranket Islands, Madang, N. E. New Guinea (2.5X); FIGS. 2-5, specimens from Japen Id., Geel- vink Baai, West Irian, New Guinea (2.5X); FIGS. 5-6, detail of sinuous outer lip, smooth columella and short anterior canal. FIGS. 7-8, Rhinoclavis vertagus (Linnaeus), detail of aperture, columellar plait and reflexed anterior canal. Vol. 89(4) suspect that some may tum up in private collections or in European museums mixed in with lots of Rhinoclavis vertagus. The following synonymy, description and remarks are given to alert other workers and solicit further in- formation about this unusual and uncommon species. Clavocerithium Cossmann, 1920 Cossmann, 1920. Bull. Soc. Scien. Natur. l’Ouest France (Nantes) serie 3, 5:94, pl. 3, figs. 24-25. Type species: C. lacazei Vasseur, 1881, by original designation, Eocene of Lower Loire, France. Description: Shell moderate in size, fusiform elongate, 12-14 whorls, solid. Sutures distinct, slightly channeled. Whorls moderately convex. Upper whorls ornamented with spiral grooves and ridges. Body and penultimate whorls THE NAUTILUS 101 smooth. Aperture oblique, fusiform. Columella concave, with a prominent bulge of the colu- columellar callus near the posterior canal. An- terior canal short and slightly reflexed to the left and upwards. Anal canal broad, bordered with prominent columellar bulge. Outer lip smooth, prominently sinuous and extending over the suture of the previous whorl. Stratigraphical Range: Eocene. Subgenus Indocerithium Chavan, 1952 Chavan, 1952. Cahiers Geologiques de Thoiry- Seyssel, No. 12:104. Type species: Cerithiwm (Vertagus) jonkeri Martin, 1884, by original designation, Pliocene of Java. Differs from Clavocerithium by presence of axial plications or riblets. Lacks bulge on columellar callus. Body and penultimate whorls sometimes ornamented with spiral cords. Anal canal bordered with prominent anal sulcus that FIGS. 9-12, Radula of Clavocerithium (Indocerithium) taeniatum (Scanning Electron Micrographs): FIG. 9, halfrow of radula (160 X); denticle on central tooth (275xX); tiny denticles (250 and 550X). Fig. 10, view of central and lateral teeth showing tricuspid FIGS. 11-12, detailed view of scythe-like lateral teeth showing 102 THE NAUTILUS extends well within aperture. Periostracum smooth and thin. Operculum corneous, ovate and paucispiral with an eccentric nucleus. Radula with tricuspid central, multicuspid broad laterals and long, hook-like marginals minutely serrated with indistinct denticles. Geographical Range: Guam, the Philippines, Indonesia (all fossil records) and New Guinea (Recent). Stratigraphical Range: Pliocene to Recent. Clavocerithium (Indocerithium) taeniatum (Quoy and Gaimard) (Figs. 1-6) Synonomy — 1834 Cerithium taeniatum Quoy and Gaimard, in d’Urvilles “Voyage Astrolabe”, Zoologie, vol. 3, pl. 113, pl. 54, fig. 21 (Dorey Baai, Netherlands New Guinea; holotype and co- type, Paris Museum) [non taeniatum Eudes-Deslongchamps, 1842; non Sowerby (in): Reeve, 1865] 1841-42, Kiener, Coquilles Vivantes, pt. 1, pl. 21, pl. 19, fig. 2; 1855, Sowerby, Thesaurus Conchyliorum, vol. 2, p. 848, pl. 176, fig. 1. 1895 Vertagus implicatus Brancsik, Jahresheft des Naturwissenschaftlichen Vereines des Trencsener Comitates, vol. 17-18, pl. 217, pl. 5, figs. 2a, b. (NE New Guinea, “Papua”; 3 syntypes, Budapest Museum). 1898 Cerithium (Vertagus) taeniatum Quoy and Gaimard. Kobelt [2m] Martini-Chemnitz, Conchilien Cabinet, vol. 1, pt. 29, Certh- dum, p. 252, pl. 5, figs. 7-8; 1887, Tryon, Manual of Chonchology, vol. 9, p. 149, pl. 29, fig. 70. Description: Adult shell 27 to 52 mm long, 10 to 16 mm wide, turrited, solid, stout and fusiform consisting of 11 to 13 whorls; nuclear whorls 1% turns, smooth, white. Upper 11-12 whorls in spire each ornamented with 14-16 longitudinal riblets that are more nodulose on the post nuclear whorls; each whorl in upper spire with three dominant spiral cords that are nodulose where they cross the axial riblets; a fourth, smaller spiral cord is at the base of the whorl near the suture. Numerous microscopic spiral grooves are between spiral cords in upper spire. On the third whorl the axial riblets are broader, smoother and more weakly defined and spiral cords and grooves are weak or absent. October, 1975 Vol. 89(4) Penultimate whorl relatively smooth, weak axial plications sometimes present near sutures; body whorl usually smooth except for 2-3 weakly defined spiral cords near the lower cen- tral portion of the whorl; neck of body whorl with about five small spiral cords. Sutures distinct, slightly channeled. Former varices present on most whorls; prominent former varix opposite outer lip. Aperture oblique, fusiform and mostly white within, stained with brown along edges. Columella concave, smooth with a moderate callous. Anterior siphonal canal short, broad, only slightly reflexed (65-70) degrees) and stained with dark brown at its tip. Anal canal broad and bordered with prominent columella ridge forming a deep sulcus extending well within shell. Outer lip smooth to weakly crenulate, broad, flaring and distinctly sinuous, extending over suture of previous whorl by about one third. Shell color yellowish-white with pink or tan broad band present on upper portion of each whorl; body whorl more darkly pigmented. Banding pattern may be weak or entirely lacking. Periostracum thin, light tan, slightly rust colored on lower whorls. Operculum, corneous, dark brown and ovate with an eccentric nucleus. Animal (preserved) color yellow-pink; foot and snout darkly pigmented; mantle papillate, flesh colored and with darkly pigmented edge; anterior siphon of mantle muscular, dark brown and with 2 dark spots. Hypobranchial gland long, white; gill large. Eyes close to ends of long tentacles. Anus and opening of genital duct close to mantle edge. Genital ducts open; males aphallic. Radular ribbon narrow, delicate and short (0.5 mm _ long), taenioglossate, (2+1+1+ 1+ 2). Rachidian tooth triangular, bearing prominent tricuspid central tooth with two to three denticles on each side. Base of rachid- ian with one large central and two shorter longitudinal projections. Lateral tooth large, rhomboid, broad and deeply rooted with a long lateral basal extension; upper portion finely serrated with many small denticles tapering off laterally. Inner and _ outer marginals long, tapering anteriorly and scythe like; inner marginals with a few indistinct den- ticles and outers completely smooth. -Vol. 89(4) Measurements (in mm): no. of length width whorls 52 16 12 44 15 2 41 16 13 locality N. shore of Maroepi, Japen Id. Geelvink Baai, West Irian, Indonesia. 3B 13 12 29 12 12 N. end of Kranket Id. Madang, 27 10 aut N.E. New Guinea REMARKS This species is distinguished from Rhinoclavis vertagus by its wide aperture, sinuous outer lip, distinctive anal canal, the three spiral cords and nodulated axial riblets on whorls of the up- per spire, and by a unique, tiny radula. Anatomically, the eyes are nearer the ends of the tentacles than in R. vertagus. Specimens from Japen Id., Geelvink Baai, West Irian, Indonesia (NW New Guinea) (figs. 2-6) do not have the bright colors depicted by Quoy and Gaimard. They tend to be whitish with brown blotches on the lower whorls and have occasional weak traces of wide, brownish- rose bands near the sutures. The siphonal canals are stained a dark chocolate. Specimens from the Kranket Islands, Madang, N.E. New Guinea (fig. 1) are smaller and white with a chocolate-stained anterior canal. They are quite variable in sculpture; the last three whorls may be entirely smooth or adorned with axial and spiral sculpture. These specimens were collected in the intertidal zone. Although there is no other ecological information, fecal pellets of preserved specimens from both localities consist of fine particles of mud or sand and are arranged in transversely oriented capsule-like pellets stacked in layers in the intestine. This may indicate Clavocerithium taeniatum lives on a muddy or fine sandy bottom. It appears to be restricted to shallow bays on the northern coast of New Guinea. I have seen similar fecal pellet arrangement in the intestine of Proclava_ sor- didula Gould, 1849 [= P. pfefferi Dunker, 1882]. The tiny radula of Clavocerithium taeniatum, in marked contrast to that of Rhinoclavis ver- tagus, is unique among most cerithiid radulae. The tricuspid central, the broad, weakly-serrated lateral teeth and the long, scythe-like marginals are quite distinctive and probably reflect a mud-gathering function (figs. 9-12). Although THE NAUTILUS 103 Proclava sordidula is far removed concholog- ically from Clavocerithium taeniatum, the radula of the former is almost identical to that of taeniatum. Undoubtedly this is an example of covergence due to similar function and in- dicates that cerithiid radulae should not be heavily weighted as reliable characters for su- praspecific groupings. An examination of taenioglossate radulae in Troschel (1863) shows similar radulae in Xenophora trochiformis Born and Aporrhais pespelicani (Linnaeus). Clavocerithum taeniatum, however, is anatomically a cerithiid. TYPES AND NOMENCLATURE The holotype and paratype of C. taeniatum are in the Paris Museum (no register number). Color slides of the types do not show as color- ful a shell as that represented by Quoy and Gaimard’s figure (pl. 54, fig. 21). The paratype is an immature shell. There are two primary junior homonyms of Clavocerithium taeniatum: that of Eudes- Deslongchamps (1842) and another included by Reeve (1865) in his monograph of Cerithiwm and attributed to Sowerby. Cerithium taeniatum Eudes-Deslongchamps 1842, is a fossil species described from the Upper Jurassic of France (Mém. Soc. Linn. Normandie, 7:200, pl. 11, fig. 14). Reeve’s description and figure (Conch. Icon. 15, pl. 17, fig. 119) bear no resemblance to the taeniatum of Quoy and Gaimard. Moreover, Reeve did not even place Sowerby’s taeniatum in his Vertagus section and his figure looks like a typical Cerithiwm species, sensu stricto. Vertagus implicatus Brancsik, 1895 was described from specimens in a collection made from Kaap d’Urville to Astrolabe Bay (NE New Guinea). Brancsik (1895) noted his species’ resemblance to R. vertagus, but remarked that taeniatum could be separated from the latter by the lack of a columellar plait and by its distinct spiral sculpture. I have not seen the paratypes that are in the Budapest Museum, but Brancsik’s figure (pl. 4, fig. 2a, b) and diagnosis unequivocally correspond with C. taeniatum. FOSSIL RECORD A fossil species described by Martin (1884) as Cerithium (Vertagus) jonkeri is identical to 104 THE NAUTILUS Recent specimens of C. taeniatum. Figures of C. jonkeri in Martin (1884), Tesch (1920), Wissema (1947) and Ladd (1972) indicate that it is a variable species and is probably conspecific with C. taeniatum or a direct ancestor of it. I have not seen Martin’s holotype of jonkern and hesitate to synonymize it with taematum; however, many other Recent cerithiids also were living during the Tertiary and it is not unreasonable to suggest that the two are con- specific. Clavocerithium jonkeri is known from the Pliocene of Java and other islands in Indonesia and from the Pleistocene of Java (Ladd, 1972). It has also been recorded from the Upper Miocene of Luzon and the Pliocene of Min- danao, Philippines (Wissema, 1947). Ladd (1972) found it in the Mariana Limestone of Guam (Pliocene or Pleistocene). On the basis of this geological evidence, it appears that the present geographic range of C. taeniatum is much reduced. Other related Tertiary species are C. poet- janganensis (Altena, 1941), from the Pleistocene of Java, and both C. altenae (Wissema, 1947) and C. escheri (Wissema, 1947), from the Ter- tiary and Quarternary of Nias, Indonesia. I refer all of these fossil species to the genus Clavocerithium, subgenus Indocerithium Chavan, 1952. ACKNOWLEDGEMENTS I wish to thank Dr. Joseph Rosewater of the Division of Mollusks, National Museum of Natural History, for critically reading the manuscript and Dr. R. Tucker Abbott of the Delaware Museum of Natural History for his suggestions and comments during the preparation of this paper. I am endebted to Dr. Robert Robertson of the Academy of Natural Sciences of Philadelphia and to Dr. Winston Ponder of the Australian Museum for the loan of specimens in their charge. My thanks to typist Janice Clark and to Richard Hammer for proofing the final manuscript. I acknowledge the Photographic Services Division of the Smithsonian Institution for the photographs in this paper. The scanning electron micrographs were taken on a Cambridge Mark MII-A Stereoscan at the Scanning Electron Microscope October, 1975 Vol. 89(4) Laboratory of the National Museum of Natural History, Smithsonian Institution. LITERATURE CITED Altena, Van Regteren. 