JANUARY 27, 1977 THE NAUTILUS Vol. 91 No. 1 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-0M8 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. Aurele 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. Donald R. Moore Division of Marine Geology School of Marine and Atmospheric Science 10 Rickenbacker Causeway Miami, Florida 33149 Dr. Joseph Rosewater Division of MoUusks 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 duseum of Zoology /he 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 1 0 Rickenbacker Causeway Miami, Florida 33149 Dr. Charles B. Wurtz 3220 Penn Street Philadelphia, Pennsylvania 19129 KDITOR-IN-CHIEF Dr. R. Tucker Abbott Delaware Museum of Natural History Box 3937, GreenvUle, Delaware 19807 Mrs. Horace B. Baker Business and Subscription Manager 1 1 Chelten Road Havertown, Pennsylvania 1 9083 OFFICE OF PUBLICATION Delaware Museum of Natural History Kennctt Pike, Route 52 Box 3937, Greenville, Delaware 19807 Second Class Postage paid at Wilmington, Delaware Sut)scrlptlon Price: $7.00 (see inside back cover) THE NAUTILUS Volume 91, Number 1— January 27, 1977 CONTENTS Raymond W. Neck Geographical Range of Praticolla griseola (Polygyridae, Correction and Analysis 1 David Nicol Geographic Relationship of Benthic Marine Molluscs of Florida 4 William F. Gale Growth of the Fingernail Clam, Sphaerium transversum (Say) in the Field and Laboratory Experiments 8 Eileen H. Jokinen The Formation and Structure of the Shell Varix in Stagnicola elodes (Say) (Gastropoda: Lymnaeidae) 13 WiUiam H. Gilbert and Ellen F. Suchow Predation by Winter Flounder (Psevdopleuronectes amerkanus) on the Siphons of the Clam, Tellina agilis 16 Dee S. Dundee and Anna Paine Ecology of the Snail, Melanoides tuberculata (Miiller), Intermediate Host of the Human Liver Fluke (Opisthorrhiii sinerms) in New Orleans, Louisiana 17 Joseph C. Britton and Clifford E. Murphy New Records and Ex;ological Notes for Corincvla manilensis in Texas 20 Elizabeth V. Gardo Opisthobranchs Found Off Little Egg Inlet, New Jersey, with Notes on Three Species New to the State 23 William G. Lyons Notes on Occurence of Eupleura sulcidentata Dall (Gastropoda: Muricidae) 28 Henk K. Mienis North American Land Snails in Israel 30 S. K. Raut and K. C. Ghose Effect of Upwardly-directed Shell Aperture on the Aestivating Land Snail, Achatina fuiica 31 Ralph W. Taylor and Clement L. Counts, III The Asiatic Clam, Corbicula manilensis, as a Food of the Northern Racoon, Procyon lotor 34 Obituary of Allyn Goodwin Smith (1893-1976) 37 Publications received 7 Book review: (of) S. van der Spoel 36 STATEMENT OF OWNERSHIP, MANAGEMENT AND CIR- CULATION (Required by) Act of October 23, 1962: Section 4396 Title 39. United States Code, and postal regulation 132-622. 1. 2. a 4. Titleof publication: THE NAUTILUS Date of filing, September 25, 1976. Frequency of Issue: Quarterly (4 per year). Location of known office of publication: Delaware Museum of Natural History. Kennett Pike, Box 3937, Greenville, De. 19807. Location of the Headquarters of General Business Offices of the Publishers: Delaware Museum of Natural History, Kennett Pike, Box 3937, Greenville, De 19807. 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 editor, none. Owner: Mrs. Horace Burrington Baker, 11 Chelten Rd., Havertown, Pa. 19803. Known bondholders, mortgages, and other security C. D. E. F. holders owning or holding 1 percent or more of total amount of bonds, mortgages or other securities: none. Extent and Nature of Circulation: Total No. copies Printed (Net Press) Paid Circulation 1. Sales through dealers and car- riers, street vendors and counter sales 2. Mail subscriptions Total Paid Circulation Free Distribution (including samples) by mail carrier or other means Total Distribution (Sum of C&D) Office use, left-over, unaccounted and back start subscription copies Total (Sum of E&F)-should equal net press run shown in A. I certify that the statements made by me above are correct and com- plete, (signed) R. Tucker Abbot. Editor Average Single 12 Mos Issue 1,000 1.000 none none 645 632 645 632 14 14 659 646 341 EDITORIAL 341 1,000 1,000 Rapid publication of research papers is now possible, usually within two or three months of submission of the manuscript, providing the author pays page charges (.$30.00 per page). This priority does not in any way delay the papers of other authors, since articles with paid page charges merely increase the normal size of an issue. LIVING MARINE MOLLUSCS C. M. Yonge and T. E. Thompson BEHAVIOUR Two distinguished British marine biologists have combined their knowledge and talents to produce a compact, well-rounded account of the largest marine group of animals. "The first modem book on the biology of marine moUusks that is of textbook quality, yet so beautifully written and illustrated that the legions of amateur conchologists will readily absorb its wealth of information"—/?. Tucker Abbott, Ph.D. Send check or money order to: American Mulacologistx, Puhl. P.O. Box 4208 Greenville, De. 19807 U.S.A. Available March 1977 Clothbound, 288 pp., 162 text figures, 16 plates with 18 glorious color photographs of living marine molluscs. Only $13.9.5. Vol. 91(1) January 27, 1977 THE NAUTILUS 1 GEOGRAPHICAL RANGE OF PRATICOLELLA GRISEOLA (POLYGYRIDAE) CORRECTION AND ANALYSIS Raymond W. Neck Texas Parks & Wildlife Department John H. Reagan Office Bldg. Austin, Texas 78701 ABSTRACT The geographical range of Praticolella griseola (Pfeiffer) in Texas and Mexico is discussed; erroneous but published collecting sites are discussed. The climatic causes of the discontinuity of geographic range of the species are discussed. Three species of Praticolella von Martens (Polygyridae) occur in Texas: pachyloma (Menke), berlandieriana (Moricand) and griseola (Pfeiffer). Early records placed griseola over much of southern and central Texas; these records were later corrected only to be subsequently republished. In light of the reoccurrence of this misinformation, all literature records are reconsidered and the geographical range of griseola is re-evaluated. Mexican and Central American records of this species are also discussed. Confusion of the range of griseola is no doubt due to a lack of definite phenotypic breaking points between griseola and berlandieriana even though the classic types are quite different. Some workers have felt that these two species definite- ly blend together (von Martens 1892; Singley 1893) while others such as Pilsbry (1940:695) felt that there were "no common links" between them. Genitalia of berlandieriana and griseola are similar but distinguishable (Webb 1967). A definitive solution to the taxonomic problem wall be difficult to obtain and may be impossible due to contemporary habitat destruction. Adding to the complexity is the possibility of hybridization involving all three species in southern Texas (Hubricht 1961; in Cheatum and Fullington 1971). The first published records of P. griseola that I have found are those of Binney (1885:394) for Calhoun (at Indianola) and Bosque Counties. Townsend (1897) reported it on the "lower Rio Grande." Pilsbry (1940:690-692) completely dis- counted the Bosque County record and doubted the Indianola record. P. griseola is native in neither county. Pilsbry gave the range of griseola as "environs of Brownsville" which is in Cameron County. In the first synthesis of Texas molluscan records, J. A. Singley (1893) reported griseola from the following counties: Caldwell, Cameron, Duval, Gillespie, Goliad, Gonzales, Kendall, Milam (from Askew); Lampasas (from Mrs. Sinks); Williamson (from Walker); Bexar, Comal, Hays, Travis (Strecker's personal records). In the next compilation of Texas snail records, J. K. Strecker (1935) reported specimens in his collection from Cameron and Hidalgo Counties. He stated that "all other counties Singley men- tions for P. griseola are no doubt based on P. berlandienana" except Duval County. No reason was given for acceptance of the Duval County record. The latest compilation of Texas polygyrid snail records (Cheatum & Fullington 1971) re-publishes the suspect records of Singley with no mention of the intervening correction by Strecker. No men- tion is made, however, of the records of Binney. Significantly, all post-Singley records listed by Cheatum and Fullington come from Cameron and Hidalgo Counties in south Texas along the Rio Grande River. Thus, we are left with positive records for only two counties for griseola in Texas. Personal col- lecting in most of the central Texas counties has revealed no populations of griseola. I have per- sonal records from Brownsville (southern Cameron County) and Laguna Atascosa Wildlife Refuge (northeastern Cameron County). Webb 2 THE NAUTILUS January 27, 1977 Vol. HI (1) (1967) worked with griseola collected at Harl- ingen (central Cameron County) by J. Campbell. Such a restricted Texas range for land snails is not unique, as Euglandina texasiana (Pfeiffer) and Thiisdiinphiira plaginpt i)cha (Shuttlewnrth) exhibit similar distributions. These snails in Texas are restricted to soils of the modem delta of the Rio Grande River which includes southern and eastern Hidalgo County, all of Cameron County and most of Willacy County. Shells of griseola have not yet been repwrted from Willacy County although the Laguna Atascosa locality is no more than thirteen kilometers from the Cameron-Willacy county line. Shells collected by Ideker in Willacy County in 1974 included no definite griseola shells although some berlan- dieriana shells from this area may indicate in- trogression with griseola. Populations of gyiseola are to be expected in southern Willacy County. The south Texas populations of g-riseola are isolated from Mexican populations (except for those in the southern Rio Grande delta) which oc- cur no further north than the Tampico area at the border between Vera Cruz and Tamaulipas. Other populations occur at scattered localities in north- ern Yucatan, Guatemala and Nicaragua (Rehder 1966). Other populations have resulted from introduc- tions. McLellan (19.50) reported griseola (could it have been berlandieriana?) to be abundant in his yard and adjacent lots in Bellaire, Harris County, Texas. Other adventive populations include Cuba (probably from Vera Cruz) and Key West, possibly from Cuba (Pilsbry 1940:642). The disjunction of populations of griseola is similar to the dry lowland tropical Gulf Arc distribution as exhibited by several species of reptiles and amphibians (Martin 1958:92-94). Herptile migration between these areas may have occurred via a dry corridor through presently wet tropical woodland areas at some time in the Pleistocene. The occurrence of the Texas popula- tions of griseola indicates a northward extension of its normal range. At some time in the recent past grifiPola apparently existed over large areas of coastal Central America, Mexico and (at least southern) Texas. Environmental change may have resulted in widespread extinction of griseola, with survival occurring only in a few scattered refugia. The restriction of griseola in Texas to the relatively mesic deltaic soils of the Rio Grande River in- dicates that increased aridity was the en- vironmental factor involved. The area between the Rio Grande delta and the Panuco River floodplain (Tampico area) contains only one significant drainage system. The floodplain of the Rio Soto La Marina in Tamaulipas should be ex- amined for populations of griseola. Although the entire area is arid, these rivers provide suitable moisture as a result of periodic flooding. The decline of griseola may have been accompanied by an expansion of berlandieriana, as the latter species occurs (possibly sparingly) in the area between the Rio Grande River and Rio Soto La Marina (Rehder 1966). A similar range disjunc- tion in northeastern Mexico is exhibited by the Texas pocket gopher (Selander et al. 1962). The second break is apparently not due to aridity. On the contrary, the break below Vera Cruz may result from excess moisture in the humid forest of the Campeche Lowlands. This area exhibits higher temperature, rainfall and humidity levels than either bordering area which contains griseola (Vivo E. 1964), Competition from tropical snail species specifically adapted to warm, moist habitats may exclude griseola. Much additional field work on geographic and habitat distribution of griseola is needed before a definitive answer to the reasons for range fragmentation and existence of particular refugia. It is difficult at best to correlate the distributions of organisms with compilations of environmental data from the literature. The refugia of griseola apparently represent areas of varied vegetation, geological and climatic regimes (Leopold 1950; Wagner 1964; West 1964; Vivo E. 1964). Alter- nate wet-dry cycles could be important because Webb (1967) indicated such conditions were necessary for the culture of both griseola and berlandieriana. Fragmentation of the species range of griseola would be favorable for genetic differentiation be- tween refugia. This has, apparently, occurred as Rehder (1966) reported "P. griseola consists of a number of more or less well-characterized races" which he based on shell characters. Vol. 91(1) January 27, 1977 THE NAUTILUS 3 One additional factor may be involved in the spotty distribution of griseola. A number of workers have suggested that griseola is not native to Yucatan and Guatemala (Bequaert & Clench 1936; Harry 1950). All Guatemalan material (see Goodrich & van der Schalie 1957) was probably collected within a 20 km radius of each other ac- cording to Harry (1950); furthermore all Yucatan material collected by Harry (1950) definitely was from such a small area. These two centers of distribution are about 500 km apart. In these areas griseola is found exclusively in sites with orchards, railroad embankments, urban areas and savannahs managed for cattle grazing (see Be- quaert & Clench 1933; Goodrich & van der Schalie 1937). Basch (1959) did not find griseola in Tikal National Park, Guatemala. Other workers failed to find griseola when collecting in various parts of Guatemala and the Yucatan (Hinkley 1920: Pilsbry 1891; van der Schalie 1940). Stating that griseola is a species of open, rather than forested areas, Branson & McCoy (1963) felt that "man may augment the distribution of this form by his clearing activities, rather than ac- tually transporting it to new localities." Time and source of these putative introduc- tions into these southern areas are unknown. The existence of noticeable phenotypic types or "races" in the various areas of occurrence in- dicates the possibility of early introduction (pre-Conquest). Mayan and pre-Mayan set- tlements have existed in this area for centuries. Introduction of a limited stock (founder effect) and/or natural selection for individuals better adapted to local conditions would result in such genetic differentiation. The most likely source would be the Tampico-Vera Cruz populations, simply because of its close proximity. Branson & McCoy (1965) reported that specimens from Campeche were intermediate between Yucatan and Guatemalan material but closer to the Guatemalan specimens. The possibility of these populations being in- troduced to southern Texas is a strong possibility. Although almost all areas of the southern tip of Texas have been cleared or overgrazed at some time in the past century, griseola does not appear to be particularly associated with human impact areas. One would not expect a snail from tropical Mexico to flourish in natural habitats of sub- tropical Texas. Frosts occur in most years and hard freezes are not unkown. Additionally, long periods of dryness accompanied by high temper- atures are common in this area. A number of foreign snails have become established in this area (Neck, R. W. 1976). These snails, however, are generally restricted to human -associated sites. LITERATURE CITED Basch. P. F. 19.59. Land molluscs of the Tikal National Park. Guatemala. Mas. Zoot. Univ. Mich. Occ. Pap. 612: 1.5 pp. Bequaert, J. C. and W. J. Clench. 19,33. The non-marine mollusks of Yucatan. Carnegie Inst. Wash. Pub. 431:525-545. Bequaert, J. C. and W. J. Clench. 1936. A second contribution to the moUuscan fauna of Yucatan. Carnegie Inst. Wash. Pub. 457:61-75. Binney, W. G. 1885. A manual of American land snails. Bidl. U.S.N.M.2S:52Spp. Branson. B. A. and C. J. McCoy. 1963. Gastropoda of the 1961 University of Colorado Museum expedition in Mexico. The NautUus'76:Wl-im. Branson, B. A. and C. J. McCoy. 1965. Gastropoda of the 1962 University of Colorado Museum expedition in Mexico. Univ. Colo. Stud. Ser. Biol. 13:16 pp. Cheatum, E. P. and R. W. Fullington. 1971. The Recent and Pleistocene members of the gastropod family Polygyridae in Texas. Bull. Dallas Mus. Nat. Hist. 1(1):74 pp. Goodrich, C. and H. van der Schalie. 1937. Mollusca of Peten and North Alta Vera Paz, Guatemala. Univ. Mich. Mus. Zool. Misc. Pubt. 34:.50 pp. Harry. H. W. 1950. Studies on the nonmarine mollusca of Yucatan. Mus. Zool. Univ. Mich. Occ. Pap. 524:34 pp. Hinkley. A. A. 1920. Guatemala mollusca. The Nautilus 34:.37-.55. Hubricht, L. 1961. Eight new species of land snails from the southern United States. The Nautilus 75:26-32. 60-63. Leopold. A. S. 1950. Vegetation zones of Mexico. Ecology 32:.507-518. von Martens, E. 1892. Land and fresh-water molluscs. Bioldgia Centrali-Americana. 708 pp. Martin. P. S. 1958. A biogeography of reptiles and amphibians in the Gomez Farias region, Tamaulipas, Mexico. Mus. Zool. Utiiv. Mich. Misc. Pub. 101:102 pp. McClellan. J. H. 1950. Texas snails. The Nautilus 64:41. Neck, R. W. 1976. Adventive land snails in the Brownsville. Texas aLTea.Southwestem Nai uralist 21: 133-135. Pilsbry, H. A. 1891. Land and fresh-water mollusks collected in Yucatan and Mexico. Pr(x. Adad. Nat. Sci. Phil, for 1891:310-334. Pilsbry, H. A. 1940. Land mollusca of North America (north of Mexico). Monoy. Acad. Nat. Sci. Phil. (3): vol. 1, pt. 2. 4 THE NAUTILUS January 27, 1977 Vol. 91(1) Rehder, H. A. 1966. TTie non-marine molluscs of Quintana Roo, Mexico, with the description of a new species of IMfmaeus (Pu!monata:Buiimulidae). /Vw. BioL Soc. Wash. 79:27.3-296. van der Schalie. H. 1940. Notes on mollusca from Alta Vera Paz, Guatemala. Mxis. Zool. Univ. Mich. Orr. Pap. 413:11 pp. Selander. R. K.. R. F. .Johnston, B. .J. Wilks and G. G. Raun. 1962. Vertebrates from the barrier islands of Tamaulipas. Mexico. Univ. Kan. Pub. Mus. Nat. Huit. 12:309-.34.5. Singley, J. A. 189.3. A preliminar>' list of the land. fresh-water, and marine mollusca of Texas. Fourth Annual Rep. Geol. Survey Tex. (1892), Contri. Nat. Hist. Tex. Part 1:299-34.3. Strecker, .J. K. .Jr. 193.5. Land and fresh-water snails of Texas. Trans. Tex. Acad. Sci. 17:4-44. Townsend, C. H. T. 1897. On the biogeography of Mexico and the southwestern United States. II. Thins. Tex. Acad. Sd. 2(1): 33-86. Vivo E., J. A. 1964. Weather and climate of Mexico and Cen- tral .America. In Natural environment and early cultures (R. C. West. ed.). Handbook of Middle American Indians 1:187-21.5. Wagner, P. L. 1964. Natural vegetation of Middle America. In Natural environment and early cultures (R. C. West, ed.). Handbook of Middle American htdians 1:216-264. Webb, G. R. 1967. Erotology of three species of Pratieolella, and ofPolygifra pustula. The Nautilus 80:133-140; 81:11-18. West. R. C. 196^1. Surface configuration and asscx-iated geology of Middle America. In Natural environment and early cultures (R. C. West, ed.). Handbook ' and Entomology, Iowa State University, who directed the research and made many helpful suggestions concerning the manuscript. were conducted in a field laboratory above Ft. Madison, Iowa (about 200 m upstream from the Ft. Madison/Niota bridge). Water pumped from near the river channel into the laboratory kept temperatures and chemical conditions similar to those in the river and provided clams with food. Clams were housed in individual plexiglass rearing chambers, 3.8 cm square and 5.0 cm deep inside (Fig. 1, A); the upper 3.3 cm of the chambers were covered on two sides with plastic screen (mesh with 12 openings/cm) for water passage. A set of nine rearing chambers was placed in each of nine painted plywood compart- ments (Fig. 1, B). A 5-cm baffle kept water levels about 6 mm below the top of the rearing chambers. Clams could not escape or move be- tween chambers without crawling out of the water. Each rearing chamber contained about 10 cc of strained clayey silt from the river bottom where experimental clams were collected. Water in the chambers was initially 3.5 cm deep but decreased to about 2.5 cm as chambers silted in. Compart- ments holding the chambers had a maximum flush rate of 6 minutes; fluctuating pump discharge and partial clogging of distribution tub- ing reduced flushing rate. Vol. 91(1) January 27, 1977 THE NAUTILUS 9 ^L ^9,C. 41 CM (" (' r' r' r' r' r' SCREEN ^ PLEXIGLASS STRIP 4CM I-4CMH ^BAFFLE B 42 CM X- ■^ t + + FLOW 2ICM -SPLASH BOARD FIG. 1. Rearing apparatus. A, set of nine rearing chambers (side view). B, compartment ivith rearing chambers in place (top view). TABLE 1. Reproduction and growth o/S. transversum in chambers in the laboratory between 21 July and 23 August. 1967. and numbers present on November 7.5. One large (over 10.0 mm long), two medium (4.0-6.0 mm long) or four small (newborn) clams were randomly assigned to each chamber; each compartment had three chambers of clams of each size group (chamber identification numbers were adjusted for presentation in Table 1). Large and medium-sized clams were collected in the river, but small clams were born in the laboratory. Small clams were removed with camel-hair brushes (Thomas, 1959) within an hour after their birth in pans of river water and measured with an ocular micrometer. Larger clams were measured with a vernier caliper; damaged clams were discarded. Similar sized clams were used as chambermates so that mark- ing was unnecessary and handling was minimized. The laboratory growth experiment began July 21, 1967; after 33 days, 3 units were removed, the 27 chambers cleaned, and the contents screened. Clams were measured as before and living ones returned to their respective chambers (Table 1) with fresh substrates. To measure clam growth in the field, two re- tainers with 80 clams each were submerged in the river on July 6. One retainer was put in a sheltered cove adjacent to emergent and July 21 August 23 November 15 Chamber No- per chamber Length mm No, Dead No. broken in handling No, with no growth Lengths of those which grew (mm) Young No Length Numbers Livinp Dead (mm) 1-6,9 4 1.7-2.2 .3 3 19 27 3.4 5.7 2.8 4.3 3.0 5.3 0 - 100 22 7 4 2.0-2..3 0 1 0 5.1 6.0 8.1 2 1.4 13 9 8 4 2.0-2.,3 0 0 0 3.0 6.5 3.4 4.9 1 1.8 22 7 10-18 2 4.9-5.7 6 0 0 6.0 6.5 6.9 7.5 6.2 6.6 7.0 8.1 6.2 6.8 7.2 9.0 76 1.6-6.0 170 65 19-27 1 10.2-12.1 9 - - — 53 1.6-9.0 237 .32 Chambers 7 and 8 were treated the same as 1-6 and 9, but are listed separately since the clams showed reproduction and more growth. The clams with shells broken in handling on August 23 had not grown, nor had the dead clams in 1-6 or 19-27, but five in 10-18 had grown 0.1 to 2.6 mm and one showed no growth. 10 THE NAUTILUS January 27, 1977 Vol. 91 (1) submergent vegetation (transect 5 station 2 of Gale, 1969, p. 11) where there were less than 1,000 clams/m^; the other was placed in open water (transect 4 station 14 of Gale, 1969, p. 11) where there were about 42,000 clams/m^ Each retainer (Fig. 2, A) held 40 rearing tubes (Fig. 2, B) suspended through holes in a plex- iglass plate by aluminum rods. Rearing tubes were 7 to 8 cm lengths of polyvinylchloride pipe (I.D. 2.5 cm) with plastic screen attached near the bottom: a painted wooden disk closed the lower end of the screen. A tube like that in Figure 2, C could be constructed and cleaned more easily. Two randomly selected clams 5-7 mm long and 10 cc of strained clayey silt from station 14 were placed into each tube. The retainer was then forced into the river bottom until the two plex- iglass flanges on the sides halted penetration with the rearing tubes just above the substrate. The retainer at station 2 was removed on September 6. It had been turned over and many tubes nearly filled wath mud. Tube contents were screened and the clams counted and preserved in PLASTIC TUBE PLEXIGLASS PLATE FIG. 2. Rearing apparatus used in maintaining S. transver- sum in the field. A, clam retaining apparatus: B, enlarged side view of a rearing tube used in 1967: C, rearing tube with alterations. 10% buffered formalin. Buoys marking the re- tainer at station 14 disappeared by September, and the retainer was lost. RESULTS Clam Growth in the Laboratory Although the nine large clams stocked in chambers 19-27 died shortly after the experi- ment started, 53 young, 1.6-9.0 mm long (Table 1), were produced (some may have been second generation offspring). In only 33 days, or less, one of the offspring had grown approx- imately 7.0 mm in length (newborn clams in Pool 19 average 2.2 mm long) (Gale, 1969) to near maximum size.(S. transversum usually do not exceed 12.0 mm in Pool 19, but clams up to 15.9 mm long and 8.1 mm thick were found.) Reproduction in chambers 7 and 8, where newborn clams had been stocked, demonstrated that S. transversum not only could grow large in a month but could complete its life cycle as well. Many newborn clams, stocked in chambers 1-9, had not grown by August 23 (Table 1) and some of them did not move for several minutes after removal from their chambers; some seemed dor- mant (in a resting state). The periostraca of the nongrowing clams were discolored and chalky. Most of the 12 medium-sized clams that sur- vived in chambers 10-18 grew slowly with a mean length increase of 1.3 mm. Clam growth in chamber 12 was not determined because five clams exceeded the initial size of parental stock and offspring and parents could not be distinguished. In most instances, offspring of the medium-sized clams grew rapidly and one was 9.0 mm long. By November 15, when the chambers were reexamined, reproduction had occurred in all but two of the 27 chambers. Reproduction was max- imum in chambers where one large clam had originally been stocked (19-27) and one clam left 79 descendants. Many of the clams that seemed dormant in August (chambers 1-9) had grovm to 9.0 mm or longer (Fig. 3). Most of the clams stocked in chambers 10-18 had died without reaching 9.0 mm, and many were smaller than their offspring. Because observations of growth in chambers 28-81 did little more than confirm Vol. 91(1) January 27, 1977 THE NAUTILUS 11 observations in chambers 1-27, precise data were not collected. In November the periostraca of nearly all clams longer than 2.5 mm were speckled with dark deposits and some were nearly black. S transversum usually seems very clean, and it is not known why deposits had accumulated on the clams. Clam Growth in Field Experiments Clams grew well in the rearing tubes at station 2, and after 62 days, 45 were 4.0 mm or more thick; the largest was 13.8 mm long and 6.6 mm thick. Clams in the tubes were larger than those living at station 14, the collection site (over 5,000 clams were examined there in mid-September but none was 4.0 mm thick). That four clams in each of 2 tubes were over 5.0 mm thick means that within 62 days, one or both stocked clams grew to maturity and discharged young that also had grown large. Clams in the tubes contained many embryos and one large individual that seemed to have given birth to 35 young (its chambermate had died before reaching reproductive size) contained 86 embryos. A few of the 35 young may have been second generation offspring. A specimen of Sphaerium striatinum, placed into a tube by mistake, had growm to a thickness of over 4.0 mm but had not given birth. Clams in 21 tubes were dead, perhaps from senility, leech predation, or other causes (Gale, 1973). One live clam had a fungal growth nearly covering outer portions of the inner gill; embr>'os in the gill seemed unaffected. DISCUSSION In laboratory and field experiments, S. transversum grew extremely fast and completed its life cycle in about a month or less. Rapid grow1;h has been noted for some other species of Sphaerium. Sphaerium partumeium grew large in 7 to 10 weeks in laboratory experiments (Thomas, 1965) and gave birth when less than 14 weeks old; clams grew even faster in the field. S. par- tumeium (as M. partumeium) reared by Krull (1936) grew to 4.5 to 5.0 mm long in about two months and gave birth. Sphaerium corneum, Sphaerium rivicola, and Sphaerium solidum JUL. AUG ' NOV. FIG. 3. Length changes in small and medium-sized S. transversum in the laboratory, 1967. suspended in baskets in the Elbe River grew rapidly (Thiel, 1928, 1930), and some S corneum. born in early summer, matured, gave birth, and died that autumn. If S. transversum in the natural environment grew as rapidly as those in laboratory and field experiments, several generations could be pro- duced annually. At station 14, however, medium- sized clams seemed to have grown only 2 mm longer in July and 3 mm in August (Gale, 1972), considerably less than those in growth ex- periments. Clam grovrth may have been hindered at station 14 by high clam density. Also, the clams were probably debilitated by high infesta- tions of larval trematodes (Gale, 1973). Although clam growth rates in the laboratory and at station 2 were similar, clams grew much larger at station 2. Because parental stock of both groups came from the same site and presumably from the same genetic stock, some factor or fac- 12 THE NAUTILUS January 27, 1977 Vol. 91(1) tors in the laboratory seem to have stunted the clams. Clams at some sites in the river did not reach ma.ximum size either. Thiel (1928) observed that 5. comeum in the Elbe River did not grow to maximum size in "overpopulated" areas. The fact that some medium-sized S. transvermm. which did not grow much during the first :33 days of the laboratory experiment, remained smaller than their offspring in November (Fig. 3), sug- gests that, once growth is arrested or retarded, it is not completely compensated for later, when growth conditions become favorable. Why some clams had initial growth lags and their chambermates did not is not clear, but delayed growth does not seem to have been genetically controlled (Gale, 1972). Delayed growth may involve metabolic slowdown that enables clams to bury themselves deep in the substrate to escape predation, parasitism, or un- favorable water conditions (Gale. 1973). In tem- porary ponds in Michigan, Kenk (1949) found that only fairly young Sphaerium ocddentale and S. partumemm (as S. truncatum) survived the dry period. It is sometimes pointed out that fast growth is of great advantage to inhabitants (such as some fingernail clams) of temporary ponds, because they can take advantage of a short growing period. One might conclude that, through evolu- tion and natural selection, the advantage of being able to survive short growing periods has pro- duced clams with tremendous growth rates. But, the fact that S. transversum grows rapidly but does not often inhabit temporary ponds, suggests that other factors produced rapid growth. This rapid growth may be a form of preadaptation. That S. transversum may have originated in tem- porary ponds and then moved to other habitats merits consideration. But, regardless of why S. transversum grows rapidly, the fact that it can complete its life cycle in about a month may be a major factor in its success in Pool 19, where predation pressures are great. If a population is to sustain itself under heavy predation, quick growth and reproduction would be advantageous, if not essential, for the shorter the prereproductive period, the greater the probability an organism has of reproducing before being consumed. LITERATURE CITED Gale. W. F. 1969. Bottom fauna of Pool 19, Mississippi River with emphasis on the life history of the fingernail clam, Sphaerium transversnm. Ph.D. thesis. Iowa State Univ., Ames. Univ. Microfilm No. 69-20642. Ann Arbor. Mich. Gale, W. F. 1972. Seasonal variability in calyculism in Sphaerium transversum (Say). The Nautilits S6: 20-22. Gale. W. F. 1973. Predation and parasitism as factors affecting Sphaerium transversum (Say) populations in Pool 19, Mississippi River. Res. Popul. Ecol. 14: 169-187. Kenk. R. 1949. The animal life of temporary and permanent ponds in Southern Michigan. Misc. Publ Mus. Zioi. Univ. Mich. 71: ,5-66. Krull. W. H. 19136. Raising Musculium partumeium (Say) under laboratory conditions. Papers Mich. Acad. Sci. Arts, ami Letters 21: ^35-638. Thiel. M. E. 1928. Zur Biologie unserer Siisswasser-muscheln. Z Mnrphol Okol. Tiere 13: 65-116. Thiel. M. E. 1930. Untersuchungen liber den Einflti-ss der Ab- wasser von Hamburg-Altona auf die Verbreitung der Arten der Gattung Sphaerium in der Elbe bei Hamburg. Int. Rev. gesam. Hydrobiol. Hydrogr. 24: 467-484. Thomas. G. J. 19.59. Self-fertilization and production of young in a sphaeriid clam. The Nautilus 72: 131-140. Thomas. G. J. 1965. Growth in one species of sphaeriid clam. The Nautilus 79: 47-54. Thompson. .1. D. 1973. Feeding ecology of diving ducks on Keiikuk Pool. Mississippi River. Jmir. Wikil. Manage. 