1942. The marine mol- lusca of the Kendeng Beds (East Java) Gas- tropoda — part 2 (Families Planaxidae-Nati- cidae inclusive). Leidsche Geologische Mede- deelingen, 12: 1-86. Brancsik, C. 1895. Contributiones ad faunam molluscorum insulae Papua. Jahresheft des Naturwissenschaftlichen Vereines des Trenc- sener Comitates, 17-18: 209-228, pls. 5-6. Cernohorsky, W. O. 1972. Marine shells of the Pacific, vol. 2, 411 pp., 68 pls. Sydney. Chavan, A. 1952. Quelques intéressants types de Cérithes. Cahiers Geologiques de Thoiry, No. 12: 103-104. Cossmann, M. 1920. Mollusques éocéniques de la Loire-Inférieure, Bull. Soc. Scien. Natur. l'Ouest France (Nantes). Serie 3, 5: 53-141, 4 pls. Dunker, G. 1882. Molluscorum maris Japonica: Kessel, Theor. Fisher, 301 pp., 16 pls. Eudes-Deslongchamps, M. 1842. Mémoire sur les cérites fossiles. Mém. Soc. Linné. Norman- die, 8: 189-214, 11 pls. Gould, A. A. 1849. Shells collected by the United States Exploring Expedition under the command of Charles Wilkes. Boston Soc. Nat. HMist., Proc., 3: 118-121; 140-144. Kiener, L. C. 1841-42. Spécies général et icono- graphie de coquilles vivantes, etc. 2, Genre Cérite, 104 pp., 32 pls. Kobelt, W. 1898. [in] Martini, F. H. W. and J. H. Chemnitz, Neues systematisches Con- chylien Cabinet etc. 1(26) Centhium 297, 47 pls. Ladd, H. KKS. 1972. Cenozoic fossil mollusks from western Pacific islands: Gastropods (Turritellidae through Strombidae). Geol. Surv. Prof. Papers 532: iv. + 79 pp., 20 pls. Martin, K. 1884. Palaeontologische Ergebnisse von Tiefbohrungen auf Java. Gasteropoda [in] Martin, K. and A. Wichmann, Beitrage zur Geologie Ost-Asiens und Australiens, Sammlungen des Geologischen Reichs-Mu- seums in Leiden, Series 1: 3: 48-184, pl. 4-9. Martyn, T. 1784-92. The Universal Conchologist, 4 vols. 39 pp., 160 pls. London. Vol. 89(4) Quoy, J. R. C. and J. P. Gaimard. 1882-35. Voyage de L’Astrolabe... pendant .., 1826-29, sous le commandement de M. J. d’Urville, etc. Zoologie, vols. 2-3, 686 + 954 p., Atlas, 93 pls. Reeve, L. A. 1865. Conchologia Iconica, 15: Cerithium, 20 pls. + index. Sowerby, G. B. 1855. Thesaurus Conchiliorum, 2: Cerithium: 847-859, pls. 176-186. Swainson, W. 1840. A treatise on Malacology. 419 pp. London. Tesch, P. 1920. Jungtertiare und Quartare Mol- lusken von Timor; part 2: Palaontologie von Timor, No. 8: 41-121, pls. 128-160. Thiele, J. 1931. Handbuch der Systematischen Weichtierkunde, 1: vi + 1778 pp., 783 text figs. Jena. Troschel, F. H. 185663. Das Gebiss der Schnecken... Berlin, 1:viii + 252 pp., 20 pls. Tryon, G. W. 1887. Manual of Conchology; structural and systematic; with illustrations of the species. First series: 9: Cerithiwm 127- THE NAUTILUS 105 149, pls. 20-29. Vasseur, G. 1881-1882. Recherches geologiques sur les terrains tertiares de la France occi- dentale. Part 1: Bretagne. Thése soutenne de- vent faculté des Sciences de Paris le 2 Julliet 1881. pp. 432, 6 pls., 29 figs. Paris. Vignal, M. L. 1904. Liste des coquilles de la famille des Cerithidés recueillies par M. Ch. Gravier aux environs de Djibouti et d’Obock (1904). Bull. Mus. Nat. dhistoire Naturelle Paris 10: 354-359. Wenz, W. 1938-44. [in] O. H. Schindewolf: Handbuch der Palazoologie, Gastropoda 6(1): 1693 pp. Berlin. Wissema, G. G. 1947. Young Tertiary and Quar- tenary gastropods from the Island of Nias. Rijksuniversiteit, Leiden, doctor’s thesis, pp. 1-212, 6 pls., 1 map. Woodring, W. P. 1928. Miocene mollusks from Bowden, Jamaica, Pt. 2, Gastropods and dis- cussion of results. Carnegie Inst. Wash. Pub. No. 385, vil + 564 pp., 39 pls. PUBLICATIONS RECEIVED Cheng, Thomas C. (editor). 1974. Molluscicides in Schistosomiasis Control. Academic Press, N.Y., 266 pp. Hardback. $12.50 Proceedings of an international symposium held in Lon- don, 1973. Contains 13 articles on the latest various aspects of molluscicides, with em- phasis on copper and planorbid intermediate hosts. Authors include E. A. Malek, T. C. Cheng, J. Duncan, L. S. Ritchie, N. F. Car- darelli, and others. Oliver, A. P. H. 1975. Shells of the World. Hamlyn Publ. Group, London. 320 pp. Paper- back. U.K. price £2.25. An excellent and well-illustrated guide to over 1,000 species of the better-known marine shells of the world. Recommended for amateurs. Warmke, G. L. and R. T. Abbott. 1975 (July). Caribbean Seashells. Dover Publ., Inc., N.Y. Paperback reprint of the formerly out-of- print hardback. 348 pp. $4.00. Bandel, Klaus. 1975. Embryonalgehause kari- bischer Meso-und Neogastropoden (Mollusca). Akademie der Wissenschaften und der Lit., Abhandl. Math.-Nat. Klasse, year 1975, no. 1, 133 pp., 21 pls. Scanning electron microscope study of the embryonic shells of 81 species of marine gastropods of the Caribbean. DM 48.20 (about U.S. $20.00). Burch, J. B. 1975. Freshwater Sphaeriacean Clams of North America. 96 pp., illus. Re- vised. $10.00. Paperback. Burch, J. B. 1975. Freshwater Unionacean Clams of North America. 204 pp., illus. Re- vised. $16.00. Paperback. Both of these useful illustrated keys are available from Malacolog- ical Publications, P. O. Box 193, Hamburg, Michigan 48139. Scase, Robert and (photographs by) Eric Storey. 1975. The World of Shells. 106 pp., 106 color illus. An introduction to collecting pretty shells. The author’s names of the spe- cies are omitted. Osprey Publ., London £3; Larousse & Co., N.Y. Hardbound, $8.95; paper- back, $4.95. Franchini, Dario A. and others. 1975. Il Libro nat.-mal. Illus. Quatt. Sett. [The Illustrated Naturalistic-Malacological Book from 1400- 1700]. Mantua Public Library, via R. Ardigo, 13, Mantova 46100, Italy. 1500 Lira, plus postage. 86 pp., 18 Figs. 106 THE NAUTILUS October, 1975 Vol. 89(4) THE FRESHWATER PROSOBRANCH, TAREBIA GRANIFERA, IN ORIENTE, CUBA Morris K. Jacobson American Museum of Natural History Central Park West at 79th Street, New York 10024 While determining some gastropods collected in Cuba in 1969 and 1973 by Dr. Stefan Negrea of Bucharest, Romania, I was surprised to find several small lots of Tarebia granifera (Lamarck, 1816). The species does not seem to have been recorded previously from that island, although Murray (1971) states that it has been reported from Puerto Rico and the Dominican Republic. The identity of the species was con- firmed by Dr. H. D. Murray (personal com- munication) who has written on the presence of the species in ponds and streams in the San Antonio, Texas Zoo. There it occurs together with the related Melanoides tuberculatus (Miller, 1774), and it serves as the intermediate host of the trematode (Philophthalmus megalurus) infecting the nictating membrane of aquatic birds (Murray, 1964; Murray & Stewart, 1968; Murray & Haines, 1969). 7. granifera originally came from China and has recently appeared in southern Florida and Texas (Dun- dee, 1974: 6). In China it serves as the in- termediate host of the Oriental lung fluke (Paragonmus westermani) (Abbott, 1952; Murray, 1964, 1971). In addition to their roles as potential vectors of disease, Tarebia and Melanoides are harmful because with their high reproductive rates they can displace native species (Murray, 1971). Cuban melaniids (genus Hemisinus) which could possibly be displaced by the introduced species, occur only in the western half of the Island, where no infestation has as yet been reported. The Cuban snails are small, the largest being only 16 mm in length, whereas in Guam specimens reach a length of 40 mm (Abbott, 1952: 104). The snails in Lithia Spring, Florida, also reach about 16 mm as they do in Cuba. There was no way of determining if the present Cuban specimens, all of which were collected dead, were fully mature, but enough shells are at hand to indicate that in all likelihood they are at, or very near, their maximum size. The Cuban snails were taken at the following localities, all in Oriente Province: Rfo Baracoa at La Tinta, near Cabo Maisr, 7 spms; Rio Yumurt, 23 km from Sabanilla, Baracoa, 5 spms; Laguna Baconao, 37 km E of Siboney, 4 spms; Rio Mogote, Matfas, about 50 km W of San- tiago de Cuba, 25 spms; Rfo Ceiba, tributary of Rio Mayarf, Mayar{f Abajo, 2 spms; Arroyo Colorado, Venado, near Mayari Arriba between Seboruco and Alto Songo, 1 spm; Arroyo Jarahueca near Mayari Arriba, between Seboruco and Alto Songo, 2 spms. Murray (1971) reports that 7. granifera in the United States appears to be confined ecologically to warmer springs. This does not seem to be the case in Oriente. Specimens will be deposited in the American Museum of Natural History, the Museum of Comparative Zoology, and in the conchological collection of the Institutul de Speologie ‘Emil R. Racovita’, Bucharest, Romania. LITERATURE CITED Abbott, R. T. 1952. A study of an intermediate snail host (Thiara granifera) of the oriental lung fluke (Paragonimus). Proc. United States Nat. Mus. 102: 71-116, pls. 8, 9, figs. 32-45. Dundee, D. S. 1974. Catalog of introduced mol- luscs of eastern North America, north of Mexico. Sterkiana, no. 55, pp. 1-37. Murray, H. D. 1964. Tarebia granifera and Mel- anoides tuberculata in Texas. American Mal- acological Union Report for 1964 pp. 15-16. Murray, H. D. 1971. The introduction and spread of Thiarids in the United States. The Biologist 53(3): 133-135. Murray, H. D. and D. Haines. 1969. Philophthal- mus sp. (Trematoda) in Tarebia granifera and Melanoides tuberculatus in south Texas. Amer- ican Malac. Union Report for 1969, pp. 44-45. Murray, H. D. and A. Stewart. 1968. Establish- ment of a trematode cycle in Turebia granifera (Lamarck) in Texas. Ibid. for 1968, pp. 17-18. - Vol. 89(4) TERRESTRIAL SLUGS IN THE VICINITY OF VANCOUVER THE NAUTILUS 107 ’ BRITISH COLUMBIA’ C. David Rollo and W. G. Wellington Department of Plant Science and Institute of Animal Resource Ecology, The University of British Columbia Vancouver, B.C., Canada V6T 1W5 ABSTRACT Twelve species of slugs were recorded during an extensive survey around Van- couver, British Columbia. There were only three native species. Ariolimax co- lumbianus (Gowld), Deroceras laeve (Miiller), and Prophysaon andersoni (Cooper). Of the mne introduced species, Arion hortensis Férussac, A. intermedius (Nor- mand), A. subfuscus (Draparnaud) and Deroceras caruanae (Pollonera) are new records for the area. Of the Arion fasciatus complex, A. circumscriptus Johnston was abundant but A. silvaticus Lohmander was not. A. fasciatus (Nilsson) was not found. Notes on the introduction, economic importance and life history of each of the 12 species are included. Chichester and Getz (1968) emphasized the need for more detailed information concerning the dis- tribution of introduced slugs. Such species have been more intensely studied in eastern than in western North America (Getz and Chichester, 1971). In the west, records from British Colum- bia are especially scarce (Hanna, 1966). This paper is a preliminary evaluation of the slugs in the vicinity of Vancouver, British Columbia, with special reference to their economic importance. It is based on collections from 23 locations in and around Vancouver, where we have made extensive surveys since September, 1974. Descriptive works consulted for identification included Ellis (1926), Pilsbry (1948), Likharev and Rammel’meier (1962), Quick (1949, 1960) and Chichester and Getz (1973). Arion ater (Linnaeus) A. ater was probably introduced into western North America in the Puget Sound area of Washington (Hanna, 1966). By 1940 it was a recognized garden pest in Seattle (Smith, 1962) and by 1948 it was a major pest in gardens in the lower Puget Sound area (Doucette, 1954). By the 1960’s it was nearly as important economically as Deroceras reticulatum (Miiller) in the Pacific Northwest (Howitt, 1961; Howitt and Cole, 1962; Crowell, 1967). ‘This survey is part of a larger study supported by a research grant from Agriculture Canada. Hanna (1966) believed that the first record of A. ater in British Columbia was Glendenning’s (1952), but Glendenning and King (1949) record- ed A. ater near the port of New Westminster in 1945. Dr. I. McT. Cowan (pers. comm.) recalls observing “large black slugs” crossing sidewalks at Jericho Beach, Vancouver, in 1941 + 1 year; individuals which were undoubtedly A. ater. In 1955 A. ater prevented growth of all garden crops at Hope and Popcum, British Columbia (Forbes et al., 1956). Fulton (1955) ob- served these slugs traveling to gardens from rough pasture, and estimated the population to be at least one per 0.8m?. By 1962, W. M. Draycott recognized this species as one of the worst molluscan pests of southern British Columbia (Hanna, 1966). It occurs through the Fraser Valley from Hope westward to the coast, and it is also established on the valley edges (e.g., at Cultus Lake and at Mission, British Columbia (Anonymous, 1963)). A. ater was previously considered as two species, A. ater (L.) and A. rufus (L.) (Quick, 1947, 1949). Cain and Williamson (1958) present- ed evidence of hybridization, however, and Quick (1960) later recognized A. ater and A. rufus as subspecies of A. ater. The most common color forms presently in Vancouver range from reddish-brown to greenish-brown dorsally, with red, orange or 108 THE NAUTILUS yellow foot fringes. Black individuals with pale soles, variety ater (L.), and totally black slugs, variety aterrima Taylor, are also common. Other color variations include marginella Schrank, black with yellow or red fringes; castanea Dumont and Mortillet, brown with a paler fringe; succinea Miller, yellow with orange or red fringe; and aurantia Baudon, orange-colored. Immature individuals show a more variable range in color than adults. Olive green immature specimens with bright yellow fringes were common in winter, but no adults retained this pattern. Immature individuals frequently have lateral bands, and may super- ficially resemble Arion subfuscus (Draparnaud). Quick (1949) states that most of the brighter- colored forms are probably rufus and most of the duller ones ater. However, dissection revealed that even individuals referable to variety aterrima had genitalia more like rufus than ater as described by Quick (1947). The figure in Pilsbry (1948) shows the genitalia of an Oregon A. ater, which he states are typically black, but this specimen also appears to be A. ater rufus. A. ater is one of the most ubiquitous slugs in Vancouver. At Cultus Lake Park, and in many forested areas about Vancouver it occurs in a sylvan habitat, and may be as numerous as Ariolimax columbianus (Gould). It does not, however, appear to displace the latter species, which remains as abundant where A. ater is present as in regions were it is absent. R. T. Paine (Getz and Chichester, 1971) believes A. ater ater is restricted to more rural areas, whereas A. ater rufus is more confined to cities. At Cultus Lake Park, and in forested areas around the University of British Colum- bia, A. ater populations consist entirely of the variety aterryma or ater, whereas urban gar- dens and vacant lots usually contain color varieties closer to rufus. Thus our area provides some support for the suggested rural-urban division. The life cycle of A. ater in Vancouver is vir- tually identical to that described by Doucette (1954) for this species in Washington. The life cycle is also similar in Britain and Europe, so that many of the findings of Barnes (1944), Bett (1960), Quick (1949, 1960), and Smith (1966), can October, 1975 Vol. 89(4) be applied here. Quick (1949) observed that A. ater rufus matures later than A. ater ater in Britain, but we have not yet been able to corroborate that observation here. Arion fasciatus (complex) Chichester (1968) found evidence that Arion fasciatus was actually a complex of three species, A. fasciatus (Nilsson), A. circumscriptus Johnston, and A. silvaticus Lohmander. Because the three specific components were previously treated as a single entity, it is not possible to decide which records apply specifically to any one of them (Chichester and Getz, 1973). Getz and Chichester (1971) record only A. fasciatus from British Columbia, stating that the only known records of A. silvaticus and A. circumscriptus are from northeastern North America. They note that A. fasciatus is by far the most abundant and widely distributed mem- ber of the complex in the Northeast (Chichester and Getz, 1973). In our survey, only A. cir- cumseriptus and A. silvaticus were found in the vicinity of Vancouver. Either A. fasciatus has not yet been introduced into Vancouver, or the climate here has favored the other species. A. circumscriptus is the more abundant of the two species present. A. silvaticus is less numerous, occurring only in localized colonies. The color forms of our A. circumscriptus and A. silvaticus conform to the descriptions in Chichester and Getz (1973), except that the local A. cireumscriptus frequently share with A. silvaticus an abundance of white pigment flecks in the ventralmost rows of tubercles. The middle third of the epiphallus of A. cir- cumscriptus is speckled with black, an ap- parently consistent character for separating it locally from A. silvaticus. We have observed only the black form of A. circumscriptus here. Our observations show that previous local references to A. circumscriptus in British Columbia were correct. It was first recorded in British Columbia at Agassiz by R. Glendenning in 1937 (Pilsbry, 1948). It was probably present earlier, however, as Glendenning (1941) ob- served that it was already causing considerable damage by 1940. Control measures against A. circwmscriptus were necessary on carrots and beetroots at Agassiz in 1945 (Glendenning, 1945). Glen- Vol. 89(4) denning (1947) ranked this species with DP. reticulatum as major pests in the lower Fraser Valley, and King (1949) believed it was the main pest species in 1948, when it attacked let- tuce, sweet peas, peas and other crops. By 1949 it was also a pest on Vancouver Island (Glen- denning and King, 1949). In 1955 it caused heavy losses of corn, beans, and potatoes near Chilliwack in the Fraser Valley (Fulton, 1955; Forbes et al., 1956). In 1960 it damaged or- namentals, clover and truck crops, especially lettuce (Anonymous, 1961a). The life history of the A. fasciatus complex in the field is not well known (Runham and Hunter, 1970). Chichester and Getz (1973) gave an account for A. fasciatus but not for A. ci- cumserptus or A. silvaticus. Rollo (1974) described the life cycle of A. fasciatus in On- tario. A. circumscriptus appears to be an an- nual species in Vancouver. Adults are present throughout the year, but young are found mainly in fall and spring. A. silvaticus over- winters successfully, but the remainder of its life cycle is still unknown. Arion hortensis Férussac Although Carl and Guiguet (1958) suggested that A. hortensis might be present in British Columbia because it was already established in Washington, there has been no actual record of this species in British Columbia. A hor- tensis is relatively uncommon in _ North America (Chichester and Getz, 1969, 1973), form- ing localized colonies mainly in the Pacific Northwest (Getz and Chichester, 1971). In Britain, however, A. hortensis is ranked with D. reticulatum as one of the most destructive slugs (Ellis, 1926; Miles et al., 1931; Quick, 1949; Anonymous, 1959; Dunn, 1963; Stephenson, 1968). There is some cause for concern, therefore, in our finding that A. hortensis is very numerous throughout Vancouver and the adjacent districts of Burnaby and Richmond. Some of its local populations in fact exceed those of all other species. In most _ places, however, A. hortensis appears to be about as numerous as A. circumscriptus. Because of its subterranean habit, populations are easily un- derestimated. After rain on June 3, 1975, 15 in- dividuals were found within a 650 cm? area in a garden at 2585 W. 2nd Ave., Vancouver, THE NAUTILUS 109 in which none could be found in drier weather. Specimens found in gardens tend to be almost black dorsally with wide lateral bands reaching almost to the foot fringe. Those en- countered in uncultivated areas are light brown in color, with narrower lateral bands. At Guelph, Ontario, both color forms were en- countered in mixed deciduous woods and in marshy areas, indicating that the species is ex- tending its range in Canada even where there is more severe weather than in the Pacific Northwest. In the autumn of 1974, most of the recorded A. hortensis were adults, but by May, 1975, the majority were immature individuals. Eggs were observed in the field in early May. Thus, the species appears to be an annual one, breeding in fall and spring. Quick (1949, 1960), Hunter (1968), Stephenson (1968), and Chichester and Getz (1973) give some details of the life cycle. Arion intermedius (Normand) Distribution records of A. iniermedius are summarized for the West by Hanna (1966) and