37: :i67-:3Kl. Vol. 91(1) January 27, 1977 THE NAUTILUS 13 THE FORMATION AND STRUCTURE OF THE SHELL VARIX IN STAGNICOLA ELODES (SAY) (GASTROPODA: LYMNAEIDAE) Eileen H. Jokinen Biology Department Suffolk University Boston, MA. 02114 ABSTRACT A life history study carried out in 1970-71 on a population of Stagnicola elodes in a temporary pond in lower Michigan reveals that a varix is laid damn at the cessation of a period of shell growth which may or may not be followed by a period of dormancy. The adult snails of the Michigan population have 2 varices, one deposited before estivation of the juvenile snail, the other deposited after adult spring growth. It appears that the number of varices cannot be used to estimate the age of the snails unless the annual life cycle and environmental conditions are examined. The microstructure of the varix was determined by microscopic examination of acetate peels of shell sections made at right angles to the varix. The varix is fonned from greatly elongated (.5-6X normal) crystals of the prismatic layer. The probable function of the varix is to add strength to the outer lip. INTRODUCTION The freshwater snail Stagnicola elodes (Say) periodically puts down additional shell material, the varix (Baker, 1911), on the inside of the outer lip. In S. elodes the varix is purple-brown in col- or and parallels the outer lip. In Baker's opinion, varices, normally three in number in Lymnaea palustris ( = S. elodes), mark periods of "hiberna- tion" when the animal is "buried in mud" and do not represent annual growth mark- ings. However, Baker was not positive of this in- terpretation. DeWitt (1954) reports that when "growth in Physa gyrina is interrupted for some reason, the inner edge of the outer lip of the aperture is strengthened by a triangular thickened band . . . Conditions which arrest growth and lead to for- mation of these bands are obscure; production does not appear to be dependent upon en- vironmental factors, rather they are a result of a physiological pattern developed within the species and perhaps modified to some extent by environ- ment." DeWitt states that the bands might be ac- counted for in terms of periodic drying of the habitat but felt it unlikely that such a thickening would be produced under adverse conditions of drought or estivation. Herrmann & Harman (1975) believe that varices in Helisoma anceps (Menke) reflect slow winter growth. FIELD OBSERVATIONS During 1970-71 a study was carried out on the life history of a population of Stagnicola elodes (Say) in a woodland pond in the Pontiac Lake Recreation Area, Oakland County, Michigan. The annual life cycle begins in May when eggs are laid. Egg laying continues through July. The new- ly hatched generation feeds until the snails reach 2-7 mm in length. At this point the young cease growth and actively leave the water to estivate on grasses and tree trunks above ground. The ma- jority of the older snails follow the receding pond water to become stranded on the dry pond floor and there be preyed upon, most commonly by sciomyzid (Diptera) larvae. The young estivating snails eventually leave their above-ground loca- tions and come to lie under the pond leaf litter to 14 THE NAUTILUS January 27, 1977 Vol. 91(1) over-winter. TTie immature snails (mean shell length = 8 mm) become active in the spring as soon as the ice melts. The snails grow rapidly so that by June the mean shell length is approx- imately 15mm (Jokinen, in prep.). The snails of the Michigan population of S. elodes were noted to deposit several varices dur- ing their life times. In 1970, varices on the outer lips were first noted on July 12 on 4 snails (shell lengths from 10.3 to 21.7 mm) out of 123 (3.3%). Egg masses were in evidence by this date. By Ju- ly 26, 13 out of 121 snails (10.7%) had varices. On August 9, estivating immature snails were first observed and noted to have varices (100%). In 1971, 5 snails were collected from under the ice in February and March. The snails ranged from 3.7 mm to 11.8 mm and all 5 had varices on their outer lips. On April 20, 1971, 34 snails were col- lected. The winter varix was evident on all of the snails, and 32 had new, fragile, and thin shell growth beyond the varix. The mean linear incre- ment of new growth beyond the varix was 1.5 mm (range .2-3.5 mm). Shell growth was rapid during May and egg masses appeared by the end of the month. By June 6, the entire sample population of 153 snails (except one) had deposited new varices. MICROSCOPIC STRUCTURE OF THE VARIX In order to determine the structure of the varix of S elodes, a portion of shell was cut at right angles to the aperture, so that the section was at right angles to the length of the varix (Figure 1). Acetate peels were made from polished shell sections following the method of Boardman & Utgaard (1964). a: PLANE OF FIGURE 2 VARIX FIG. 1. Locaticn of the varix in Stagnicola elodes (Say). FIG. 2A. Acetate peel of a polished shell section cut at right angles to the varix. The normal shell iMth i's demonstrated in the tipper portion of the photograph. The thicker portion is the varix. p., peroist racum : 1.1., longitudinal lamellar layer; c.1.1, first crossed lamellar layer; c.1.2, second crossed lamellar layer; pr., prisniatie layer. FIG. 2B. 7.5X magnification of the area between the arrows of A. There are two layers of periastracum and a space beneath the periostracum. p., periosiranim ; I.I., longitudinaJ lamellar layer; c.1.1, first crossed lamellar layer; pr. prismatk layer. (?50x total magnificatian). According to Boggild (1950), the calcareous por- tion of the shell of Stagnicola pitluxtriit (= S. elodes) is composed of aragonite deposited in four distinct layers. The shells of S. elodes from Michigan were examined and found to also possess four calcareous layers arranged as follows: (1) a very thin outer longitudinal lamellar layer under the periostracum; (2) a crossed lamellar layer; (3) a prismatic layer; and (4) a second crossed lamellar layer (Figure 2). As illustrated, the varix is formed by an increase in the length of the crystals of the prismatic layer. The crystals are approximately 5-6 times as long Vol. 91(1) January 27, 1977 THE NAUTILUS 15 in the varix as in the normal shell. Gross ex- amination of a ground section demonstrates that the purple-brown color of the varix is due to streaks of pigment laid down in the thickened prismatic layer. The thickened outer lip of mature Helix IThebnl pisana MUller is also formed by elongated prismatic crystals (Matthes, 1914). CONCLUSIONS Field evidence shows the pattern of varix deposition to be associated with cessation of growth. Snails without a varix were rapidly growing individuals, including the newly hatched. Snails with a terminal varix were estivating juveniles, overwintering individuals, and egg-lay- ing adults which had completed their spring grovrth. The varix is laid down at the end of a period of growth and not during a period of dor- mancy. Therefore, the number of varices cannot be used to estimate the age of snails unless the annual life cycle and environmental conditions are examined. The number of varices in adult snails will dif- fer, depending upon annual activity. If a pond dries up in summer, gains water again before temperatures become too cold for gastropod ac- tivity, and then warms up again the following spring, breeding adult snails will have 3 varices; two representing periods of pre-dormancy and one the termination of growth before egg deposi- tion. This is probably the situation observed by Baker (1911) who found 3 varices normal for L. palustris (= S. elodes), one varix on the third whorl, one on the fifth, and a third on the aper- tural lip of the adult. The snails from Michigan all had a varix inside the outer lip in early spring before the ice thawed. In this case the summer-fall estivation, marked by a varix on the juveniles, had con- tinued into the overwintering period, the pond not refilling until freezing temperatures had ar- rived. Therefore, the snails were not given the op- portunity to renew growth in the fall. After the pond thawed and the water warmed, new shell material was rapidly laid dovm, the pur- ple-brown color of the summer-fall varix mark- ing the initiation of dormancy. By June the snails had grovra considerably in length and the new shell growth was very thin. Then linear growth slowed, the new shell material thickened and another varix was deposited. Under such con- ditions an adult snail will exhibit only two varices. Microscopic examination suggests that the varix adds considerable strength to the shell lip as is the case with the shell lamellae found in Biomphalaria (Richards, 1964). It is doubtful that the varix would protect against desiccation since it extends into the shell aperture only a short distance. A likely function would be to strengthen the shell lip and thus protect against breakage between f)eriods of growth, whether or not the snails are active. ACKNOWLEDGEMENTS I wish to express my sincere gratitude to Dr. David R. Cook for his advice and encouragement. Dr. Osborn B. Nye for technical instruction, and Dr. Peter H. Rich for critically reviewing the manuscript. Preparation of the manuscript was aided by the facilities of the Biological Sciences Group at the University of Connecticut. LITERATURE CITED Baker, F. C. 1911. The Lymnaeidae of North and Middle America, recent and fossil. Spec. Publ. No. 3. Chicago Acad. Sci. Boardman, R. S. & Utgaard, J. 1964. Modifications of study methods for Palezoic Bryozoa. J. Palemit. 38:768-785 Boggild, 0. B. 1930. The shell structure of the mollusca. K. danske Vidensk. Selsk. Skr., Natunndensk. math. Afd. (9) 2(2):231-3a5 DeWitt, R. M. 1954 Reproduction, embryonic development and growth in the pond snail Physa gyrina Say. TVans. Amer. Micros. Soc. 73:124-137 Herrmann, S. A. & Harman, W. N. 1975. Population studies on Helisoma anceps (Menke) (Gastropoda: Planorbidae). A'ojrfi7jis89(l):5-ll Jokinen, E. H. (in prep). Estivation in Stagnicola elodes (Say) (Gastropoda: L>Tnnaeidae). Matthes, W. 1914. Beitrage zur Anatomie von Helix pisana Mull. Je«a Z. Naiiirwiss. 53: 1-.50. Richards, C. S. 1964. Apertural lamellae as supporting struc- tures in Australorbis glabrattis (Say). The Nautilvs 78: 57-60. 16 THE NAUTILUS January 27. 1977 Vol. 91 (1) PREDATION BY WINTER FLOUNDER (PSEUDOPLEURONECTESAMERICANUSJ ON THE SIPHONS OF THE CLAM, TELLINA AGILIS William H. Gilbert > Department of Biology Colby College Waterville. Maine 04901 and Ellen F. Suchow Belle W. Baruch Institute University of South Carolina Columbia, South Carolina 29208 The bivalve Tellina agilis Stimpson commonly inhabits marine, shallowwater, sand-mud sediments (see Maurer, et ai, 1974). These small clams (max. length = 1.6 cm) burrow 1-3 cm into the sediment and deposit -feed on the sediment surface with separate, extensible, inhalent siphons (Gilbert, 1970), movements of which may attract visual predators such as the commercially important winter flounder, Psendopleuronedes americanus (Walbaum). Edwards, et al. (1970) have shown that small flounder, Pleumnectes platessa (L.), in Scotland obtain a large part of their food by preying on siphons of Tellina tenuh da Costa, which can regenerate their siphons. The aim of our study was to seek evidence that small winter flounder prey on siphons of T. agilis in nature. Eight winter flounder (lengths = 4-6 cm) were collected (27 September 1969) at the mouth of Barnstable Harbor (Cape Cod Bay), Massachusetts. The fish were captured by hand net during the flooding tide on a sand flat 0.5 m above mean low water. An abundant population of T. agiUs (100-600/m^) occurred on the flat, but other clams with similar siphons (e.g., Cumingia, Macoma, and Petricola) were rare or absent (see Edwards, 1975). The fish were placed immediately in 95% ethyl alcohol to terminate digestion, and stomach contents were examined later in the laboratory. Stomachs of four of the eight fish contained 1-3 siphon fragments (9 total). These fragments and intact siphons of T. agilis collected at the site had similar measurements (made at 7X power with an eye-piece micrometer) for total width, width of circular muscle bands, and width of longitudinal bands (Fig. 1). The length of an ex- tended siphon is 3-4 times shell-length; the fragments ranged from 0.5-2.5 mm in length and were usually identifiable as the siphon tip. Levinton (1971; Levinton & Bambach, 1975) report that Macoma tenia (a subtidal clam) deposit-feeds on detritus at night when its siphons are not visible to fish predators, but that T. agilis deposit-feeds on benthic diatoms during the day. Many benthic diatoms concentrate dur- ing the day at the sediment surface, which turns a golden-brown hue as a result (Sanders, et al., 1962). Thus the efficiency of daytime grazing by T. agilis may outweigh the hazard of exposing siphons to fish predators. In the laboratory, we observed the behavior of a small winter flounder placed in a water tank with a tray of sediment containing several live T. agilis. On two occasions, the fish uncovered clams by lunging at the sediment surface where siphons were deposit-feeding. When each clam attempted to burrow back into the sediment, the fish took a bite out of its foot. ' Present address: Environmental Studies Program, Ottawa University, Ottawa. Kansas 66067. FIG. 1. Intact .-tiphim of a Tellina agilis (shell-length = 1.0 cm) in .W/o ethyl alcohol. Vol.91 (1) January 27, 1977 THE NAUTILUS 17 Martin (1940) reports that T. agilis (as T. tenera) is an intermediate host for Monorcheides cumingiae, a parasitic trematode which encysts (as metacercariae) in siphon and foot tissues of the clam. Martin fed infected clams to eels and flounders (species unspecified) and obtained adult Monorcheides later from intestinal mucusa of the fish. Our observation that small winter flounder prey on T. agilis suggests that these fish might take in Monorcheides. Further studies are needed to determine (1) whether or not winter flounder is a definitive host for this parasite, and (2) the importance of T. agilis siphons in the diet of young winter flounder. We thank Drs. D. C. Edwards, J. S. Levinton, and F. J. Vemberg for their comments about this manuscript. LITERATURE CITED Edwards, R. R. C, J. H. Steele, and A. Trevallion. 1970. The ecology of 0-group plaice and common dabs in Lock Ewe. III. Prey-predator experiments with plaice. J. Exp. Mar. fto/.£coU: 156- 173. Gilbert, W. H. 1970. Territoriality observed in a population of Tellma agilis (Bivalvia: MoUusca). Biot. Bvll 139:423-424 (abstr.). Levinton, J. S. 1971. Control of tellinacean (Bivalvia: MoUusca) feeding behavior by predation. Limnol. Oceanogr. 16:660-662. Levinton, J. S., and R. K. Bambach. 197.5. A comparative study of Silurian and Recent deposit-feeding bivalve com- munities. Paleobiology 1:97-124. Martin, W. E. 1940. Studies on the trematodes of Woods Hole. III. The life cycle of Monorcheides cumingiae (Martin) with special reference to its effect on the invertebrate host. Biol. Bull. 79:131-144. Maurer. D., L. Watling, and G. Aprill. 1974. The Distribution and Ecology of Common Marine and Estuarine Pelecypods in the Delaware Bay area. The Nautilus 88: 38-45. Sanders. H. L.. E. M. Goudsmit, E. L. Mills, and G. E. Hamp- son. 1962. A study of the intertidal fauna of Barnstable Harbor, Massachusetts. Limnol. Oceanogr. 7:63-79. ECOLOGY OF THE SNAIL, MELANOIDES TUBERCULATA (MULLER), INTERMEDIATE HOST OF THE HUMAN LIVER FLUKE (OPISTHORCmS SINENSIS) IN NEW ORLEANS, LOUISIANA Dee S. Dundee and Anna Paine Department of Biological Sciences University of New Orleans, Louisiana 70122 ABSTRA(Jr The habitat and associates of a series of populations of the prosobranch snail, Melanoides tuberculata (Thiaridae) introduced to a drainage canal in New Orleans, Louisiana, are described. These snails, and associated fish, could serve as intermediate hosts of the Chinese Liver Fluke, Opisthorchis sinensis. In the spring of 1975, two populations of Melanoides tuberculata (Miiller) (Thiaridae) were discovered in New Orleans, one in the People's Avenue Canal, Orleans Parish, and the other in the canal on the neutral ground of General DeGaulle Drive, Jefferson Parish. A third popula- tion has recently been reported to us in 1975 from the west Metairie canal in Jefferson Parish. This oriental prosobranch had previously been reported from two localities in Texas (Murray, 1964; Murray and Wopschell, 1965), one in Arizona and another in Oregon (Murray, 1971). Abbott (1973) summarized its spread into Mexico at Vera Cruz and in Panama and Puerto Rico. The role of M. tuberculata as an intermediate host in the life cycle of the Chinese Liver Fluke, 18 THE NAUTILUS January 27, 1977 Vol, 91(1) LAKE PONTCHARTRAIN lEGEM: CANALS PIPE LINES JTyPT AREA SrHESTS PUUPING STATIONS ! 1 i I f 1 I ! MALE M METIM FIG. 1. A portion of the New Orleans drainage system in rela- tion to the Peopk's Avenue carud. Opisthorchis sinensis, makes the occurrence of it in the U. S. of more than casual interest. This study was done in a section of People's Avenue Canal which is part of the New Orleans storm drainage system. Since this city is largely below sea level, drainage is accomplished by pump- ing stations at intervals in the drainage canal network (Fig. 1). This locality (Fig. 2) is per- manently supplied with slightly brackish water from a 600' well tapped by American Standard Co. for use as cooling water in their air condi- tioning system. THE HABITAT The reported habitat of Melanoides tuberculata elsewhere in the U. S. is freshwater springs with a pH of 7.0-7.5, a water temperature of 18-25° C, and soft mud or gravelly-mud bottoms (Murray, 1971). The People's Avenue habitat is similar to this. With few exceptions the stream bed is 50-70 cm wide and 10-40 cm deep. The flow during the study was 42-51 cm/sec. Once we noticed a brief threefold flow increase, from an unknowoi source. At this time the level in the basin at the north end rose 20 cm in a five minute period. The non- vegetated bottom is sandy with scattered pebbles and shells of Ravgia cuneata, a brackish -water mactroid clam which is used for gravel. Few Melanoides are found in this type of bottom. Flow is much slower and the accumulation of silt and detritus much greater behind the overhang- ing stems and protruding roots of the bank vegetation. This seems to be the prime Melanoides microhabitat, supporting up to 251 snails/sq. ft. (2700/m^). The canal banks are covered with vegetation. The predominant cover is a prostrate species of medium-height grass (probably Eragrostiit) with Tifpha and Lysimachia constituting most of the rest of the cover. The grass and Lysimachia are IQ 8 o en z I r 20 30 I LENGTHimm)' FIG. 2. Histogram shounng population aye groups in the spring of 1975. mill IIIL^iiiik.. 40 Vol. 91(1) January 27, 1977 THE NAUTILUS 19 ES. AA4 ■ ■■■ b rrggi 1 ♦ 2 X AAA All [nil AAOO nil ■ Ul^ • ••• 1 3 A 4 A 5 X 6 X 7 X - AAOo AAAA ■ III ■ ■1 ■ III 7AV I — ot n , smsh AAA AAA -> 8 X 9 X drain pipe 10 A 11 A ■ ■■■ ■ pipe IXIII ■over canal ■ 12 A aaAa E N AAAA _D 23 scale in meters VEGETATION SUBSTRATE INDIVIDUALS/2 FT.1 1 Eragrostis O Typha ALysimachic • Phragmites D Spartina ISagittaria ♦ Gravelly X Soft mud A Sandy 1- 0 2-0 3-6 4-7 5-8 6-12 7 0 8-62 9 253 10 140 11 152 12 16 FIG. 3. Diaymm of People s Avenue Canal showiny di. the only plant species directly in contact with Melanoides. At the stream bank they create the sheltered environment that Melanoides seems to prefer. Other plants in the area are: Polygonum sp., Spartina altemiflora, Phragmites communis, and Sagittariafalcata. Animal species associated with Melanoides at this site include insects (Ranatra and Pelocoris, both predaceous hemipterans; Chironomidae, dipterans), crayfish, oligochaetes, and fishes (Poecilia latipina and Heterandria formosa). The fishes are of particular interest since various poecilids are known to be second intermediate hosts for Opisthorchis sinensis, the human liver fluke which has Melanx)ides tuberculata as its first intermediate host. POPULATION SAMPLINGS Square foot (.093 m) quadrat samples were taken starting from the northernmost end of the canal (Fig. 3) at 46-meter intervals downstream (12 stations in all) to the point where the canal turns westward and goes underground. Two samples were taken at each station, at opposite banks just underwater and at the surface. In- dividuals were returned to the lab, counted, measured, and whorl counts made. Histograms were then plotted from these data for each sta- tion. The population for September-October 197.5 follows a normal curve pattern with a few young of 10 mm and 8 whorls, a few older individuals of 44 mm and 14.5 whorls, and the bulk of the population in-between. The best-represented size class is 25 mm long with 12 whorls. Fig. 2 is a histogram of the snail total lengths— lumping all Uribii tlon ofsnails in relation to substrate and vegetation. of the stations (656 individuals) to present an overview of the population. The histogram will doubtlessly shift considerably during reproductive seasons. Only one cluster of young was found indicating that late summer is not a major reproductive season for these live-bearers here. A parthenogenetic mode of reproduction has been reported tor Melanoides (Jacob, 1957). TABLE 1. The range of physico-chemical values encountered for each parameter. Low High chlorides in ppt 1.39 1.65 salinity in ppt 2.50 3.00 dissolved oxygen in ppm 3.70 5.00 free CO; in ppm 24.00 41.00 phenolphthalein alkalinity ex- pressed as ppm CaCOj 0.00 0.00 t»tal alkalinity expressed as ppm CaCOa 300.00 560.00 Temperature (water) 20.5-C 25.0*C pH 7.5 7.5 The flow from the well is 4500 liter/min. This water has some interesting properties related to its origin. The usual alkalinity values en- countered for Lake Pontchartrain are in the 30-50 ppm range; free CO2 is generally less than 5 ppm. At the pH values we recorded, carbonate ion is absent; the high CO2 and alkalinity values are what might be expected for a subterranean water source that is far from being in equilibrium with the atmosphere. The low dissolved oxygen content (saturation at 25° C is 8.1 ppm) also suggests this water is recovering from subsurface conditions. All these water quali- ty parameters may have been affected by passage 20 THE NAUTILUS January 27, 1977 Vol. 91 (1) through the American Standard Company air conditioning system. The slight brackishness of this water is usual for southeastern Louisiana waters and does not seem to inhibit Melanmdes. SIGNIFICANCE The introduction of Meldmildpn tuberrulntd in- to an area where poecilid fishes occur plus the fact that Vietnamese people are being settled nearby could be highly significant, particularly if some of these people are infected with trematodes and if they are still including raw fish in their diet. It is not known at the time of this writing whether the incoming Vietnamese were screened for liver flukes. Since all of the ingredients for the Opi.'^thorchut life cycle might now be present, it is important that we learn more about the snail and continuously monitor the spread of it. ACKNOWLEDGEMENTS We wish to thank Dr. Harold Murray of Trini- ty University for verifying our determination of the snails. Voucher specimens have been deposited in the Delaware Museum of Natural History, No. 113847. Also the following Univer- sity of New Orleans graduate students were equally responsible for the results of this study: Bill Copeland, Tom Chin, Ben Garrett, Cheryl Noble, Mike Rayle and Mary St. Martin. LITERATURE CITED Abbott. R. T. 1973. Spread of Melanmdes tuberculata. The .V(iM/i7».s87(l):29. .lacub. .J. 19.57. Cytological Studies of Melaniidae (Mollusca) with Special Reference to Parthenogenesis and Polyploidy. I. Oogenesis of the Parthenogenetic Species of Melanoides (Prosobranchia-Gastropoda). Trans. Roy. Soc. Edinburgh 63: *1 1-3.52. Murray, Harold D. 1964. Tarebia granifem and Melanoides tuberculata in Texas, (an abstract). Ann. Reports Amer. Malacol. Union, 15-16. Murray, Harold D. 1971. The Introduction and Spread of Thiarids in the United States. The Biologist 53(3): 133- 135. Murray, Harold D. and Leon J. Wopschell. 1965. Ex»logy of Melanmdes tuberculata (Miiller) and Tarebia granifera (Lamarck) in South Texas (abstract). Ann. Reports Amer. Malacol. Union, for 1965, pp. 25-26. NEW RECORDS AND ECOLOGICAL NOTES FOR CORBICULA MANILENSIS IN TEXAS Joseph C. Britten and Clifford E. Murphy Department of Biology Texas Christian University, Fort Worth, Texas 76192 ABSTRACT Corbicula manilensis is distnbuted through seven major drainage systems in Texas. Potential mechanisms of dispersal are discvssed. The species seem to prefer sandy substrates in Texas reser^wirs but occm's in a variety of bottom types. Specimens of Corbicula have been removed from stomachs of three species of yis/i— Lepomis microlophus, Minytrema melanops and Aplodinotus grunniens. The first reports of Corbicula manilensis in Texas were from the western portion of the state (Metcalf, 19(56 and Metcalf and Smartt, 1972). Murray (U)71) discusses the presence of Corbicula in S(juth Texas and notes its eastward progres- sion from the Rio Grande drainage to Lake Cor- pus Christi, 25 miles north of Corpus Christi. He also reports large populations of the Asiatic clam from Lake LBJ in the Colorado River drainage of Central Texas (Murray, 1972). Corbicula was reported in Ijouisiana waters as early as 1961 (Dundee and Harman, 1963). Con- sidering its rapid range expansion in other parts of the United States, it is interesting that no Vol. 91 (1) January 27, 1977 THE NAUTILUS 21 reports of Corbicula in eastern Texas have yet ap- peared in the literature. It seems inevitable, however, that the eastern and western popula- tions of Corbicula will finally converge in this state. We have compiled a list of new distributional records of Corbicula in central, northeastern and eastern Texas. The first record of the species in northeastern Texas was from Lake Grapevine (Tarrant County), a reservoir of the upper Trinity River drainage. Mr. Donnie Roberts provided the senior author with several specimens collected from Lake Grapevine in November, 1972. Subse- quently, several reservoirs in Tarrant County were found to harbor Corbicula populations. The authors recovered specimens from Lake Arlington on January 21, 1974; from Lake Benbrook on February 3, 1974; and from Eagle Mountain Lake in September, 1974. In August, 1973, the senior author collected a specimen from the Colorado River at Marble Falls in central Texas. During October and November, 1974, and March and April, 1975, the Texas Christian University Research Foundation provided finan- cial support which enabled us to briefly survey a number of Texas reservoirs east of the Colorado River system. We visited Possum Kingdom Reservoir (Brazos River drainage). Lake Play Hubbard, Navarro Mills Reservoir, C«dar Creek Reservoir, and Lake Livingston (Trinity River drainage). Lake Conroe (San Jacinto River drainage). Lake Tawakoni (upper Sabine River drainage). Diversion Lake, Lake Wichita, and Lake 0' the Pines (Red River drainage), and Lake Sam Rayburn and Steinhagen Reservoir (Neches River drainage). Most of the surveys were not exhaustive (exceptions were those at Possum Kingdom, Diversion Lake and Lake Wichita) so the failure to detect Corbicula at a locality does not necessarily indicate the absence of the species in an area. In fact, only Lake Sam Rayburn and Lake Texoma yielded specimens. The Rayburn specimens were collected from a sandy substrate on the northwestern shore of the lake on October 18, 1974, whereas specimens from Lake Texoma were taken from sand along the northern shore of the lake near the University of Oklahoma Biological Station on April 24, 1975. Harold Murray has provided additional distribution data from central Texas. He has received specimens collected by Emily Mims from Lake Buchanan on June 30, 1973. On September 21, 1973, the ecology class of Trinity University recovered Corbicula from Canyon Lake, Guadalupe River. Scott Horn provided Murray with specimens collected on September 8, 1974, from the Guadalupe River below the dam at Highway 90 and 90A near Seguin, Texas. Ray Dinges of the Texas Water Quality Board has provided us additional records. He has col- lected Asiatic clams from Lake Austin on the Colorado River, along the Colorado River between Austin and Bastrop, and in the Nueces River along Texas Farm Road 1025, north of Crystal City. The known distribution of Corbicula in Texas now includes seven major drainages: the Rio Grande, Nueces, Guadalupe, and Colorado Rivers, with dispersal apparently occurring within these systems generally from west to east, the upper Trinity River drainage and the Red River drainage with populations recruited from an uncertain source, and the Neches River drainage with this population possibly recruited from Louisiana (see Figure 1). Considering the ap- parent lack of Corbicula populations immediately adjacent to the upper Trinity River assemblage, it seem possible that the species gained access to FIG. 1. The knoum distribuiion of Corbicula manilensis in Texas through April 1975. 22 THE NAUTILUS January 27, 1977 Vol. 91 (1) T lA T T 12 10 T T T T T T T TT TTT TTT 8 T T T T TTT TTT TTT 6 T TTT TTTT TT T TTT T T TTTT TTT 4 T TTTTTT T T TTTT TTT T TTTTTTTT TTTTTTTTTTTT 2 TTTTTTTTTT TTTTTTTTTTTTTT TTTTTTTTTTT TTTTTTTTTTTTTT 10 15 20 25 30 SHELL LENGTH (mt) FIG. 2. Size frequency di.ftrihulidii of a nindom sample nf paired rnlres of Corbicula manilensis collected from Lake Benhrook. Texas. November. l!)7Jt. North Texas waters as a result of introduction from a remote source. Many live-bait establishments obtain minnows from Arkansas or Louisiana, transporting several hundred gallons of water with each shipment of minnows. Perhaps Corbicula larvae may have been transported with this water. Fisherman could just as likely bring an establishing population in- to the area in a live-bait hold of a boat. The pat- tern of distribution of Corbicula in Texas is decidedly trending along a roughly north to south axis. This fact may be due only to coincidence, but since it parallels closely a migratory bird flyway, it may suggest an alternative dispersal mechanism. From whatever source that Corbicula became established in Tarrant Cbunty reservoirs, it is certain the Asiatic clam is firmly entrenched there. In 1973, Britton, Murphy, Keith and Mauldin completed a study of the bivalve fauna of Tarrant County Reservoirs. From June 1971 to August 1972, extensive bivalve collections were made in Benbrook and Eagle Mountain reser- voirs. At that time there was no evidence of Cor- bicula in either lake. By November 1974, shell debris accumulations of Corbicula along portions of the western shore of Benbrook Lake yielded densities in excess of 800 valves per foot. A ran- dom sample of 140 paired valves was taken from this shell debris material. Measurements were made of each individual in the sample. The length of the largest was 30.4 mm. A frequency distribution of length or height measurements ob- tains a distinctly bimodal curve, suggesting two major age classes among the Benbrook Corbicula population (Figure 2). This correlates well with the time available for the species to have become established. Considering the rapid spread of Corbicula in southwestern Texas and among the Tarrant County reservoirs, it is interesting that the species apparently has not yet entered the Brazos River system (or, at least the upper Brazos from Possum Kingdom Reservoir to Waco, Texas). In the summer and fall of 1974, we made extensive collections of bivalves from Possum Kingdom Reservoir during a period when the lake was significantly below normal. Corbicula was never observed. In addition, Mr. Chuck Fontainer has been intensively studying unionid populations in the Brazos River near Waco. He has employed numerous collecting techniques including SCUBA diving to recover clams. To date he has not en- countered Corbicula in the Waco area. The Brazos drainage should be monitored closely dur- ing the next few years, as it is the only major river system between western and eastern Cor- bicula populations which still lacks the species. The substrate preferences of Corbicula in Texas are variable. We have taken the species from san- dy gravel, sandy mud and muddy sand, and from deeper water muds. The most abundant popula- tions seem to be on or in sandy or muddy sand substrates. Clams can be found on the surface of the substrate or buried as much as two cen- timeters below the surface. At Sam Riiyburn Reservoir we found a population of Corbicula in a muddy sand substrate. The clams were approx- imately 2 cm below the surface, but produced a hole which emerged at the sandy water-substrate interface for water currents to enter the mantle cavity. The origin of this tube is curious, as the siphons of Corbicula are too short to be extended 2 cm to the surface to produce it. Although we have tried to reproduce the situation with laboratory specimens, we have not been suc- cessful. The largest concentrations of Corbicula have been collected from shore to depths of about 8 Vol. 91 (1) January 27, 1977 THE NAUTILUS 23 feet. Living specimens have been recovered by dredging in silty substrates in Lake Benbrook at a depth of approximately 20 feet. Our students have removed Corbicula from stomachs of three fish species from North Texas waters. A red ear sunfish, Lepomis microlophuii, from Lake Benbrook was found to contain Cor- bicula shells up to 5 mm in length. A spotted sucker, Minytrema melanops. from the same lake had ingested shells up to 3 mm in length. From Eagle Mountain Lake a freshwater drum, Aplixiinotus gmnniens. had five specimens of Corbicula in the gut ranging from 3 to 5 mm in length. LITERATURE CITED Britton, Joseph C. C. E. Murphy, D. E. Keith, and Virginia Mauldin, 1973. A quantitative and (jiialitative survey of the plankton and benthic invertebrates including bivalves of Eagle Mountain and Possum Kingdom Lakes Part III, Bivalves Texas Electric Service G)mpany Research Report 178. 101 pp. Dundee, D. S. and W. J. Harman. 196."!. Oirbicula fluminea (Mailer) in Louisiana. The Nauiduii 77(1): 30. Metcalf. Artie L., 1966. Corbicula manilensia in the Mesilla Valley of Texas and New Mexico. The Nautilus 80(1 ): 16-20. Metcalf, Artie L. and Richard Smartt, 1972, Records of in- troduced mollusks: New Mexico and western Texas. The A^aM/i7«s 85(4): 144-145. Murray. Harold D., 1971. New records of Corbicula manilensis (Philippi) in Texas. The Nautilux 85(1): 3.5-36. Murray. Harold D.. 1972. Freshwater mussels in Lake LBJ, Te.\as. Bulletin of the American Malacological Union for 1971, pp. .36-37. Sinclair, Ralph M., 1971. Annotated bibliography on the exotic bivalve Corbicula in North America. 1900-1971. Sterkiana 43: 11-18. OPISTHOBRANCHS FOUND OFF LITTLE EGG INLET, NEW JERSEY, WITH NOTES ON THREE SPECIES NEW TO THE STATE Elizabeth V. Carlo Ichthyological Associates, Inc. Box 70-D, R. D. 2, West Brook Lane Absecon, New Jersey 08201 ABSTRACT An intensive ecological survey in the incinity of Little Egg Inlet, New Jersey found three species of opisthobranchs which are new to New Jersey (Pleurobran- chaea tarda, Onchidoris bilamellata, and Facelina bostoniensis) and southern range extensions for Dendronotus frondosus and Tergipes tergipes. The occurrence of cold water opisthobranchs in New Jersey is explained in part by ocean water temperatures which rarely exceed 25°C, by the numerous submerged artificial structures, and by the predominant southwest flow of coastal water which may transport eggs and young from breeding populations located to the north. INTRODUCTION In October, 1971, Ichthyological Associates, Inc. began an ecological survey of the New Jersey coast from Long Beach Island to Brigantine Island. Since March, 1972, invertebrates were systematically collected by a variey of methods including substrate panels, clam dredge, ponar grab, lobster pots, trawl, and SCUBA gear as reported by Carlo, Hondo, and Miller (1975) and McCullough (1975). Recent reports by Franz (1968a, 1970) and Loveland, Hendler, and Newkirk (1969) recorded nudibranchs from Shark River, Delaware Bay, Manasquan River, and Bamegat Bay. Loveland et al. (1969) provided a checklist which summarized distributional records of nudibranchs from New Jersey. Franz (1968b), Marcus (1958), Miner (1950) and Pruvot-Fol (1954) discussed their tax- onomy and distribution. 24 THE NAUTILUS January 27, 1977 Vol. 91(1) ^ I •a ^ + £ »-• ^ >• r- > 5-^ o &^ f» o cn ? l. 00 aa TO 00 OQ c*3 i. a 00 2 en T3 t" n E ^ g. q ■o K c' 3 ST 8 o 9- " g. o CO c S* 3 S" a. 1 C7 c £••« p S 3 > s: »-• rt M B- PT R s o « t O o f-» o o o g. 8 w e C^ > O a> 8 3 S- lu s n n oa OQ m 8S > 3 •;^ 5 5 ^1 rt 13 •o re " O T3 o fT ~3 3r S S n re m i^ 3 m m ? 1 X 3 m c/i TO 00 OQ OQ ET TO CO en 00 00 CO ■^ C3i CO OQ rt en m n> a ■J' mg a -" 4^ o £■3 !f *. 2, i^ h 7r ?r —*i S"- i 5" -I 2 W n 3 n > a a o •< o i n CD B. a. a. o ST 3 s 3 & =r z > O c < 00 3 5 -J 3 ^^ £/) i^ ^ > en CJ li 1 CO to o en O gz s o Vol. 91 (1) January 27, 1977 THE NAUTILUS 25 RESULTS More than 325 macroinvertebrate taxa were collected from the study area during the period between 1971 and 1975. Opisthobranchs were taken between Little Sheepshead Creek and 15 kilometers southeast of Little Egg Inlet (Fig. 1). Nine species of opisthobranchs (represented by 1,082 specimens) are discussed below (Table 1). Specimens are deposited in the collections of Absecon Laboratory of Ichthyological Associates, Inc. Some 95% of the specimens collected were taken from artificial structures which included lobster pots, substrate panels, buoy lines, ship wrecks, and a weather tower. The rest were col- lected from natural substrates such as shell rub- ble encrusted with bryozoans and drifting hydroids. Pleurobranchaea tarda (Verrill 1880) Thirteen specimens were collected by trawl during August, October, and November, 1975, ap- proximately 15 kilometers southeast of Little Egg Inlet. Specimens were taken at depths of 18 to 20 m. Bottom water temperature at the time of col- lection ranged from 14.2° to 17.0° C and salinity was 32.0 ppt. Abbott (1974) reported specimens off Massachusetts and Delaware at depths from 51 to 567 m. Moore (1964) noted specimens from floating Saiyassum in Vineyard Sound, Mass. and in dredge samples taken at depths from 60 to 400 m. Our specimens are the first reported oc- currence for New Jersey. Acanthodoris pilosa (Miiller 1776) Forty-four specimens were collected from 27 April 1972 through 3 September 1974. They were taken in Little Sheepshead Creek, and from Lit- tle Egg Inlet to a point 4.8 kilometers southeast of Little Egg Inlet at depths of 2 to 11 m. Bottom temperatures were 6.5° to 25.0° C and salinities were 29.0 to 30.5 ppt. Egg masses were collected in June when bottom temperature was 16.0° C and salinity was 29.0 ppt. Acanthodoris pilosa was found on shell rubble which was covered with encrusting bryozoans (particularly Alcyonidium sp.) and on cement and masonite substrate panels colonized by Al- - l/J NEW «' 40"- Bexh Haven Inlel €it^^g^;gi FIG. 1. Area sampled in the vicinity of Little Egg Inlet, New Jersey. cyonidium, Obelia Jlabellata, and Tubularia crocea; 7 were found on the gamma stage of Cliona sp. The color of A pilosa varied from gray to gray-pink to yellow and blended with the habitat. Abbott (1974) reported that it was found from the Arctic to Ocean City, Maryland and in the north Pacific, Japan, and Europe. A specimen found in Delaware Bay, New Jersey, was reported by Loveland et al. (1969). Acanthodoris pilosa is established in natural and man-made habitats near Little Egg Inlet but is uncommon. Onchidoris bilamellata (Linnaeus 1767) (Lamellidoris fusca in Abbott 1974, On- chidoris fusca in Moore 1964) Eight specimens were collected on a lobster pot set from 23 July to 14 August 1973 near a wreck located approximately 6.4 kilometers southeast of Little Egg Inlet. They were relatively small (total length ranged from 5.7 to 6.9 mm; mean 6.3 mm). The depth ranged from 14 to 16 m; the bottom temperature was 12.5° C, and salinity was 30.5 ppt. Abbott (1974) reported its range in the Atlan- tic from the Arctic to Massachusetts and Europe. 