for the East by Dundee (1974). The species was previously recorded only from California in western North America. We found A. intermedius in two widely separated localities near Vancouver. On the U.B.C. Campus it was found near or in greenhouses, but it was also actively breeding outdoors, as its eggs were found under boards on October 18 and November 26, 1974. One specimen was also collected on the roadside of a rural area of Richmond in May, 1975. Both collection sites were short-grass habitats. This slug is easily recognized by its small size, hedgehog appearance, and lemon-yellow slime. Some of our specimens had faint traces of dark lateral bands, whereas others lacked bands. Stephenson (1968) classed A. intermedius as an agricultural pest in Britain. It is typically a woodland and ecotonal animal (Chichester and Getz, 1973), however, and is not yet considered to be of agricultural im- portance in North America (Anonymous, 1961). Quick (1949, 1960), and Chichester and Getz (1973) gave details of its biology. Arion subfuscus (Draparnaud) A. subfuscus was reported from the Pacific 110 THE NAUTILUS Northwest by R. T. Paine (Getz and Chichester, 1971). Except for one interception at Penticton in a shipment from Holland (Anonymous, 1962), the species does not appear to have been previously recorded from British Columbia. In Europe, A. subfuscus lives in mixed and coniferous forests, under dead wood and the bark of dead trees (Likharey and Ram- mel’meier, 1962; Quick, 1960), feeding mainly on fungus (Chichester and Getz, 1973). In north- eastern North America this slug readily en- ters woodland (Chichester and Getz, 1968), in- dicating an ability to become established throughout the forested areas of that region (Chichester and Getz, 1969; Getz and Chi- chester, 1971). In contrast, there has been no indication that A. swbhfuscus has been able to establish itself in forested regions of the North- west (Getz and Chichester, 1971). We have now found A. subfuscus in the natural wooded areas surrounding the University of British Columbia. Specimens were discovered under the bark of cedar logs in coniferous woodland, and many individuals were also found under logs in a deciduous-coniferodus area. Hundreds of eggs were discovered October 28, 1974, under logs in the coniferous area. Adults were found in the autumn of 1974 and in the spring of 1975. Miss Susan Elliott (pers. comm.) collected A. subfuscus from a cultivated area at 58th Avenue and Cartier Street in Vancouver in May, 1975. This slug probably was first established here in the suburban gardens, being introduced later into adjacent woods when gardeners dumped garden refuse and compost in such areas. Such dumping offers a major means of dispersal for introduced species within the city of Vancouver. The typical dorsal coloration of A. swbfuscus is orange- to mahogany-brown, slightly darker in the mid-dorsal region. The sides are lighter, and the foot fringe may be white or yellow with distinct striations. Lateral bands may be present or absent. Tentacles range from light brown to black. Slime is always yellow to bright orange. A. subfuscus is regarded as a_ pest in European U.S.S.R. (Likharev and Rammel’meier, 1962), and in Britain (Miles et al., 1931). It has October, 1975 Vol. 89(4) not become a serious agricultural pest in North America (Anonymous, 1961b). However, Chichester and Getz (1969) stressed that it might have some impact on natural com- munities. Chichester and Getz (1973) should be consulted for details of biology. Ariolimax columbianus (Gould) A. columbianus is a native slug ranging from Alaska to California. In British Columbia it occurs west of the Cascade Range (Mead, 1942; Pilsbry, 1948). Hanham (1914) observed damage to a garden by A. columbianus, but it is usually restricted to forests and woodlands, rarely damaging gardens unless they are on recently cleared land (Spencer, 1961). Dr. J. P. Kimmins (pers. comm.) believes that this species is a major herbivore in west-coast forests, where it eats the herb layer, especially bracken fern. One of his students, using radiotracers, estimated its maximum feeding rate as 53.01 - 865 mg dry weight of leaves/slug/day (Fahlman, 1972). Introduced species which are invading uncultivated habitats may be having comparable effects. In 1961, Spencer reported that A. columbianus was the dominant species of slug in the natural set- tings of Stanley Park, Vancouver. However, we now find that A. ater is most abundant there. In most localities, both the spotted and the unicolored forms of A. columbianus are com- mon. Black individuals were found at Long Beach, Vancouver Island. Some of these in- dividuals had a coalesced spotted pattern, but others were dark with overlying darker maculations. At Capilano Park, North Van- couver, several uniformly straw-yellow in- dividuals were discovered. In California, there is a comparable color variety that has distinc- tive genitalia (Mead, 1942, 1943: Pilsbry, 1948), but the Capilano specimens were typical A. columbianus in all respects. Mead (1942) observed dark necrotic areas on some individuals of A. columbianus which he suggested were fungus infections. Dr. H. R. MacCarthy (pers. comm.) discovered that such spots continued to develop when field-collected slugs were reared in isolation, thus reinforcing Mead’s suggestion. . Vol. 89(4) Adults of A. columbianus are found throughout the year, but young are mainly en- countered in spring. Eggs were found as early as October by J. Spence in 1974 (pers. comm.), and Taylor (1889) observed that they were com- mon under bark or logs during the winter on Vancouver Island. Details of the biology can be found in Mead (1942; 1943), Pilsbry (1948), and Westfall (1960). Deroceras caruanae (Pollonera) The only previous North American records of D. caruanae have-been from California (Han- na, 1966) and Quebec (Getz and Chichester, 1971; Dundee, 1974). We found the slug in sev- eral parts of the campus of the University of British Columbia. Adults were present in the autumn and the spring. This species closely resembles Deroceras laeve (Miiller) externally, except that it is larger with better-defined spots on the mantle. Internally the black mesentery lining the body cavity and the unusual genitalia make it easy to recognize (Pilsbry, 1948; Ellis, 1967). Lange (1944) ob- served that it invades gardens in California In association with D. reticulatwm, and Burch (1960) listed it as an economically important slug. Quick (1949, 1960) gives some details of its biology. Deroceras laeve (Miller) D. laeve is a native species found through- out North America (Pilsbry, 1948). It appears to be less common around Vancouver than in Ontario, although it is widely distributed in marshes, fields, woodlands and gardens. Iso- lated individuals are usually encountered, but large populations develop in greenhouses at the University of British Columbia, so that control measures must be routinely applied. D. laeve has not been considered of economic importance in British Columbia, but elsewhere it has damaged seedling plants and tomato fruits that ripen near the ground (Fox and Landis, 1973). It may also do considerable damage in greenhouses (Chichester and Getz, 1973). Details of the biology of this slug may be found in Quick (1949, 1960), Getz (1959), Chichester and Getz (1973), and Rollo (1974). THE NAUTILUS 111 Derceras reticulatum (Miiller) Older literature referred to Deroceras reticulatum (Muller) as Agriolimax agrestis (L.), a species with a more limited distribution (Quick, 1960; Chichester and Getz, 1973). Since both species have been found in North America (Grimm, 1971), dissection is necessary for proper identification. Ellis (1967) gives characters and figures for separating D. ~reticulatwm, D. agrestis, D. laeve, and D. caruanae. No D. agrestis has been encountered in Van- couver. D. reticulatum is the most abundant single species and also the most economically important slug in British Columbia. Taylor (1889) first recorded this species in British Columbia at Victoria. He observed that it was present around 1886 and that it was a “dread- ful pest” in gardens by 1891 (Taylor, 1892). In 1921, Glendenning (1923) observed much damage to corn in the Fraser Valley which was probably due to D. reticulatum. Many reports of slug damage do not specify which species is involved. Most of our local reports of slug damage can be attributed at least partially to D. reticulatum, however, as it is as dominant here as in_ western Washington, where Howitt and Cole (1962) estimated that it comprised 60% of the slug population. In the appropriate environment, slugs can be very destructive. Lovett and Black (1920) esti- mated that slugs (mostly D. reticulatwm) caused more damage to truck crops in the Pacific North- west than any single species of garden insect. In certain areas of New Brunswick in 1936, slugs caused more loss to the potato crop than the combined activities of all potato insects (Anonymous, 1937). Severe damage to field comm occurred in Ohio in 1968 and 1969 (Musick, 1972), and H. Gerber (pers. comm.) notes that appreciable acreage of corn in British Columbia has also been lost to slugs, especially where there are weeds. Up to 50% damage to potatoes (Anonymous, 1943), 25% damage to lettuce (Anonymous, 1948) and 10% damage to tomatoes (Nielson and Handford, 1955) have been reported here. On Vancouver Island, vetch plantings have been almost totally destroyed (Anonymous, 1947). Up to 75% damage to sweet corn, bush beans and 112 THE NAUTILUS strawberries occurred in Washington (Hanna, 1966; Anonymous, 1968), and clover can be destroyed within a single growing season in the Pacific Northwest (Howitt, 1961). Adult D. reticulatum can be found throughout the year in the Vancouver area, but most eggs are laid in the spring and autumn. Adults which we brought into the laboratory in the spring often died after laying eggs, and they probably also die after depositing spring eggs in the field. More details of the biology of this species are given in Lovett and Black (1920), Hawley (1922), Carrick (1988, 1942), Stephenson (1968), Judge (1972a), and Rollo (1974). Limax maximus Linnaeus The first record of L. maximus in western North America was from San Diego (Orcutt, 1890). Henderson (1929) includes a record from Salem, Oregon. Pilsbry (1948) does not list L. maximus from British Columbia, but it was already a pest in the Fraser Valley in 1947 (Glendenning, 1947). In 1960 it caused damage in gardens in the Vernon district (Arnott and Arrand, 1961). Spencer (1961) found it in a Vancouver garden, but it was much less abun- dant than A. ater. L. maximus now appears to be as widely distributed as A. ater in the Vancouver area. Pilsbry (1948) and Chichester and Getz (1973) stated that it was not found in woods or anywhere far from human habitation in North America. However, we have found it in small numbers in forests at Cultus Lake park and in wooded areas and fields not closely associated with dwellings around Vancouver. Adults and immature specimens were found in the autumn of 1974 and the spring of 1975. There appears to be some reduction in the adult population by June. Nightly observations in a garden revealed that particular individuals ate the same kind of food repeatedly, some taking only compost, and others green plants. Over a two-month period one individual was observed to eat only dog faeces, whereas others were feeding on green plants. White (1918) found that individuals of this species only changed their diet slowly unless starved, and Gelperin (1974) believes that October, 1975 Vol. 89(4) learning is involved. If so, repellents may be ef- fective in protecting garden plants. L. maximus is extremely variable in color. The mantle may be mottled or spotted, and the body may be spotted or striped. More rarely an individual is uniformly dark brown. The photograph which Wilkinson (1964) refers to as A. ater is probably a unicolored L. maximus. Pilsbry (1948), and Quick (1960) give more details of the biology of this species. Prophysaon andersoni (Cooper) P. anderson is a native species which ranges from California to Alaska (Hand and Ingram, 1950). In late summer it frequently becomes a garden pest in British Columbia (Glendenning, 1952), and it is also a pest in Oregon and California (Lovett and Black, 1920; Runham and Hunter, 1970). This species is common on the University of British Columbia campus. In spring, only im- mature specimens were encountered, whereas in late summer and fall, all individuals were large. Although it may become a garden pest, it is more abundant in forests and woodlands. MISCELLANEOUS OBSERVATIONS British Columbia appears to be a particularly favorable region for slugs, so that several other species could become established here. In fact, Iimax flavus Linnaeus was recorded earlier from North Vancouver by W. M. Draycott (Hanna, 1966). However, we found no specimens during our survey, nor any later reference to this slug in British Columbia. It is common in California (Hanna, 1966) and is now present in Oregon (Crowell, 1967). Glendenning (1952) and Wilkinson (1964) ob- served that Milax gagates (Draparnaud) was widely distributed but mainly confined to green- houses. We found no specimen of this species in the Vancouver area. It is very destructive in California (Lange, 1944; Hanna, 1966) and in Oregon (Lovett and Black, 1920), and should be considered a potential threat to the Vancouver area. Another slug which could become economically important if introduced is Leh- mannia valentiana (Férussac). This species is very destructive in California where it may be as abundant as D. reticulatum (Gregg, 1944). . Vol. 89(4) Establishment of these species around Van- couver may be limited because of our cooler winters. For example, Howe (1972) found that L. valentiana was killed by winter in Manitoba and so was limited to greenhouses there. We examined the Canadian Insect Pest Review and its successor, the Canadian Agricultural Insect Pest Review, for records of slugs in British Columbia for the period 1930- 1972. The records show that in general slug damage has been reported very locally and sporadically. This sporadic occurrence is the main reason there has been slow progress in slug control (Judge, 1972b). Damage has been widely distributed in British Columbia, ranging from Vancouver Island and the Fraser Valley to the Okanagan Valley and Prince George. Out- breaks have occurred in wet seasons, especially in consecutive wet years. In consecutive dry years, damage has been restricted to irrigated, low lying, or poorly managed areas. Damage suddenly increased after the introduction of A. circumscriptus, and again with the appearance of A. ater. Spencer (1961) stated that introduced slugs were approaching outbreak proportions in Vancouver, and damage reports from previously untroubled areas attested to the dispersal of the pests inland. The official reports, combined with a list from Banham and Arrand (1970), show that at least 26 crops have been attacked in British Columbia. The more important of these are corn, potatoes, lettuce, cabbage, beans, peas, strawberries, tomatoes and clover. In addition, the extent of damage to horticultural crops may exceed field- or truck-crop damage (Runham and Hunter, 1970). It appears that an introduced species can become a pest within ten years, so that any new introduction is potentially dangerous. Crop damage by slugs can be expected to increase in severity in British Columbia as new species become established, and the recently established species continue to disperse. ACKNOWLEDGMENTS We express appreciation to members of Agriculture Canada, especially Dr. H. R. Mac- Carthy, for help with the local records and ob- servations on slugs. We also thank Miss S. Elliott for assistance in collections, Dr. J. P. THE NAUTILUS 113 Kimmins for observations on Ariolimaz, and Dr. H. Gerber for some of the information on slug damage. Voucher specimens of all species recorded in this survey have been deposited in the Delaware Museum of Natural History (nos. 102516-102527), together with a copy of the detailed locality records. LITERATURE CITED Anonymous. 1937. Summary of insect conditions in Canada in 1936. Canad. Insect Pest Rev., 15(1): 1-16. Anonymous. 1943. Canad. Insect Pest Rev. 21(4): 250. Anonymous. 1947. Canad. Insect Pest Rev., 25(1): 26-27. Anonymous. 1948. Canad. Insect Pest Rev. 26(5): 219. Anonymous. 1959. Slugs and snails. Min. Agr. Fish, Food (Brit.) Adv. Leaflet 115:8 pp. Anonymous. 196la. Insects of the season 1960 in the lower Fraser Valley. Canad. Insect Pest Rev., 39(1): 4-6. Anonymous. 1961b. Canad. Insect Pest Rev., 39(3): 137-161. Anonymous. 1962. Canad. Insect Pest Rev. 40(1): 33. Anonymous. 1963. Canad. Insect Pest Rev., 41(3): 86. Anonymous. 1968. Coop. Econ. Insect Rept., 18(24): 511. Arnott, D. A. and J. C. Arrand. 1961. Insects of the season 1960 in the interior of British Columbia. Canad. Insect Pest Rev. 39(1): 7-14. Banham, F. L. and J. C. Arrand. 1970. Recogni- tion and life history of the major insect and allied pests of vegetables in British Columbia. B.C. Dept. Agr. Entomol. Br. 70-9: 43 pp. Barnes, H. F. 1944. Seasonal activity of slugs. Ann. Appl. Biol., 31: 160-163. Bett, J. A. 1960. The breeding seasons of slugs in gardens. Proc. Zool. Soc. Lond., 135: 559- 568. Burch, J. B. 1960. Some snails and slugs of quarantine significance to the United States. Sterkiana, 2: 13-53. Cain, A. J. and M. H. Williamson. 1958. Varia- tion and specific limits in the Arion ater aggregate. Proc. Malac. Soc. Lond., 33: 72-86. 114 THE NAUTILUS Carl, G. C. and C. J. Guiguet. 1958. Alien ani- mals in British Columbia. B. C. Prov. Mus. Handbk. 14: 94 pp. Carrick, R. 1938. The life history and develop- ment of Agriolimax agrestis L., the grey field slug. Trans. Roy. Soc. Edinb., 59: 563-597. Carrick, R. 1942. The grey field slug Agriolimax agrestis 1. and its environment. Ann. Appl. Biol., 29: 43-45. Chichester, L. F. 1968. The zoogeography, ecol- ogy and taxonomy of arionid and limacid slugs introduced into northeastern North America. Ph.D. Thesis, Univ. of Connecticut, 234 pp. Chichester, L. F. and L. L. Getz. 1968. Terres- trial slugs. Biologist., 50(3): 148-166. Chichester, L. F. and L. L. Getz. 1969. The zoogeography and ecology of arionid and limacid slugs introduced into northeastern North America. Malacologia, 7: 313-346. Chichester, L. F. and L. L. Getz. 1973. The terrestrial slugs of northeastern North Amer- ica. Sterkiana, 51: 11-42. Crowell, H. H. 1967. Slug and snail control with experimental poison baits. J. Econ. Entomol., 60: 1048-1049. Doucette, C. F. 1954. An introduced slug, Arion ater (L.) and its control with metaldehyde. J. Econ. Entomol., 47: 370. Dundee, D. S. 1974. Catalog of introduced molluscs of eastern North America (north of Mexico). Sterkiana, 55: 1-37. Dunn, E. 1963. The slug problem on arable crops. Scot. Agr., 43(2): 101-104. Ellis, A. E. 1926. British snails: a guide to the non-marine Gastropoda of Great Britain and Ireland, Pliocene and recent. Clarendon Press, Oxford. 275 pp. Ellis, A. E. 1967. Agriolimax agrestis (L.): some observations. J. Conch., 26: 189-196. Fahlman, R. A. 1972. Radiotracer and gravi- metric estimates of the food consumption of the giant west coast land slug, Amolimax columbianus Gould. BSc. Thesis, Univ. of British Columbia. Forbes, A. R., H. G. Fulton, and A. T. Wilkin- son. 1956. A regional review of insects of the season 1955. British Columbia insect pests of fruits and ornamentals on Vancouver Island and in the lower Fraser Valley, 1955. Canad. Insect Pest Rev., 34(1): 1-3. October, 1975 Vol. 89(4) Fox, L. and B. J. Landis. 1973. Notes on the predaceous habits of the gray field slug, Deroceras laeve. Environ. Entomol. 2(2): 306-307. Fulton, H. G. 1955. Canad. Insect Pest Rev., 33(2): 144. Gelperin, A. 1974. Olfactory basis of homing behavior in the giant garden slug, Limax maximus. Proc. Nat. Acad. Sci. U.S.A. 71(8): 966-970. Getz, L. L. 1959. Notes on the ecology of the slugs: Arion circumscriptus, Deroceras reticu- latum, and D. laeve. Am. Midl. Nat. 61: 485-498. Getz, L. L. and L. F. Chichester. 1971. Intro- duced European slugs. Biologist, 53: 118-127. Glendenning, R. 1923. Insects of economic im- portance in the Fraser Valley in 1921. Proc. BC. Entomol. Soc, 17: 167-172. Glendenning, R. 1941. Field crop and garden insects of the season 1940 in British Colum- bia. Canad. Insect Pest Rev., 19(1): 84-87. Glendenning, R. 1945. Canad. Insect Pest Rev, 23(2): 167. Glendenning, R. 1947. Slug control in British Columbia. Canad. Sci. Serv. Dept. Agr., Div. Entomol. Publ., 70:4 pp. Glendenning, R. 1952. Slug control in Canada. Canad. Dept. Agr. Sci. Ser. Publ., 85. Glendenning, R. and K. M. King. 1949. In K. M. King (ed.), Regional pest faunas: The more important insect pests of British Columbia. Proc. Seventh Pacific Sci. Cong., 4: 121-148. Gregg, W. O. 1944. Notes on land slugs of Los Angeles and Orange County, California. The Nautilus, 57: 109-115. Grimm, F. W. 1971. Annotated checklist of the land snails of Maryland and the District of Columbia. Sterkiana, 41: 51-57. Hand, C. and W. M. Ingram. 1950. Natural history observations on Prophysaon andersont (J. G. Cooper) with special reference to ampu- tation. Bull. S. Calif. Acad. Sci., 49: 15-28. Hanham, A. W. 1914. Notes on molluscs from British Columbia. The Nautilus, 28: 87-88. Hanna, G. D. 1966. Introduced mollusks of western North America. Occ. Papers Calif. Acad. Sci., 48: 108 pp. Hawley, I. M. 1922. Insects and other animal pests injurious to field beans in New York. Vol. 89(4) Cornell Umwv. Agr. Exptl. Sta. Mem. 55: 945-1037. Henderson, J. 1929. Non-marine Mollusca of Oregon and Washington. Univ. Colorado Stud., 17: 47-190. Howe, G. T. 1972. Ecology of slugs in Manitoba and accumulation, storage and excretion of D.D.T. in their bodies. M.Sc. Thesis, Univ. Manitoba. Howitt, A. J. 1961. Chemical control of slugs in orchard grass-ladino white clover pastures in the Pacific northwest. J. Econ. Entomol. 