26 THE NAUTILUS January 27, 1977 Vol. 91(1) These are the first specimens reported from south of Ijong Island, New York (Rozsa 1974). Dendronotus frondosus (Ascanius 1774) One specimen (1.8 mm total length) was col- lected on a masonite panel which was set from 23 April to 1 July 1974. The panel was placed ap- proximately 5 m below mean low water on a weather tower located 3.7 kilometers southeast of Little Egg Inlet. The bottom temperature was 20.0° C and the salinity was 29.5 ppt. Den- dnmotus was associated with the hydroids Obelia flahellata and Tubularia crocea. Abbott (1974) reported its range in the Atlantic is from the Arctic to New Jersey and Europe. Loveland et al. (1969) found hundreds of specimens associated with Tubularia on a floating wharf in Shark River, N. J. Tergipes was reported previously from the Arc- tic to New Jersey and Europe and Brazil (Abbott 1974). Loveland et al. (1969) stated it was rare in New Jersey; the two previous records were from the Shark River. Facelina bostoniensis (Couthouy 1838) Three specimens were collected between 29 August 1972 and 8 October 1973 from lobster pots and a buoy line located between 3.2 and 4.0 kilometers southeast of Little Egg Inlet in depths of 9 to 10 m. Bottom temperatures were 19.0° to 22.0° C and salinities were 29.0 to 29.5 ppt. Abbott (1974) gave its range as Nova Scotia to Connecticut. Rozsa (1974) reported specimens from Long Island, New York. These are the first reported from New Jersey. Doto coronata (Gmelin 1791) Twenty-nine specimens were collected from early May, 1973, to early December, 1974. Small specimens and eggs were collected on floating hydroids (Sertularidae) in May, 1973, in Little Egg Inlet. A few were found associated with Obelia flahellata on cement and masonite panels placed 3.7 kilometers southeast of Little Egg In- let. Bottom temperatures were 6.0° to 20.0° C and salinities were 26.0 to 30.5 ppt. Abbott (1974) reported it was distributed from the Bay of Fundy to New Jersey and Europe. Loveland et al. (1969) noted that it was originally described from a collection taken in Great Egg Harbor. N. J. by Verrill and Smith (1873). They rediscovered it in Shark River in 1968. Our find- ings indicate it is established but uncommon in the coastal waters off New Jersey. Tergipes tergripes (Forskal 1775), (Tergipes despectus in Moore 1964, and in Franz 1968a) Some 815 specimens were collected between 29 August 1972 and 6 December 1974 from a weather tower, buoy lines, and cement and masonite substrate panels located between 3.2 and 4.8 kilometers southeast of Little Egg Inlet. Bottom temperatures were 6.0° to 20.0° C and salinities were 29.0 to 31.0 ppt. Most specimens were found where 0. flxiheUata was abundant and T. crocea was common. Cratena pilata (Gould 1870) Some 164 specimens were collected between 29 July 1972 and 5 August 1974 on lobster pots, buoy lines, and cement panels located 3.2 and 4.8 kilometers southeast of Little E^g Inlet at depths from 8 to 15 m. Bottom temperatures were 13.0° to 21.5° C and salinities were 30.0 ppt. Most specimens were collected where T. crocea was abundant. It occurs from Nova Scotia to North Carolina (Abbott 1974) and has been reported from Barnegat and Delaware bays. New Jersey by Franz (1968a). Our findings indicate it is abun- dant in the coastal waters off Little Egg Inlet. Aeolidia papillosa (Linne 1761) Four specimens and several egg masses were collected on 11 June 1973 by SCUBA divers on a wreck approximately 8.8 kilometers southeast of Little Egg Inlet at a depth of 15 m. Metridium senile, the prey of A. papilhsa, was abundant on the wreck. Bottom water temperature was 10.0° C and salinity was 30.5 ppt. Its range in the Atlantic is from the Arctic to Maryland and Europe (Abbott 1974), and it has been reported from the Shark and Manasquan rivers, N. J. by Loveland et al. (1969). Our find- ings indicate that breeding populations exist in some coastal waters off New Jersey. Vol. 91(1) January 27, 1977 THE NAUTILUS 27 DISCUSSION Of the 9 opisthobranchs collected from the study area, 6 are amphi-Atlantic (occur on both sides of the Atlantic) and 3 are west-Atlantic endemic. Franz (1970) concluded that 37% of the species north of Cape Hatteras are west-Atlantic endemics and our findings agree. Of the amphi-Atlantic species, A. pilosa, D. cor- onata. and T. tergipes are boreal and successful reproduction cannot occur above 25° C (Franz 1970). In this study egg masses of D. coronata and A. pilosa were collected at 15° C and 16° C, respectively. 0. bilamellata, D. frondosus. and A. papillosa are boreo-subarctic species and suc- cessful reproduction cannot occur at temperatures above 15-20° C. In this study egg masses of ^. papillosa were found at 10° C. Three factors contribute to successful establish- ment of northern nudibranchs in New Jersey. Temperature regimes near shore and in Little Egg Inlet favor boreal species. Bottom temperature never exceeded 25° C between March, 1972, and December, 1974. At depths greater than 15 m bottom temperature never ex- ceeded 21° C, however, during the summer it was between 20 and 21° C about 12% of the time. One boreo-subarctic species was found reproducing below the summer thermocline and this is a suitable area for other boreo-subarctic species to inhabit. Loveland et al. (1969) stated that nudibranchs and their eggs may be transported southward and become rapidly established on man-made struc- tures in New Jersey. Some 95% of those collected in this study were from submerged man-made substrates. In summer, 1973, small specimens of 0. bilamellata and D. frondosa were collected on recently deployed substrates; this suggests they were transported by water currents. Charlesworth (1968) redrew maps from Bumpus (1965) which show the general southwest drift in the Middle Atlantic Bight. E. G. & G., En- vironmental Consultants (1974) found that the prevailing current in the study area in summer, 1973 was southwest with an average velocity of 12.1 km/day (surface) and 4.3 km/day (bottom). D. frondosa could drift from existing populations in Shark River to Little Egg Inlet in less than 2 weeks. The southwest drift may transport eggs and young from northern populations and the availability of suitable habitats and thermal regimes in the study area facilitate their sur- vival. ACKNOWLEDGMENTS This work is part of an ecological study for the proposed offshore Atlantic Generating Station sponsored by Public Service Electric and Gas Company of New Jersey. Martha M. McCul- lough, Jeffrey J. Hondo, and Charles B. Milstein collected many of the specimens. Dr. David R. Franz, Brooklyn College, confirmed the identifica- tion of Acanthodoris pilosa and Lamellidoris fiisca and Dr. Larry G. Harris, University of New Hampshire, verified the identification of Facelina bostoniensis. I thank Dr. David R. Franz and Dr. Edward C. Raney for reviewing the manuscript, Felicia A. Swiecicki for the figure, and Linda N. Dill for typing. LITERATURE CITED Abbott, R. T. 1974. American Seashells, the marine moUusca of the Atlantic and Pacific coasts of North America. Second ed.. Van Nostrand Reinhold Co., New York, N. Y. 663 p. Charlesworth, L. J. 1968. Bay, inlet and nearshore marine sedimentations: Beach Haven— Little Egg Inlet region, New Jersey, Doctoral Thesis. Pts. 1, 2, and 3, University Microfilms. Univ. Michigan, Ann Arbor. E. G. & G., Environmental Consultants. 1974. Discussion of general circulation in the New York Bight area. p. 6-1 through 8-1 in Summary of oceanographic observations in New Jersey coastal waters near 39° 28' N latitude and 74° 15' W longitude during the period May 1973 through April 1974. Waltham, Mass. Franz, D. R. 1968a. Occurrence and distribution of New Jersey Opisthobranchia. Vie Nautilus 82(1): 7-12. Franz, D. R. 1968b. Taxonomy of the eolid nudibranch, Cratenapilata (Gould). Ches. Set. 9(4): 264-266. Franz, D. R. 1970. Zoogeography of northwest Atlantic opisthobranch molluscs. Mar. Biol. 7(2): 171-180. Garlo, E. V., J. J. Hondo, and G. J. Miller. 1975. Benthic in- vertebrates. 2: 26-64. In Ecological studies in the bays and other waterways near Little Egg Inlet and in the ocean in the vicinity of the proposed site for the Atlantic Generating Station, New Jersey. Ichthyological Assoc, Inc., Ithaca, New York. Loveland. R. E., G. Hendler. G. Newkirk. 1969. New records of nudibranchs from New Jersey. Veliger l\{i): 418-420. McCullough, M. M. 1975. Epifauna, 2: 13-21. In Ecological studies in the bays and other waterways near Little E^g 28 THE NAUTILUS January 27, 1977 Vol. 91(1) Inlet and in the ocean in the vicinity of the proposed site for the Atlantic Generating Station, New Jersey. Ichthyological Assoc.. Inc.. Ithaca. N. Y. Marcus. E. 1958. On western Atlantic opisthobranchiate gastropods. Amer. Mus. Nointates. No. 1906. 82 p. Miner. R. W. 1950. Field Bonk of Seashore Life. G. P. Put- nam's Sons. New York, N. Y. 888 p. Moore, G. M. 1964. Shell-less Opisthobranchia, p. 1.5.3-164. In R I. Smith (ed.) Keys to marine invertebrates of the Woods Hole Region. Contr. 11, System.-Ecol. Program. Mar. Biol. Lab.. Woods Hole, Mass. Pruvot-Fol, A. 1954. MoUusques opisthobranches. Faune de France 58: 421-436. Rozsa, R. 1974. Preliminary checklist of the nudibranchs and sacoglossa of Long Island. New York Shell Oub Notes 200: 7-8. NOTES ON OCCURRENCE OF EUPLEURA SULCIDENTATA DALL (GASTROPODA: MURICIDAE) Wiliiam G. Lyons Florida Department of Natural Resources Marine Research Laboratory' St. Petersburg, Florida 33701 ABSTRACT Eupleura sulcidentata is reported from estuarine and coastal sites in southeast Florida. Cuba, and tivo Bahamian Islands, demonstrating that the species is not a west Florida endemic, and confirming Doll's original record fi-om Cuba. In 1972, I collected six freshly dead shells of Eupleura (Fig. 1) in beach drift along a sand spit at White Sound on the lagoonal side of Elbow Cay, Great Abaco, Bahamas. A literature search (part of an ongoing treatment of the shallow water Bahamian molluscan fauna) failed to reveal any Bahamian records of Eupleura, so specimens were sent to Dr. Emily Yokes, Tulane University, who identified them as E. sulciden- tata Dall, 1890. The specimens are deposited in the Marine Research Laboratory invertebrate reference collection (FSBC I) at St. Petersburg. In his original description, Dall defined the range of E. sulcidentata as "Gulf coast of Florida, shores of Cuba." Smith (1937) also listed Cuba within the range of the species, but Dall's Cuban citation was evidently considered erroneous by Johnson (1934), who listed only the Gulf coast of Florida and Florida Keys, and by Abbott (1954, 1968), who further restricted it to west Florida. Lyons et al. (1971) followed the latter in consider- ing the species a west Florida endemic. Abbott (1974) listed E. sulcidentata at Bimini, Bahamas, revising its range to include both the west coast of Florida and Bimini. A report of E. sulciden- Contribution No. 290. tata from Caibarien, on the north central Cuban coast (Jaume and Sarasua, 1943) has evidently been overlooked by subsequent authors. Dr. Ab- bott suggested I contact Mr. J. C. Finlay, who allowed me to examine nine Cuban specimens (Figs. 2, 3) collected by him during 1957-1958 in depths of 3-4 m on the Varadero side of the Bay of Cardenas, about 200 km northwest of Caibarien. Mr. Dan Steger provided an addi- tional specimen from Varadero. Mr. Finlay also provided three specimens (Fig. 4) collected off Rickenbacker Causeway, Biscayne Bay, Miami, Florida, during 1949-50. Most recently, I have ex- amined 12 specimens (Fig. 5) collected by Mr. Gene Everson while night diving in depths of 5-6 m immediately off Lake Worth Inlet, north of West Palm Beach, Florida. Eupleura sulcidentata occurs in estuaries along the entire Florida west coast. Tabb and Manning (1961) report specimens from Cape Sable and northern Florida Bay, Cooley (manuscript) has found the species at Pensacola Bay, and others have been reported at many points intermediate to these localities. The snails are common in Tampa Bay (Fig. 6). where they usually live on rocks over sand, on oyster reefe, or in grassbeds in higher salinity portions of the Bay: they also Vol. 91(1) January 27, 1977 THE NAUTILUS 29 FIGS. 1-6. Eupleura sulcidentata DaH: Fig. 1 - Elbow Cay. Gt. Ahaco (FSBC I 10131). Pigs. 2, 3 - Cardenas Bay. Cuba (Finlay Coll.). Fig. 4 Biscatpte Bay (Finlay Coll.). Fig. 5 — Lake Worth Inlet (Everson Coll.). Fig. 6 — Tampa Bay. Florida (FSBC 1 2672). All figures X2. occur near beaches where conditions remain essentially estuarine. Habitat near the beach at Elbow Cay included sand and turtle grass, (Tlmlassia testudinum Konig) with occasional rocks scattered throughout the area. Mr. Finlay states that he commonly dredged E. sulcidentata in 2-3 m on muddy sand in the Bay of Cardenas. At Biscayne Bay, specimens were "not infre- quently found clinging to the outside of smooth objects such as bottles, cans, etc." Lake Worth In- let specimens were found in shell rubble on sand, apparently similar to areas where the species oc- curs in nearshore waters of west Florida. The Bahamian, Cuban, and Biscayne Bay sites are relatively estuarine compared to other tropical habitats, but faunal assemblages differ con- siderably from those where E. sulcidentata occurs along west Florida. Lake Worth Inlet may approach the northern range limit of E sulcidentata on the Florida east coast. Extensive collecting by me at St. Lucie In- let. 45 km to the north, has not produced this species, although its northern congener, E. candata (Say, 1822) has been found there. Mr. Finlay 's specimens, as well as the report by Jaume and Sarasua, confirm Ball's original contention that E. sulcidentata is a component of the Cuban fauna. Specimens from Lake Worth, Biscayne Bay, and two Bahamian localities demonstrate that the range of the species is con- siderably greater than has been recently recognized. ACKNOWLEDGMENTS I thank Messrs. John C. Finlay, Newark, Delaware, the late Dan Steger, Tampa, Florida, and Gene Everson, Ft. Lauderdale, Florida, for graciously loaning specimens, and Mrs. Sally D. Kaicher. St. Petersburg, for preparing the figures. Dr. R. Tucker Abbott. Greenville. Delaware, pro- vided additional information and comment. David K. Camp and Mark J. Poff kindly read the manuscript. LITERATURE CITED Abbott, R. T. 1954. American Seashells. D. Van Nostrand Co., Inc.. Princeton. 541 p. Abbott, R. T. 1968. Seashells of North America. Golden Press, New York. 280 p. Abbott, R. T. 1974. American Seashells. 2nd ed. Van Nostrand- Reinhold Co., New York. 663 p., 24 pis. Cooley. N. R. (Manuscript). An inventory of the estuarine fauna in the vicinity of Pensacola, Florida. Dall. W. H. 1890. Contributions to the Tertiary fauna of Florida, with especial reference to the Miocene silex-beds of Tampa and the Pliocene beds of the Caloosahatchie River. Part I. Pulmonate. opisthobranchiate and orthodont gastropods. Trans. Wagner Free Inst. Sci. Phila.. 3: 200 p. Jaume. M. L. and H. Sarasua. 1943. Notas sobre moluscos marinos cubanos. Rev. Soc. Mai. "Carlos de la Torre" 1(2): 52-61, 1 pi. Johnson, C. W. 1934 List of marine mollusca of the Atlantic coast from Labrador to Texas. Proc. Boston Soc. Nat. Hist., 40(1): 204 p. Lyons, W. G., S. P. Cobb. D. K. Camp. J. A. Mountain, T. Savage. L. Lyons, and E. A. Joyce, Jr. 1971. Preliminary in- ventory of marine invertebrates collected near the electrical generating plant. Crystal River, Florida, in 1969. Fla Dep. Nat. Resour. Mar. Res. Lab.. Prof. Pap. Ser., 14: 45 p. Smith, M. 1937. East coast marine shells. Edwards Brothers, Inc., Ann Arbor. 308 p. Tabb. D. C, and R. B. Manning. 1961. A checklist of the flora and fauna of northern Florida Bay and adjacent brackish waters of the Florida mainland collected during the period July 1957 through September 1960. Bull. Mar Set. Gulf Carib.. ll(4):552-649. 30 THE NAUTILUS January 27, 1977 Vol. 91 (1) NORTH AMERICAN LAND SNAILS IN ISRAEL Henk K. Mienis Department of Zoology Hebrew University Jerusalem , Israel ABSTRACT snails: Gastrocopta procera (Gould). Hawaiia Three North American land minuscula (Binney) and Zonitoides arboreus (Say) are reported fi-om Israel. Recent investigations have revealed the presence of several North American land snails in Israel. Preliminary information is given in this report in the hope that more attention will be paid to other cases of introduced land mollusks in the Middle East. The material on which this work is based was collected during field work carried out by the author in support of the land snail project of the "Fauna Palaestina Committee". The following North American land mollusks were collected in Israel: Gastrocopta (Gastrocopta) procera (Gould, 1840) In December 1972 a few empty shells of this species were collected by Mr. S. Davis during a field trip of students of the Hebrew University of Jerusalem to the oasis of 'En Gedi, on the western shore of the Dead Sea. About one week later, very large numbers of this minute species were found in litter under palm trees in the ir- rigated palm gardens bordering the fields of kib- butz 'En Gedi by Prof. G. Haas, Mr. S. Davis, Miss T. Felsenburg and the author. More than ten thousand specimens were extracted from less than four kilograms of litter. It was first identified as Gastrocopta procera mcclungi (Hanna & Johnston, 1913) by Dr. L. Forcart, but according to Mr. L. R. Hubricht (per. comm.) all the specimens belong to the nominate species Gastrocopta procera ((Jould). According to the latter, it is almost impossible to discriminate properly any subspecies within the species G. pi-o- cera because of the many intermediate forms. Hawaiia minuscula (Binney, 1840) Like Gastrocopta procera this species was found in large numbers in a litter sample taken in the irrigated palm gardens of kibbutz 'En Gedi. The identification of this species based on shell characters was confirmed by Dr. L. Forcart. Dr. A. Riedel later found the anatomy of a living specimen to agree in every detail with that of typical//, minuscula. Zonitoides (Zonitellus) arboreus (Say, 1816) Very large colonies of this species are present in the open tree nursery of kibbutz Netzer Sereni. Snails were first observed by the author in January 1970, but this species must have already been well established as thousands of liv- ing snails were present. The snails are living on and underneath containers (mainly tin cans) in which saplings of sub-tropical fruit trees are cultivated, in densities reaching 25 per container. Eggs and juveniles are found during the entire year, but are most numerous in the spring (March-May). With the sale of young trees, snails are transported to orchards and other nurseries. The identification of Z. arboreus from kibbutz Netzer Sereni has been confirmed by Dr. L. For- cart and Dr. C. 0. van Regteren Altena. Recently additional specimens of Z. arboreus were collected by the author in an open greenhouse of the Old Botanical Garden of the Tel Aviv University near Abu Kabir, Tel Aviv (8 January 1975). A single specimen was found in a hothouse of the Botanical Garden at the Givat Ram campus of the Hebrew University of Jerusa- lem (5 June 1975). DISCUSSION Zonitoides arboreus is a well known greenhouse species which is widely distributed Vol. 91(1) January 27, 1977 THE NAUTILUS 31 over the whole world. (Pilsbry, 1946). It may have been introduced with plants imported from North America or from hothouses in Europe. In the cases of Gastrocopta procera and H(uraiia miymsmla. there is a clear indication that they were imported directly from Southern California. Both species were found in litter under palm trees which were directly imported from a nursery in the Coachello Valley in the Salton Lake area. According to Pilsbry (1948) this species was not known to live outside America. From the large numbers in which these three species have been collected, it is clear that all have adapted very well under the artificial condi- tions in Israel. Further passive dispersal of Zonitoides arboreus is currently going on. However, there is no positive data available regarding the presence of this species in other nurseries or orchards in Israel. Further dispersal of Gastrocopta procera or Hawaiia minuscula seems very unlikely, as both are living in the isolated oasis of 'En Gedi in the Judean Desert, and there only in irrigated palm gardens. ACKNOWLEDGMENTS Tlie author wishes to express his gratitude to Dr. L. Forcart (Basel), Dr. C. C. van Regteren Altena (Leiden), Dr. A. Riedel (Warszawa) and Mr. L. R. Hubricht (Meridian) for their help in the identification of the discussed material. LITERATURE CITED Pilsbr>', H. A. 1946. Land MoUusca of North America (North of Me.xico). Acad. Nat. Sci. Philadelphia, Monog. 3. 2(1): 481. Pilsbry. H. A. 1948. Land Mollusca of North America (North of Me.xico). Acad. Nat. Sci. Philadelphia, Monog. .3, 2(2): 907-910. EFFECT OF UPWARDLY-DIRECTED SHELL APERTURE ON THE AESTIVATING LAND ^NAlh ACHATINA FULICA S. K. Raut and K. C. Ghose Department of Zoology University of Calcutta 35 B.C. Road, Calcutta - 70(X)19 INDIA. Water conservation is a serious problem in land snails. Aestivation is the normal mechanism to tide over the adverse conditions during dry seasons in temperate and tropical countries. Studies on the orientation of the shell aperture in hibernating snails are very few. An upwardly directed aperture during hibernation is common in many land snails (Binney, 1851), in Mesodon thifroidu,^ and Allogona profunda (Blinn, 1963), and commonly upward in A. ptychophora (Carney, 1967). A pronounced effect is expected in specimens with long periods of aestivation, which is supported from the studies on Achatinafulica. METHODS AND MATERIALS Three cages measuring 600 x 450 cm and 240 cm high were erected in a shady place in the campus of Calcutta University at Ballygunge. Sized wood, 7.5 x 5 cm thick, and of appropriate length were used. The posts were fixed in the soil with concrete bases. The sides and the ceiling were covered with 1-cm expanded metal net. The soil of the floor of the cages was loosened with forks. A limited amount of water was sprayed on the soil on October 13 and 14, 1974. Then 200 healthy, active, juvenile and adult Achatina collected from their natural habitat were released in each of the cages No. 1 and 2. The snails were acclimatized for 18 days and water was regularly sprayed during the period to keep the soil sufficiently moist and maintain a high percentage of humidity in the cages. Favourite food was supplied in excess and strict hygienic conditions were maintained. The 32 THE NAUTILUS January 27. 1!)77 Vol. 91(1) snails were vigorously active in the period of ac- climatization. To simulate the natural habitat of Achatina. water-spraying was stopped on 2nd November, but the food supply was continued. OBSERVATIONS Nov. 7, 1974: Most of the snails in both the cages were partially buried in the soil or moving to a corner indicating preparation for aestivation. Some of the snails started moving up the frame of the cage but they were brought down and released on the soil. Nov. 11, 1974: The rest of the snails became in- active. Nov. 13, 1974: Epiphragm was formed in all specimens. In all cases the shell aperture was directed downward. Nov. 17, 1974: The aestivating snails in cage No. 1 were turned upside down, i.e., the aperture was directed upwards. The snails of the cage No. 2 were left undisturbed. There was no rainfall until February, 1975, when there occurred a total rainfall of 10.2 mm in 5 days at certain intervals. Feb. 11, 1975: rain- fall 3.9 mm. Feb. 12, 1975: rainfall 3.2 mm. The humidity in February was maximum 95%, minimum 35%. Temperature mean maximum 27°, mean minimum 15.5°. Feb. 12, 1975: 173 snails became active in cage No. 1. The remaining were already dead. Four specimens pushed out the epiphragm but soon died. 114 snails became active in cage No. 2. Ten snails were found dead under the epiphragm. In a few days the snails in both the cages underwent aestivation, all with the aperture downward. The snails of cage No. 1 were again turned upside down, so that the aperture faced upward. The month of March was dry. In the following month the total rainfall was 5.1 mm in 4 days. Apr. 25, 1975: Rainfall 3.2 mm; Apr. 26, 1975: Rainfall 1.6 mm. The humidity in April was ma.x- imum 91% and minimum 19%. Temperature mean maximum 35.4°, mean minimum 24.8°. Apr. 26, 1975: 107 snails became active in cage No. 1. They were immediately transferred to cage No. 3. 76 snails were active in cage No. 2. Apr. 27, 1975: 55 snails were dead under the epiphragm. the foot and head of 11 snails were pushed out of the shell and died in that state in cage No. 1, and dead snails counted were 26 in cage No. 2. The snails in cages 3 and 2 aestivated within a few days with the aperture downward. The snails of cage No. 3 were again turned upside down. A weak monsoon appeared in the first week of June and with heavy showers in the middle of the month all live snails in the cages became ac- tive. The number dead was 44 in cage No. 3 and .56 in cage No. 2. DISCUSSION The aestivation period in Stylommatophora dif- fers with species and the country where they live. For Achatina, the period is long between the rains in Mauritius and Ceylon (Green, 1910: Hut- son, 1920); during the dry spell in Singapore (South, 1926); November to March in Hong Kong (Herklots, 1948); November to June in India (Ghose, 1959) and February to March in Hawaii (Kondo, 1964). Helicella virgata aestivate for about 5 months in Australia (Pomeroy, 1968), while the period is only 2 months during summer for Macrochlamys glaum in India (Hora, 1928). Aiiophnnta is reported to aestivate in summer in India (Hora and Rao, 1928) but the duration is not on record. Observations on the orientation of shell aper- ture during hibernation in cold countries are on record (Binney, 1851; Blinn. 1963; Carney, 1967). The sole information on the influence of orienta- tion of shell aperture during aestivation in Allogona ptychophora is that of Carney (1966) in Montana, U.S.A., where the snails are covered with snow for sometime. The main function of epiphragm appears to be conservation of water. Both permeable and non- permeable epiphragms have been reported in dif- ferent Stylommatophora. The epiphragm is per- forated in Helix aspersa (Allman, 1894-95), but Smith (1899) recorded no perforation in the epiphragm of H. aspersa and H. pomatia. Rees (1964) considers the epiphragm of H. pomatia as slightly permeable. Perforations on the epiphragm have been reported from Thau mast us sangoae (Smith, 1904), Gessula hastula and Zootecus insularis (Hora, 1928) but these are Vol. 91(1) January 27, 1977 THE NAUTILUS 33 lacking in M glauca (Hora 1928). The epiphragm of Achatina is not permeable and a narrow slit- like opening in the epiphragm against the pneumostome maintains communication between the lung and the atmosphere. Smith (1899), however, states that the slitlike structure in A. immaailata is closed. Loss of water, though in small amounts, is associated with a reduced rate of respiration dur- ing aestivation. It appears that to minimize the loss further the shell aperture in A. fidica is placed against the substratum, be it soil or some other substance. The air locked in between the epiphragm and the soil is considerably cooler than the surrounding air. After two months of aestivation and a week after a shower, con- siderable amount of moisture in the expired air condenses into small drops of water on the epiphragm. In specimens with upturned apertures such phenomenon was totally absent. In Allogona ptychoph'peda) of North America. Biota of Freshwater Eco- systems Identification Manual No. 3. U. S. Elivironmental Protection Agency. .'11 p. hxkbiad, .James N.. 197.5. The Asian clam Corbiaila in the up- per Mississippi River. The Nautiltis 89(1): 4. Illinois Environmental Protection Agency, 1972. Water quali- ty network. 1972 summary of data. Vol. 2. Illinois, Fox. Sangamon, and Kankakee Basins. 243 p. Vol. 4. Mississippi River (South. South Central, Central, North Central, North), Big Muddy River. Kaskaskia River, and Rock River Basin, 538 pp. Springfield. Illinois. Ingram. William M., 19.59. Asiatic clams as potential pests in California Water Supplies. Journal American Water WwA".s Association 51(3): 3a3-370. Ingram. William M.. L. Keup, and C. Henderson, 1964. Asiatic Clams at Parker, Arizona. The Nautilus 11 (i): 121-124. Parmalee. Paul W.. 1965. Asiatic clam (Gwbicula) in Illinois. Transactions of the Illinois State Academy of Science 58(1): 39^5. Sinclair. Ralph M. and Billy G. Isom. 1961. A preliminary report on the introduced Asiatic clam Corbicula in Ten- nessee. Tennessee Department of Public Health. Tennessee Stream Pollution Control Board. 33 pp. Sinclair. Ralph M. IWi!. Effects of an introduced clam (Cor- bicula) on water quality in the Tennessee River Valley. Proceedings of the Second Industrial Waste Conference, Vanderbilt University. Tennessee Department of Public Health Tennessee Stream Pollution Control Board. 14 pp. Sinclair, Ralph M. and B.C. Isom, 1963. Further studies on the introduced Asiatic Clam (Corbicula) in Tennessee. Ten- nessee Department of Public Health. Tennessee Stream Pollution Control Board. 75 pp. Sinclair, Ralph M., 1971. Annotated bibliography on the exotic bi-valve Corbicula in North America, 1900-1971. Sterkiana 43: 11-18. Thomerson. Jamie E. and Donal G. Myer. 1970. Corbicula manilensi.'i: range extension upstream in the Mississippi River.5(erfria«o37:29. United States Geological Survey. 1973. Water resources data for Illinois. District Chief. Water Resources Division. U. S. (jeological Survey. Champaign. Illinois. 300 pp. BOOK Pseudothecosomata, Gymnosomata attd Heteropoda (Gastropoda). By S. van der Spoel. 1976. 484 pp., 246 figs. Bohn, Scheltema and Holkema, Utrecht. Hardbacii, $60.00 U.S. This book serves to bring together most of the current information on the pelagic pteropods and heteropods. A large mass of data, identification keys and drawings, and distributional maps will assist oceanographers working on plankton. The bibliography is extensive. The book, however, is difficult to use. The several indices are tucked away in various places in the text, and upon finding a reference the reader is led, not to a page number, but to a species number located on pages 16-22. Finally at this point the figures, maps and page numbers are revealed. The main treatment of a species does not give any geographical information, nor a reference to the proper maps at the end of the book. One must search first among the systematic table of contents to find a reference to the maps. REVIEW The nomenclatorial treatment of the heteropods is very unsatisfactory, with a few names being entirely ignored, such as Atlanta in- flata Orbigny, 1836. The Atlanta names legitimately proposed by Orbigny in 1836, Man- dralisca in 1840 and J. E. Gray in 1850 are erroneously considered to be nomina nuda (tesselata [sic] Gould, 1852 and pulchella Verrill, 1884), presumably in an attempt to conserve cer- tain better-known names. However, Gray's 1850 Cavolinia names are accepted. The genus Mirrodonta Bonnevie, used by van der Spoel. is three times a homonym, and should be replaced by Prionoglossa Tesch, 1950. Some additional illustrations of recently described, shelled pteropods and newly recognized forma are included with convenient keys. The new subfamily Glebinae is proposed in the Cym- buliidae. R. Tucker Abbott Delaware Museum of Nation History Vol. 91(1) January 27, 1977 THE NAUTILUS 37 Portrait o/All-j/n G. Smith taken in 1955 by Moulin Studios of San Francisco. OBITUARY ALLYN GOODWIN SMITH, 1893-1976 With the passing of Allyn G. Smith on August 18th, 1976, malacology lost one of its most ad- mired and knowledgeable students of West American mollusks. Bom June 4, 1893, in Hart- ford, Connecticut, Allyn went to California in 1908, and later attended the University of California at Berkeley, receiving a B. S. in Elec- trical Engineering in 1916. After serving in the U. S. Army in World War I, he returned to his Alma Mater, to chair the Technical Department in the Extension Division (1920-1924). In 1925, he joined the Pacific Telephone and Telegraph Co., where he held the title of Supervisor of Personnel at the time of his retirement in 19.55. His special interests in pulmonate gastropods and the chitons was initially generated by his close friend, S. Stillman Berry, who fondly refers to him as "one of my boys". He also knew the Californian malacologist, Jo.siah Keep. During his business career Allyn devoted much of his spare time to field work, and he contributed numerous malacological articles to journals. A major con- tribution was a survey of "The Marine Mollusks and Brachiopods of Monterey Bay, California and Vicinity" (with Mackenzie Gordon, Jr.) published in 1948. Upon his retirement, he had hoped to devote full time to research, but his administrative talents were drafted by the California Academy of Sciences, where he had served as a Research Associate in Malacology since 1939. There he started a new career in the capacity of Executive Assistant to the director, 1955-1960, and as Chairman and Associate Curator, he later revitalized the Department of Invertebrate Zoology, 1960-72. Despite these duties, he prepared the section on "Amphineura" for the Treatise on Invertebrate Paleontology, 1960, and he continued publishing and field work, including participation in the Galapagos International Science Project in 1964. Author of 104 papers, two of which appeared in 1976, he was active until shortly before his death. An energetic and compassionate man of many interests and achievements, Allyn will be sorely missed by his many friends and colleagues. He leaves his wife, Katharine, and three children. William K. Emerson, Curator of Mollusks The American Museum of Natural History New York, New York Murex Shells of the World An Illustrated Guide to the Muricidae. George E. Radtvin & Anthony D'Attilio. Photos by Davtd K. Mt4lliner. Prepared for the ama- teur collector as well as the professional conchologist and malacologist, this exhaustively detailed work is the first reliable taxonomic treatment of the Muricidae since 1880. It offers many innovations in classification, and pro- vides descriptions, range data, and synonymy for some 390 species (15 described here for the first time). Illustrations include full-color photos of 456 specimens, 61 black-and-white drawings or photos, and 179 line drawings. Introduction, Glossary, Bibliography, Index. $35.00 Marine Algae of California Isabella A. Abbott & George J. Hollenberg. Contributions by specialists. This first complete systematic study of California seaweeds, an extension of G. M. Smith's classic Marine Algae oj the Monterey Peninsula, covers 80 percent of the species known from Alaska to Panama. Designed as a combined laboratory and field reference, it illustrates each of the 701 taxa treated by one or more line drawings, and includes comprehensive information for all species treated, an Introduction, a history of West Coast algal study by G. F. Papenfuss, maps, a Master Key to Genera, Glossary, Bibliography, Index. $2.2.. 50 Stanford University Press INFORMATION FOR SUBSCRIBERS The annual subscription rate for The Nau- tilm is $7.00 for individuals and $12.00 for in- stitutions (domestic or foreign). Subscriptions may begin in January. Send check or money or- der to "The Nautilus" to Mrs. Horace B. 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Explanatory terms and symbols within a drawing should be neatly printed, or they may be pencilled in on a trans- lucent 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, in- formation 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 sam- pling 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 modem facilities and equipment for the housing and curating of voucher specimens. Material 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. APRIL 25, 1977 THE NAUTILUS Vol. 91 No. 2 A quarterly devoted to malacology and the interests of conchologists 0 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. Division of Mollusi'pes in Ecole des Mines, Paris 39 John H. Rodgers, Jr., Donald S. Cherry, et. al. The Invasion of Asiatic Clam, Corbicula manilensis, in the New River, Virginia 43 Robert C. Wall Seasonal Movements of the Pond Snail, Lymnaea catascopium, in a Northern Lake 47 Eva Pip Frequent Scalariformy in a Population of the Pond SnaW Zymnaea stagnalii 52 Robert F. McMahon Shell Size- Frequency Distrihutions of Corbicula manilerisis Philippi from a Clam-fouled Steam Condenser 54 M. G. Harasewych Abnormal Hyperstrophy in Littorina lineolata (Gastropoda: Littorinidae) 60 Leroy H. Poorman and Forrest L. Poorman Four Opisthobranchs Living on Marine Algae from West Mexico 62 Clement L. Counts, III The Miocene Bivalve Cumingia medialis (Semelidae) from South Carolina 66 Tom M. Spight Latitude, Habitat, and Hatching Type for Muricacean Gastropods 67 Walter 0. Cemohorsky Comis viola, a New Name for C. inolacea Reeve 72 Tom M. Spight Is Tfiaiii canalicidata (Gastropda: Muricidae) Evolving Nurse Eggs? 74 Branley A. Branson The Chinese Apple Snail, Cipangopaludina chinensis,on Orcas Island, Washington 76 Fred G. Thompson The Polygyrid Genus McLeawm in Hispaniola 77 Publications received v Recent Deaths 80 PUBLICATIONS RECEIVED Yonge. C. M. and T. E. Thompson. 1976. Liiing Marine Molluscs. 228 pp., 162 text figs., 16 color pis. A well-written textbook introduction, with the two opisthobranch chapters by T. E. Thompson. Distributed in the U.S. by Amerirnn Malai-nhKitsts. Publ., Box 42t)8, Greenville. De. 19807. $13.9.5. Alonso, M. R. 1975. Fauna Malocologica Terrestre de la Depre- sion de Granada (&pana). II. H Genero Helkella Ferussac, 1821. Cuademos de Ciencias Biologicas Granada, vol. 4, no. 1, pp. 11-28; I Pulmonados Desnudos, pp. 71-88. Warmuth, John H. 1976. The Biogeography and Numerical Taxonomy of the Oegopsid Squid Family Ommastrephidae in the Pacific Ocean. Bull. Scripps Institute Oceanography, vol.2;?,90pp. Paper.$:B..%. Paraense, W. Lobato. 1976. Helisoma trivolris and Some of Its Synonyms in the Neotropical Region (Mollusca: Planor- bidae). Rev. BrasU. Biol. 36(1): 187-204. Paraense, W. Lobato. 1975. Estado Atual da Sistematica dos Planorbideos Brasileiros. Arg. Mus. Nac. RJ, vol. 55, pp. 105-128, 69 figs. Anatomy and shells well-illustrated. Abbott, R. Tucker (Editor). April 1976. ne Best of ne Nautilus. A Bicentennial Anthology of American Con- chology. viii + 280 pp., 1 color pi., text figs. American Malacologists, Publishers, Box 4208, Greenville, De. 19807. Hardback, $13.95. Presentation copy with slip box, $38.00. Hastings, Louise B. 1976. Index to the Taxonomic Names in Edwin A. Joyce, Jr., 1972, A Partial Bibliography of Oysters, with Annotations. Florida Dept. Natural Resources, St. Petersburg. Pamplet, 40 pp. Available from Delaware Museum of Natural History, Box 3937, Greenville, De. 19087, by sending 3 13-cent postage stamps. Quayle, D. B. 1975. Tropical Oyster Culture-A Selected Bibliography. 40 pp. (267 entries). International Develop- ment Research Center, Box 8500, Ottawa, Canada KIG 3H9. $2.50. Gasull, Luis and Juan Cuerda. 1974. Malacologia del Conten- ido Gastrico de las Grandes E^trellas de Mar. Bol. Soc. Hist. Nat. Baleares. vol. 19, pp. 1,5,5-173, 3 pis. Franchini, Dario A. (EMitor). 1976. Simposio sui molluschi ter- restri e dulcicoli dell' Italia Settentrionale. Mantova. 102 pp., 9 pis., text figs. 11 articles on such mollusks as Cingulifera, Ancylus. Lartetia. Paladilhiopsis and Dreissena. Tchang. Si, et al. 1975. A Checklist of Prosobranchiate Gastropods from the Xisha Islands, Guangdong Province, China. Studia Marina Sinica. no. 10 pp. 105-132, 7 pis. (7 Nan-Hai Rd., Tsingtao, People's Republic of China). Handel, Klaus. 1976. Morphologie der Gelege und Okologische Beobachtungen an Buccinaceen (Gastropoda) aus der Siidlichen Karibischen See. Bonn. Zool. Beitr., vol. 27, pp. 98-1X3. Also treats with fasciolariid and turbinellid egg cap- sules. Hubendick, B. and A. Warren. 1976. Framgalade Srackor fran Svenska Vastkusten. Collection of 7 articles on the marine prosobranchs of Sweden. Excellent illustrations in this usefull handbook originally published 1969-1976. Box 11049, Naturhist. Mus., Goteborg, Sweden 400.30. 25 kronors. Shells and Shores of Texas By Jean Andrews This guide to the mollusks of the shallow marine waters of Texas and the Gulf coast is arranged according to the latest classification system, and each entry Is accompanied by an illustration. This book contains the clear, detailed depiction of more minute species than any other one source as well as one of the most extensive bibli- ographies in the field. 512 pages, 24 color plates, 367 b&w photo- graphs, 77 line illustrations $19.95 through Dec. 31 , 1977; $24.95 thereafter University of Texas Press == Box 7819 V^ Austin, Texas 7871 2 FOR SALE Several complete original sets of Jdhiii^ouia, vol. 1 to vol. 5, no, 50 $130 each; | postpaid (unbound). Several incomplete sets (pt. 5 absent) of | Dall's Teii inry Fauna < )/ Florida, 1890-1895 (Gastropods and some bivalves). Send for price list. Write: Dept. G., The Nautilus, Box 4208 Greenville Delaware 19807. Vol. 91 (2) April 25, 1977 THE NAUTILUS 39 DESHAYES' TEREBRID TYPES IN ECOLE DES MINES, PARIS Twila Bratcher 8121 Mulholland Terrace Hollywood. Ca. 90046 It has been well over a hundred years since Cierard Paul Deshayes published his descriptions of 95 new terebrid taxa. The 33 species published in 1857 in the Journal of Conchyliologie were written with surprising detail for that period. Those written by most of his contemporaries were sketchy descriptions in Latin and could fit any number of species. Deshayes followed his Latin descriptions with excellent word pictures in French of the species he was describing. Deshayes must have loved each species he described. He discussed them with such phrases as "beautiful and precious," "this very beautiful and remarkable species," "charming species." In one description he said, "All the shell is smooth, polished, shining as though it were made of porcelain." The figures in his 1857 monograph are exceptionally good in quality and detail. The 62 taxa Deshayes described in the Pro- ceedings of the Zoological Society of London, 1859, are less easy to evaluate. Although the Latin descriptions are somewhat more detailed than most of that period, they were not followed by his fine French descriptions. They were published without figures. Some of the taxa were subsequently figured by Reeve. Some have never been figured. In all his descriptions Deshayes stated whether the material was from the Cum- ing collection, now in the British Museum (Natural History), or from his own collection, now in the Ecole des Mines, Paris. In 1944 in his "Deshayes Review of Terebra in the Journal of Conchology," Tomlin stated, "Probably there is more synonmy to be worked out with regard to Deshayes" new species. It would-be a great ad- vantage to get the types at the Ecole des Mines overhauled." When I visited the Ecole des Mines in the spring of 1975, I located nine of the holotypes and one probable holotype in the Deshayes collection. Deshayes' detailed French descriptions, in addi- tion to his original measurements, made this task easier than it might have been. Because of his careful attention to detail, specimens differing substantially in measurement from those published by Deshayes could not be accepted as holotypes. An exception was Terebra eximia Deshayes, 1859. Deshayes' measurements were 92 x 8 mm, which is evidently a misprint. The specimen which appears to be the holotype measures 46 x 8 mm. It is obvious that if a specimen of this species should reach a length should reach a length of 92 mm , the diameter would be greater than 8 mm. Some of the Deshayes taxa represented as be- ing from his own collection could not be found at all. The measurements of some differed substan- tially from the original Deshayes measurements, and are here considered paratypes. TEREBRIDS FROM DESHAYES' COLLECTION Terebra archimedis Deshayes, 1859, holotype, fig. 1 & lA. Not previously figured. Dimensions 31 x 5.8 mm. Original measurements 31 x 6 mm. In his description Dehayes stated that this species was representated in his collection only. Therefore I believe the specimen in the Ecole des Mines is the holotype rather than the specimen in the British Museum (Natural History) cited as the type by Cemohorsky (1969) which measures 32.7 mm in length. Type locality unknown. This is conspecific with the Indo-Pacific species, T. funicidata Hinds, 1844, and T. langfordi Pilsbry, 1921, as there are integrades between the forms. Schepman illustrated T. archimedis in his Siboga Expedition report, but the figure was of the funicidata form rather than the archimedis form. Terebra approximata Deshayes, 1859. No figure was published. Type locality unknown. Reeve con- sidered this taxa to be a junior synonym of T. un- dulata Gray, 1834, a fairly common Indo-Pacific species. No specimens of this taxa were found in the Deshayes collection . 40 THE NAUTILUS April 25.1977 Vol. 91 Terebra argeninllii Deshayes, 1859. No figure was published. Type locality unknown. Reeve places this taxa in synonymy with T. strigilata Lin- naeus, 1758. No specimens of this taxa were found. Terebra chilensis Deshayes, 1859, holotype, fig. 2. No figure previously published. Dimensions 40.2 .\ 7.9 mm. Original measurements 42 x 8 mm. TVpe locality Chile. Tliis is a synonym of T. gemmidata Kiener, 1839, a rare species reported from Chile, Patagonia, and Brazil. Terebra chinensis Deshayes, 1859. No figure was published. Type locality is China Seas. Reeve con- sidered this conspecific with T. cingnlifera Lamarck, 1822, a common Indo-Pacific species. No specimens of this taxa were found. Terebra columnam Deshayes, 1859. No figure was published. Type locality unknown. Reeve con- FUJ. 1. Terebra archimedis IJeshayes. 18.59, holotype. FIG. 2. Terebra chilensis Deshayes, 18.59, holotype. FIG. X Terebra crassula Deshayes. 18.59, paratype. FIG. 4. Terebra crosxei Deshayes. 18,59. holotype. FIG. 5. Terebra exiniia Deshayes. 18.59, holotype. FIG. 6. Terebra mat heroniana Deshayes, 1859, holot>T)e on left, paratype on right. sidered this conspecific with T. cingulifera Lamarck, 1822, as did Tryon. No specimens of this taxa were found, Terebra crassula Deshayes, 1859, paratype, fig. 3. No figure was previously published. Dimensions 23. 6 X 5.2 mm. Original measurements 27 x 7 mm. Differences of measurements are sufficient that this must be considered a paratype. Type locality unknown. This is a synonym of Ha,'>tula hmtata (Gmelin, 1891), a common western Atlan- tic species. Terebra crossei Deshayes, 1859, holotype, fig. 4. No figure was published previously. Dimensions 24 X 5 mm. Original measurements 23 x 5 mm. Type locality Indian Ocean, this is a synonym of Hastula penicillata (Hinds, 1844) a common Indo-Pacific species, Terebra difficilis Deshayes 1859. Figured by Reeve, Conch. Icon. vol. 12, pi. 18, fig. 86. Type locality unknown. Reeve said of this species, "a shell of solid growth, partaking somewhat of the character of T. laiDoefomm. in which the fine ribs are so crowded as almost to lap one on the other. It comes even nearer to T. souleyti " Tryon said it is conspecific with T. cancellafa Quoy & Gaimard, 18.32. No specimens were found in the Deshayes colletion. Terebra dispar Deshayes, 1859. Figured by Reeve, pi. 25, fig. 1.37. Type locality unknown. Reeve said, "shining-white, semi-transparent. Very closely resembles T. micans. " Tryon said it equals both cinerea (Bom, 1778) and aciculina (La- marck), two species which are quite distinct from one another. No specimens found in the Deshayes collection. Terebra eximia Deshayes, 1859, probable holotype, fig. 5. Figured by Reeve, pi. 21, fig. 106. Dimensions 46.2 x 8 mm. Original measurements 92 X 8 mm, evidently a typographical error. Type locality unknown. This is conspecific with T cor- rugata Lamarck, 1822. Terebra fimbriata Deshayes, 1857, holotype, fig. 10. Figured by Deshayes, pi. 5, fig. 1. Length 88.6 mm. Original measurements 88 x 19 mm. Type locality unknovwi. There is a paratype in the British Museum (Natural History). This taxa is a Vol. 91 (2) April 25, 1977 THE NAUTILUS 41 junior synonym of T. crenulata Linnaeus, 1758. Terebra glabra Deshayes, 1857. Figured by Deshayes. Type of locality is China Seas. No specimen was found in the Deshayes collection in the Ecole des Mines. There is a specimen in the British Museum (Natural History) marked Type, T. glabra, which is obviously erroneous. Cemohor- sky (1969) pointed out that "The specimen pres- ent in the Cuming collection and measuring 43.3 mm in length (original measurement 70 mm) is not the type; the holotype is probably in the Ecole des Mines in Paris". The specimen in the British Museum is a worn specimen of T. consors Hinds, 1844, and Tomlin said it equals T. consors. Deshayes said in shape, size, and coloration it more nearly resembles T. cingulifera Lamarck, 1822. He also stated that the shell is all white or of a white washed with pale beige. He made no mention of the yellow blotches typical of T. con- sors. Tomlin made his evaluation from the specimen in the British Museum, and whether that specimen- is the same species as Deshayes' T. glabra probably will not be known unless the Deshayes holotype is found. Terebra histrio Deshayes, 1857. Figured by Deshayes. Type locality unknown. Reeve and Tomlin both mention that the type is cited from the Deshayes collection but that there was one in the Cuming collection which is merely a form of T. cormgata Lamarck, 1822. Neither Deshayes' description nor his figure is that of T. corTugata. No specimen found in the Deshayes collection. Terebra matheroniana Deshyes, 1859, holotype, fig. 6 paratype, fig. 6 (right). Not previously figured. Dimensions 17.4 x 3.3 mm. Original measurements 18 x 3 mm. Type locality Tahiti. TTiis is a species about which there has been much confusion. E. A. Smith considered it a good species and Tomlin agreed, citing Terebra lauta Pease, 1869 as a synonym. I agree with that. Reeve considered T. matheroniana a synonym of T. aciculina Lamarck, 1822, to which it bears no resemblance. Terebra nbsoleta Deshayes, 1859, holotype, fig. 7. Figured by Reeve, pi. 21, fig. 107. Dimensions 38.9 X 7 mm. Original measurements 40 x 7 mm. Type locality unknown. Reeve mentioned that this shell had indications of a brown band at the base FIG. 7. Terebra obsoleta Deshayes, 1859, holotype. FIG. 8. Terebra pundicidata Deshayes, 18.59, holotype. FIG. 9. Terebra splendens Deshayes, 1859, holotype. FIG. 10. Terebrafimbriata Deshayes, 1857. holotype. FIG. 11. Terebra subanguluia Deshayes, 18.59, holotype. FIG. 12. Terebra verreaun Deshayes, 1857, holotype. which may have faded during the last hundred years. Terebra puncticuLata Deshayes, 1859, holotype, fig. 8. Previously figured by Reeve, pi. 20, fig. 99. Dimensions 24.6 x 6.2 mm. Original measure- ments 25 X 6 mm. Type locality unknown. Synonyms: T flava Hinds, 1844 (non Gray, 1834); f. lutescens E. A. Smith, 1873. Terebra souleyeti Deshayes, 1859. Figured by Reeve, pi. 17, fig. 78. Type locality Gulf of Mexico. No specimens fotmd. Terebra splendens Deshayes, 1857, holotype, fig. 9. Figured by Deshayes, pi. 5, fig. 11. Dimensions 73.8 X 12.6 mm. Original measurements 75 x 12 mm. Type locality is China seas. This is T. dimidiata Linnaeus, 1758. Terebra semidecussata "Deshayes". This is evidently a manuscript name. It equals T dislocata (Say, 1822). 42 THE NAUTILUS April 25,1977 Vol. 91 (2) Terebra subangidata Deshayes, 1859, holotype, figs. 11. Previously figured by Reeve, pi. 18, fig. 87. Dimensions 33.6 x 6.8 mm. Original measure- ments 34 X 7 mm. Typ)e locality unknown. Terebra verremtxi Deshayes, 1857, holotype, figs. 12 & 12 A. Figured by Deshayes, pi. 5, fig. 3. Dimensions 37.9 x 7.8 mm. Original measure- ments :38 X 9 mm. Type locality unknown. This is a synonym oiHastula strigilata (Linnaeus, 1758). ACKNOWLEDGMENTS I am indebted to the personnel of the Ecole des Mines in Paris, particularly Mme. E. Fatton, for the privilege of working with and photographing the Tcirhridac in the Deshayes collection and for help through correspondence since my return. I also wish to thank Sally Kaicher for her advice on shell photography and for her work in making prints for publication from my negatives taken at the Ecole des Mines; Dr. James McLean for his comments and suggestions regarding this man- uscript: and Dr. R. Tucker Abbott for the use of his picture of the holotype of Terebra fimbriata Deshayes. LITERATURE CITED Bom, Ignatius von. 1778. Indei Rerum Naturalium Muxpi Casenrpl Vi iidnbonens-is. Part 1; Testacea pp. 1-458, 1 pit. Cernohorsky, Walter Oliver. 1969. List of Type Specimens of Terebridae in the British Museum (Natural History). The Veliyer.um:2\0-2i. Deshayes. Gerard Paul. 1857. Descriptions de nouvelles especes du genre Terebra. Jmtr. de Conchyl. 6: 65-102, pits. 3-.5. 1859. Deshayes, G. P. 18.59. A general review of the genus Terehni. Rare and Exotic Specimen Shells for the discriminating collector Free price list Janowsky's MAL DE MER ENTERPRISES 946 Ralph Avenue Bnjoklyn, New York 11236 USA (212) iS5-S550 bJlb^ki^Lrf^^^ .aaJ and a description of new species. Pnic. Zool. Sue. London, pp. 270-321. Gmelin. Johann Frederich. 1791. Carol! a Linne Systema naturae per regna tria naturae. Editio decima tertia. pp. ,'M98-3506. Gray. John Edward. 1834. Enumeration of the species of the genus Terebra, with characters of many hitherto un- described. /Voc Zoal. Soc. Umdim for 1832, pp. 59-63. Hinds. Richard Brinsley. 1844. Descriptions of new Shells, col- lected during the voyage of the Sulphur, and in Mr. Cum- ing's late visit to the Philippines. [On new species of Terebra]. Proc. Zool. Soc. London for 1843, pp. 149-68. Lamarck, J. B. P. A. de M. de. 1822. Histoire naturelle des animaux vertebres, pp. 238-91. Linnaeus. Carolus. 1758. .Systema naturae per regna tria naturae. Eiiitio decima. reformata. pp. 741-42. Pilsbry, Henry Augustus. 1921. Marine Mollusks of Hawaii Vlli-XIII, Proc. Acad. Nat.. Set Philadelphia, pp. 300-09, pi. 12. Reeve. Lovell Augustus. 1860. A monograph of the genus Terebra. Conch. Icon. vol. 12, Terebra, pis. 1-27. Reeve, Lovell A. 1860. A commentary of M. Deshayes's Revi- sion of the genus Terebra. Proc. Zool. Soc. London, pp. 448-50. Say, Thomas. 1822. An account of some of the marine shells of the United States. Joitm. Acad. Nat. Sci. Philadelphia 2: 221-48. Schepman, Matteus Martinus. 1912. The Prosobranchia of the Siboga Expedition, part 5, Toxoglossa, Terebra, pp. 369-77, pit. 25. Smith, Exigar Albert. 1873. Remarks on a few species belong- ing to the family Terebridae and descriptions of several new forms in the collection of the British Museum. Annals and Magazine of Natural History ll(4th): 262-71. Tomlin, John Read le Brocton. 1944. Deshayes' review of Terebra. Jam. Conch. 22: 104-8. Tryon, George Washington. 1885. Man. of Conch., vol. 7, Terebridae. pp. 3-64; 12 pis. Price Reduced: LIVING VOLUTES A Monograph of the Recent Volutidae of the World by Weaver and duPont A classic identification book with :?75 pages and 79 full-color plates. Form- erly $55.00, now only $36.00, plus post- age (25 cents in the U.S.). Order now from your local bookdealer or: Delaware Museum of Natural History Box 3937, Greenville, DE. 19807, U.S.A. ••W^s. Vol. 91 (2) April 25, 1!»77 THE NAUTILUS 43 THE INVASION OF ASIATIC CLAM, CORBICULA MANILENSIS IN THE NEW RIVER, VIRGINIA John H. Rodgers, Jr., Donald S. Cherry, James R. Clark, Kenneth L. Dickson and John Cairns, Jr. Center for Environmental Studies and Department of Biology Virginia Polytechnic Institute and State University Blacksburg, Virginia 24061 ABSTRACT Corbicula manilensis appems to have successfully invaded the New River at Glen Lyn. Giles County, Virginia in 1975. Mean population densities of 18 Cor- bicula, m'^ were recovered doumstream from, a coal-fired generating plant while 29 individuals m'^ were found immediately upstream. This seems to be the pre- sent limit of Corbicula immigration in the New River as no specimens were taken from .^ampliiig si fes farthe r upstream. Relationships between shell deniensions and shell weights, and viscera wet and dry weights were calculated from the one size "year class" present. Correlation coefficients ranged from 0.9683 for shell length and viscera wet weight to 0.6135 for shell dry weight and viscera dry weight. INTRODUCTION The present paper is the first report of Cor- bicula manilensis Philippi in the New River, Virginia, and to our knowledge, only the second report of Corbicula in this state (Diaz, 1974)'. Un- til recently, extensive investigations of benthic macroinvertebrates of the New River (con- sidered by many to be the second oldest river in the world) and its tributaries had not reported any specimens of this clam. The range extension of the Asiatic clam up this river is being careful- ly monitored, since the New River is an impor- tant source of water for various industries and municipalities. The biology of this organism and its relationships to other benthic and molluscan fauna can be studied, since pre-invasion data are available and this potential problem was revealed in its infancy. MATERIALS AND METHODS Forty specimens of Corbicula manilensis were ' Tlie Delaware Museum of Natural History has numerous adult specimens collected in 1974 by Mrs. Betty Piech near Lanexa. Virginia, in the Chickahominy River which flows in- to the James River. randomly selected from quantitative collections starting on 12 October 1976, from sites above and below a coal-fired generating plant located on the New River at Glen Lyn in Giles County, Virginia (latitude-37°22'20", longitude-30°51'45", river mile 95) (Fig. 1). The upriver station was established 45 m above the intake pump station through which water is drawn for condenser cool- ing in the power plant. The plant generating capacity is approximately 300 MW with a max- imum of 340 MW. After passage through the plant, the heated water may be raised to a max- imum of 8 C above above ambient; however, dur- ing these collections there was a 3 C difference between the upriver and downriver stations (13 C and 16 C respectively). The substrate was characterized by gravel, sand and silt with sand and silt comprising minor portions (after Hynes, 1970). The downriver station was located approx- imately 50 m below the pipe through which the heated water is discharged. The heated effluent was usually chlorinated three times daily to con- trol biofouling of the condenser pipes. At this sta- tion, the substrate ranged from cobbles and peb- bles to very fine sand with a predominance of the former. During sampling, water depth at both 44 THE NAUTILUS April 25.1977 Vol. 91 (1: Stations ranged from 0.5 to 0.9 m with average flows of 18-21 cm see"'. Alkalinity (as CaCOj), pH and turbidity were 39 mg 1"', 7.80 and 35.0 Jackson Turbidity Units, respectively. Samples were taken at each station using a 0.25 m^ quadrant and a net to a depth of 15 cm. Clams were picked from each sample, counted, placed in water on ice and transported to the laboratory for further analyses. Travel time was less than two hours and samples were processed immediately. Dimensions and weights were deter- mined as described by Joy and McCoy (1975). 0 C 20 so KILOMETERS FIG. 1. Kanawha River basin and sampling sites on the New River. X—Mud River, (hbell (.krunty. West Virginia; second report of Corbicula from West Virginia, 10 October 1973 (Joy and McCoy. 197,5); h—Oielyan. Kanawha Qnmty. We.it Virginin; first report of Corhicnld from West Virginia, 17 July 196:1 -population had been established .iince 1961 by size "year class" data (Thomas and Mackenthun. 1961,1; C—den Lyti. (riles County. Virginia; Corbicula collected IJ October 1976 -pcrpulation had been estahlvihed since 197!> by size "year class" data (River Mile 95); D—Ltirich. (riles (hiinty, Virginia (River Mile 97); E— Narrows, (riles (hunty. Virginia (River Mile i(>2); ¥— McCoy, Montgomery County. Vi rgi n ia (Ri ver Mile 1 .11). RESULTS AND DISCUSSION The invasion rate of Corhieida in the Upper Ohio and Kanawha River Drainage basin can be estimated from available reports. Due to the distinctive morphology of the adults and larvae, the Asiatic clam is easily and likely to be distinguished from indigenous bivalves. A collec- tion of Corbicula reported from Chelyan. West Virginia, (Fig. 1) indicated, by size "year classes," that a population had been established there .since 1961 (Thomas and Mackenthun, 1964). A subsequent collection in Cabell County, West Virginia, was made in 1973 (Joy and McCoy, 1975). If the downriver area is the source of pro- pagules for the population becoming established at Glen Lyn, Virginia, the clams would have traversed a distance of about 138 river miles in a period of 15 years, or an average rate of about 9 miles year"'. Several physical barriers encoun- tered alone the suspected path of invasion include London Lock and Dam above Chelyan, Kanawha County, West Virginia, and Kanawha Falls and Bluestone Dam at Hinton, Summers County, West Virginia. This dam forms Bluestone Lake, a reservoir which is utilized for both flood control and hydroelectric power. The relatively rapid movement of the clam implies some augmenta- tion of its natural dispersive mechanisms. It is highly improbable that the nonparasitic plank- tonic veliger larvae would be capable of moving against the current at such a rate. Since no parasitic stage is present in the life cycle, a fish host would not be involved in dissemination (Sinclair, 1964). More likely, their movement was probably aided by fishermen as fishing pressure is relatively intense in this river system. Addi- tionally, transportation may have been provided by waterfowl since Clench (1970) stated that Cor- bicula may be able to pass through the intestinal tracts of ducks in viable condition. Live specimens are being sold and shipped to fish hob- byists around the country (Abbott, U)75). Subse- quent intensive sampling of the New River upstream from Glen Lyn at Lurich, Narrows and McCoy, Virginia, did not yield any specimens (Fig. 1). These results indicated that the clam had not yet been able to invade these areas. Based on approximations of age from shell Vol. 91 (2) April 25, 1977 THE NAUTILUS 45 TABLE 1. Means l± S E) and ranges of parameters meaKured far Corh\cu\a sampled friiin upriver and dmenriver stations. i'pnvcr iMnninvrr Measured Pnrameler X±S; Rafiiie X±S.r Ram/r Shell Length (mm) 9.8 ± 0.37 7.2 - 12.3 9.6 ± 0.32 7.1 - 12.0 Shell Width (mm) 6.6 ± 0.27 5.0 - 8.3 6.6 ± 0.25 .5.1 - • 8.4 Viscera Wet Weight (mg) 26.8 ± 1.34 18.7 - .^5.1 25.9 ± 1.09 19.0 - 34.1 Vise-era Dry Weight (mg) 8.0 ± 0.45 5.2 - 10.7 8.7 ± 0.54 5.7 - 14.6 Shell Dry Weight (mg) 105.4 ± 9.74 8.9 - 141.1 1066 ± 7.99 8.3 - 140.9 lengths (Joy and McCoy, 1975), it was apparent that the Corbkida collected at Glen Lyn were in their first year (Table 1). Most of these specimens were probably sexually mature (Gardner et al., 1976) and should have been in the area since 1975. Mean density at the downriver station of 18 clams m"^ was significantly less (t-test, 0.05 level) than the mean density of 29 m'^ at the upstream station. This difference may be attributed to the influence of the power plant discharge or a substrate-associated distribution phenomenon. This subject as well as seasonal density dynamics will be further examined in future research. Least squares regressions (of the form y = a + bx) and Pearson product-moment correlation coefficients (r) were calculated for ten relation- ships between shell dimensions and weights, and viscera mass weights (Table 2). All correlations TABLE 2. Regression analysis equations (y = a + bx) and correlation coefficients for various relationships between shell dimensions and weights, and wet and dry viscera weights of Corbicula.' Equations - Vaki. W = - - 0.1613 + 0.7072 L 0.9a59 S= - - 92.5123 + 20.5729 L 0.8017 VWW = - - 6.5322 -1- 3.4099 L 0.9683 VDW = - - 2.2559 -1- 1.0988 L 0.7616 S = - - 55.0134 -1- 1.0988 L 0.7197 VWW = - - 1.4196 -1- 4.2002 W 0.9052 VDW= - - 2.5536 -1- 1.6476 W 0.8666 VWW = 15.7612 -1- 0.10(»S 0.7292 VDW = 4.6899 -1- 0.0345 S 0.6ia5 VDW = 0.0892 + 0.ia34VWW 0.7648 'W = width of shell (mm) L = length of shell (mm) VWW = wet weight of visceral mass (mg) VDW = dry weight of visceral mass (mg) S = dry weightof shell (mg). ' Significance level, P = 0.0001. were highly significant (P<0.01) although the cor- relation coefficients were slightly less than those of Joy and McCoy (1975). This can be explained by the variability associated within the one size class in this study compared with a range of size classes (from about one to more than four years) collected by Joy and McCoy (1975). It is in- teresting to note that the width of their specimens averaged about 66% of the clams' lengths which agreed closely with the average of 70% in this study. Sinclair and Ingram (1961) reported somewhat different morphology in specimens from the Tennessee River (shell width about 89% of length based on their published photographs). Only the correlation between shell length and viscera wet weight was greater in this study (r = 0.9683) than in the investigation of Joy and McCoy (1975) (r = 0.9407). Results of this study agreed with the observation of Joy and Mc- Coy (1975) that viscera wet, rather than dry, weight correlation coefficients are greater and in- dicate that noncombustible mineral uptake varied more per individual than water content. It is anticipated that the impact of Corbicula on this river system will be exhibited primarily in two different areas: 1) decline in populations of other bivalves as seen during the invasion of the Altamaha River in Georgia (Gardner et al., 1976); and 2) increase in problems associated with industrial and municipal water use (Sin- clair, 1964, 1971). The survival of indigenous species of Margaritifera, Tristigonia, Elliptio, Sphaerium and Piddium in the New River ap- pears to be seriously threatened. ACKNOWLEDGMENTS Appreciation is expressed to James H. Ken- nedy, Biology Department, Virginia Polytechnic Institute and State University, for confirming 46 THE NAUTILUS April 25,1977 Vol. 91 (2) identification of Corbicula and to employees of Applachian Power Company's Glen Lyn Plant for cooperation during the river collections. LITERATURE CITED Abbott. R. Tucker 197.5. Beware the Asiatic Freshwater Oam. Tropical Fish Hnhhi/ist. 23: 1.5 (Feb.). Clench. W. J. 1970. Corbicula manilensis (Philippi) in lower Florida. The Nautilus 84(1): 36. Diaz, R. .J. 1974. Asiatic clam, Corbicula manilensis (Philippi), in the tidal .James River, Virginia. Chesapeake Sci. 15(2): 118-120. Gardner, J. A., Jr., W. R. WoTies, H. B. N. 1970. The Ecology of Running Waters. Univ. of Toronto Press, Toronto. 555 pp. Joy, J. E. and L. E. McCoy. 1975. Comparisons of shell dimen- sions and viscera mass weights in Corbicula manilensis (Philippi, 1*4«). The Nautilus 89(2): .51-.54. Sinclair, R. M. 1964. Clam pests in Tennessee water supplies. Jour. Amer. Water Works Assoc. 56: 592-599. Sinclair, R M. 1971. Annotated bibliography on the exotic bivalve Corbicula in North America, 1900-1971. Sterkiana 43:11-18. Sinclair, R. M. and W. M. Ingram. 1%1. A new record for the Asiatic clam in the United States, the Tennessee River. The Nouh/iAs 74(3): 114-118. Thomas, N. A. and K. M. Mackenthun. 1964. Asiatic clam in- festation at Charleston, West Virginia. The Nantilux 78(1): 28-31. a sumptious and appropriate Bicentennial Gift Regular Library Edition A handsome, durable hardback edition bound in simulated leather and of the highest quality of printing, with marble- ized end papers. A dozen well-known shells are shown in full color. Only $1.3.95. A Bicentennial Anthology of American Corwhology Edited by R. Tucker Abbott american malacologists p. 0 BOX 4208 CREFNViUt. DEUWARE 19807. USA BICENTENNIAL PRESENTATION COPY Only a few numbered copies are available and only by ad- vanced subscription; each is handdated. numbered and per- sonally autographed by the editor tn the individual pur- chaser. Struck on soft, high-quality paper, with marble-ized end leaves, and with a ribbon bookmark, this valuable in- vestment is an 18th Centurylike masterpiece of hwk manu- facturing This elegant book, in simulated leather, is matched with a specially designed, presentation slip box. Sfrl.dO. Vol. 91 (2) April 25. 