54: 778-781. Howitt, A. J. and S. G. Cole. 1962. Chemical control of slugs affecting vegetables and strawberries in the Pacific northwest. J. Econ. Entomol., 55: 320-325. Hunter, P. J. 1968. Studies on slugs of arable ground II. Life cycles. Malacologia, 6(3): 379- 389. Judge, F. D. 1972a. Aspects of the biology of the gray garden slug (Deroceras reticulatum Miller). N.Y. EHzxpt. Sta. Geneva Search., 2(19): 1-18. Judge, F. D. 1972b. Cultural practices and slug control. N.Y. Food Life Sci., 5(3): 16-17. King, K. M. 1949. Insects of the season 1948 in British Columbia. Canad. Insect Pest Rev., 27: 1-4. Lange, W. H. 1944. Land slugs of California. Bull. S. Calif. Acad. Scr, 43: 33-48. Likharev, I. M. and E. S. Rammel’meier. 1962. Terrestrial molluscs of the fauna of the USS.R. Jerusalem Israeli Prog. Sci. Transl. 578 pp. Lovett, A. L. and A. B. Black. 1920. The gray garden slug with notes on allied forms. Oregon Agr. Expl. Sta. Bull., 170: 43 pp. Mead, A. R. 1942. The taxonomy, biology, and genital physiology of the giant west coast land slugs of the genus Amolimax Morch (Gastropoda : Pulmonata). Ph.D. Thesis, Cornell Univ. 142 pp. Mead, A. R. 1948. Revision of the giant west coast land slugs of the genus Amolimax Moerch (Pulmonata: Arionidae). Am. Midl. Nat., 30: 675-717. Miles, H. W., J. Wood, and I. Thomas. 1981. On the ecology and control of slugs. Ann. Appl. Biol., 18: 370-400. THE NAUTILUS 115 Musick, G. J. 1972. Efficacy of phorate for con- trol of slugs in field corn. J. Econ. Entomol., 65(1): 220-222. Neilson, C. L. and R. H. Handford. 1955. Insects of the season 1954 in the interior of British Co- lumbia. Canad. Insect Pest Rev., 33(1): 9-15. Orcutt, C. R. 1890. West American notes. The Nautilus, 4: 67-68. Pilsbry, H. A. 1948. Land Mollusca of North America (north of Mexico). Phil. Acad. Nat. Sci. Mono. 3(2): 521-1113. Quick, H. E. 1947. Arion ater (L.) and A. rufus (L.) in Britain and their specific dif- ferences. J. Conch., 22: 249-261. Quick, H. E. 1949. Synopses of the British fauna. No. 8. Slugs (Mollusca). (Testacellidae, Arionidae, Limacidae). Linn. Soc. Lond. 8 29 pp. Quick, H. E. 1960. British slugs (Pulmonata; Testacellidae, Arionidae, Limacidae). Bull. British Mus. Nat. Hist. (Zool.), 6(3): 103-226. Rollo, C. D. 1974. Ecology of the slugs Dero- ceras reticulatum, D. laeve, and Aron fas- ciatus in Ontario corn fields. M.Sc. Thesis, Univ. Guelph. 173 pp. Runham, N. W. and P. J. Hunter. 1970. Ter- restrial slugs. Hutchinson Publ. Lond. 184 pp. Smith, A. G. 1962. Arion ater (Linnaeus) in California. Veliger, 4: 215-216. Smith, B. J. 1966. Maturation of the reproduc- tive tract of Aron ater (Pulmonata: Arioni- dae). Malacologia, 4: 325-349. Spencer, G. J. 1961. A record of slugs in Van- couver gardens. Proc. Entomol. Soc. B.C, 58: 47-48. Stephenson, J. W. 1968. A review of the biology and ecology of slugs of agricultural impor- tance. Proc. Malac. Soc. Lond., 38: 169-178. Taylor, G. W. 1889. The land shells of Vancou- ver Island. Ottawa Nat., 3: 84-94. Taylor, G. W. 1892. Limax agrestis Linn. on the Pacific Coast. The Nautilus, 5: 92-93. Westfall, J. A. 1960. Oviposition, hatching, and early growth of Ariolimax columbianus (Gould). Veliger, 2(1): 10-12. White, W. H. 1918. The spotted garden slug, Limax maximus L. U.S.D.A. Farm. Bull. 959: 7 pp. Wilkinson, A. T. S. 1964. Control of slugs. Canad. Dept. Agr. Publ., 1213: 4 pp. 116 THE NAUTILUS October, 1975 Vol. 89(4) OBSERVATIONS ON MOLLUSKS FROM A NAVIGATION BUOY WITH SPECIAL EMPHASIS ON THE SEA SCALLOP PLACOPECTEN MAGELLANICUS Arthur S. Merrill National Marine Fisheries Service Middle Atlantic Coastal Fisheries Center Resource Assessment Investigations Oxford, Maryland 21654 and Robert L. Edwards National Marine Fisheries Service Northeast Fisheries Center Woods Hole, Massachusetts 02543 ABSTRACT Twelve species of postlarval mollusks were found among fouling organisms collected from a nawgation buoy. Length data for the three most abundant species, Placopecten magellanicus, Anomia aculeata,' and Mytilus edulis, were analyzed in an attempt to explain normal and log-normal frequency distribution patterns. Molluscan community relationships on the buoy were closely observed and reported. The ocean bottom under the buoy was sampled by dredge, and the population composition of mollusks on the bottom did not include the postlarval forms found on the buoy. INTRODUCTION Many objects floating at the ocean’s surface eventually acquire an imposing community of sessile marine organisms. An impressive body of literature exists with reference to such fouling organisms (Woods Hole Oceanographic In- stitution Contribution No. 580, 1952). In this paper, we present the results of a study of the mollusks attached to an ocean buoy. One specific purpose of this study was to learn more of the early life history of the sea scallop, Placopecten magellanicus (Gmelin). United States Coast Guard navigation buoys come in many shapes and sizes. Those for ocean duty are usually made up of a superstructure carrying a light and a bell or whistle, a cylin- drical float chamber, and a stabilizer to hold the buoy upright. They are anchored to large blocks of concrete by heavy chain. Immediately upon launching, buoys become attractive bases for colonization by marine organisms. The organisms which settle, survive, and grow are, for the most part, species which are able to attach themselves securely. When the buoy is returned for cleaning and servicing, the entire community of organisms can be con- veniently observed and sampled. The outside buoy surfaces are subjected to strong tidal currents and wave action, which restrict at- tachment to those organisms with the most tenacious holdfasts. The inside of the stabilizer tube (Fig. 1) offers a more sheltered en- vironment with considerable, but gentler, water exchange as the buoy surges up and down. Here are found the densest populations, and here the struggle for space is readily observed (Merrill, 1965). METHODS The collection was taken from the Nantucket Shoals Lightship (NSLS) buoy. The buoy was FIG. duwates the sheltered, stabilizer tube. 1. Typical navigation buoy. Arrow tn- inner portion of the Vol. 89(4) placed on station October 8, 1957, at N. lat. 40°33’; W. long. 69°28’, 1 mile north of the Nantucket Lightship, and returned to the Coast Guard Base at Woods Hole for cleaning and repairs on May 10, 1958. It offered a par- ticularly attractive fouling community for study, since the buoy had been on station for only a limited time (7 months), and during a period when many species with pelagic larvae were not spawning (the winter months). The NSLS buoy is 24 ft long and its greatest diameter is 9 ft. About half of the buoy is sub- merged when in position. Collecting was re- stricted to the area 8 ft inward from the mouth (bottom) of the buoy stabilizer, which is 2 ft in diameter (see arrow, Fig. 1). This area, ap- proximately 50 sq ft, was carefully scraped and then wire-brushed to loosen many small in- dividuals still hidden in crevices. The total sam- ple of 1% gal (12 pt) was taken to the laboratory for sorting, study, and analysis. Since the buoy had been out of water about 3 weeks, the fouling community had de- hydrated slowly and was in excellent condition for collection and study. Much of the material consisted of sizable thin pieces of rust (Fig. 2) with animals and plants attached in their original positions. Measurements of mollusks were made to the nearest 0.1 mm with the aid of an ocular micrometer. The greatest overall size, height or length was used as the basic measurement. FIG. 2. A piece of iron rust removed from within the stabilizer tube of a buoy. The material dried slowly and a number of organisms can be seen adhering in_ their original positions. THE NAUTILUS ialy/ Hydrographic data for the area were available from the nearby lightship. To compare the population of the buoy with that of the bottom below, the area was dredged on May 26, 1958, about 2 weeks after the buoy was brought in. A 10-ft-wide sea scallop dredge with a *%-inch stretched mesh liner was towed from the Bureau of Commercial Fisheries Research Vessel Albatross III to make the collection. The contents of a 5-min tow which covered approximately 15,000 sq ft of bottom area were analyzed. Several of the smallest scallops from the buoy measured as little as 0.5 mm. The prodissoconch measured about half this size, so these smallest specimens had approximately doubled in size since settling. To our knowledge, these are the smallest metamorphosed sea scallops ever col- lecteds. After death, the ligamental structure in the hinge of the scallop continues to hold the valves together, but gaping. In this condition, sea scallop valves tend to tangle in filamentous bryozoa or amongst the byssal threads of the TABLE 2 Number of specimens Tive Gastropoda Colus pygmaea Gould 1 5 Nassarius trivittatus Say’ 8 Buccinum undatum Linnaeus 62 60 Lunatia heros Say 74 64 Cremdula plana Say? 78 0 Pelecypoda Placopecten magellanicus Gmelin? 6 1 Artica islandica Linnaeus* 8 125 Pnsis directus Conrad* 0 5 Astarte castanea Say 2) 0 Venericardia borealis Conrad 5 0 Modiolus modiolus Linnaeus 1 1 Anomia simplex d’Orbigny 1 0 Spisula solidissima Dillwyn* 9 1 1 This species had deposited numerous egg cases on the in- terior of practically every dead valve of the mahogany clam (Arctica islandica). 2 Found attached inside large dead shells, usually Lunatia heros. 3 The heights of these in millimeters were 59.9, 85.2, 117.8, 131.7, 157.4, 164.7; one upper valve, 28.2. 4 The animal lives in the substratum, consequently not adequately collected by the type of dredge used. 5 We have since taken from buoys scallops as small as 0.3 mm, the prodissoconchs having barely a fringe of dissoconch growth. 118 THE NAUTILUS mussels. There were 233 dead specimens of scallops in the total population, the mode at about 2.0 mm. Size-frequencies for the dead and live scallops (Table 1) show similar curves which suggests that valves do not remain long in the buoy after death. The pint sample con- tained 214 dead mussels (Fig. 3, dotted line), many of them of smaller size. In fact at about 12 mm, more dead than live mussels were counted. Some of these were found trapped in aggregates of mussels, while many were found partly or completely buried in the light layer of fine silt and debris that builds up in the buoys. The great mortality in the smallest mussels occurred over a period of time, judging from the various degrees of shell decomposition observed. The top and bottom valves of A. aculeata' soon separate after death and shell remains are quickly flushed from the buoy; hence, dead specimens are rarely found. In order to discuss growth, the time of set- ting must be ascertained with some degree of accuracy. It is possible to determine quite closely the spawning season (and hence the probable time of setting) for two of the major species on this buoy. Observations on the spawning of sea scallops have been made by several investigators. These observations have been summarized by Dickie (1955, p. 848) and show that the spawning period, for all geographical areas, may extend from mid-July to early October. From extensive study, we can definitely state that scallop spawning in the offshore area of Cape Cod occurs between late September and the middle of November. Allowing as much as an extra month in the larval state, all spat should have settled by mid-December. This means larvae of the sea scallop could, and probably did, settle on the buoy during the first few weeks after it was placed on station, and, judging by the similarity of their population structures, so did the other species as well. ‘Abbott in the second edition of American Seashells (1974, p. 452) follows Winckworth, 1922, and others, in calling this species squamula Linné, 1758. 