1977 THE NAUTILUS 47 SEASONAL MOVEMENTS OF THE POND SNAIL. LYMNAEA CATASCOPIUM IN A NORTHERN LAKE Robert C. Wall Division of Mathematics and Science Lake-Sumter Community College Leesburg, Florida 32748 ABSTRACT These data from a 3-year study in Lake Ann, located north of Interlochen in the northern Lower Peninsula of Michigan, indicate that the freshwater pulmonale snail Lymnaea catascopium (formerly L. emarginata) does not migrate into deep water with the approach of winter. Tfii^'i behavior pattern dif- fers from that reported by Cheatum (1931t). The observations indicate that while these snails do move within the popdation, their movements are random in nature with no tendency to migrate into deeper off-shoal water in the fall. If anything, the data collected actually show their movements were more toward shore than away from it. The difference in migration reported could be due to differerwes in the periods the observations were made. The studies by Cheatum and Brackett were primarily in late summer, early fall, and late spring; thw study covered all seasons in the course of 3 years, i.e.. late fall winter, and early spring as ivell as the periods designated by Cheatum and Brackett. It was established that while there were snail movements within the population as ex- hibited by L. catascopium during the winter, those movements were random in nature, and not migratory. INTRODUCTION migration patterns of pulmonate snails in Some pulmonate snails that inhabit temperate Douglas Lake. The following information was lakes are known to migrate from shallow into obtamed durmg a 3-year study of Lymnaea deeper water with the onset of cold weather in catascopium Say, 1817 (of which L emarginata the fall; they return from deeper water onto Say, 1821, is a synonym, fide H. J. Walter, shoals of the lakes in the spring. This pattern of 1969). The observations were made in Lake migration has been assumed to be normal for ^nn, north of Interlochen in the northern I^wer most of the larger pond and lake snails and Peninula of Michigan to determine whether this malacologists assumed it was the usual pattern. ^nail shows any appreciable seasonal migratory However, data obtained in a 3-year study in- movement. dicates that the seasonal migration of at least Snails involved in the transmission of a skin one species does not follow that pattern. disease in the Great Lakes region known as Earlier work by Cheatum (1934) in Douglas schistosome dermatitis or swimmers' itch, are Lake, Cheboygan County, Michigan indicated often in colonies or "beds" covering fairly exten- there was seasonal movement of several aquatic sive areas in shallow water (less than 1.5 meters gastropod species which he interpreted as in depth). Assuming a seasonal migration takes "migration." Later, Brackett (1940) concluded place and the host snails migrate into deeper that snails he observed did not have an annual water in the fall to assemble in smaller and migratory cycle, but remained "year round in restricted profundal areas, control could then be the vicinity of where they hatched." Un- easier, more efficient, and less costly. Under fortunately, neither Cheatum nor Brackett ob- those circumstances less damage would occur to tained winter data from Michigan's northern the biota in the lake than with the treatment lakes. More recently, Clampitt (1972a,b) studied methods currently utilized. The best method of 48 THE NAUTILUS April 25.1977 Vol. 91 (2) control would involve applying chemical treat- ment just after fall migration or early in spring before the snails come back into shallower water. Such considerations tend to stress the im- portance of resolving the controversial question as to whether host snails migrate or not in the seasonal way described. LAKE ANN STUDY SITE This investigation was started August 1966 and terminated in June 1969 at the beginning of the annual breeding season of Lynniaea catascopium. During the summer of 1966 an ex- tensive survey was undertaken in the Lower Peninsula of Michigan to determine which lakes were reported to have outbreaks of schistosome dermatitis. Among them, Lake Ann, Benzie County, had on its northern shoal a thriving colony of Lymnaea (Stagnicola) catascopium. the snail reported by Cort (1950) as a principal vector of schistosome dermatitis. Although "swimmers' itch" was reported in that lake and copper sulphate treatment had been applied, several years had intervened prior to this study, so that the snail population had again become well established. Lake Ann is 13 miles southwest of Traverse City, Michigan in Benzie County, T. 27N, R. 13W, Sections 22, 23, 26 and 27, and covers 515 acres; its maximum depth is 23 meters. The bot- tom of the lake, at about 12 meters in depth, is covered with a pulpy peat. In the more shallow areas marl covers the bottom; a narrow band of sandy shore occurs only along the north and east with a long stretch of beach to the west. The snails studied were on a sandy shoal along the north side of the lake where they were most abundant in the area extending from shore to 8 meters out into water up to 0.5 meters deep. Snail density near shore averaged 240 per square meter; it declined sharply with increased depth of water, so that beyond 39 meters from shore and at depths greater than 1.5 meters, snails were scarce. Using a motor boat and wire-mesh dredge, quadrat sampling was made from 1.5 meters of depth to 12 meters of depth; however, no live specimens of L. catascopium were recovered. The snail bed clearly was confined to that shallow shoal area. PROCEDURE AND OBSERVATIONS The First Year: Trips were made from Ann Arbor to the study area at Lake Ann on a schedule as follows: August 15, September 25, October 6 and 25, and November 17, 1966; January 24, March 28, April 27, June 1, July 12, and September 28, 1967-a total of 11 trips dur- ing the first year of the study. On October 25, 1966, 1280 snails were marked with red nail polish covered by lacquer. Specimens varied in size from 11 to 22 mm in length (measured from apex to base of aperture). As soon as the mark- ings were dry, the snails were returned to the area from which they were collected and scat- tered randomly over the snail bed. During the periodic visits to that site in the fall, winter and spring of 1966 to 1967, it was clearly evident that, contrary to information ob- tained from Cheatum's earlier studies, these snails did not exhibit a seasonal migration. While they tended to "group" in two's or three's, there was no mass movement of that population into deeper water as compared to their position on the shoal area then inhabited during August. Observations made of their position on the shoals and under the ice during January and March 1967 also indicated that they remained in the same area inhabited during that fall and winter. In January and March a thick ice cover was found on the lake except for a strip about 3 meters wide along the shore. Snails were seen from the water's edge outward. Since the opa- queness of the ice made observations through it impossible, a hole was chopped and live snails were seen on the substrate. Many of the marked snails were observed among others in the open water near shore; however, none of the marked individuals were seen through the hole in the ice. Although the red nail-polish on the marked snails had faded badly, it still was visible. In April, soon after the ice had melted, a quadrat sampling was made using a wire dredge. Sam- ples were taken at approximately 25 meter inter- vals from near shore (in a southwesterly direc- tion) out into water 12 meters deep. The total distance of the quadrat was about 350 meters. No snails other than a few small Campeloma Vol. 91 (2) April 25, 1977 THE NAUTILUS 49 decisum were recovered in water deeper than 2 meters. The number of marked individuals seen dur- ing the June visit was estimated to be about 10 per cent of the sample marked. By this time the nail polish had almost completely faded making it extremely difficult to distinguish marked from unmarked individuals. Even with the aid of a glassbottom bucket, wave action made observa- tion difficult in shallow water. Very few (about 5 per cent) of the marked, dead (shells) were recovered during the April and June visits. Possible explanations for the small percentage of "sightings" of marked individuals, both living and dead, are: fading of the nail polish made them difficult to spot; many in- dividuals were almost completely buried in the substrate; disappearance as caused by various snail "predators;" marked individuals may have been selected because of their conspicuousness; marking materials may unknowingly have been toxic to the animals; wave action which tended to be quite severe on this shoal made seeing them difficult. For whatever reason, the true significance of this study was finding marked animals only in the immediate vicinity of the shoal where they had been placed rather than where these snails were subsequently recovered. Although during the 3-year period numerous checks made in all directions from the area in which marked individuals were placed. No marked individuals, living or dead, were ever found more than 2 meters from the shoal on which snails had been placed. The Second Year: Based on information ob- tained during the first year, the frequency of visits to the study area during the next 2 years was reduced from 11 to 5 trips. However, throughout the 3 years, observations were made at the study site every month of the year except December. In October of the second year, 3 study quadrats, each covering one quarter square meter, were laid out as follows: Plot I, 14 meters from shore in water .12 meters deep; Plot II, 27 meters out in water .51 meters deep; and Plot III, 39 meters from shore in water .69 meters deep. These measurements were made from the shore to each study plot, compass readings were made, and onshore landmarks were recorded so that several criteria were available to help relocate the study plots on subsequent visits. The purpose of these quadrats was to determine whether the snails moved around within the larger snail bed. The number of snails in each of the 3 plots was counted and a sample of 15 snails per plot was marked with red India ink and then returned to their respective plots. Because of its longer lasting quality, India ink was used instead of the nail polish to mark those shells. There were 115 snails in Plot I; 41 in Plot II; and 35 in Plot III. During subsequent visits the number of marked and unmarked snails per plot was determined. Visits to the study area were made on November 16, 1967; February 14 and May 15, 1968. During the November visit the weather was cold (air temperature 1.5''C, water temperatue 3.0°C) and windy. Many snails were tossed about by wave action, others were observed buried to various degrees of submergence in the substrate: only 2 snails (unmarked) were seen in Plot I; some may have been buried in the substrate. In order not to disturb the study plot, it seemed ad- visable not to dig into the substrate. Two marked snails (13.2% of the sample placed in this area) were sighted .5 meter from Plot I toward shore; 12 snails, including 2 marked individuals, were seen in Plot II. Two additional marked snails were found .3 meter inshore from Plot II. Thus, 26.4% of the marked snails placed in this area were seen. Fourteen snails were observed in Plot III, none of which had been marked. Two marked specimens were observed .3 meter inshore from this plot. The area around each study plot, out to a distance of 3 meters, was checked. No other marked snails were seen. Although more speci- mens were observed outside the study plots than inside, they were less numberous everywhere than in October. Many were now buried in the substance. During the following February a heavy ice cover was on the lake ranging from 5 cm at the shoreline to 45 cm at 27 meters from shore. Although snails were seen at the shore and through a hole chopped in the ice 27 meters from shore, no marked snails were seen during this 50 THE NAUTILUS April 25,1977 Vol. 91 (2) visit. On May 15, the air temperature at Lake Ann was 25.5°C and the water temperature was 16.0°C. Only one marked snail (6.6% of the marked sample) was found in the area around Plot I; it was 3 meters west of the plot. Three marked animals (19.8% of the sample placed in Plot II) were found inshore within 5 meters of Plot II. None of the marked snails placed in Plot III was found. Since all snails had been marked with the same color of India ink, there was no way to determine the plot from which they had come. As expected in terms of the annual cycle, population density again dropped drastically from an average of 240 per square meter in Oc- tober to an average of 30 per square meter in mid-May. Population densities were greatest near shore and declined rapidly toward deeper water during all of the months in which observations were made. The results of the first year were again substantiated since these snails did not migrate into deeper water off the shoal, but remained where they had been during summer and fall. While there were movements of snails within the population, it was impossible to determine whether these movements gave evidence of a pat- tern or were of a random nature. The Third Year: Based upon the studies of the first and second years, some innovations were made this third and final year of investigation. The three established quadrat plots were left in- tact. Three samples, each with 200 individuals, were marked but a different color of a paste In- dia ink was used for each of the samples. Sample one was yellow; sample two, red; and sample three, blue. Specimens in sample one (yellow) were then scattered in a 20 meter radius arc in the study Plot I, some 14 meters from shore; the sample two (red) snails were scattered in a 30 meter arc in Plot II at a distance of 27 meters from shore; and the sample three (blue) snails were likewise scattered in a 40 meter arc in Plot III at 39 meters from shore. Care was taken to be sure that these samples passed through each of the 3 earlier study quadrats established during the second year of the study. This arrangement served to determine the extent to which the snails ranged within the total population area. The 3 snail samples were marked October 25, 19()8. Subsequently, 3 trips to examine the extent of movement were made to the study area on March 7, April 19 and June 16, 1969. An unfore- seen accident made visits to the study area im- possible during December or January as original- ly planned. By March 7 the air temperature was 4.0°C and the water was 4.5°C. TTie lake was still covered with a thick cover of ice except for a strip about 6 meters wide along the shore. Although all 3 study plots were ice covered, 4 yellow-marked snails (2% of the total sample) and numerous un- marked animals were seen in that open water. The population density again had decreased con- siderably as in the previous 2 years. On April 19 it was ascertained that the ice on that lake disappeared about April 15. The air temperature on the 19th was 15.0°C, the water was 5.0°C. Using a glass-bottom bucket and the distance guide used for setting the 3 plots, a careful survey was made in each area. Dredgings were made with sweeps on the arcs established for Plots I, II and III; additional sweeps were made at 1 meter intervals between plots. Only those snails marked with the color designated within the plot distances (Plot I, yellow; Plot II, red; Plot III, blue) were found within the plot arcs. With but one exeption, all marked snails observed at other than the plot arc distance from shore were inshore from their respective plot arcs. The exception was 2 red-marked individuals found 3 meters out from the Plot II distance arc. A total of 77 per cent of the marked snails recovered were at plot arc distance from shore, 19 per cent were inshore from their plot arc distance, and only 4 per cent of the marked snails recovered were out beyond their plot distance arc. Of the 2(K) yellow marked specimens 23 or 11.5% were seen on this visit; 13 or 6.5% of the 2(H1 red: and 17 or 8.5% of the blue were found. During the final visit on June 16, the air temperatue was 22.0"C; the water was 21.0°C. A general survey of the whole snail bed revealed that most adult snails had already died. Many shells had eggs attached to them; however, no young snails were found. As during the April 19 visit, a careful survey was made of the studv Vol. 91 (2) April 25, 1977 THE NAUTILUS 51 area. In sweeps made at 1 meter intervals from shore outward to 2 meters beyond the Plot III distance from shore, very few live sails were seen and but a few shells. The following marked shells and 1 live, marked snail were found: 1 yellow shell at Plot I arc distance from shore; 1 red shell 1 meter inshore from the Plot II arc distance: 1 blue shell 3 meters inshore from Plot III arc; 1 blue shell 2 meters inshore from Plot III arc distance; 1 live blue marked near Plot III; and 2 blue marked shells (one with eggs attached) 2 meters out from Plot III arc distance from shore. ACKNOWLEDGMENTS The investigation was supported (in part) by PHS Training Grant No. 5 TI 41 from the Na- tional Intitute of Allergy and Infectious Diseases, U.S. Public Health Service, Washington, D.C. The assistance of Henry van der Schalie and Elmer G. Berry, curators in the Mollusk Divi- sion, Museum of Zoology, University of Michi- gan is gratefully acknowledged. The work in the field was supported by several members of the Mollusk Division and my family. LITERATURE CITED Brackett, Sterling. 1940. Studies on schistosome dermatitis. VIII. Notes on the biology of the snail hosts of schistosome cercariae in Wisamsin and epidemiological evidence for life cycles of some avian schistosomes. Amer. J. Hyy.. 32: 85-104. Cheatum, Elmer P. 1934. Limnological investigations on respiration, annual migratory cycle, and other related phenomena in fresh-water pulmonate snails. TVan.s. Micros. Soc. 53: 348-407. Clampitt, P. T. 1972a. Seasonal migrations and other movements in Douglas Lake pulmonate snails (Abstract). Malacol. Review, 5(1): 11-12. Clampitt. P. T. 1972b. Seasonal migratory cycle and related movements of the freshwater snail Physa integra (Pulmonata: Basommatophora) (Abstract). Bull. Ecol. Soc. .4mpr.. 53(2):21. Michigan Department of Natural Resources. Institute for Fisheries Research. 1950. Lake Inventory Map: Lake Ann. Wall, Robert C. 1968. An analysis of the current status of schistosome dermatitis problem in Mighigan. Doctoral Thesis. University of Michigan. Walter. Harold J. 1969. Illustrated biomorphology of the "angulata" lake form of the Basommatophoran snail. Li/m- luwn ratn.'^rdpiiim Say. Mnlncnl. Rev.. 2: 1-102. LIVING MARINE MOLLUSCS C. M. Yonge and T. E. Thompson BEHAVIOUR Two distinguished British marine biologists have combined their knowledge and talents to produce a compact, well-rounded account of the largest marine group of animals. "The first modem book on the biology of marine mollusks that is of textbook quality, yet so beautifully written and illustrated that the legions of amateur conchologists will readily absorb its wealth of information"— R. Tucker Abbott, Ph.D. Send check or money order to: American Malacotogists, Publ. P.O. Box 4208 Greenville, De. 19807 U.S.A. Available 1977 Cldthbound, 288 pp., 162 text figures, 16 plates with 18 glorious color photographs of living marine molluscs. Only $13.95. 52 THE NAUTILUS April 25,1977 Vol. 91 (2) FREQUENT SCALARIFORMY IN A POPULATION OF THE POND SNAIL, LYMNAEA STAGNALIS Eva Pip Department of Botany University of Manitoba Winnipeg, Manitoba Canada R3T 2N2 ABSTRACT T7VI) populations of Lymnaea stagnalis that had been exposed to chronic low- level (jammn radiation in situ were examined for the presence of shell ab- normalities. One population shoived no abnonnalities. In the other population sea la ri form y UHhs found at a frequency of 0.5%, and occurred nmsi.-itentlij in ini- tiallti non-scalar shells. Gnmnin mdintinn )'.s apparently nut a direct cause if scidarifiruiy. Scalariformy in natural populations of Lym- naea stiujuulis (Linnaeus) is normally a rare and isolated occurrence, the causes of which are unknown. Studies of this phenomenon are dif- ficult because of the very few, scattered and poor- ly documented specimens known to be in ex- istence (Pip, 1975) and because the probability of recurrence in wild populations that have pro- duced such individuals is too low to merit obser- vation. However there is evidence that popula- tions showing a relatively high frequency of scalariformy exist. F. C. Baker (1911) cited a population sample from Spoonbill Slough, Deuel County, South Dakota, that contained several scalariform individuals. This study documents the discovery of another such population of L. stmjncdis. Perhaps coincidentally, this population has been exposed to chronic low-level gamma radiation. METHODS The study sites were located in an area, 1 km in diameter, of mixed boreal forest that had been reserved in the late 1960's for a radiation ecology study within the Whiteshell Nuclear Research Establishment's controlled area near Pinawa in eastern Manitoba. Chronic gamma radiation began in early 1973 by a 10,000 effective curie '" Cs source located at the top of a 20 m tower placed at the center of the area (Dugle and Thibault, 1974). Irradiation continued at an average of 19 hours per day. By the end of August, 1975, the area had received a total of 17,000 hours of irradiation. The western portion of the area contained numerous small shallow ponds that had originated as gravel excavations prior to 1965. Of these ponds, two contained populations of Lymnaea stagnalis, their centers located 300 m (site 1) and 480 m (site 2) from the irradiator respectively. Site 1 was densely col- onized by cattails (Typha latifolia); small patches of open water contained the pondweeds Potamogeton gramineus, P. pectinatus and P. nutans (nomenclature after Scoggan, 1957). The mean dose rate at site 1, estimated during the growing season by lithium fluoride dosimeters placed 1 m above the center of the pond's surface, was 12.428 mrad/h. Site 2 was much more ex- posed: there was no emergent vegetation except for one small stand of cattails. The sparse submerged vegetation consisted of Potamogeton fnliosvs and a species of the algal stonewort Chara. The mean dose rate 1 m above the center of the pond's surface was 3.082 mrad/h. Because of the pond's exposure, water temperatures dur- ing midsummer reached 30 C. Although both ponds were less than 1 m deep, temperatures at site 1 were consistently lower because a large proportion of the water surface was shaded. Sur- face water samples collected in July, 1975 were analyzed according to methods recommended Vol. 91 (2) April 25, 1977 THE NAUTILUS 58 by the American Public Health Association (1971). The two sites showed few differences in the monitored variables: pH 7.7 - 8.7, total filtrable residue 135 mg/1, alkalinity 80 mg CaCOj/l, sulphate 0 mg/1, chloride 0 mg/1, nitrate 1 mg/1, orthophosphate 2 mg/1 (site 1) and 7 mg/1 (site 2). Besides L. xtagnali.^ site 1 also con- tained Staynicola pal ustris while site 2 contained S. palustris and Physa gyrina. During the 1975 season all visible live and dead individuals of L. stagnalis at the two sites were scored for presence or absence of shell ab- normalities. Individuals of other species were ex- amined as well. RESULTS AND DISCUSSION The small populations of L. stagnaliji and S. palustris at site 1 showed no evidence of mor- phological abnormalities. The larger population of L. stagnalis at site 2 showed a constant frequency of scalariformy during the 1975 season of 5 per 1000 individuals. Scalariformy occurred con- sistently in initially non-scalar shells (Fig. 1), a characteristic noted in previous reports (Pip and Paulishyn, 1970; Jackiewicz, 1972; Pip, 1975). Onset of scalariformy was abrupt and well- defined. In approximately 75% of the affected in- dividuals, scalariformy commenced in the fourth and fifth whorls. In the remainder of specimens scalariformy was apparent earlier; in some in- dividuals it occurred as early as in the second 4444 FIG. 1. Scalariform shells of Lymnaea stagnalis cnlleeted nt site 2 in Manitoba, Canada, during 1975. i'/> whorl. One specimen showed onset of scalari- formy in the sixth whorl; this was the only specimen where mechanical injury to the shell was apparent. Scalariformy was frequently ac- companied by curvature or breakage of the shell axis. Other aberrations were not observed in L. sta/inalis. The small populations of S. palustris and P. gyrina at site 2 were morphologically nor- mal. The unusually high frequency of scalariformy at site 2 is difficult to explain. Because site 1 received 4 times the mean dose rate of site 2, with no scalariformy or other abnormalities recorded, radiation appears to be an unlikely direct cause. Radiation may have contributed towards the stress already placed on the organisms by elevated temperatures. The two fac- tors are related in that elevated temperatures in- crease the time breathing at the surface (McDonald, 1973). Since attenuation of radiation with increasing water depth is considerable, the snails are exposed to the maximum dose rate when they are at the surface. The additional ex- posure to radiation, combined with the effects of heat stress, may result in some disturbance to growth. Because scalariformy occurs, as a rule, relatively late in the development of the snail, the causative agent is not operating at the nuclear level. Verdonk (1973) has shown that in L. Stagnalis few gene deficiencies become active beyond the veliger stage. It is therefore likely that mechanical or physiological agents are among the responsible factors. The occurrence of Cham at site 2 is interesting in that Geyer (1929 in Jackiewacz, 1972) and Pip (1975) have noted the presence of this alga in habitats where scalariform snails have been collected. Further study is necessary before this phenomenon is understood. ACKNOWLEDGMENTS I would like to thank Drs. J. Dugle and J. Guthrie of the Whiteshell Nuclear Research Establishment for their advice and encourage- ment during the pursuit of this problem. 54 THE NAUTILUS April 25.1977 Vol. 91 (2) LITERATURE CITED American Public Health Association. 1971. Standard Method'^ for the Eiaminatifm of Water and Wastewaters.^. 874 pp. Baker. F. C. 1911. The Lymnaeidae of North and Middle America. Ot icago Acad. Sri. Spec. Pub. No. .y. 539 pp. Dugle. J. R. and D. H. Thibault. 1974. Ecology of the Field Irradiator-Gamma area, 111. Revisions to botanical methods and vegetation sampling procedures (AECL-41.3.5). Atomic Energy of Canada Limited, report AECI^4668. 41 pp. Jackiewicz. M. 1972. Anormalnosci w budowie shorupki niekorych mi^zakow wodnych. Przeglad Zoologiczny 16:1: 95-98. (in Polish). McDonald, S.C. 1973. Activity patterns of Lymnaea atagnalis (L.) in relation to temperature conditions: a preliminary study. Malacolngia 14: 39,5-396. Abstract only. Pip, E. 1975. Scalariformy in the pond snail. Li/mnaea stagnalis. The Nautilus 89: 36-37. Pip, E. and W. F. PaulishvTi. 1970. Unusual fr«sh water mollusk collected. Hawaiian Shell News 18: 11: 6. Scoggan, H. J. 19.57. Flora of Manitoba. Nai. Mus. Canada, Bull. No UO, 619 pp. Verdonk. N. H. 1973. Gene expression in early development of Lifmnof a stagnalis. Devel. Buil. 35: 29-35. SHELL SIZE-FREQUENCY DISTRIBUTIONS OF CORBICULA MANILENSIS PHILIPPI FROM A CLAM-FOULED STEAM CONDENSERS Robert F. McMahon Department of Biology TTie University of Texas at Arlington Arlington, Texas 76019 ABSTRACT Specimens and empty whole and half ahelh of the introduced Asiatic freshwater clam. Corbicula manilensis, were collected from the inlet (cold water) box. con- denser tubes and outlet (warm water) box of a clam-fouled steam condenser of an electric generator utilizing raw water from Lake Arlington, Texas. Size-frequency distributions of length, height, and width of shells removed from these three sec- tions indicated that the clams were not growing in the condenser but had been carried into it with intake currenUi from an external population in the intake em- bayment and tunnel. It appers that the condenser tubes acted as a sieve becoming fouled only unth shells of an appropriate size to become lodged in the tubes while smaller specimens passed thnmgh and larger shells were retained in the inlet box. It is siHjge.'ited that increasing tube inside diameter to 29.0 mm or mitre icill (illmr even the largest specimens of C. manilensis to /la.w thnoigli cinidniscrs mid therehii a void fouling problems with th /.s' species. The introduced Asiatic freshwater clam, Cor- bicula manUetisis. was first recorded in the Col- umbia River, Washington, in 1938 and has since spread through a large portion of the freshwater ' Supported by grant number 16-6.53 from Organized Research Funds of The University of Texas at Arlington to Robert F. McMahon. environments of the southern United States (Sinclair, 1971, and references within). The high reproductive capacity and fast growth of this clam has allowed it to become a major pest species in many drainage systems (Ingram, 1959; Sinclair and Isom, 1961. 1963; Sinclair, 1963, 1964, 1970; Prokopovich and Herbert, 1965; Prokopo- vich, 1969). Recently C. manilensis has been Vol. 91 (2) April 25, 1977 THE NAUTILUS 55 reported to have fouled raw watercooled steam condensers of electric generating and other in- dustrial facilities in several regions of the United States (Ingram, 1959; Sinclair and Isom, 1961. 1963: Sinclair, 1963, 19&4, 1970; Thomas and MacKenthun, 1964; Thomerson and Myer, 1970; Diaz, 1974). This report describes the distribu- tions and means of shell size for specimens of C. manilerms collected from a clam-fouled steam condenser of an electrical generator and proposes a possible design solution to the problem of foul- ing by the shells of this species. MATERIALS AND METHODS On 12 January, 1976, whole specimens and whole and half shells of Corbieida manilensis were collected from the clam-fouled steam con- denser of the Number Two electrical generator of the Handley Steam-Electric Generating Plant, maintained by the Texas Electric Service Com- pany on Lake Arlington, Texas (USGS map quadrangle, Arlington, 32° 43' 15" N: 97° 12' 57" W). This plant utilizes raw lake water as a coolant for the steam condensers of its three generating units. The maximum flow of lake water through the condensers is 1.298X10* liters per minute (1.870X10' 1/day) and the monthly average discharge rate is 1.052X10* 1/per minute (1.514X10' 1/day (Hall, 1972; McMahon. 1975). The clams were collected from three areas in the steam condenser: the inlet or cold water box (CWB) which receives raw lake water for cooling from the intake canal; the condenser tubes (CT) which carry water from the CWB and which are used to cool and condense the steam passed over them before it is returned to the generator's boilers: and the outlet or warm water box (WWB) which receives warmed water from the condenser tubes. Water is passed from the WWB to the discharge canal and is then returned to the lake (for a more complete description of the Handley Power Plant's operation see McMahon, 1975). The condenser tubes of the Number Two gererator have an outside diameter of 22.2 mm, an inside diameter of 19.7 mm and a tube wall thickness of 1.24 mm. The Number Two generator is a "peaking" unit which operates only during periods of high demand. It has an output of 80 MW and a maximum flow through its condenser of 132,469 1/min. Average water velocity in the intake tube to the condenser is 2.44 m/min and velocity increases to 2.26 m/sec in the condenser tubes. C. manilenda was first observed in Lake Ar- lington during the spring of 1973 (John Barnett, personal communication) and it first fouled the Number Two condenser at the Handley Power Plant in the summer of 1974. Since that time the Number Two unit has been shut down several times in order to remove C. manilensis shells from its condenser tubes. Such fouling has never occurred in the larger Number Three unit, a con- tinuously running "base load" generator, with an output of 400 MW and a water flow through its condensers of 435,322 1/min. This unit's water velocities are similar to that of the Number Two unit, but the condenser tubes are larger with an outside diameter of 25.4 mm, an inside diameter of 22.9 mm and a tube wall thickness of 1.24 mm. Living specimens and empty whole and half shells of C. manilensis were collected from the Number Two condenser 72 hours after the generator had been shut down on January 9, 1976. Samples were randomly removed from each of three areas (CWB, CT and WWB) and re- turned to the laboratory. For each individual in each sample three shell dimensions were meas- ured to the nearest 0.05 mm using a dial microm- eter. The shell dimensions recorded were: shell length (SL), the greatest dimension anterior- posterior across the shell; shell height (SH) the greatest dimension dorsal -ventral across the shell from the umbones to the ventral edge of the valves: and shell width (SW), the greatest lateral dimension between the two valves (for single valves shell width was estimated by multiplying the greatest lateral dimension by two). No sig- nificant differences occurred in the mean dimen- sions of whole and half shells in each sample (P > 0.10); therefore, the dimensions of whole shells and single valves were combined, allowing the computation of a mean SL, SH and SW with cor- responding standard deviations for each of the three samples (CWB, CT. WWB). The distribu- tions of sample shell dimensions from all three 56 THE NAUTILUS April 25,1977 Vol. 91 (2) collection sites were then compared for sig- nificance using students' t test. RESULTS Figures one, two and three illustrate the shell size distributions of C. nunulrnsis collected from the cold water box (CWB) (Fig. 1), the condenser tubes (CT) (Fig. 2) and the warm water b)X (WWB) (Fig. 3) of the Number Two steam con- denser. Approximately 20-30% of the shells removed from each of the three portions of the condenser contained intact soft parts. There was no evidence of byssal attachment by the clams to tube walls or any other portion of the condenser as has been previously suggested for fouling by this species (Sinclair and Isom, 1961, 1963). The 122 shells collected from the intake or cold water box (CWB) had a mean SL of 21.1 mm (s.d. = ±6.19 mm, range = 5.7 - 33.(S mmj.a mean SH of 19.98 mm (s.d. = ±5.29 mm, range = 4.9 - 28.1 — I r CWB 10 15 20 25 SHELL LENGTH in mm FIG. 1. Lfiujth frequency distrihutiona of Corbiciihi niiinilensis sheik collected from the inlet or cold water box (CWB), condenser tubex (CT) and outlet or warm ivater box (WWB) of a steam condenser utilmng raw lake water as a roolivit. The vertical axis is per cent of total sample mimhers and the hwizontal axis is shell length (SL) in millimeters. The darkened circles represent mean shell lengths for each s 29.0 mm) might eliminate all possiblity oiCorbicula fouling. ACKNOWLEDGMENTS I wish to express my deep appreciation to Mon- ta Zengerle, Texas Electric Service Company Biologist, who allowed me to be present when the condenser was inspected and who supplied data on the steam condenser's operation; to David W. Aldridge for his advice and discussions on the biology of C. manilensds; and to Nancy B. Banks, for her assistance with the preparation of the manuscript. LITERATURE CITED Aldridge, D. W. 1976. Growth, reproduction and bioener- getics in a natural population of the Asiatic freshwater clam, (hrbinda manilen.tis Philippi. Maiytfr'n Thexis. TTie University of Texas at Arlington. 93 pp. Diaz. R. J. 1974. Asiatic clam, Girhinda manUends (Philippi). in the Tidal James River, Virginia. Chesapeake Si-i. 15: 118-120. Hall. F. M., III. 1972. Species diversity and density of the ben- thic macroinvertebrates inhabiting a reservoir receiving a heated effluent. Master's The^s. The University of Texas at Arlington. 82 pp. Ingram, W. M. 19.59. Asiatic clams as potential pests in California water supplies. Jour. Amer. Water Works Assoc. 51: 36.3-.369. McMahon. R. F. 1975. Effects of artificially elevated water temperatures on the growth, reproduction and life cycle of a natural population of Physa iri.rgata Gould. Ecology 56: 1167-1175. Prokopovich, N. P. 1969. Deposition of clastic sediments by dam&.JmrSed. Petrology 39: 891-901. Prokopovich, N. P. and D. J. Hebert. 1965. Sedimentation in the Delta-Mendota Canal. Jour. Amer. Water Works Assoc. 57: 375-382. Sinclair, R. M. 1963. Kfects of an introduced clam (Corbicula) on water quality in the Tennessee River Valley. In Pro- ceedings of the Second Indiistnal Waste Conference. Vanderbilt University. Tennessee Department of Public Health. Tennessee Stream Pollution Control 3oard. pp. 43-50. Sinclair, R. M. 1964. Clam pests in Tennessee water supplies. Jour. Amer. Water Works Assoc. 56: 592-599. Sinclair, R. M. 1971. Annotated bibliography on the exotic bivalve Corbieida in North America, 1900-1971. Sterkiana 40: 11-18. Sinclair. R. M. and B. G. Isom. 1%1. A preliminary report on the introduced Asiatic clam Corbiada in Tennessee. Ten- nessee Stream Pollution Control Board. Tennessee Depart- ment of Public Health. 31 pp. Sinclair. R. M. 1963. Further studies on the introduced Asiatic clam in Tennessee. Tennessee Stream Pollution Con- trol Board. Tennessee Department of Pulbic Health. 51 pp. Thomas. N. A. and K. M. MacKenthun. 1964. Asiatic clam in- festation at Charleston. West Virginia. The NautUus 78: 28-29. TTiomerson, J. E. and D. G. Myer. 1970. Corbiada manilensis: Range extension upstream in the Mississippi River. Sterkiana 37: 29. 60 THE NAUTILUS April 25,1977 Vol. 91 (2) ABNORMAL HYPERSTROPHY IN LITTORINA UNEOLATA (GASTROPODA: LITTORINIDAE) M. G. Harasewych College of Marine Studies University of Delaware Newark, Delaware 19711 ABSTRACT A specimen of Littorina lineolata Orbigny from Oistint^ Bay. Barbados was found to have a normal orthostrophic protoconch and an abnormal. hypertrophic teleoconch. based on examination of anatomy, shell, protoconch and (rperculum. This is believed to be the first report of such an abnormality in gastropod'^. The occurrence of anomalous shell mor- phologies is well documented in the Littorinidae of tropical as well as boreal waters (Rosewater, 1972). It was therefore not too surprising to discover what appreared to be a sinistral specimen of Littorina lineolata Orbigny. 1840 while sorting material collected in Oistins Bay, Barbados. Closer examination, however, revealed this specimen to be dextral and hyperstrophic. It is necessary at this point to make a distinc- tion between asymmetry of the shell and asym- metry of the soft parts. The terms dextral and sinistral, in the strict sense, refer to the orienta- tion of organ systems in the gastropod body. The vast majority of prosobranchs are dextral and have lost the osphradium, ctenidium, hypobran- chial gland and auricle on the post -torsional right side of their body. This was accompanied by a shifting of the anus to the right side of the body and modification of the right kidney into a reproductive organ. The reverse is true of sinistral gastropods, which are mirror images of their dextral counterparts. Dextrality or sinistrality is detectable as early in development as the late two cell stage (Crampton, 1894), long before even the first appearance of a shell. The terms orthostrophy and hyperstrophy refer to the orientation of the asymmetrical shell with regard to the soft parts. The term orthostrophic is applied to gastropods in which the spire is on the same side of the body as the anus and pallial reproductive organs, while the term hyper- strophic is applied to gastropods in which the spire is on the same side of the body as the un- paired osphradium, ctenidium, hypobranchial gland and auricle. Tlie direction of coiling is determined in the larval stage, but, in some gas- tropods, is changed at the time of metamorphosis (e.g. Architectonicidae, Pyramidellidae). Robertson and Merrill (196;3) reported the ab- normal occurrence of post -larval hyperstrophy in two species of Heliarus. in which the normal hyperstrophy of the protoconch was abnormally retained by the teleoconch. The specimen of Ldt- torina lineolata discussed here, however, is be- lieved to be the first reported occurrence of a gas- tropod with a normal orthostrophic protoconch and an abnormal hyperstrophic teleoconch. This specimen (figure 1), in the collection of the Academy of Natural Sciences of Philadelphia (ANSP no. 342287), was compared to normal specimens from the same locality (ANSP no. 342286) and proven to be dextral and hyper- strophic on the basis of the following evidence. Anatomy. Tissue as far up as the rear of the mantle cavity was well preserved. The orientation of the mantle cavity organs was that of a de.xtral animal, the anus and capsule gland being on the right side of the body, while the osphradium, ctenidium and hypobranchial gland were on the left. Operculum. As demonstrated by Pelseneer (1893, fide Robertson and Merrill, 1963), the direction of coiling of the operculum can be used to distinguish between dextral and sinistral animals, the former producing opercula which Vol. 91 (2) April 25, 1977 THE NAUTILUS 61 FIG. 1. .4, luirmiil apecunen nf Littorina lineolata Orbigny fmm Oistins Bay. Barbados. x2. B. Hifperstrophic specimen from the .same locality. xS. coil counter-clockwise when viewed externally, and latter produce opercula which coil in the clockwise direction when viewed externally. The operculum of the specimen in question (figrure 2) is coiled in the counter-clock-wise direction, in- dicating that the animal which produced it was dextral. ProtoctDirh. As there is considerable pitting of the early whorls, it is not possible to locate the exact boundary between protoconch and teleoconch stages, but there is clearly a change in the direction of coiling of about 140 degrees bet- ween the axis of the early whorls of the pro- toconch and the axis of the adult shell (figure 3), indicating that the specimen was initially dextral FIG. 2. Ertenial mew of operadum of the hifperstrophic Littorina lineolata. xlO. FIG. 3. Early whorls of the hifperstrophic Littorina lin«)- lata. xl2. and orthostrophic but became abnormally hyperstrophic near the time of metamorphosis. Shell. There are two major shell characters which attest to the hyperstrophy of this specimen: the location of the major spiral cords relative to the shoulder, and the direction of the brown axial bands relative to the columella. Nor- mal specimens are characterized by having 11 or 12 major spiral cords on the apical side of the shoulder and a variable number of very fine spiral threads on the adapical side of the shoulder. This situation is reversed in the hyperstrophic specimen, the fine spiral threads being located on the apical side, while 11 major spiral cords are located on the adaptical side of the shoulder. When viewing the orientation of the brown axial lines relative to the columella, it can be seen that in normal individuals the brown bands approach the columella tangentially, while in the hyperstrophic specimen the bands appear to be almost perpendicular to the columella. It should be noted that the actual shape of the aperture relative to the animal is not very drastically changed, the left side being more spacious than the right. This would have de- creased the compression of the ctenidium, which would have been a serious impediment to the sur- vival of the organism. I thank Dr. Robert Robertson (Academy of Natural Sciences of Philadelphia) for reviewing the manuscript. 62 THE NAUTILUS April 25.1977 Vol. 91 (2) LITERATURE CITED Crampton, HE. 1894. Reversal of Qeavage in a Sinistral Gastropod. Annals N. Y. Aaui. Sci 8: 167-170. pi. .5. Pelseneer. P. 1893. A propos de 1' "Asymetrie des Mollusques univalves." Jtmrn. Qmchyliologie iO: 229-23.3, 1 fig. Robertson. R. & Merrill, A.S. 196:?. Abnormal Dextral Hj^perstrophy of Post-Larval Heliacius (Gastropoda: Ar- chitectonicidae). The VeliyerG: 76-79, pi. 13-14. Rosewater, J. 1972. Teratologicai Littorina scabra angulifera. The Nautilus 86: 70-71. 6 fig. FOUR OPISTHOBRANCHS LIVING ON MARINE ALGAE FROM WEST MEXICO Leroy H. Poorman and Forrest L. Poorman Los Angeles County Museum of Natural History Los Angeles, California 90007 ABSTRACT Field notes on Lobiger souverbii, Oxynoe panamensis, Berthelina chloris, and Phyllaplysia padina, nil from HV,s-/ Mexico, are munmarized. 77n'.s' inrlndetf descn{jtion,s of the living animals and obseirations on their habits and habitats. Range extensdons northwaM into the Gulf of California are recorded for the first three species. Geographical rongcs in the Tropical Eastern Pacific arc <] ircn for all four species. The last several years have presented op- portunities for intensive collecting and observa- tion of Panamic opisthobranchs. Collecting sta- tions ranged from Cabo Tepoca. Sonora, to Man- zanillo. Colima. Mexico. Several stations on the east coast of Baja California at Bahia de Concep- cion and Bahia de Los Angeles were visited. Opisthobranchs were observed and photographed in the field and in aquaria. Numerous species were preserved and are on deposit at the Natural History Museum, Los Angeles County, California. Copies of 35 mm slides are also on deposit. A review of our field notes reveals some in- teresting information on four of the opistho- branchs living on marine algae. We believe that these notes and comments will be of some in- terest and will stimulate further field observa- tion. Lobiger souverbii Fischer, 1857 On February 17, 1974, during^ a series of low tides, we were collecting at Bahia de Tenacatita, Jalisco. On Caulerpa racemosa var. turbinata (type 1), which resembles bunches of tiny grapes (Keen & Smith. 1961), we found 25 specimens of Lobiger souverbii Fischer, 1857. Several were crawling over the surface of the Caidoim: but most were in nests along the lower edge of the algae, usually adjacent to sand. Sometimes, as many as five animals were in the same nest. A number of specimens were kept alive in an aquarium for several days for observation and photographing. The living animal is well-figured in Keen. 1971. Lobiger souverbii has four parapodia which are lateral extensions of the foot and are not to be confused with cerata which are dorsal appen- dages containing diverticula associated with digestion. The parapodia are extensions of the foot below the four corners of the shell and curl upward. The branches are like long narrow leaves with ruffled edges. They are a lighter green than is the body, which is the green of the algae. On approximately half of the animals observed, there was an orange band on the upper side of each branch, inset slightly from the margin. The Vol. 91 April 25, 1977 THE NAUTILUS 63 parapodia were normally extended upward at an angle of 45° and were partially rolled inward. When disturbed, the animals flexed and recurled these in a rapid cyclic sequence. When oxygen was depleted, the animals became lethargic and the parapodia were completely extended horizon- tally. The caplike shell is on the dorsum, exactly between the four branches of the parapodia. Mot- tled green of the internal organs and a strong blue veining shows through. When removed from the animal, the shell is clear but became translu- cent when dry. While the animals were in the tank, auto- tomizing of the parapodia was observed. Several individuals had previously discarded one or more of the lobes. No instance of regeneration was ob- served. This species appears to be very social. Not only did several animals share a common nest, but when 25 specimens were placed in an acquarium, they at once formed a close group. Within min- utes, sexual activity was observed, involving two or more individuals at the same time. Within hours, the algae was covered with gelatinous strings containing thousands of microscopic, spherical yellow eggs. In December, 1975, we found one specimen of Lobiger sourerbii sharing a common nest with two other opisthobranchs. They were on a dif- ferent type of Caiderpa (type 3) at Bahia de Algodones, Guaymas Area, Sonora. This is a northward range extension for the species. The known range is now from Bahia de Algodones, Sonora, to Bahfa de Tenacatita, Jalisco, on the mainland of Mexico. It is also recorded from Cabo San Lucas, Baja California Sur (Larson & Bertsch, 1974) and from the Galapagos Islands, Ecuador (Sphon & MuUiner, 1972). Oxynoe panamensis Pilsbry & Olsson, 1943 A single specimen of Oxynoe panamensis Pilsbry & Olsson, 1943, was found on the Caider- pa at Bahia de Tenacatita. Like Lobiger. it had the ability to cling to the algae by suction of the foot. When attempts were made to remove the animal from the algae, a greenish white mucus was excreted from glands along the side of the foot. This mucus seemed to have adherent proper- ties for the animal. It is more probable that the mucus served as a defense mechanism (Sphon & Mulliner, 1974). Oxynoe panamensis was described from a single shell in the beach drift on Isla Bocas, Golfo de Panama (7° 30' N, 80° 37' W). The living animal is figured in Keen, 1971. The body is long, slender, and slightly humped (30 x 4 x 4 mm). The first one-fourth of the body is made up of the head and neck. The second one-fourth comprises the shell, most internal organs, and two para- podia, one on each side. The posterior one-half of the body is the tail. The head is small and blunt with relatively large, nonretractable, inrolled rhinophores projecting horizontally from the lat- eral extremities. The angle between the rhino- phores is 90-120°. The mouth is on the underside of the head and is preceded by two rounded lips. The short neck extends back to the rounded anterior end of the shell. This is broad and cap- like on the dorsum and contains most of the vital organs. Behind the shell, the body tapers narrow- ly into a sharp tail. There is a ridge extending from just behind the shell along the back to the posterior extremity. Tine foot is extended laterally into two para- podia which rise upward over the shell to meet dorsally. Normally, the shell is completely covered except for the forward edge. The para- podia extend around the shell to the rear but do not quite meet until about 1 mm behind, where they fuse to form the ridge down the back. Ex- cept for the head, the body and parapodia are sparsely covered with sharp papillae. Overall color of the animal is the green of the algae. The papillae are white and there are small white dots over the entire animal, most numerous along the lower edge of the foot and toward the extremities of the rhinophores. Black spots alter- nate with white dots along the foot margin and are scattered with white on the upper one-half of the rhinophores. Blunt papillae and white spots are concentrated along the posterior dorsal ridge. When the parapodia are removed, the internal organs are revealed through the transparent shell. The organs are varying shades of green and clearly show a pattern of white dots. 64 THE NAUTILUS April 25,1977 Vol. 91 In November, 1974, 32 specimens of Orjfnoe panmnptifns from 4 to 30 mm in length were col- lected from a feathery form of Caulerpa (type 2) at Tinajas, Bahia de Bachwibampo, Sonora. This algae resembled Calerpa racemosa var. ser- tularioides reported by Keen & Smith, 1961, from Lsla Flsp'ritu Santo. One year later, the algae in the same region had greatly diminished in quan- tity and deteriorated in quality and only a few animals were found. The collected animals were kept in an aerated aquarium for six weeks. Fresh algae was pro- vided at intervals. The animals moved about free- ly on the algae and tank walls, exhibiting the same social habits as Lobiger except for the flex- ing of the parapodia. This species seems to be less e.xcitable than Lobiger. When placed in the tank, the animals began sexual activity at once. Soon, the glass walls showed numerous spirally coiled egg masses containing microscopic, spherical yellow eggs. Actual laying of the eggs was ob- served and photographed through the glass as the egg mass was deposited. One animal moved along an irregular path with the gelatinous ribbon ap- pearing from the broad front of the foot to be deposited on the glass. Two other animals crowded close on the right side and just behind the head of the animal that was depositing the egg mass. We further noted that Lobiger souverbii from the southern part of the range was abundant, with the animals large, brightly colored, and vigorous; but that the specimen from Bahia de Algodones was in poor condition. In contrast to this, ()xi/)io(' paudmcnsis was abundant at Guaymas. The animals were in fine condition compared to the single pale specimen from Bahia de Tenacatita. Autotomizing of the parapodia, which is not uncommon with Lobiger. was not observed with OxifHoe. However, the latter have been reported able to autotomize the tail section. The actual act was not observed in our tank; but several tail sections were found on the bottom of the tixnk and several animals without tails were observed. When dropped into alcohol, almost all of the animals seperated the tail se.lion from the body at a point just behind the parapodia and the .shell. The recorded range for Oxijnoe panamensis is at lsla Espiritu Santo, Gulf of California, (Keen, 1971). and from the Guaymas area, Sonora. Mex- ico, to Golfo de Panama (type locality). BertheIiniachloris(DaIl, 1918) We were collecting at the south end of Bahi'a de Algodones on November 29, 1975. At low water, we were out on the reef, which is 2 or 3 acres in extent. The tangled mass of Caulerpa (type 3) was encountered for the first time. We picked up a small rock with a clump of the algae attached, thinking to e.xamine the holdfast where we had previously found Sulcoretusa. Nestling among the branches was what seemed to be a small green bivalve. When the specimen was removed to a vial of sea water, a small green slug-like body emerged and began to crawl about. There were two valves inverted on its back with what appeared to be the hinge oriented upward and to the rear. Four small clumps of the algae yielded 13 specimens. We knew that we had found our first Betihelinia chloris (Dall, 1918). This is a range extension northward from lsla Espiritu Santo (Keen, 1971). The known range is now Abreojos to La Paz, Baja California Sur. Keen. 1971, states that the species possibly occurs at Guaymas. This is now confirmed. The species has also been reported from the Galapagos Islands. Ecuador (Sphon & Mulliner. 1972). The living animal was illustrated in Sphon & Bertsch, 1974. When collected, all of the animals were withdrawn and with the shells closed. One nest in a cavity in the algae yielded eight specimens. Several very small individuals were in this nest and would have been overlooked except that they were clinging to the shells of the adults. As the animals were removed, they were found to be at- tached to the algae with the fine elastic threads which have been previously reported (Sphon & Mulliner, 1972). Betihelinia were subsequently observed to produce large amounts of mucus from glands along the posterior foot margin. TTie mucus soon sets, in the salt water, into elastic threads which the animal spins. When first placed in the aquarium, the ani- mals clung together in a tight ball. As they slow- ly dispersed, the young ones continued to cling to Vol. 91 (2) April 25, 1977 THE NAUTILUS 65 the shells of the larger ones. Sexual activity was not observed. The presence of so many juveniles in November may indicate that reproduction is seasonal and occurs in late summer. The largest specimen had a shell 9.5 mm long. When placed in sea water, the valves parted slightly and the narrow slug-like body appeared, oriented so that the shell would be supported by the branches of the algae. On the bottom, the animal could support the weight of the shell in an upright position for only a few seconds before it would fall to one side. The animal moved with an alternating motion between the front part and the back part of the foot. The animals in the tank tended to crawl up the sides to the surface where they would form a cup with the bottom of the foot and use surface tension to float upside dovm with the heavy shell hanging down. Most of the internal organs appeared to be in- side the heavy shell and gave it a mottled green color. The shell opened only about 1' 2 mm as the small green body extended in front about 4 mm and the tail showed only slightly behind. The body was about 2 mm in height and less in width. On the front of the head were two rolled, yellow-tipped rhinophores which were about 2 mm in length. The forepart of the foot was slight- ly extended and widened. Just above the exten- sion of the foot was a flangelike lip. Behind the rhinophores on top of the neck was a small tur- retlike hump with two eye spots on the front. A slight ridge extended from this hump along the neck and into the shell. Under 20 magnifications, the body was clear and gelatinous, with horizon- tal rows of microscopic green nodules as inclu- sions. There was a row of small white dots along the margin of the foot and on the rhinophores. When the animal withdrew, a sequence of events took place. The foot folded downward along a central line, the rounded cheeks folded inward, the rhinophores came together vertically, and the body disappeared into the shell which then closed. The shell was translucent yellow-green with several clear rays extending from the umbones to the margins. Two dark rays were on either side of each umbone and extended laterally for about 1 mm. The tightly coiled nucleus of the em- bryonic shell was attached to the umbone of the left valve and extended horizontally across the umbone of the right valve. Phyllaplysia padina Williams & Gosliner, 1973 In March, 1975, a number of specimens of Phyllaplysia padina Williams & Gosliner, 1973 were collected from Padina in tide pools at Cabo Tepoca, Sonora. The animals were observed, photographed, and preserved. Several shells were extracted and photographed. Excellent drawings of the animal have been published (Williams & Gosliner, 1973a); but the living animal has not been figured. Numerous specimens have since been taken from Padina intertidally in the Guaymas Area as far north as Bah'a de Algodones. In May, 1975, and again in May, 1976, large numbers of these animals were observed at Bahi'a de Los Angeles, Baja California Norte. On Isla Smith in this region, there is a man-made turtle pond. When the tide is out, water pours over a six foot dam into a pool. There is some Padina in this pool. In 1975, six Phyllaplysia padina were taken from here but there were no animals found in 1976. At Punta la Gringa, across the channel on the mainland, the species was abundant on the algae from low water out to at least 10 meters. In May, 1976, high wind and rough water left large amounts of Padina at the high tide line. The algae was populated with this species. Twenty- four hours later, the algae was drying in the hot sun and wind. A few animals were still clinging to it and revived completely when placed in fresh sea water. We did observe a previously unrecorded fact concerning the coloring of the living animal. When studied under 20 magnifications, the body was uncolored and clear. The apparent greenish brown color was due to inclusion in the tissue of longitudinal rows of microscopic nodules. Several photographs show this so clearly that individual nodules can be distinguished. Individual animals differed widely in the concentration of the nodules. The normal habitat and range for this species seems to be wherever Padina will grow and from the head of the Gulf of California at least as far south as the Twenty-eight Parallel. m THE NAUTILUS April 25.1977 Vol. 91 (2) ACKNOWLEDGMENTS TVie p;uidance of Mr. Gale Sphon, Curatorial Assistant, Natural History Museum of Los Angeles County, in the preparation of the manuscript is gratefully recognized. We also thank Dr. James McLean, Curator of Invertebrate Zoolog>', Natural History Museum of Los Angeles County, who read the manuscript and made helpful suggestions. LITERATURE CITED I>dll, W. H. 1918. Description of new species of shells, chiefly from Magdalena Bay. Lower California. Pi-oc. Hiol. Soc Wiish tnijtwL 31: .5-8 (Feb. 27). Fisc-her. Paul. 18.57. Description d'especes nouvelles. Jour, de Co/ic/if//. 5(2): 273-77 (.Jan.). Keen, A. Myra. 1960. The riddle of the bivalved gastropod. ne Velujer 3(1): 28-.30 (.July 1). Keen, A. Myra. 1971. Sea sheik of tropical West Ameiica : marine mollusks from I5aja California to Peru. Stanford Univ. Press. Stanford. Calif, i-xiv-t-1066 pp.; ca. 4000 figs., 22colorplts. (Sept. 1). Keen. A. Myra and Allyn Smith. 1961. West American species of the bivalved ga,stroix)d genus Berthelinia. Proc. Calif. Acad. Sci. 30(2): 47-66; figs. 1-33; 1 pit. (March 2f)). Larson, Mary and Hans Bertsch. 1974. Northward range ex- tensions for Lobiger souverbii (Opisthobranchia: Sacoglossa) in the Eastern Pacific. The Veliger 17(2): 225 (Oct. 1). Pilsbry. H. A. and A. A. OLsson. 194.3. New marine mollu.sks from the west coast. Ue Nautibu, 56: 78-81, pit. 8 (Feb. 15). Smith, Allyn. 1961. Notes on the habitat of Berthelinia sp. nov. from the vicinity of I^ Paz, Baja California, Mexico. The Veliger 3(3): 81-82 (.Jan. 1). Sphon. Gale. 1971. New opisthobranch records for the Eastern Pacific. Tfie Veliger 13(4): .368-69 (Oct. 1). Sphon. Gale and Hans Bertsch. 1974. Green Dragons. Terra (Quarterly Mag. Nat. Hist. Mus. Ljs Angeles Co.. Calif.) 12(3): 21-29; color illustrated (Winter). Sphon, Gale and David K. Mulliner. 1972. A preliminary list of known opLsthobranch from the Galapagos Islands w^llected by the Ameripagos expedition. The Veliger 15(2): 147-.52; 1 map (Oct. 1). Williams. G. C. and T. M. Gosliner. 197.3a. A new species of anaspidean optisthobranch from the Gulf of California. Ihe VW(!/f;- 16(2): 216-.32 (April 1). Williams, G. C. and T. M. Gosliner. 1973b. I^nge extensions for sacoglossan opisthobranchs from the coasts of California and the Gulf of California. The Veliger 16(1): 112-16; 2 maps (.July 1). THE MIOCENE BIVALVE CUMINGIA MEDIALIS (SEMELIDAE) FROM SOUTH CAROLINA Clement L. Counts, III Department of Biological Sciences Marshall University Huntington, West Virginia 25701 Previous reports of the Miocene bivalve Cum- imjid DK'dialis Conrad, lS()(i have been almost en- tirely limited to North Carolina, Maryland and Virginia. Glenn (1904) reported C. mcdiali.^ from the Miocene of Maryland and cited localities for specimens taken from Virginia and North Caro- lina. Shimer and Shrock (1944) also reported (\ nicdialis from the Choptank Formation of Maryland and gave ranges of Maryland, Virginia, North Carolina and South Carolina without citing specific localities. Richards (1947) reported a specimen taken from a well, 18.3 m from the surface, dug at Edenton, Chowan County, North Carolina. This specimen was placed in the collec- tion of the Academy of Natural Sciences of Philadelphia (ANSP 16773) where the holotype and paratypes, from James River, Vii-ginia, also reside (ANSP 18839). The present note reports the second locality in South Carolina from which C. mi'diulit< has been taken. A right valve of C. medialift was found in sea-wrack at the high tide line at Crescent Beach, Horry County, South Carolina 18 Vol. 91 (2) April 25, 1977 THE NAUTILUS 67 August 1975. The shell was believed to be of re- cent origin and was sent to Dr. R. Tucker Ab- bott for confirmation. However, upon examina- tion by Dr. Abbott at the Delaware Museum of Natural History, it was properly identified as a fossil or subfossil and accessioned DMNH 103141. It was suspected by Dr. Abbott that the shell may have washed up from a fossil outcrop offshore. A specimen from the Peedee River, just south of the new locality, was reported by Glenn (1904). This specimen was the only such find of C. medialis in South Carolina prior to the pre- sent report. Mr. Robert H. Schlutter (personal com- munication) has noted that the specimens reported by Glenn (1904) from Maryland are most probably not from Maryland but from Virginia. Thus, the possibility that C. medialis is a Maryland form is doubtful and its citation as a representative bivalve of Maryland dubious. This was pointed out by Glenn (1904) but later references to the species place it in Maryland without noting this possibility. The author wishes to thank Dr. R. Tucker Abbott and Mr. Robert H. Schlutter for their ad- vice and assistance. LITERATURE CITED Glenn. L. C. 1904. Mollusca (Pelecypoda). Maryland Geol. Survey, Miocene. 274-401. Richards, H. G. 1947. Invertebrate fossils from deep wells along the Atlantic coastal plain. Jour. PaleontoL 21(1): 23-37. Shimer. H. W., and R. R. Shrock. 1944. Index Fossils of North AmeHca. MIT Press (Cambridge, Mass.). ix + &37 pp. LATITUDE, HABITAT, AND HATCHING TYPE FOR MURICACEAN GASTROPODS Tom M. Spight Woodward-Clyde Consultants 3 Embarcadero Center, Suite 700 San Francisco, California 94111 ABSTRACT Among rocky shore and oyster-reef muricaceans. all high latitude species hatch as young stiails, while all tropical species hatch as veiigers. In contrast, species from other habitats at all latitudes generally hatch metamorphosed Among prosobmnchs in general, more species of both hatching types are fonnd at low latitudes than at high latitudes and, m Europe, on continental suites rather than on islands. INTRODUCTION One of the most intriguing generalizations of prosobranch ecology is that in some places most species hatch as planktonic larvae, while in other places most species hatch as fully formed snails. The predominant hatching type varies both with latitude and with habitat. Typically many species have planktonic larvae at tropical sites and in shallow waters, while in the deep sea or in the arctic, most hatch metamorphosed (Thorson, 1950). These generalizations raise two questions: (1) are species that hatch metamorphosed in cold water areas replaced by ecological equivalents with planktonic larvae in warm-water areas; and (2) is one hatching type replaced more completely in some habitat types than others? 68 THE NAUTILUS April 25,1977 Vol. 91 (2) The latitudinal change in prevailing hatching ty'pe does not require species replacements. The change parallels a large change in community diversity. As long as most species added along the latitudinal gradient have swimming larvae, the prevailing hatching type will change, whether species with metamorphosing larvae are replaced or are about equally numerous everywhere. In the data presented by Thorson (1965) for Euro- pean prosobranchs, about equally many species with metamorphosed hatchlings are found at all latitudes, while the diversity of species with swimming larvae rises abruptly between 30°N and eO^N (Fig. 1). Thorson's data (Fig. 1) include 50-60% of the total fauna and therefore 200 150 o 0. tn o 100 - a: ui B 50 60 LATITUDE CN) FIG. 1. Pint of estimated number af ftpecies of prnnohrnnrh snaik hatching metnmorphoaed (triangles) and hatching as .•fwimming larvae (circles) for various European localities as a functon of latitude. Each paint is obtained by midtiplying the estimated total number of prosobranchs for the site by the fraction of species for each hatching type, as based on a sam- ple of iO-60% of known hatching lifpes. Data fnmi Thorson (19U and 1965). Solid figures and solid lines, mainland sites: open figures and dotted or dashed lines, island sites. The lines are fitted by linear regression and have the follouing r' valties: metamorphosed, mainland O.Oi, island 0.01; smmming larvae, mainland 0.81, island 0.87. estimates of faunal composition based on these are both relatively unbiased and comparable to each other. Within the 40-70" latitudinal range, and among prosobranchs as a whole, species hatching metamorphosed are supplemented rather than replaced by species with plantonic larvae. Figure 1 also demonstrates an additional habitat variable: isolation. At all latitudes, island sites have fewer species of both hatching types. Frequencies of the larval types also vary from one habitat to another. Most tropical .shore species have planktonic larvae (91% o( 21 species, Lewis, 1960; 100% of 13 species, Ostergaard, 1950), while in deeper waters (here "deep" refers to waters in the range of lO-l(X) m) many species hatch metamorphosed (25%, Thorson, 1940a: 69%, Knudsen, 1950). Hatching types were obtained for relatively few species in these studies, and the selection undoubtedly reflects the particular tax- onomic groups these authors chose or were able to study. To confirm the habitat-larval type rela- tionships, further data are required. Larval types of many species have been reported incidentally, and these can be used to confirm the pattern of changes observed in the regional faunal studies. With this in mind. I have reviewed the published data on members of one major group, the superfamily Muricacea (including the thaidids). METHODS The available habitat descriptions (obtained from the papers cited or from standard works) fall into 4 major categories: intertidal rocky shores, oyster reefs, shallow-water sand bottoms, and deeper waters (10-100 m, as opposed to the deep sea). Thais cornnata, found on mangroves, fits into none of these categories, and is arbitrari- ly included with the oyster reef species. The oyster reef species appear to be found on more kinds of substrates than the other species are; in- dividuals of most of these species can be found feeding on clams on muddy bottoms or barnacles on rocky shores as well as on oysters. Larval types are summarized by wide lati- tudinal bands (Table 1). Latitudinal bands were chosen to approximate equatorial, tropical, sub- tropical, temperate, and boreal areas. Too few Vol. 91 (2) April 25, 1977 THE NAUTILUS 69 TABLE 1. Percentage of species 0/ Muricaceans hatching as long-term veligers (more than 1 week) as a function of lot it tide and habitat. Number of species in parentheses. HABITAT Ijatititde RiickijShoT€ Estuary Shathw-water Deep-water -NorS Saiul 0-15 100%(6) 100%(1) 0%(2) 0%(3) 16-24 100%(1) - 33%(3) - 25-35 75%(12) 100O/o(l) 25%(8) 100%(2) 35-45 20%(5) 50%(4) 50%(2) 0%(3) 46-90 0%(6) 0%(3) 0%(3) data are available to identify local patterns, and therefore no attempt was made to accommodate more subtle features of species distributions. The latitudinal band for each species was ob- tained from the site at which observations were made rather than from the species range. Single sites were used to avoid the bias of including wide-ranging species in more than 1 band. How- ever, of 6 species studied by more than one author, 3 were studied in different latitudinal bands (Cuma turbinoides = Thais carinifera?, Occnebra japonwa = Tritonalia japonica, and Thais floridana = Thais haemastoma floridana) and are entered twice in Table 1. Three species were studied by two authors within the same latitudinal band: Thais fasciata (T. rustica). Acanthina lapilloides (A. spirata), Favartia ceUulnsus. These 3 species are entered only once in Table 1. HATCHING TYPES IN THE MURICACEA Each species is listed as given by the original author, together with the approximate latitude of the original author's observations. Intertidal Rocky Shores Hatch as veligers: Thais bufo (Lamarck) 8''N (Natarajan 1957), Thais tissoti (Petit) S^N (Natarajan 1957), Vitularia salebrosa (King and Broderip. 