2 Temperature records for the time and locality involved in this study are available in published form (Day, 1959a; 1959b). October, 1975 Vol. 89(4) In Milford Harbor, Connecticut, spawning of M. edulis is restricted to those months when the temperature is approaching and above 60°F? (Engle and Loosanoff, 1944). In “Marine Fouling and Its Prevention” (Woods Hole Oceanographic Institution, Contribution No. 580, 1952), early to late June is indicated as the beginning of the breeding season for Mytilus at Woods Hole, Massachusetts. Mytilus larvae, then, must have been in the water after the buoy was placed on station, and, because of the low temperatures that prevailed, there could have been no further sets in the spring before the buoy was taken off station. No spawning information is available for A. acweata, but the size-frequency distribution suggests that the spat of this species settled about the same time. as the other two species. Both M. edulis and A. aculeata showed signs of polymodal distribution not obvious in P. magellanicus. The use of probability paper in an attempt to define polymodal distribution as outlined by Harding (1949) failed to show any significant secondary set or group for the sea scallops. However, similar analysis of the Anomia data indicated possible modes at 3.7 mm and 7.2 mm, and for the mussel at 1.6 mm, 28 mm, 7.0 mm, and possibly others. This suggests that, within the spawning period, one strong set of sea scallops and two or more heavy sets for the other two species settled on the buoy. From observations of the buoy material, there is indirect evidence that more than one group of larvae settled. For instance, many small Anomia were seen attached to larger shells of the same species; a small Anomia and a small Mytilus were found attached to the inner valve of a much larger dead mussel; and there were many instances in which one organism grew upon another in such a way as to suggest that it set some time after the other. Indirect evidence can also be found in the data; for in- stance, the smallest mussel was 0.4 mm and the largest just under 25 mm - far too much dif- ference in growth, it is felt, for a single set. The average and maximum sizes of the four common species of pelecypods found in the buoy were: Vol. 89(4) THE NAUTILUS 119 Average Maximum ter the buoy was on station. Initial settlers Placopecten magellanicus 2.9 mm 13.2 mm would have had less competition from their own Mytilus edulis AG aaa DAR cain kind, as well as a warmer and longer period in Fiatella arctica 3.7 mm 9.5 mm which to ee Vee aileata enn 12D savin It should be pointed out that a factor such as The averages represent shell growth for 6 to 7 months after setting, and during the coldest months of the year. The maximum sizes at- tained are an indication of the amount of growth that can be achieved under the existing conditions. The location of the NSLS buoy is such that pelagic bivalve larvae could be transported from many coastal areas, and this could effectively extend the setting season. The currents that sweep over Nantucket Shoals undoubtedly carry planktonic larvae originally spawned in many different estuaries and bays of the Massachu- setts coast, as well as from a large area of the Gulf of Maine. It seems most reasonable to suggest that, for Mytilus at least, the peak of setting may have occurred for several weeks af- overcrowding might lead to arrested growth. Arrested growth in one segment of the population might yield a mode that possibly could be interpreted as indicative of age. The strongly skewed size distributions of Figure 3 deserve further mention. Such distributions are not uncommon in youthful populations of many organisms, and can con- ceivably arise in one or more ways, including (1) simple differences in growth due to time of setting, especially when spatfall occurs over a period of time associated with a change in tem- perature; (2) decreased growth rate for later arrivals due to increased density and com- petition; and/or (3) some characteristic of the buoy that causes unusual mortality (or loss to the buoy) amongst the larger individuals. The sea scallop size-frequency is well fitted by a log-normal transformation, as can be seen 50 aie NUMBER OF INDIVIDUALS %) ° T Anomia aculeata Placopecten magel/lanicus Mytilus edulis a a CR a Ti aR Rg A 7 | | LENGTH IN MILLIMETERS FIG. 3. Size-frequency distribution of the three common mollusk species found on the Nantucket Shoals Lightship buoy (1-pt subsample). 120 THE NAUTILUS October, 1975 Vol. 89(4) NUMBER OF INDIVIDUALS 1 Placopecten magellanicus 74 8 9 10 im) 12 13 14 LENGTH IN MILLIMETERS FIG. 4. Size-frequency distribution of the sea scallops found on the Nantucket Shoals Lightship buoy. in Figure 5. The length-frequencies of Mytilus and Anomia are not so well fitted, perhaps because more than one set is represented in the data. However, since any one or any com- bination of the factors mentioned above can result in a log-normal distribution, this trans- formation does not of itself shed additional light on the subject. It would appear that the observed skews can be largely attributed to setting over a period of time during which sea surface temperatures were cooling. The possibility that many Mytilus and Anomia settled after temperatures were too cool for any further significant growth cannot be dismissed. The problem is worthy of further study, and material from buoys may be par- ticularly useful in this respect. RESULTS Three species of pelecypods - the sea scallop, Placopecten magellanicus, the jingle shell, Anomia aculeata, and the common, blue mussel, Mytilus edulis — dominated the community found on the buoy. Because the two latter species were so numerous, a 1-pt subsample (of the 12-pt total sample) was taken and all specimens were counted and measured. The length-frequency distributions obtained of the three most common mollusks are shown in Figure 3. As a check on the validity of this subsample, all molluscan species in the total sample, except the numerous A. aculeata and M. edulis, were also counted and measured. |500}— 1000}— NUMBER OF INDIVIDUALS 1 1 — ft§j_ 9 | 2 3 4 5 6 76910 LENGTH IN MILLIMETERS FIG. 5. Size-frequency distribution of the sea scallops found on the Nantucket Shoals Light- ship buoy plotted on semilogarithmic paper to produce the symmetry of a log-normal curve. Vol. 89(4) THE NAUTILUS 121 TABLE 1. Frequency by size of the mollusks taken from the Nantucket Shoals Lightship buoy. Species Size_(mm) Total _ | Range o1 | 12 [23 [34] 45 [56 | 67 [78 | 89 [910] >10 [Live [Dead [in size eASTaRTan No. | No. | No. | No.| No. | No. | No. | No.| No.| No.| No.| No. | No. | mm Mitrella lunata Say 4 13 12 12 41 3] 14 46 Lacuna neritoidea Gould 7 6 13 1] 0.3- 1.8 Spiratella lesuewri D'Orbigny 2 2 7 Anachis avara Say 1 1 14 Unidentified 2 2 0.3 PELECYPODA Placopecten magellanicus Gmelin|148 |1,845 |3,433 |}2174} 868 | 425 371 | 275) 154) 86 27) 9,806 0.5-13.2 P. magellanicus (dead) Ine) || || Ba a a | 20- 6.9 Anomia aculeata Gmelin 396 |2,400 [3,900 | 4608) 4,452 | 3,516 }2.472 | 2,160} 1,500) 732 468 26,6044 108° | 0.5-13.0 Mytilus edulis Linnaeus 0.4-24.3 M. edulis (dead) 204 |1,800 | 396] 60} 2] 43| 12] 121 12 0.4 83 Miatella arctica Linnaeus 4 14 14 6 5 3 il 1 48 2) 11- 9.3 Anadara ovalis Bruguiere 1 1 2.5 Tellina agilis Stimpson 1 1 0.9 Periploma papyratium Say 1 : 11 55,120 2915 “Calculated from 1/12 aliquot of total sample. Figure 4 shows the frequency distribution of P. magellanicus found in the total sample. The frequency distributions in Figures 3 and 4 are strongly skewed to the right and only that for M. edulis is obviously polymodal. In the subsample, there were 731 P. magellanicus with a range in size of 0.5-13.2 mm and a mode at about 3 mm; 2,217 A. aculeata with a range of 0.5-14.0 mm and a mode at about 4 mm; and 1,550 M. edulis with a range of 0.4-24.3 mm and obvious modes at about 1.7 and 2.8 mm (Fig. 3). In the total sample, there were 9,806 magellanicus with a range of 0.5-134 mm and modes at about 2.5 and 2.8 mm (Fig. 4). The mussel produces a stout and intricately woven byssus, and the jingle shell a short thickened byssal plug, both of which are capable of holding shell remains securely to a substrate after drying. The thin byssal threads of scallops become brittle upon drying and break easily. Therefore, the size-frequency data _ presented in Figure 3 for the mussel and jingle shell are possibly more representative of the total sample than for the scallop. Propor- tionally, there were fewer small Placopecten in the pint subsample than in the total sample, and the mode was about 0.5 mm higher. Ap- parently, some of the smaller scallops settled to the bottom of the original scrapings before the aliquot was obtained. However, aside from these minor differences, the scallop size-frequency distribution in the aliquot (Fig. 3) is similar to that in the total sample (Fig. 4). All the mollusks collected from the buoy are listed in Table 1, together with their size- frequency by 1l-mm groups. The size-frequency of the shells of dead P. magellanicus and M. edulis is also given. The total number of A. aculeata and M. edulis is estimated on the basis of subsample counts. The total number of living mollusks from the 50-sq-ft area was 55,120 or an average of 7.7 individuals per square inch. The material obtained by dredging the bot- tom under the buoy was compared with the sample from the buoy (Table 2). The bottom was of a mud-sand texture; the sand dollar, Echinarachnius parma, proved to be the com- monest species of the area with over 1,200 cap- tured. Some of the larger gastropods such as Iunatia heros and Buccinum undatum were present in fair numbers, and there were many dead double valves of the bivalve, Arctica islan- dica. The molluscan faunal composition of the bottom was completely different from that of the buoy except that it contained a few large sea scallops. None of the same larval mollusk species that had settled on the buoy found their way to the bottom in this area. 122 THE NAUTILUS DISCUSSION Each species exhibited patterns of preference in utilizing the substrate within the 8-ft length of buoy tube. The spat of Mytilus, for example, first attached directly to the substrate, and later tended to aggregate and intermingle their byssal threads to form colonies. Even though the mussel may detach and _ reestablish elsewhere (Field, 1922), our observations showed that in some cases unusually dense masses of byssal threads may entrap certain segments of a population. As a result, some mussels became smothered, or grew at a slower rate than neigh- boring specimens. Anomia spat attached directly to solid substrate, preferring crevices, but did attach to all other available surfaces. Individual Hiatella were randomly distributed and grew competitively within aggregates of mussels, or freely on open substrate. The spat of Placopec- ten showed a marked preference for areas that were free from other mollusk association. The smallest scallops, those under 1 mm, were in- variably attached to the filaments of bryozoa, to the byssal threads of Mytilus, or directly to shells, where they could move about freely. Scallops over 1.5 mm were generally attached to solid substrate, far removed from other organisms, when possible. Young sea scallops do not seem to compete well in fouling communities. The mantle is ap- parently easily injured, and evidence of serious shell malformation was seen in situations where other organisms were in close proximity to the scallop. This was particularly noticeable when an occasional larger specimen had been trapped within the byssal maze of a Mytilus colony. Young Anomia, Mytilus, and Hiatella, unlike Placopecten, adjust to the necessity for living close to other organisms. Anomia conforms easily to close contact; if an obstacle in the im- mediate area interferes with normal develop- ment, the individual will change shell symmetry and become elongate in any plane which offers the opportunity for further growth. Mytilus and Hiatella suffer least from close contact, probably because their siphons, not their mantle edges, are most exposed. However, both species are known to exhibit shell distortion in con- ventional habitats — Hiatella in peat and coral burrows, and Mytilus in dense colonies. October, 1975 Vol. 89(4) Baird (1953), in examining many “bushy” organisms obtained from dredgings, found only the bryozoan Gemellaria to be a consistent host for settling sea scallop larvae. He suggested the possibility of a direct relationship betwen Gemellaria and Placopecten in the larval ecology of the scallop. In light of our ob- servations, we wish to amend this slightly. Ap- parently when the scallop spat settles, it is too delicate to take advantage immediately of bot- tom substrate, composed entirely of particulate matter continuously shifting with the bottom currents. Thus, those that land on sedentary branching plants and animals, or any other hard surface on or above the ocean floor which offers freedom of shell movement on all sides, may have a distinct survival advantage. It should be noted that, as with Placopecten, many of the smallest individuals of Mytilus and Anomia were attached to bryozoa and to byssal threads; however, just as many of the smallest were attached to solid substrate. From ob- servations on the distribution of these species in the buoy, it appears that all are able to disengage themselves and travel some distance - the mussels to aggregate, the scallops to spread out, and the jingle shells to seek any solid substrate available. Mytilus and Anomia appear to fix more or less permanently at an early age, while Placopecten and Miatella may continue to disengage from time to time. SUMMARY 1. All the mollusks within an area of 50 sq ft were collected from within the stabilizer tube of a heavy duty navigational buoy. Twelve species were recovered from approximately 55,000 mollusks that made up the fouling population. Three species, Placopecten magellanicus, Anomia aculeata, and Mytilus edulis, were found in the largest number. 2. The ocean bottom under the buoy was dredged, and the population composition and structure were found to be completely different from the buoy population. 3. The population structure and the in- terrelationships of species in the mollusk com- munity were closely observed. Methods of at- tachment and distributional patterns, par- Vol. 89(4) ticularly patterns of preference in utilizing surface area, are discussed in some detail. 4. Analysis of the length-frequency distribution, using probability paper to define polymodal groups, suggested one heavy set of P. magellanicus and two or more of A. aculeata and M. edulis. 5. Taking into consideration the season and length of time the buoy was on station (7 months from October 8, 1957, to May 10, 1958) and using available evidence regarding the time in which sea scallops and mussels spawn, it was possible to predict that these species had settled on the buoy before the first of the year. Hence, growth was related to the size-frequency distribution after that time. 6. Size-frequency graphs for the three com- mon species on the buoy show that large num- bers of small individuals form obvious modes and that a persistent but diminishing number of larger specimens spread over a considerable range; i.e., the major modes for the three species are skewed to the right. Possible reasons for such size-frequency distribution are discussed. ACKNOWLEDGMENTS We wish to acknowledge the cooperation of the Commander of Base, U. S. Coast Guard Station, Woods Hole, Massachusetts, and other base personnel who assisted in the collection of samples. The writers are grateful to Dr. L. B. Slobodkin for helpful suggestions relative to distribution of animals. THE NAUTILUS 123 LITERATURE CITED Baird, F. T. Jr. 1953. Observations on the early life history of the giant scallop (Pecten ma- gellanicus). Maine Dep. Sea Shore Fish., Res. Bull. No. 14, pp. 2-7. Day, C. G. 1959a. Oceanographic observations, 1957, east coast of the United States. U.S. Fish Wildl. Serv., Spec. Sci. Rep.-Fish, No. 282, 123 pp. Day, C. G. 195%. Oceanographic observations, 1958, east coast of the United States. US. Wildl. Serv., Spec. Sci. Rep.-Fish. No. 318, 119 pp. Dickie, L. M. 1955. Fluctuations in abundance of the giant scallop, Placopecten magellanicus (Gmelin), in the Digby area of the Bay of Fundy. J. Fish. Res. Board Can. 12: 797-857. Engle, J. B. and V. L. Loosanoff. 1944. On the season of attachment of larvae of Mytilus edulis Linn. Ecology, 25: 433-440. Field, I. A. 1922. Biology and economic value of the sea mussel, Mytilus edulis. U.S. Bur. Fish., Bull. 38: 127-259. Harding, J. P. 1949. The use of probability for the graphical analysis of polymodal fre- quency distribution. J. Mar. Biol. Assoc. U.K., 38: 141-153. Merrill, A. S. 1965. The benefits of systematic biological collecting from navigation buoys. ASB Bull., 12: 3-8. Woods Hole Oceanographic Institution. 1952. “Marine Fouling and Its Prevention.” USS. Naval Inst., Annapolis, Md. (Prepared for Bur. Ships, Navy Dep., by Woods Hole Ocean- ogr. Inst., Contrib. No. 580). 388 pp. Winckworth, R. 1922. Note on the British Spe- cies of Anomia. Proc. Malacological Soc. London, vol. 15, pt. 1, pp. 32-34, 1 pl. 124 THE NAUTILUS October, 1975 Vol. 89(4) DISTRIBUTIONAL AND ANATOMICAL OBSERVATIONS OF BERTHELLA TUPALA (OPISTHOBRANCHIA: NOTASPIDEA) Hans Bertsch‘ Smithsonian Tropical Research Institute P.O. Box 2072, Balboa, Canal Zone ABSTRACT Berthella tupala occurs on the Caribbean coast of Panama, in addition to Florida, Puerto Rico, and Brazil. Scanning electron micrographs illustrate the morphology of the internal shell and radular teeth, and the development of the jaw platelets. DISTRIBUTION The occurrence of Berthella tupala Marcus, 1957, has been reported only rarely, but from greatly separated areas of the Caribbean zoogeographic province. It is known from Sao Paulo and Rio de Janeiro, Brazil (Marcus, 1957); Puerto Rico (Marcus and Marcus, 1970); and the southern tip of Florida, U.S.A. (Marcus and Marcus, 1967). On August 28, 1974, I found one specimen of B. tupala under a rock on the Galeta reef flat, Panama Canal Zone (9° 24’ N; 79° 52’ W). This is the first record of this species from the Caribbean coast of Central America, and represents a range extension of over 1500 km from the closest previously published locality. ANATOMY Externally, the 5-mm specimen matched the coloration pattern described by the Marcuses: yellowish, with a central, white T-shaped marking, and additional white specks scattered over the notum. Shell. The strongly calcified shell was quite prominent, covering almost the entire main body of the slug internally. The nuclear whorl is clearly visible, but lacks the sculpture pat- tern of growth rings and longitudinal lines that are prominent on the rest of the shell (Fig. 1). Irregularities of the sculpturing can be seen to increase in the newer portions of the shell; figure 63 of Marcus (1957) is probably a drawing of these more peripheral regions. Radula. There are three different shapes of teeth in each radular half-row. The outermost laterals are erect, with a smaller accessory cusp - (Marcus, 1957). Central laterals from the middle of the half-row are simple hooks with a long, thin base (Fig. 2). Marcus and Marcus (1967, 1970) have reported that the innermost tooth of each half-row has a basal denticle. Close examination of scanning electron micrographs of the center of the radula (Figs. 38 and 4) of our Panama specimen shows that at least the first three inner lateral teeth have a basal denticle, not just the innermost one. Jaws. Marcus and Marcus (1967) state that the jaw platelets of B tupala have 0-5 denticles on either side of the tip; the specimen I collect- ed in Panama had no denticles. However, of special note, are the developmental stages of the platelets visible in different parts of the jaw. The base and about one-third of the tip above the lateral flanges form first (Fig. 5). In this earliest stage, the tip is not yet free, and terminates in two antero-lateral points separated by a deep concavity. Further growth results in a lengthening of the tip, and a relative straightening of the distal margin (Fig. 6). The final shape of the platelet (Fig. 7) is brought about by additional lengthening in the central portion of the tip, creating the convex, unattached distal tip. ACKNOWLEDGEMENTS I am grateful to Dr. David Meyer and his wife, Kaniaulono, for their kind assistance in ‘ Donner Laboratory and (mailing address): Department of Zoology, University of California, Berkeley, California 94720. Vol. 89(4) THE NAUTILUS 125 the field, and to Mrs. Emily Reid for help with Marcus, Er., and Ey. Marcus. 1970. Opistho- preparing the illustrations. My research in branchs from Curacao and faunistically re- Panama was supported by a fellowship from lated regions. Stud. Fauna Cur. Carib. Isl. the Smithsonian Tropical Research Institute. 33: 1-129. : Marcus, Ev., and Er. Marcus. 1967. American LINEAR CIES Opisthobranch Mollusks. Stud. Trop. Ocean- Marcus, Er. 1957. On Opisthobranchia from ogr, Miami 6: viii + 256 pp. Brazil (2). Jour. Linn. Soc. Lond., Zool. 43: 390-486. AKRRVARRE? ARAARARDA, VAAAAAAR FIGS. 1-4. Scanning electron micrographs of the shell and radular teeth of Berthella tupala. FIG. 1. Embryonic whorl of shell, 78X. FIG. 2. Teeth from middle of half-row, 470X. FIG. 3. Innermost lateral teeth, 470X. FIG. 4. Accessory denticle on innermost lateral teeth, 1565 X. 126 THE NAUTILUS October, 1975 Vol. 89(4) FIGS. 5-7. Three areas from jaw platelets of Berthella tupala, showing developmental stages; all scanning electron micrographs, 720 X. INDEX TO AMU BULLETINS An index to the Annual Reports and Bulletins of the American Malacological Union from 1932 through 1973 (39 volumes) will be published in early 1976. This valuable collection of authors, titles and taxa was assembled by Margaret C. Teskey. 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