1832) 9''N (D'Asaro 1970b), Thais tieltoidea Lamarck LTN (Lewis 1960), Thais flofidana Conrad 13°N (Lewds 1960), Thais patula Linnaeus 13°N (Lewis 1960), Cuma turbinoides Blv. 22°S (Risbec 1935), Thais rustica Lamarck 25°N (D'Asaro 1970a), Thais carinifera (Lam.) 27°N (Thorson 1940a), Jopas francolinuyn Bruguiere 27''N (Gohar and Eisawy 1967), Thais hippocastaneum (Lam.) 27"N (Thorson 1940a), Dicathais aegrota (Reeve 1846) 32"S (Phillips 1969), Thais fasciata Rve. 32»N (Lebour 1945), Ocejiebrapoulsoni Carpenter 33°N (Fotheringham 1971), Shasktrus festivus (Hinds) 33°N (Fother- ingham 1971), Morula marginalba (Blainville) 33°S (Anderson 1967), Bedevina birileffl (Lischke) 33°N (Amio 1957), Concholepas conchoiepas (Bruguiere) 39°S (Gallardo 1973). Hatch as snails: Favartia cellulosu^ (Conrad) 25<'N (Raeihle 1966), Favartia nuceus (Morch) 32°N (Lebour 1945), Thais dubia 34''S (Bokenham and Neugebauer 1938), Bedeva hanleyi (Angas) 35''S (Anderson 1967), Acanthina lajnlloides 36°N (Hewatt 1934), Acanthina spirata (Blainville), 37''N (personal observations), Nucella calcar 39°S (Gallardo, 1973), Ocenebra lumaria Yokoyama 41°N (Luckens 1970), Ocinebra aciculata Lamarck 43''N (Franc 1940), Ceratostoma foliatum (Gmelin) 48»N (Spight et al. 1974), Thais canaliculata (Duclos) 48°N (original), Thais emarginata (Deshayes) 48°N (original), Thais lamellosa (Gmelin) 48°N (original), Nucella lapfillus (Linnaeus) 54''N (Pelseneer 1910), Thais lima (Gmelin) 51°N (original). Oyster Reefs Hatch as veligers: Thais coronata Lam. 6°^ (Knudsen 1950), Thais haemastoma floridana (Conrad) 26"N (D'Asaro 1966), Purpura clavigera Kuster 37°N (Amio 1963), Purpura bronni Dunker41''N (Amio 1963). Hatch as snails: Eupleura caudata (Say) 37°N (MacKenzie 1961), Ocenebra japonica (Dunker) 43°N (Amio 1963), Ocenebra japonica 47''N (Chap- man and Banner 1949), Ocenebra erinacea (L.) 52°N (Hancock 1960), Urosalpinx cinerea (Say) 52°N (Hancock 1959). Shallow-water Sand Bottoms Hatch as veligers: Chicoreus brunneus Link 22°S (Risbec 1932), Hexaplex kosterianus Tapp. 27''N (Thorson 1940a), Leptoconchus cumingii (Deshayes) 27''N (Gohar and Soliman 1963), Rapana thomasiana Crosse 37''N (Hirase 1928). Hatch as veliconchas and/or snails: Murex trapa Roding 8°N (Natarajan 19,57), Chicoreus mrgineus var. ponderosa Sowerby S^N (Natarajan 1957), Chicoreus incamatus (Roding) 27°N (Gohar 70 THE NAUTILUS April 25,1977 Vol. 91 (2) and EisawT 1967), Chicoreus ramomts (Linne) 27»N (Gohar and Eisawy 1967). Hatch as snails: Chicoreus torrefactus (Sower- by) 18'S (Cernohorsky 1965), Ton'amnrex fem/».s (Reeve) 22°S (Murray and Goldsmith 1963), Chicoreus florifer Reeve 26°N (D'Asaro 1970), Chicoreus pomum Gmelin 26°N (D'Asaro 1970a), Calotrophon ostrearum (Conrad) 30°N (Radwin and Chamberlin 1973), Urosalpinx perrugata (Conrad) 30°N (Radwin and Chamberlin 1973), Hexaplex trunculu,'< (Linne) 43°N (Fioroni 1966). Deeper Waters Hatch as veligers: Hexaplex fvlvescens (Sow) 28°N (Moore 1961). Rapana bidbosa Sol. 28»N (Thorson 1940a). Hatch as snails: Chioreits quadrifrons (Lam.) 5°N (Knudsen 1950), Chicoreus senegalensw (Gmel.) 5°N (Knudsen 1950), Murex fasciatus Tryon 1880 10°N (Knudsen 1950), Muricopsis blaimnllei (Payraudeau) 41''N (Fioroni 1966 after Franc 1948), Murex brandaris Linne 43°N (Fioroni 1966), Ocenebra spec. 43°N (Fioroni 1966), Trophon muricntus (Montagu) SO^N (Labour 1936), T)vphon truncahis (Str6m) 57''N (TTiorson 1946), Trophon clathratus (L.) var. Gun- neri Loven 65<'N (Thorson 1940b). CONCLUSIONS The predominant type of hatching changes more markedly among rocky shore murica ceans than it does among prosobranchs as a whole (Fig. 1). In this habitat, all high-latitude species metamorphose before hatching, and all tropical species have planktonic larvae. The rock>' shore fauna is relatively well known, because it is accessible at all latitudes; therefore further work is unlikely to change this generalization. Species of one hatching type are completely replaced by ecological equivalents of the other along the latitudinal gradient. The two hatching types are mixed between 25-30° (Table 1), and studies at these latitudes should reveal the relative ad- vantages of the two hatching types, and possible instances of competition between them. A parallel latitudinal trend is observed among oyster reef species. Hatching types for shallow-water sand species and deep-water (10-100 m) species do not change in the same manner. Species with metamorphosed hatchlings prevail at most latitudes in both of these habitats. In the shallow-water sand habitat, one also finds an intermediate hatching type, a non-feeding Veliconcha that metamorphoses a few days after hatching. Considering all habitats, diversities of both hatching types are probably greatest at low lat- titudes. According to available data, the latitudinal gradient in hatching type is striking (Milekovsk>', 1971) and might imply a low number of tropical species that hatch metamor- phosed. However, a disproportionately large number of the tropical observations are on rocky shore species. Species from other near-shore habitats are likely to have metamorphosed hat- chlings at all latitudes. When these are included, species with metamorphosed hatchlings will pro- bably be shovra to be most diverse at lower latitudes. In the only whole-fauna available to date (Fig. 1), species with metamorphosed hatch- lings are more diverse at the lowest latitude (Portugal, 41°N) than at the highest. LITERATURE CITED Amio, M. 1957. Studies on the eggs and larvae of marine gastropods. Part I../ Shunonosek-i Coll. Fisk 7: 107-116. Amio. M. 1963. A comparative embryology of marine gastropods, with ecological emphasis. J. Shinwnoseld ColL F-ish. 12: 229-.'353. Anderson, D. T. 1967. Further observations on the life histories of littoral gastropods in New South Wales. Proc. Linnean Sue. New South Walea 90: 242-251. Bokenham. N. A. H. and F. L. M. Neugebauer. 1938. The ver- tical distribution of certain intertidal marine gastropods in False Bay. with notes on the development of two of them. .4«H.A'(i/(!/.A/i«. 9:113-137. Cemohorsky. W. 0. 1965. The radula. egg capsules, and young of Murex (Chicoreus) torrefactus Sowerby. Veliger 8: 231-233. Chapman, W. M. and A. H. Banner. 1949. Contributions to the life history of the .Japanese oyster drill (Tritonnlia japnnica) with notes on the other enemies of the OI>Tnpic Oyster ((htrea lurida). Wiishinytim Dept. Fixh. Biol, kept 49A: 167-2tK), U'Asaro. C. N. 1966. The egg capsules, embryogenesis. and ear- ly organogenesis of a common oyster predator, Thais haemastoma floridana (Gastropoda Prosobranchia) Bull Mar. Sci 16: 884-914. D'Asaro. C. N. 1970a. Egg capsules of prosobranch molluscs from South Florida and the Bahamas and notes on spawn- ing in the laboratory. Bull. Mar. Sci. 20: 414-440. Vol. 91 (2 April 25. 1977 THE NAUTILUS 71 D'Asaro. C. N. 1970b. Egg capsules of some prosobranchs from the Pacific Coast of Panama. Veliger 13: 37-43. Fioroni. P. 1966. Zur morphologie und embryogenese des Darmtraktes und der transitorischen Organe bei Prosobran- chiern (Mollusca, Gastropoda). Renie Suisse de ZooUxjie 73: 621-876. Fotheringham. N. 1971. Life history patterns of the littoral gastropods Shaskyus feMiinis (Hinds) and Ck-enebm /Wwwi Carpenter (Prosobranchia: Muricidae).&()%i/52: 742-757. Franc. A. 1940 Recherches sur le developpement D'Ocinehra aacidata, Lamarck (Mollusque gasteropode). Bull. Biol. FV. Belg. 74: 327-345. Gallardo, C. 1973. Desarrollo intracapsular de Concholepas corwholejxis (Bruguiere) (Gastropoda Muricidae). Museo Nn- Clonal de Historia Nntuml Santiago de Chile Publ. Oca.'!. 16: 1-16. Gohar, H. A. F. and A. M. Eisaw>'. 1967. The egg-masses and development of five rachiglossan prosobranchs (from the Red Sea). Pubis, mar. biol. Stn. Ghardaqa 14: 215-268. Gohar. H. A. F. and G. N. Soliman. 1963. On the biology of three coralliophilids boring in living corals. Pubis, mar. biol. Sta. Al Ghardaqa 12: 99-126. Hancock, D. A. 19.59. The biology and control of the American whelk tingle Uro.'' of marine bottom inveriebrates. Biol. Rev. 25: 1-45. Thorson. G. 196.5. The distribution of benthic marine mollusca along the N.E. Atlantic shelf from Gibraltar to Murmansk. Proc. First Eiirop. Malar. Congr. (1962) pp. 5-25. Thorson, G. 1946. Reproduction and larval development of Danish marine bottom invertebrates. Medd. Komm. Danm. Fisk. -og Havunders.. ser Plankton. 4: 1-523. 72 THE NAUTILUS April 25,1977 Vol. 91 CONUS VIOLA, A NEW NAME FOR C. VIOLACEUS REEVE Walter 0. Cernohorsky Auckland Institute and Museum Private Bag, Auckland, New Zealand ABSTRACT The new subfititute name Conus viola is here proposed fur the hoinouymous C. violaceus Reeve, from the tropical West Pacific region. Conus viola Cernohorsky, new name Figs. 1 - 3 1844. Co«M.s violaceus Reeve, Conchologia Iconica, vol. 1, pi. 44, fig. 241; 1858 Sowerby, Thesaurus Conchyliorum, vol. 3, p. 45, pi. 208, fig. 537; 1875 Weinkauff, Martini & Chemnitz Syst. Conchyl. Cabinet, ed. 2, vol. 4, pt. 2, p. 76, pi. 46, fig. 11; 1937 Tomlin, Proc. Malac. Soc. Lon- don, vol. 22, p. 328 (erroneously synonymized with C luteus Sowerby^ [non C. violaceus Gmelin, 1791] 1884. Conus violaceus Reeve [pars], Tryon, Manual of Conchology, vol. 6, p. 88, pi. 28, fig. 82 (only) 1964. Conus luteus var. Sowerby, Marsh & Rip- pingale. Cone shells of the world, p. 124, pi. 18, fig. 7 {non Sowerby, 1833) 1972. Cvnus species Hinton, Shells of New Guinea and the central Indo-Pacific, p. 82, pi. 40, fig. 6. 1975. Conus molaceus. C. tendineus or Conus sp.? Leehman, Hawaiian Shell News, vol. 23, No. 6, p. 6, text figs. Type locality: Matnog, Island of Luzon, Philif)- pines. Type specimens: TTie three syntypes of C. molaceus Reeve, accompanied by a label which bears Tomlin's remark = luteus Broderip, are in the British Museum (Nat. Hist.), London. The specimen measuring 41.0 mm in length and 15.0 mm in width, is here selected as the lectotype of C. violaceus ( = C. viola new name). Conus violaceus was first described in literature by Reeve (1844), who based his FIGS. 1-2. h'ctdtyi)!' (i/ ('onus violaceus Rerve (= C. viola Cernohorsky, new name: B.M.N.H.. length 1,1.0mm. uMlh 15.0 mm. 3. Specimen o.f C. viola from Bathurst Id., Nth. Australia: Icni/th ■'io.S mm. u-idth .Hi mm. 4-5, Topotype of C. luteus Sowerby, from Anaa Id.. Tiiamotus; B.M.N.H., length SS.Omm. Vol. 91 (2) April 25, 1977 THE NAUTILUS 73 diagnosis on three specimens from the Cuming collection. Reeve's C. violaceus, however, is a primary homonym of C. vwlacem Gmelin, 1791, which is an earlier name for the Indian Ocean species C. tendineus Hwass in Bruguiere, 1792. Tomlin (1937) did not propose a replacement name for the homonymous C. violaceus Reeve, as he considered this species to be synonymous with C. luteus Sowerby, 1833. C. viola and C. luteus are similar but quite distinct species, with C. viola known only from an area between the Philippines and North Australia, whereas C. luteus is widely distributed throughout the tropical Pacific. The average size of C. viola is about 50 mm, the shell is cylin- drical, the first 2-3 post-embryonic whorls are finely nodulose, the penultimate whorl is inflated and telescopic in appearance, sutures are firmly but irr^ularly adpressed, the outline of the body whorl is cylindrical with the first two-thirds of the body whorl descending almost vertically before tapering towards the base, the aperture is narrow at the start but slightly flaring basally, and the sculpture consists of 6-10 spiral threads on the spire whorls, obsolete spiral threads on the body whorl and up to a dozen close-set cords at the base. Fresh specimens are pale violet and or- namented with brown spots on the spire whorls, three broad but often dilacerated brovra bands on the body whorl which are usually interrupted in the centre of the whorl by a pale band, and spiral rows of small brown spots, aperture pale violet. C. luteus is considerably smaller, averaging about 30 mm in length, the spire is short and convex, whorls are not inflated but tight, the 2-3 post-embryonic whorls are smooth, the sutures are narrowly canaliculate, the shoulder is moderately broad, smooth and sloping and the body whorl tapers rapidly toward the slender base; shell glossy, obsoletely spirally striate on the body whorl, the arcuate axial striae on the spire whorls are crisper and spiral threads fewer and the aperture is uniformly narrow and does not flare basally. The colour is yellow, orange, pink or rose-red, the centre of the body whorl has a narrow white band or blotches which are bordered by quadrate, irregular and distinctly smudged dark brown spots, and spiral rows of dark brown interrupted lines are present in some individuals. Dark coloured specimens of C. viola have been illustrated by Leehman (1975) and the banded form by Hinton (1972). The lectotype of C viola is a form where the brown bands are dilacerated in- to longitudinal zones. LITERATURE CITED Hinton, A. 1972. Shells of New Guinea and the Central Indo- Pacific. R. Brown & Associates Pty. Ltd., Port Moresby, and Jacaranda Press, Milton, 94 pp., 44 col. pis. Leehman, E. G. 1975. Conus confusion. Hawaiian Shell News. 23(6): 6, text figs. Reeve, L, 1843-44. Conchologia Iconica; monograph of the genua Qmits. L. Reeve, London, vol. 1. 47 pis. Tomlin. J. R. le B. 19.37. Catalogue of Recent and Fossil Cones. Proc. Malae. Soc. London, 22: 205-330. THE NAUTILUS Back Volumes 1 through 40 High quality reprintings are now available from our office. The cost of the handsomely bound set, in green buckram, is little more than the price of the pajierbound. Index to volumes 1 through 34 available separately for .$12.00 (paperbound). aothhnund, vols. 1-40 (with Index) .$482.00 Paperbouml vols. 1-40 (with Index) $412.00 Orifjinal. unbound vols. 72-89 $10.00 per vol. Postage free if payment accompanies order. Order from: The Nautilus P.O. Box 4208 Greenville, De. 19807 74 THE NALITILUS April 25,1977 Vol. 91 (2) IS THAIS CAN ALICULATA (GASTROPODA: MURICIDAE) EVOLVING NURSE EGGS? Tom M. Spight Woodward-Clyde Consultants 3 Embarcadero Center, Suite 7()0 San Francisco, Calif. 94111 ABSTRACT Thais canaliculata appears to be in the course of evolving from one reproductive mode (!()()% fertility) to another fprovmon of nurse eggs for em- bryos). In some populatiori% all eggs are fertile. In other populations, as few as 16% in each capsule may he fertile and the infertile eggs are used as nurse eggs by the embryos. If T. canaliculata is to complete the transition to nurse- egg feeding, two major adaptive problems must be solved: fertility must be regulated, arui new larger hatchlings must become much more likely to survive to maturity. Some Thais canaliculata (Duclos, 1832) females produce infertile eggs, and these are used by the embryos as nurse eggs, while other females produce only fertile eggs (Lyons and Spight 1973). These variations in reproductive mode may indicate that T. canaliculata is in the process of abandoning one mode in favor of another. This paper will examine available data on fertility in order to evaluate this hypothesis. METHODS Egg capsules were collected at Cattle Point and South Beach (on the southeast tip of San Juan Island, Washington) during May, 1970, at Cattle Point during May, 1972, and near Friday Harbor during May and August, 1972. One of the Friday Harlx)r clusters was attended by a 44-mm female, and one by a 31-mm female. Capsules were opened shortly after collection, and contents (eggs and/or embryos) were counted. The 41-mm female continued to deposit capsules while kept in a laboratory aquarium. Some of these capsules were kept to obtain embryo counts. RESULTS Capsules from Cattle Point and South Beach do not contain infertile eggs. The capsules collected during 1970 contained cleaving eggs or early em- bryos, and all eggs were developing. The average 1970 capsule was 8.23 mm long (N = 23, SD = 0..53) and contained 28.1 embn,'os (SD = 8.35). The 1972 capsules, which contained embryos near- ly ready to hatch, were slightly smaller (8.04 mm, N = 17, SD = 0.72), and contained W/o fewer embryos (23.5, SD = 4.39). Therefore, embryo numbers do not decline significantly during development (Fig. 1, open vs. solid circles). Capsules from Friday Harbor do contain infer- tile eggs. Several capsules from the 44-mm female were opened, and of these, 8 contained embryos that had almost reached the feeding stage. From 16% to 92% of the eggs in these capsules were developing (mean, 56%). I found feeding embryos, nurse eggs, and debris of broken nurse eggs in each of the capsules deposited by another female. Only 35% of the intact eggs were developing. Ac- tual fertility must have been even lower, since some of the nurse eggs had already been torn apart and consumed. The number of eggs per capsule is significantly correlated with capsule size (capsule length, ex- cluding the stem; Fig. 1). When all counts from Cattle Point and South Beach capsules, and counts of eggs plus embryos from Friday Harbor capsules are included, the logarithm of capsule height (X) accounts for 34% of the variation in the logarithm of egg count (Y), and the following Vol. 91 (2) April 25, 1977 THE NAUTILUS 75 linear regression between these variables is ob- tained: Y = 1.7299 X - 0.1527 for a total of 55 capsules (F , „ = 27.0891, P < 0.01). Almost all of the embryo counts for the Friday Harbor capsules fall well below this com- mon line (solid triangles, Fig. 1). 10 o tr. m 2 UJ [£ O ii nf /r( stern WiiiilniKjItiti. Various authors have reported the estab- viviparid snail, Cipangopoludina chinen.'^!^ (Gray, lishments of populations of the freshwater 1834), in widely separated sections of North ■ Part of a larger study supported by Sigma-Xi-Resa and In- America, assigning several specific epithets to the stitutional grants. snails (Dundee, 1974), including Viviparus Vol. 91 (2) April 25, 1977 THE NAUTILUS 77 malleatun Reeve and V. stelmaphoru^ Bourguignat. Previous reports of the species from the state of Washington are restricted to a population in Green Lake at Seattle (Hanna, 1966). The population reported here was thriving in 1973 in Lake Cascade at Moran State Park on Orcas Island, the largest and most highly tourist- oriented body of land in the San Juan Island off the Washington coast. Although I made no at- tempt at estimating population size, 56 in- dividuals were secured in approximately 30 minutes from an area no larger than two square meters. The smallest individual is 7.0 mm in total length, and the largest 44.0 mm, indicating, of course, that reproduction was occurring at that time. One shell and operculum were deposited at the Delaware Museum of Natural History (no. 106584) as a voucher specimen. LITERATURE CITED Dundee, D. S. 1974. Catalog of introduced mollusks of eastern North America (north of Mexico). Sterkiana 55: 1-37. Hanna. G. D. 1966. Introduced mollusks of western North America. Occ. Pap. Calif. Acad. Set. 48: 1-108. THE POLYGYRID GENUS McLEANIA IN HISPANIOLA Fred G. Thompson Florida State Museum University of Florida Gainesville, Florida 32611 Mcleania is a genus of medium-sized depressed helicoid land snails in which the species are characterized by having a series of nodelike ser- rations along the peripheral keel of the shell. Un- til now the genus was thought to be monotypic and endemic to Puerto Rico (see van der Schalie, 1948:70) where the type species, M. darlingtnni Bequaert and Clench was discovered by Philip J. Darlington, Jr. in 1938. Bequaert and Clench (1939:283-284) tentatively placed Mcleania in the Cepolidae (= Xanthonichidae, see Baker, 1956) because of resemblances in size and shell shape to some Hemitrochus. Baker (1940: 55-57) demonstrated that the reproductive anatomy of Mcleania is similar to that of Thysanopkom. Cur- rently Mcleania, Thysanophora, and allied genera are placed in the Thysanophorinae, a subfamily ofthePolygyridae. During June, 1974, and January, 1976, I col- lected shells of two undescribed land snails from the Barahona Peninsula, Dominican Republic. One species is described in this paper. The second remains undescribed because it is represented by a single immature shell that does not show definitive characteristics of its species. These two snails are tentatively assigned to Mcleania because of similarities in shell structure to M. dmiingtoni. They differ from M. darlingtnni in important characteristics of the sculpture, as well as several other traits. No live specimens of the two new taxa were found, and a more satisfac- tory basis for relating them to M. dariingtoni cannot be given at this time. Field work in the Dominican Republic was sponsored by the Florida State Museum and the National Geographic Society, Committee for Research and Exploration. I am grateful to of- ficials of both organizations for making this field work possible. Mcleania tumidula new species (Fig. 1, A-C) S/?r//. -Depressed helicord, about 0.,53-0.67 times as high as wide; medium sized, being about 78 THE NAUTILUS April 25,1977 Vol. 91 (2) FIG. 1. A-C Mcleania tumidula neiv species, holotifpe (UF 227:16). U.6 mm in width. D-F Mcleania darlin^imi Be- 1.5 mm wide. Color uniform light brown. Shell opaque. Spire low, obtuse, nearly flat sided, slightly convex in outline. Base inflated. Whorls rapidly increasing in size, keeled, with about 19-21 obliquely compressed knobby serrations along the periphery that form a scalloped fold around the shell. 'Die peripheral interior of the shell is indented beneath the knobs. Body whorls nearly flat above the periphery, strongly inflated quaert and Clench: 30 km. N.N. W.. 3 km K Ponce. Puerto Rim. mm-ll.iO m. alt. (UF 22738). below: descending very slightly along its last quarter. Umbilicus narrow, about 1/25 the diameter of the shell. Umbilicus partially obscured by reflected columella. Adult shell with 3.6 whorls, and having 1.4 embryonic whorls. First embryonic whorl smooth. Subsequent em- bryonic portion with weak incremental growth wrinkles. First quarter of post -embryonic whorl with fine incremental thread-striations that are Vol. 91 (2) April 25, 1977 THE NAUTILUS 79 replaced rapidly by heavy cord-like folds extend- ing halfway across the whorl from the suture. Folds more or less alternating with compressed knobs along the periphery. Superimposed on the cords is an oblique series of irregular, fine zig-zag striations that tend to become corrugated near the periphery and on the knobs. Base of shell with fine, irregular, incremental striations bear- ing superimposed and finer, short, scattered, zig- zag striations that tend to corrugate the base. Aperture broadly auriculate, deeply indented by previous whorl. Peristone simple, thin, weakly reflected, incomplete across parietal wall. Dorsal lip nearly straight. Columellar margin moderate- ly reflected over umbilical area. Parietal callus thin, transparent, strongly recurved near um- bilicum. nearly straight otherwise. Measurements in mm of the three known specimens are: Holot>T3e Height 7.7 Width 14.6 Aperture H. 4.6 Aperture W, 8.3 Whnrli 3.6 Paratv-pe 6.8 10.6 5.0 6.5 3.5 Paratype 5.9 8.8 4.5 5.7 3.3 Type Locality— DominicsLn Republic, Barahona Prov., Loma Cana Brava, 6 km. E, 6 km. NNE Polo, 1370 m. alt. Holotype: UF 22736: collected 18 January, 1976 by Fred G. Thompson. Para- types: UF 22735(2); same locality as the holotype. The type locality is in a wet mountain forest at the crest of the mountain Loma Cana Brava. The microhabitat occupied by the snail was not determined for live specimens were not en- countered. The shells comprising the type series were found on the ground under limestone slabs on densely shaded moss and lichen covered knolls. Remarks— Mcleania tumidida can be compared with two other species, M. darlingtoni from Puer- to Rico and another undescribed species from Hispaniola to which it is more closely related. It differs from M. darlingtoni in numerous details. The shell is much larger, attaining a major diameter of about 15 mm. It has a broadly obtuse raised spire, resulting in a height/width ratio of about 0.53-0.67. The whorls are much more in- flated, and have more (19-21) but much weaker serrated nodes per whorl along the periphery. The umbilicus is much narrower, being about 1/25 the width of the shell. The peristome is in- complete across the parietal wall, and the outer lip is only slightly reflected. The periostracum is nearly smooth, having weak incremental stria- tions and poorly defined oblique anastomosing wrinkles. The embryonic whorls are smooth in- itially, with weak incremental sculpture follow- ing the first whorl. M. darlingtoni is characterized by numerous pecularities (Fig. 1, D-F). It attains a major diameter of about 12 mm, and is planispiral with a height/width ratio of about 0.36-0.38. The whorls are relatively small in caliber and have about 12-16 strong protruding nodes along the periphery. The umbilicus is very broad and fun- nel shaped, being about 1/3 the width of the shell. The peristome is complete and the aperture is slightly free from the preceding whorl. The lusterless periostracum bears numerous course in- cremental threads and fimbriations that form scattered tufts on the base and apex. The peripheral serrations are coursely marked with radial periostracal fimbriations. Finally, the em- bryonic whorls have rather course, strongly ob- lique anastomosing wrinkles. The differences between M. tumidida and M. dnrlimjtiini are numerous and of such a mag- nitude that a congeneric assignment of the two species is only provisional. Most fundamental of these differences is the sculpture. Until the soft anatomy of M. tumidula is investigated the systematic relationships and biogeographic im- plications must be interpreted with caution. An additional undescribed Mcleania occurs in the Sierra de la Salle north of Pedernales, Peder- nales Prov., Dominican Republic. A single im- mature shell (UF 22737) was collected 1 km. south of Altagracia, at 750 m. altitude in a cocao grove. Compared to M. tumidida this other species has course, irregular radial sculpture on the spire, is nearly planispiral, and has a wide umbilicus that is about 1/6 the diameter of the shell. In other aspects it is more like M. tumidula than M. darlingtoni. 80 THE NAUTILUS April 25.1977 Vol. 91 (2) LITERATURE CITED Baker. H. B. 19.56. Family names in Pulmonata. The Nautiltis 69: 128-i:?9. Baker. H. B. 1940. Some Antillean Sagdidae and Polygyridae. The Nuut iliix 54: 54-62. Qench. Wm. J. and J. Bequaert. 1939. Mcl€ania.ai new genus of land mollusks from Puerto Rico. Meniorids dp la Siiripdntt Ciibnmi fie Histinia Natural 13: 283-284; pi. %. fig. 4-6. van der Schalie. H. 1948. The land and fresh-water mollusks of Puerto Rico. Misc. Publ. Museum ofZool. Unii: Mich. 70: 1-133; pis. I-XIV. RECENT DEATHS Alberto Carcelles, well-known and leading malacologist of Argentina, died Januar\' 23. 1977. in Alta Gracia. Cordoba. Argentina, at the age of 81. Dr. Carcelles taught at the University in Buenos Aires and was for years Chief of the In- vertebrate Section, in the Museo Argentina de Ciencias Naturales. He was bom in Buenos Aires on July 18, 1897. He authored many works on the marine mollusks of Uruguay and Patagonia. Among his students was Dr. J. J. Parodiz of Pittsburgh. Pa. John Dyas Parker, malacological archivist for the Delaware Museum of Natural History and long-time assistant to Henry A. Pilsbn,' at the Academy of Natural Sciences of Philadelphia, died February 2, 1977, of a heart attack, in Penn- sylvania, at 61. He stimulated interest in mol- lusks among amateurs who funded the Pilsbr>' Chair of Malacology, and was a co-founder of the Philadelphia and Wilmington Shell Clubs. He was active in paleonto logical field work and cave exploration. Jack was born June 5, 1915. in Woodhaven, Long Island, N. Y. where he is now bui'ied. Willard Lee Mohorter, fonner publisher and private shell collector, died October 19, 1976, in Cincinnati, Ohio, at the age of 88. He and his late wife travelled extensively from 1936 to 1975 in search of mollusks. He was honorary curator of mollusks at the Cincinnati Museum of Natural Histor>' and donated part of his collection to that institution. He was born in Kiamensi, Delaware, October 4, 1888. A short, posthumous biography of "Mr. Mo" appeared in the Hawaiian Shell Npuv. February 1977. Esther Brooks Hadley, well-known shell dealer in Newton, Massachusetts since 1936, died in North Adams, Massachusetts, on September 9, 1976 at age 87. Formerly, she worked for the Veterans Administration in Boston. She and her late husband, F. Knight Hadley, operated a shell mail order business for forty years. Her collection is for sale by her son, Norman, of Jacksonville, Vermont 05432. Kenneth R(ichard) H(odgson) Read, biochemist and marine biologist at Boston University, died February 24. 1977. at 48, in Boston, Mass. He was well-known for his underwater photography, and published on myoglobins in mollusks. He was born Spetember 9. 1928, in Dinas Powis, Wales, and obtained a Ph. D. at Harvard University in 1963. Albert B(ernhard) Kettell, for years a pastor of the United Church of Christ in New England, an Army Chaplain during World War II, and an ardent shell collector, was born in Somerville, Mass., March 7, 1896. He was a member of the A.M.U. for 25 years and a former President of the Connecticut Valley Shell Club. Reverend Kettell amassed a large collection of shells, and retired to Clearwater, Florida, where he died December 30, 1976, at the age of 81. He is sur- vived by his wife, Clara Dito Kettell. See Ameri- can Malnrologi<>tii. 1975 supplement, p. 555. 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MOLLUSK VOUCHER SPECIMENS It is becoming increasingly important for future research purposes that an identified sam- pling of species mentioned in publications be deposited in a permanent, accessible museum specializing in moUusks. This is particularly true of moUusks 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. Material 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. JULY 1, 1977 THE NAUTILUS Vol. 91 No. 3 A quarterly devoted to malacology and the interests of conchologists Founded 1889 by Henry A. Pilsbry. Continued by Editor-in-Chief: R. Tucker Abbott H^, urrington Baker. EDITORIAL COMMITTEE CONSULTING EDITORS Dr. Arthur H. Clarke, Jr. Division of Molluslts National Museum of Natural History Washington, D. C. 20560 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. Aurele 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. Donald R. Moore Division of Marine Geology School of Marine and Atmospheric Science 1 0 Rickenbacker Causeway Miami, Florida 33149 Dr. Joseph Rosewater Division of MoUusks 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 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 1 1 Chelten Road Havertown, Pennsylvania 19083 OFFICE OF PUBLICATION Delaware Museum of Natural History Kennett Pike, Route 52 Box 3937, Greenville, Delaware 19807 Second Class Postage paid at Wilmington, Delaware Subscription Price; $8.00 (see inside back cover) THE NAUTILUS Volume 91, number 3 — July 1, 1977 CONTENTS William K. Emerson Notes on Some Indo-Pacific Species of Modi w (Gastropoda; Tonnacea) 81 Helen DuShane A New Abyssal Amaea (Gastropoda: Epitoniidae) from the North Eastern Pacific Ocean ST''' Helen DuShane Epitonmm textimattum, a New Gastropod from the West Coast of Mexico 89 Craig M. Doremus and Willard N. Harman The Effects of Grazing by Physid and Planorbid Freshwater Snails on Periphyton 92 Ralph W. Dexter A Further Note on Geologic Changes in the Relative Size of Bivalve Shells 96 Kathleen A. Burky and Albert J. Burky Buoyancy Changes as Related to Respiratory Behavior in an Amphibious Snail, Pomacea urceus (Muller), from Venezuela 97 Clement L. Counts, III, John M. Dingess and James E. Joy The Electrocardiogram of the Freshwater Bivalve Lcimp.s-i'/is radiata (Bivalvia: Unionidae) 105 Dee S. Dundee Observations on the Veronicellid Slugs of the Southern United States 108 Steven T. Malek VeroniceUa occidentalis in Louisiana 115 Ralph W. Taylor, Michael P. Sweeney and Clement L. Counts, III Use of Empty Gastropod Shells (Polygridae) by Pseudoscorpions 115 Publications received 117 )1 (:5) Julv 1, 1977 THE NAUTILUS 81 NOTES ON SOME INDO-PACIFIC SPECIES OF MORUM (GASTROPODA: TONNACEA) William K. Emerson American Museum of Natural History New York. New York 10024 ABSTRACT Descriptive and distributional data are given for three poorly known and misunderstood species of Morum from the Indo-Paciflc. Additional specimens of Morum (Oniscidia) exquisitum are reported from the Subi Sea, and records other than those from the Philippines are rejected. Morum (0.) praeclarum, a species previously reported from deep water off Natal and Zuiuland. South Africa is reported from four stations in the western Indian Ocean. The recorded range of Morum (Herculea) ponderosum is extended to include New Caledonia and the Pit- cairn Islands. Specimens of two poorly known Indo-Pacific species of the genus Morum, namely: Morum ex- quisitum (Adams and Reeve, 1848) and M. praeclarum Melvill, 1919, have recently come to the attention of the writer. Morum exquisittim was described from a unique specimen obtained by Arthur Adams in the Philippines during the celebrated voyage of the HMS Samarang to the western Pacific and Indian Oceans, from 1843 to 1846. Despite the fact that this species, based on the type specimen dredged in the Sulu Sea, was well-described and illustrated by Adams and Reeve (1848, 1850) and by Reeve (1849), the iden- tity of this taxon has remained uncertain owing to its extreme rarity in collections. Most subse- quent workers followed Tryon (1885) who con- sidered it to be conspecific with Morum ponderosum (Hanley, 1858), a distinct species originally described from an unknovra prove- nance. The two species were finally separated by Melvill (1919), and he correctly recorded M. ponderosum from Japanese waters. Through the good offices of Dr. Joel Greene of San Francisco, California, a mature, live-taken specimen of Morum exquisitum (figures E, F, J) was recently brought to my attention. This specimen, together with a dead one, was taken by divers in shallow depths off Laminusa, Sulu, Philippines. Now in the collection of the Ameri- can Museum of Natural History (cat. no. 183926), this specimen compares favorably in all details with the figured holotype, except it is slightly larger with 5 post-nuclear whorls, and has 12 ax- ial ribs on the body whorl. The apex is colored a pale pink, whereas the parietal shield and the blotches on the outer lip are a light purple-pink. Of the livmg species of Morum, it appears to be most closely related to the New World "twin species," M. veleroae Emerson, 1968, from the eastern Pacific, and to M. dennisoni (Reeve, 1842), from the Western Atlantic. Attesting to the rarity of M. exquisitrim, I was able to locate only two other specimens in institutional collec- tions. Compared to M. exquisitum, M. ponderosum (figures G, H, I) has a heavier shell, which is more triangular in outline, with coarser orna- mentation and a much lower spire. The parietal wall is heavily callused and the non-pustulose, flattened shield covers most of the apertural side of the body whorl. Numerous weakly formed, ir- regular folds extend down the perietal wall into the aperture. The outer lip is thickened and the inner margin is dentate; the lip extends poster- iorly to the penultimate whorl to form a deep sulcation. The shell, including the apex, is colored creamy white with occasional streaks and blotch- es of reddish brown, which are especially prom- inent on the reflected surface of the outer lip. The parietal shield is suffused with creamy tan and is variegated with reddish brown markings. 82 THE NAUTILUS July 1. 1977 Vol. 91 (3) Perhaps one of the reasons Tryon (1885) erro- neously concluded that M. exquisitum and M. ponderosum were the same species was the result of the artist's lapsus in coloring the original figures (Hanley, 1858) of M. ponderosum reddish purple, instead of the natural reddish brown col- oration that is characteristic of this species. Morum praeclarum Melvill, 1919 was described from a unique specimen lacking locality data ob- tained from the collection of J. J. MacAndrew, FIGS. A-D Morum (0.) praeclarum MehnU; A-B Faqhuar Gniup. Seychelk hUimitt. in «/ m.. A' A/A// ho. 71862. C-D Holotypc. MehnU-Tomlin OAl. NMW (Courtesy of Naiional Museum of Wales): A-D about 3A natural size. E. F, J Morum (0.) exquisitum (Adam.': & Reeve): Lattiimiita, Sulu Sen, Philippines, in li m.. AMNH No. }SS92(>: E, F about S/J, natural size: J spire greatly enlarged to show protoconch. G. H, I Morum (H.) pondero.sum (Hanley): Oeno Island. Pitcaim Islands, off reef. NMNH No. /.ilflOI: G, H about S/i natural size: I spire greatly enlarged to. ih/'upriitnrinirh. Vol. !)1 CA) July 1, 1!»77 THE NAUTILUS 83 for whom Monim macandreui (Sowerby, 1889) had been named 30 years previously. Although the type specimen of M. praeclarum was il- lustrated recently in color (Dance, 1971), no addi- tional material had been recognized until Kilburn (1975) reported it from South Africa. Dr. Joseph Rosewater uncovered five specimens in the National Museum of Natural History collec- tions. An additional specimen was located in the Delaware Museum of Natural History by Dr. R. Tucker Abbott. These specimens were dredged by the "Anton Bruun". TVie newly discovered specimens of M. prae- clanini (figures A, B) are more diminutive than the holotype (figures C, D), the largest being 30.3 mm in length, compared to 40 mm for the type specimen. Othenvise they agree well in essential characters with the description and illustrations of the holotype (Melvill, 1919; Dance, 1971). Melvill believed this species to be "nearest" to M. exquisitum, but he also compared it to M. macan- dreui. to which it is actually more closely related. It differs, however, from M. macandreui in several respects. The shell is smaller, propor- tionally more robust and less pyriform in out- line; the axial ridges are more delicate and they form sharp, scalelike spines at the intersections of the spiral ridges; the parietal shield is thickly enameled, finely ornamented with pustules an- teriorly and lineations posteriorly, and the den- ticles on the outer lip are confined to the aper- tural surface. Dance's illustration (1971, p. 119) suggests that the brownish spiral bands are well- developed on the holotype. In the present speci- mens, these bands are more diffused and are most prominent on the reflected surface of the outer lip and the adjoining portion of the body whorl. In these specimens, the surface is suffused in huffish cream and the spiral bands form streaks of light brown. As in the holotype, the aperture, outer lip, and parietal shield are a milky white. TAXONOMY In a revision of the southwestern Pacific species, Beu (1976) reviewed the taxonomic status of the genus Morum Roding, 1798, type species by monotypy: Morum purpureum Roding, 1798 {= St nimbus onisctis Linnaeus, 1767). In addition to the nominate subgenus, he recognized two subgenera: (1) Onisddia Morch, 1852, type species by monotypy: Onkcia cancellata Sowerby, 1824; (2) Herculea Hanley, in H. and A. Adams, 1858, type species by monotypy: Oniscia ponderosa Hanley, 1858. The attribution of the first valid use of Oniscidia to Morch, 1852, by action of the Inter- national Commission of Zoological Nomenclature (Opinion 1040), precludes the use of Cancel- lomorum Emerson and Old, 1963, type species by original designation: Oniscia grandis A. Adams, 1855, and Onimusiro Kira, in Kuroda, Habe, and Oyama, 1971, with the same type species and method of designation. Both of these rejected taxa, which are currently widely used respective- ly in the American-European literature and in the Japanese literature, thus become junior sub- jective synonyms of Oniscidia Morch. Beu (1976) also referred Pulchroniscia Garrad, 1961, type species by monotypy: Pulchroniscia delecta Gar- rad, 1961 {^Oniscidia bruuni Powell, 1958, fide Beu, 1976), to the synonymy of Oniscidia Morch. Because generic synonymies of Morum sensu lata are given by Beu (1976), they are not repeated here. INDO-PACIFIC SPECIES In addition to the three species discussed below, the following nominal species of Morum are known from the Indo-Pacific: M. (Oniscidia) cancellatum (G. B. Sowerby, I, 1824); M. (0.) grande (A. Adams, 1855); M. (0.) macandrewi (G. B. Sowerby, III, 1889; M. (0.) bruuni Powell, 1958; M. (0.) teramachii Kuroda and Habe, in Habe, 1961; M. (0.) iwhiyjamai Kuroda and Habe, in Habe, 1961; and M. (0.) watsoni Dance and Emerson, 1967: quod vide for citations to the original descriptions. Morum (Oniscidia) exquisitum (Adams and Reeve, 1848) Figures E, F, J Oniscia exquisita Adams and Reeve, in Adams, 1848, p. 35 [text p. 35, issued in May, 1850], pi. 5, figs. 3a, 3b, [References To Plates, p. x and pi. 5, issued in November, 1848], "Sooloo [Sulu] Archipelago; outside a coral reef near the city 84 THE NAUTILUS July 1, 1977 Vol. 91 (3) of Sooloo (Jolol in about sixteen to twenty fathoms, sandy mud." Reeve, 1849 [issued in August], vol. 5, Oniscia pi. 1, fig. 3, "Sooloo [Sulu] Archipelago" [repeats data of Adams and Reeve, 1850]. Oniscia exquisita Reeve, Kiister, 1857, p. 58, pi. 55, fig. 10 (after Reeve, 1849, fig. 3), "Soulou- Archipel von Belcher entdeckt." Oniscia (OniscidiaJ exquisita Adams and Reeve, Tryon, 1885, p. 282, pi. 8, fig. 100 (after Reeve, 1849, fig. 3), "Sooloo [Sulu] Sea; Australia." Morum (Oniscidia) exquisitum, Melvill, 1919, p. 72, "Sooloo [Sulu] Archipelago [etc.], Philippine Isles (Hidalgo), Japan (Hirase), Saya de Malha Banks, S. Indian Ocean (J. Stanley Gardiner)." Morum exquisihim Adams and Reeve, Abbott, 1962, p. 66, color illus., "Philippines, rare." Tifpe depository: not known (Melvill, 1919, p. 72; Dance and Emerson, 1967, p. 95). The specimen figured by Reeve (1849), the apparent holotype, was sold in 1865 when the famous col- lection of John Dennison was disposed by public auction in London (Melvill, 1919; Dance, 1966, p. 210). The holotypic specimen is apparently lost. Type locality: off Jolo [Sulu City], Sulu Island, Sulu Archipelago, Philippines, in 30 to 36 meters. Verified geographic range: Known only from the Sulu Archipelago, Philippines, in 6 to 36 meters. Material examined: Philippines: 6 meters, Laminusa, Sulu Archipelago, 1 specimen, 46.7 mm in length, 27.4 mm in width, ex Joel Greene, AMNH 183926; Tawi-Tawi, Sulu Archipelago, 1 specimen 30.3 mm in length, 19.5 mm in width, ex Mrs. P. Bautista, ANSP 218411, illustrated in Abbott (1962, p. 66); Zamboanga, Mindanao, 1 specimen, 32.4 mm in length, 22.5 mm in width, NSMT .54630. Remarks: The early citations in the literature to records from Japan, Australia, and the Indian Ocean appear to be erroneous. Dr. Habe (personal communication) has no knowledge of specimens from Japanese waters. The specimen in the British Museum (Natural History) reported by Melvill (1919) from the Indian Ocean was sent to me on loan. It is apparently referable to Morum praeclarum Melvill, being a badly worn, broken and discolored juvenile shell. The Japanese and Australian records were based most likely on misidentified specimens of M. (H.) ponderosum. At the present time M. (0.) exquisitum is known only from the Sulu Sea. Oniscia exquisitum Adams and Reeve dates from November 1848, when the name was applied to figures 3a, 3b of plate 5 in the "References To Plates, Mollusca" of the Zoology of the Voyage of the H.M.S. Samarang. The description appeared subsequently, in May 1850, when the text was issued. Morum (Oniscidia) praeclarum Melvill, 1919 Figures A— D Morum praeclarum Melvill, 1919, p. 69, text fig. "Hab.[itat]?" J. J. MacAndrew Coll. Dance, 1971, p. 119, fig. 5, "locality unkown"; 1975, Kilburn, p. 49, "off Mvoti River, 56 fms., and off Durban, South Africa, 160 fms." Type depository: holotype, here illustrated, figures C— D, Melvill-Tomlin Collection, National Museum of Wales, Cardiff (Dance and Emerson, 1967, p. 95); N.M.W. accession No. 55.158, teste June Qiatfield. Type locality: 11 mi. off Port Shepstone, South Aft-ica in 2.50 fathoms. (Kilburn, 1975). Verified geographie range: western Indian Ocean; off Somali Republic and Mozambique, Africa; Seychelle Islands, in 78 to 132 meters off South Africa. Material examined: Africa; 80 miles E. of Ras Mabber, N.E. Somali Republic; 78-82 meters, 1 specimen, 28.6 mm in length, 20.1 mm in width, "Anton Bruun," Sta. 9-445, 09°36' N. Lat.. 5r01 E. Long., ex Harold Vokes, DMNH 117851; off Mozambique; ca. 40 miles E. Quissico, 132 meters, 2 specimens, 30.3 mm in length, 21.1 mm in width, .30.1 mm in length, 19.1 mm in width, "An- ton Bruun," Cruise 7, Sta. 371-E, NMNH 761345. Seychelle Islands: ca. 80 meters, Faqhuar Group, 1 specimen, 26.7 mm in length, 17.2 mm in width, "Anton Bruun" Cruise 9, Sta. 444, 09°36' N. Lat., 5r01' E. Long., NMNH 718962; ca. 90 meters, Fa- qhuar Group, 2 specimens, 24.8 mm in length, 17.2 mm in width, 2.3.2 mm in length, 16.4 mm in width. "Anton Bruun" Cruise 9, Sta. 437, 09°25' N. Lat., .50%54' E. Long., NMNH 718953. Remarks: At my request, Dr. June Chatfield kindly compared the holotype of M. pnurlannii with the illustration of the type specimen in Dance (1971, p. 119, fig. 5). She concluded that the Vol. 91 (3) Julv 1, 1977 THE NAUTILUS 85 figure is fairly accurate in color, but it is perhaps a little darker than the holotypic specimen. The East African provenance of this species has been revealed through the dredging operations of the "Anton Bruun" in the Indian Ocean. Additional unrecognized specimens of this species probably exist in the extensive collections made in recent years from this region. Morum (Herculea) ponderosum (Hanley, 1858) Figures G. H, 1 Oniscia ponderosa Hanley, 1858, pp. 255, 256, pi. 42, fig. 9, 10, "Hab[itat]?," Cuming Coll. Tryon, 1885, p. 282, pi. 10, fig. 22 (after Hanley, 1858, fig. 10), [incorrectly cited as a synonym of Morum exquisitum (Adams and Reeve)). Stearns and Pilsbry, 1895, "Yaeyama" [Ryukyu Islands], incorrectly cited as "Oniscia exquisita," which, following Tryon, was con- sidered to be a synonym of Morum pondero- sum. Monim ponderosum (Hanley), Hirase and Taki, 1951, pi. 98, fig. 2, "Amami-Oshima," Ryukyu Islands. Kuroda and Habe, 1952, p. 68, Range: 0-29° North Latitude. Oyama and Takemura, 1961, pt. 5, Morum pi. 2, figs. 4, 5, "Amami- Oshima Isl." Morum (Herculea) ponderosum (Hanley), H. and A. Adams, 1858, p. 621. Melvill, 1919, p. 71, "Japan (Steams)." Shikama, 1963, p. 59, pi. 42, fig. 4 "Amami-Oshima, Ryukyu Group, Japan." Habe, 1964, p. 69, p.. 21, fig. 1, "rare, Amami and Ryukyu Islands, wide-ranging in the Indo- Pacific regions." Shikama, 1964, p. 114, fig. 193. Ponder, in Beu, 1976, p. 224, "Herald Cay and Lady Elliot Island, Queensland." Type depository, Lectotype: BM(NH) No. 1966724, ex Hugh Cuming Collection, selected by Dance and Einerson (1967, p. 94); syntype BM- (NH) No. 196625, ex Hugh Cuming Collection. Type locality; Amami-Oshima, Ryukyu Islands, here designated. Verified geographic range: Ryukyu Ar- chipelago, Japan; Queensland, Australia (fide Beu, 1976); New Caledonia; and the Pitcairn Islands. Material examined: Japan: Ryukyu Islands: "Oshima Osumi" [Amami-Oshima], 2 specimens, 47.8 mm in length, 31.5 mm in width, 34.5 mm in length, 21.6 mm in width, Hirase Coll., NMNH 34938; Amami-Oshima, 1 specimen, 31.7 mm in length, 21.8 mm in width, Hirase Coll., MCZ 43262; Amami-Oshima, 2 specimens, 45 mm in length, 28.5 mm in width, 32 mm in length, 22.8 mm in width, Hirase Coll., ANSP 98020; Amami- Oshima, 1 specimen, 22 mm in length, 18.2 mm in width, A. R. Cahn Coll., ANSP 275543; Okinawa, Onna sand flat, 1 specimen, 38.6 mm in length, 26.7 mm in width, Bemice Albert, leg., ANSP 276387; Okinawa, Kadena, 1 specimen, 36.6 mm in length, 24 mm in width, Rose Burch Coll., AMNH 114571; Okinawa, Kadena, 1 specemen, 37.3 mm in length, 25.8 mm in width, W. A. Mc- Carty, leg., AMNH 183950. New Caledonia: 1 specimen, C. T. Trenchmann Coll., BM(NH) 1964504, teste A. F. Blake. Pitcairn Islands: off reef, N. coast of atoll, Oeno Island, 1 specimen, 41 mm in length, 27.8 mm in width, H. A. Rehder leg., NMNH 731601: Henderson Island, 1 specimen, J. R. Jamieson and D. K. Tait leg., BM(NH) 1913.7.28.90, teste A. F. Blake. Remarks: According to Dr. Tadashige Habe (personal communication) sf)ecimens from the Hirase Collection bearing the locality Oshima Osumi are from Amami-Oshima of the Amami Group in the Ryukyu Archipelago. Early records attributed to "Japan" are actually referable to the Ryukyus and Okinawan Islands. The disjunct distribution of the uncommon species apparently represents gaps in collecting in the intermediate areas, rather than a relict distributional pattern. ACKNOWLEDGMENTS I am indebted to the following curators for pro- fessional courtesies of various kinds: Drs. R. Tucker Abbott, Delaware Museum of Natural History (DMNH); June Chatfield, National Museum of Wales (NMW); Kenneth J. Boss, Museum of Comparative Zoology, Harvard University (MCZ); George M. Davis, Academy of Natural Sciences of Philadelphia (ANSP); Tadashige Habe, National Science Museum, Tokyo (NSMT); Joseph Rosewater, National Museum of Natural History, Smithsonian Institu- tion (NMNH); and John Taylor and Miss A. F. 86 THE NAUTILUS Julv 1. 1977 Vol. 91 (3) Blake, British Museum (Natural History) (BMNH). I thank my colleague, Mr. William E. Old, Jr., for technical assistance. LITERATURE CITED Abbott, R. T. 196Z Sea shells of the World. Golden Press, New YorkieOp.. illus. Adams, Arthur. 1855. Descriptions of new genera and species of gasteropodous [sic] Mollusca. Proc. Zool. Soc. London 21: 182-186. Adams, Arthur, and Lovell Reeve. 1848-.50. Mossusca. In A. Adams, The zoology of the voyage of H.M.S. Samarang; under the rommand of Captain Sir Edward Belcher. London (see Keen, 1971, p. 971, for dates of publication). Adams, Henry, and Arthur. 1853-,58. The genera of Recent Mollusca; arranged according to their organization. London, 3vols.,661p., 138 pis. (dates of publication: vol. a p. 661). Beu. A. G. 1976. Revision of the southwest Pacific species of Manan {(Miscidia). Juur. Malac. Soc. Australia 3(4): 223-231. Dance, S. P. 1966. Shell Collecting: an Illustrated History. Univ. Calif Press, Berkeley and Los Angeles, 344, p., 35 pis. Dance, S. P. 1971. Seashells. Hamlyn, London, 159 P., illus. Dance, S. P. and W. K. Emerson. 1967. Notes on Monim den- nisoni and related species. The Veliger 10(2): 91-98, pi. 12. Einerson. W. K. 1968. A new species of the gastropod genus Murum from the eastern Pacific. Jour, de Conchyl., 107(1): .5.3-.57,pl. 1. Emerson, W. K., and W. E. Old, Jr. 1963. Results of the Puritan-American Museum of Natural History Expedition to western Mexico. 19. The Recent Mollusks: Gastropoda, Strombacea, Tonnacea, and Cymatiacea. Amer. A/)is. Novitates, 21,53. .38 p., 28 figs. Garrard. T. A. 1961. Mollusca collected by M. V. "Challenger" off the coast of Australia. Jour. Malac. Soc. Australia 1(5): 2-37, pi. 12. Habe, Tadashige. 1964. Shells of the Western Pacific in Color 2. English ed., Hokusha, Osaka, Japan. 233 p. Hanley, Sylvanus. 18.58. Description of a new Oniscia. Pruc. Zool. Soc Londm 26: 2.5,5-256, pi. 42. Hirase, Shintaro, and Isao Taki. 1951. A Handbook of Il- lustrated Shells, in Natural Cohrs. Tokyo, 134 pis. + 46.p. International Commission on Zoological Nomenclature. 1975. Opinion 1040, Oniscidia Mbrch, 1852 (Mollusca): Placed on the Official List. BuU. Zool Nomen. 32(3): 139-140. Kilbum. R.N. 1975. The rediscovery of Morum pmeclarum Melvill (Ca-ssidae). 77!eA«i((i7M.s89(2):49-.50. Keen, A. M. 1971. Sea Sheik of Tropical West America. Stan- ford Univ. Press, ed. 2, xiv + 1064 p.. illus. Kuroda, Tokubei, and Tadashige Habe. 1952. Checklist and Biblitiyraphy of the Recent Marine Mollusca of Japan, Tokyo, 210 p. Kuroda, Tokubei. T. Habe, and K. Oyama. 1971. The Sea Shells <}fSayami Bay Collected by His .Majesty the Emperor of. Japan. Tokyo, 751 -(-489-1- 51 p., 121 pis. Kiister, H. C. |1846| - 18.57. Systematisches Conchylien- Cabinet.Sd): 5.3-59; pi. 5.5. Linnaeus, Carl. 1767. Systema naturae per regna tria naturae. Editio duodecima, reformata, pt. 2, p. ,533-1327.. Melvill, J. C. 1919. Description of Morum praeclarum, sp. no., with remarks on the Recent species of the genus. Proc. Malm: &.C. Lorukm 13(3, 4): 69-72, 1 fig; Addendum, Itrid, 13(.5.6):145 Mfirch, 0. A. L. 18.52. Catalogus conchyliorum . . . de Yoldi, Regis Daniae. Copenhagen, Fac. 1, 170 p. Oyama, Katura, and Yoshio Takemura. 1961. The Molluscan Shells, Resources Exploitation Institute, Tokyo, pt. 5, Morum pis. 1,2. Powell, A. W. B. 1958. Mollusca of the Kermadec Islands. Pt. 1. Records Auckland Inst.&Mus. 5(1-2): 65-8,5, pis. 9-11. Reeve, L. A. 1842. Conchologia Systematica, or Complete System ofConchology. London, Paris, Berlin, vol. 2. Reeve, L. A. 1849. Monograph of the genus Oniscia, In, Con- chologia Iconica, London, vol. 5. 1 pi. Roding, P. F. 1798. Museum Boltenianum . . . pt. 2, Conchylia. Hamburg, vii -I- 109 p. Shikama, Tokio. 1963. Selected Shells of the World Illustrated in Colours, vol. 1. Tokyo, 154 p., 102 pis., 211 figs. Shikama, Tokio. 1964. Selected Sheik of the World Illustrated in Colours, vol. 2. Tokyo, 212 p., 70 pis., 245 figs. Sowerby, G. B., I. 1824. TTie Genera of Recent and Fossil Shells. London, vol. 1, Oniscia pi. 233. Sowerby, G. B., III. 1889. Descriptions of fourteen new species of shells from China, Japan, and the Andaman Islands... fVoc. Zool. Soc. London for 1888, p. .5&5-570, pi. 28. Stearns, Frederick, and H. A. Pilsbry. 1895. Catalogue of the Marine Mollusks of Japan. Detroit, 196 p., 11 pis. Tryon. G. W.. Jr. 1885. Manual of Conchology. Philadelphia, ser. 1, vol. 7, Family Cassididae, p. 268-283, 10 pis. Vol. 91 (3) July 1, 1977 THE NAUTILUS 87 A NEW ABYSSAL AMAEA (GASTROPODA: EPITONIIDAE) FROM THE NORTH EASTERN PACIFIC OCEAN Helen DuShane' 1M12 El Soneto Drive Whittier, California 90605 ABSTRACT Amaea siapnoi new species, a deepwater epitoniid, is described from a location about 540 nautical miles southwest of Mas Revillagigedo, Mexico. Species of Amaea are rare in the North Pacific Ocean. Until now, no species of this genus has been reported from the south eastern portion of the North Pacific Ocean. Recently, I have re- ceived, on loan, a live-collected specimen of a new species of Amaea s. s. for purposes of identifica- tion. Deepsea Ventures, Inc., May 1975, retrieved this mollusk from 14,521 feet (4428.60 meters), ap- proximately 540 nautical miles southwest of the Islas Revillagigedo, Mexico. Superfamily Epitoniacea Family Epitoniidae Genus Amaea H. and A. Adams, 1853 [Type species (SD, deBoury, 1909: Scalaria magnifica Sowerby, 1844] Subgenus ylmoea H. and A. Adams, 1853 Amaea (Amaea) siapnoi DuShane, n. sp. (Figs. 1 and 2) Shell medium in size, off-white in color; nuclear and early postnuclear whorls missing, six whorls remaining, gradually expanding to the last whorl; sides of the whorls more perpen- dicular than in most Amaea, giving it a columnar outline; suture well-defined; costae curved and retractive, lamellar near the distinct suture, worn on the whorls, not continuous from whorl to whorl; with a change of slope in the outline of the whorls just below the suture, causing the costae to curve rather abruptly; axial costae on the last whorl 85, of varying thickness, sometimes fusing with adjoining ones, continuous over the base to the simple lip (outer lip partially fragmented); with a poorly defined basal thread, below which the sculpture is the same as that above; spiral sculpture of approximately 16 to 22 uneven but mostly extremely wide ribs, separated by narrow incised lines that cross the close-set axial costae and impart to the shell a somewhat beaded appearance; aperture round, lip thin; um- bilicus lacking; operculum dark, round, horny. Length 34 mm, width 12 mm (holotype). Type Locality— Approximsitely 540 nautical miles southwest of Isla Clarion, Islas Revillagigedo, Mexico (14°50' N, 124°29' W), from a depth of 4428.60 meters. ' Museum Associate, Department of Malacology, Los Angeles County Museum of Natural History, Los Angeles, California 90007. FIG. 1. Map showing approximate location where Amaea (Amaea) siapnoi DuShane, n. sp. was taken in a dredge haul from a depth ofUJ,28.60 meters. 88 THE NAUTILUS July 1. 1977 Vol. 91 (3) FIG. 2 Amaea (Amaea) siapnoi DuShane. n. sp. Left: Ven- tral view. Length 31, mm. uidth 12 mm. Center: Dorsal view. Right: Anterior portion enlarged to show poorly defined basal thread. X 2 Type Material— Holotype, Department of Marine Invertebrates, San Diego Natural History Museum, San Diego, California: SDSNH 65482. Etymology— The species name honors the chief scientist of Deepsea Ventures, Inc., William Siap- no. DISCUSSION Deepsea Ventures, Inc., working out of San Diego, California, is involved in exploratory min- ing for manganese nodules. William Siapno, chief scientist of Deepsea Ventures, Inc., collected this new species in May 1975. Other material in the dredge haul included coarse, gritty manganese that still adheres to the shell, manganese nodules, large Carcharodon teeth, pelagic shark teeth (probably of Miocene age), a whale ear-bone, small brittle stars, and worm tubes. The nuclear and immediate post-nuclear whorls of the holotype are missing. One can only conjec- ture that the live-taken specimen was damaged in the dredge as it was retrieved. Among the other Amaea collected in deep water are Amaea (Scalina) ferminiana (Dall, 1908) from 118 to 1333 m off the coast of Peru by the SEPBOP Program on the vessel ANTON BRUUN (DuShane, 1974; 55); Amaea (Scalina) pompholyx (Dall, 1908) collected in 1485 m near the Galapagos Islands by the ALBATROSS (sta- tion 2807) in ooze (DuShane, 1974; 56). These are the only two records of Amaea (Scalina) from deep water in the tropical eastern Pacific; these depths do not approach the depth from which the present species was taken. Comparison with Amaea luxus Okutani, 1964, collected 56 miles off Aogashima Island (32° 20' N, 140° 55.5' E), in from 3,150 to 3,350 m, shows the two species to be congeneric, each with an usually large number of costae. The live-taken specimen of luxus differs by having 140 (instead of 84) close-set costae on the last whorl, a very elongate shell with 15 whorls, and a hardly distinguishable basal disk. ACKNOWLEDGMENTS To the following people I am indebted in many ways; Drs. Myra Keen, Professor Emeritus, Stan- ford University and George Radwin, Department of Marine Invertebrates, San Diego Museum of Natural History, for reading preliminary drafts of the paper and providing constructive criticism; to Bertram Draper, Museum Associate, Los An- geles County Museum of Natural History, for the photographs; to Anthony D'Attilio, Department of Marine Invertebrates, San Diego Museum of Natural History, for the map; to William Siapno, Deepsea Ventures, Inc., and Dr. Hugh Bradner, University of California, San Diego, for their help in obtaining the holoptye for examination and description. LITERATURE CITED Dall. W. H. 1890. Scientific results of exploration by the U. S. Fish Commission steamer ALBATROSS. VII. Preliminary report on the collection of Mollusca and Brachiopoda ob- tained in 1887-88. Proc. USNM 12(773): 219-362, pis. 5-14. (7 March) deBoury, E. A. 1909. Catalogue des sous-genres des Scalidae. Jourii. de Conchyl. 57: 256-258. DuShane. Helen 1974. The Panamic-Galapagan Epitoniidae. The VeUger. Suppl. 16: 1-84, 154 photos, 1 map, 5 figs., 3 tables. (31 May) Sowerby, G. B. (2nd) [\W1] 1847-1848. Thesaurus con- chyliorum, or monograph of genera of shells, edited by G. B. Sowerby, Jr.. completed by G. B. Sowerby 3rd. London, vol. 1, part 4:83-146; pis. 32-40. (11 April) Vol. 91 (3) July 1, 1977 THE NAUTILUS 89 EPITONIUM TEXTIMATTUM, A NEW GASTROPOD FROM THE WEST COAST OF MEXICO Helen DuShane 15012 El Soneto Drive, Whittier, California 90605 ABSTRACT Epitonmm (Asperiscala) textimattum DiiShane, n. sp. (Gastropoda,) in dencrihed from sublittoral water off the west Mexican states of Nayarit, Jalisco, and Colima. It resembles E. walkerianum Hertlein and Strong. Family EPITONIIDAE Genus Epitonium Rbding, 1798 [Scala of authors; Scalaria Lamarck, 1801] Subgenus ylsperisca/a deBoury, 1909 Species referable to the subgenus Asperiscala, with its type species of Scalaria bellastriata Carpenter, 1864, are relatively common consti- tuents of the Panamic-Galapagan fauna, there be- ing 21 recognized species. The new species is known only from the sublittoral zone, 7 to 18 meters, in a mud substrate, dredged from 4 sta- tions off the states of Nayarit, Jalisco, and Co- lima, Mexico. Epitonium (Asperiscala) textimattum n. sp. (Figs. 1-8). Description: Shell medium to large in size, elongate-conic, white, sturdy; nuclear whorls .3 to 4, horn-color, rounded, glassy, with a brown sutural line, first two whorls small, subsequent ones much larger and more bulbous with no noticeable sculpture; fifth whorl down with minute indentations and small axial ribs; post- nuclear whorls 5 to 10, rounded, slightly sloping; suture distinct; axial sculpture of 10 to 12 low, rounded, chinalike ribs, inverted V-shaped on early whorls, flat-topped and of varying widths on later whorls, with fine axial grooving and widely-spaced spiral sculpture on the sides (magnification of 20X), without angulation, curv- ing into the sutures, not continuous from whorl to whorl, with an occasional one twice the width of the others; channels between ribs twice the width of the ribs; axial and spiral sculpture striolate (magnification of 40X) between ribs, carr>'ing over the ribs as fine indentations; aper- ture ovate, outer lip but slightly thickened by the last rib, with faint traces of spiral impressions; peritreme complete, narrower on the columellar portion; umbilicus lacking; operculum light horn color, paucispiral. Length, 12 mm; width, 4 mm (holotype). Discussion: This epitoniid from the Panamic- Galapagan fauna has an elongate-conic shape combined with a matte texture and sturdy ribs with faint, irregular spiral impressions. Sizes vary from 9.5 to 17 mm in length, with from 10 tol2costae. (See Figs. 1,2,3) At first it was thought that this species might be the enigmatic Epitonium (Asperiscala) regulare (Carpenter, 1856), type locality, Panama. The original description of E. regulare mentions 3 syntype specimens; Keen (1965) photographed 4 specimens labeled with this name, but the label [BM(NH) Reg. No. 19.50. 4. 18. 13/16] is not in P'IGS. 1-3— Epitonium (Asperiscala) textimattum Lhi£hane. n. .■: John Taylor). Specimen to the far right was erronemisly considered by Palmer to he theholotype. X S.U Carpenter's handwriting (teste Keen). It is doubt- ful if any of the specimens shown (Fig. 4) are E. regulare of Carpenter, therefore, I do not choose to select a lectotype from among them. Compared to E. textimattum the left hand specimen has prominent sprial sculpture between the whorls and very thin costae. The smallest specimen from the left (lost, fide Dr. John Taylor, BM(NH)), might well be the upper broken portion of the lefthand specimen. The largest specimen has more convex whorls, a less contracted suture and twice the number of costae (20-22), with narrow in- terspaces between costae. The right hand specimen has many strong costae, crowded on the whorls, with fine spiral threads between. The brief description given by Carpenter (1856: 164) makes identification of his nominal species difficult, if not impossible: therefore, their type status is questionable. Palmer (1963: 332) unwise- ly cited the last specimen mounted on the right as the holotype, which being figured by her, is tantamount to a type selection. This specimen does not fit Carpenter's original description. Because of the uncertainty of the identity of Carpenter's taxon it must stand as a species in- quirenda, Pilsbry and Lowe (1932: 120) reported having taken Epiti>nium regulare at Acapulco, Mexico, but examination of the two specimens in the Lowe collection (SDMNH 26442), at San Diego, California, proves them to be Epitonium (Asperiscala) eutaenium Dall, 1917. Except for this one reference there seems to be no other cita- tions to E. regulare other than to the syntypic J specimens at the BM(NH). " Epitonium (Asperiscala) textimattum is closer to Epitonium (Asperiscala) walkerianum Hertlien and Strong, 1951 (3.7 to 8 mm in length), than to any other species in the Panamic— Galapagan fauna. It differs from the latter by having much finer spiral threads, fewer and discontinuous ribs, with an occasional heavier rib, and by having a larger shell (9.5 to 17 mm in length). The range for E. walkerianum is from San Felipe. Gulf of California, along the west coast of Mexico as far south as Nicaragua, taken from the intertidal zone down to 23 meters, whereas E. textimattum is known only from off the west Mexican states of Nayarit, Jalisco, and Colima. The soft parts, when live, show through the shell as coral-pink in color. The color fades to a peach-tan within a few weeks. Sixty specimens of this species were dredged just beyond the wave line at Playa Los Angeles, Jalisco. Mexico, mud substrate, at a depth of 7 to 18 meters in associa- tion with the sand dollars, Encope firagilis Clark, 1948 and Encope perspective Agassiz, 1841, August 1975, by Carol and Paul Skoglund. Dredg- ing repeated at the same locality in December, 1975 revealed only two specimens of the new species and only a few specimens of Persicula sp. and Kurtziella sp. that were so numerous in PACIFIC OCEAN I lO*' SO' FIG. 5-Mn/) taken from the U. S. Hydrographic Siitfey showing the coastline along which Epitonium (.\.speriseala) textimattum IhiShane. n. sp. occurs. Tlie .tolid triangle in- dicates the type locality. Vol. 91 (3) July 1, 1977 THE NAUTILUS 91 FIG. 6— Epitonium (Asperiscala) textimattum IkiShane n. sp. Niuclear whorls showing sculpture on the fifth whorl down of minute indentations and small axial ribs (white portions). August. In addition, few sand dollars were pre- sent in the December dredgings. Type locality— Play a. Los Angeles, Tenacatita Bay, Jalisco, Mexico (Lat. 19° 18' N; Long. 104°50' W). at depths of 7 to 18 meters. (See Map) Type material— hohtype, Los Angeles County Museum, Malacology Type Collection, No. 846. Paratypes (1): To each of the following institu- tions, American Museum of Natural History, British Museum (Natural History), Delaware Museum of Natural History, Los Angeles County Museum of Natural History, National Museum of Natural History (Smithsonian Institution), Academy of Sciences of Philadelphia, Santa Bar- bara Natural History Museum, San Diego Na- tural History Museum; (2) DuShane Collection; remainder in the Bennet and Skoglund Collec- tions. Additonal paratypes.— Lo de Marcos, Na- yarit; collected by the Bennets and Skoglunds, September, 1974, dredged from 7 to 18 m, 1 specimen; Cuastecomate, Jalisco; collected by the Skoglunds, August, 1975, dredged from 11 to 27 FIGS. 7 and 8— Epitonium (.'\speriscala) textimattum DuShane, n. sp. 7— Operculum showing growth lines. Actual size 2 mm. %— Attachment side of operculum showing muscle attachment scar. m, 2 specimens; Santiago Bay, Colima; collected by the Skoglunds, August, 1975, dredged from 11 to 18 m, 1 specimen. ACKNOWLEDGMENTS To Dr. William K. Emerson I am most in- debted for having read the manuscript and of- fered useful suggestions and corrections, as well as the species name; to Dr. George E. Radwin for the loan of two specimens form the Lowe Collec- tions; to Dr. Myra Keen for her photograph of syntypic specimens of E. regulare in the BM(NH) and to Bertram Draper for photographs of the new species; to Dr. John Taylor for comparison of species involved; to Merton Goldsmith for the drawings and the map; to the Skoglunds (Carol and Paul) for the privilege of naming this new taxon. LITERATURE CITED Carpenter, Philip Pearsal. 1856. Description of new species of shells collected by Mr. T. Bridges in the Bay of Panama and its vicinity, in the collection of Hugh Cuming. Esq. Proc. Zool. Soc. London. 159-166 (for 1856), (9 June) Carpenter. Philip Pearsal. 1864. Supplementary report on the present state of our knowledge with regard to the Mollusca of the west coast of North America. Brit. Assoc. Adv. Sci.. Report. 33 (for 1863): 517-686 (post 1 August) [reprinted in Carpenter. 1872: 1-172 (dating: Carpenter. 1872)1 Clark, Hubert Lyman. 1948. A report on the Echini of the warmer eastern Pacific, based on the collection of the Velero III. Allan Hancock Pacific Expeditions, Univer. So. Calif Press. 8(5): 1-352. pits. 35-71, text figs. 1-3. deBoury, Eugene Auborg. 1919. Catalogue des sous-genres des Scaladea. Jo!(n!. de Conchyl. 57: 256-258. DuShane. Helen. 1974. The Panamic-Galapagan Epitoniidae. The Veliger. Suppl. 16: 1-84; 1.54 photos. 1 map, 5 figs. (31 May 1974) Hertlein, Leo George and Archibald McClure Strong. 1951. Eastern Pacific expeditions of the New York Zoological Society. Mollusks from the west coast of Mexico and Central America. Part X. Zoologica 36: 67-120; pits. 1-11 (20 August 1951) Palmer. Katherine V. W. 1963. Type specimens of marine mollusca described by P. P. Carpenter from the west coast of Mexico and Panama. Bull. Amer Paleo. 46(211):285-408; pits. 58-70 (22 October 1963) Pilsbry, Henry Augustus and Herbert N. Lowe. 1932. West American and Central American mollusks collected by H. N. Lowe. 1929-31. Proc. Acad. Nat. Sci. Philadelphia 84: 33-144; 7 figs.; pits. 1-17; 2 photogr. (21 May 1932). 92 THE NAUTILUS July 1, 1977 Vol. 91 (3) THE EFFECTS OF GRAZING BY PHYSID AND PLANORBID FRESHWATER SNAILS ON PERIPHYTON Craig M. Doremus and Willard N. Harman Biology Department The State University of New York College at Oneonta 13820 ABSTRACT Populations of Physa heterostropha (Say) (Physidae) and Promenetus exacuous (Say) (Planorbidae), were used in two-week experiments in controlled laboratory microeconystems. Comparison of cholorphyll extracts from periphyton in snail-less aquaria unth those containing snails were used to determine relative grazing effi- ciency. Snail population density was inversely correlated with periphyton standing crop in all sitautions, except for pure cultures of?, exacuous. Studies of this kind have application in natural areas where decimation of snail populations has effects on the species composition of the algal flora, and therefore, water quality and resource utilization. The effects of grazing by snails and other aquatic invertebrates on periphyton (benthic algae) is poorly known. Logically, one would ex- pect the standing crop of periphyton to decrease in the presence of grazing invertebrate popula- tions. Indeed, Douglas (1958) suggested that the caddis fly larvae, Agapetus fuscipes, controlled the population size of the diatom Achanthes dur- ing the spring and summer in a small stream in England. She noted a strong inverse relationship between the numbers of the caddis fly larvae and numbers of diatoms during that time. A study along the Oregon coast by Castenholtz, (1960) demonstrated how a heavy diatom population in the upper half of the intertidal zone was held in check by limpets and littorines during summer periods. Kehde and Wilhm (1972) noted how snail grazing affected the community structure of periphyton in labortory streams. They exposed the periphyton to grazing by the snail Physa gyrina Say for three months and measured a significant increase in the chlorophyll a concen- tration and a slight reduction in the standing crop of the periphyton. Beyers, (1963) in a laboratory microecosystem, showed that when the large herbivorous snail Marisa comuarietis (Linne) was added to the system, it severely overgrazed the macrophytes and associated periphyton. The following pilot study was undertaken to determine: (1) the effect that selected freshwater pulmonate snails have on periphyton standing crop, (2) the effects the population density of these snails has on the grazing ability of in- dividuals, and (3) whether one species has effects on the other's grazing ability when both are in the same laboratory microecosystem. MATERIALS AND METHODS Individuals of Physa heterostropha (Say) about 13 mm. in length and with an average wet weight of .06 gm. and those of Promenetus exacuous (Say) about 4.5 mm. in length and with an average wet weight of .01 gm. were used for the experiment. Both species are commonly found in central New York State (Harman and Berg, 1971). The individuals used for the study were taken from coexisting populations in Rat Cove, a partially protected bay along the southwestern shore of Otsego Lake, the headwaters of the Sus- quehanna River in east-central New York. The lake is morphometrically oligotrophic but chemical characteristics are typical of eutrophic waters. It has a surface area of 1,725 ha (6.7 sq. miles) and a maximum depth of 51 m (166 ft.). Rat Cove has a littoral area roughly .4 x .2 km. in size, up to 6 m. in depth and has a bottom Vol. 91 (3) July 1. 1977 THE NAUTILUS 93 TABLE 1. Oiaracteristics of gastropod populations, algal populations and water utilizedfor the study. Number of snails {Rms) wet weight of snails %of controls trans- mittance «!<-"hl.i Physical and Chemical Parameters P heter- P imtrnpha exanious Alkal Ippm) Dissolved S.)llds(ppm) pH 0, cone (ppml O.sat, (%) Temp Habitat liter •c Rat Cove 10- r .64* - - 125.0 142.0 7.8 9.4 111.0 22.5 Controls Laboratorj' Microecosystems 5 10 15 5 5 10 10 10 15 15 .3 .6 .9 .12 .04 .06 .32 .34 .62 .64 .66 .94 .96 100 70 30 25 60 75 70 30 40 60 15 35 10 20 42.17 14.06 9.37 9.38 23.43 28.12 30.46 14.06 14.06 23.43 7.03 14.06 7.03 9.37 93.0 92.0 89.0 76.0 96.0 102.5 96.0 84.5 84.5 83.0 82.0 90.0 87.5 90.5 129.3 121,0 108.5 106.0 137.5 134.5 130.5 124.0 120.0 108.0 125.0 124.5 124.0 124.0 8.3 8.3 8.1 8.0 8.4 8.4 8.2 8.3 8.2 8.3 8.1 8.3 8.3 8.1 7.2 7.6 7,5 7.6 7,3 7,6 7.4 7.2 7.2 7.6 7.2 7.2 7.5 7.6 90.3 925 94.5 93.0 93.5 94.5 93.0 93.5 93.5 96.0 93.5 92.0 94.5 94.0 27.3 26.0 27.5 26.0 28.5 26.5 27.5 29.5 29.5 28.5 29.5 29.5 28.0 26.5 * estimates per unit area equal to one laboratory microecosystem. composed of deep organic muds (Herrmann and Harman, 1975). Laboratory microecosystems were set up in twenty-nine covered, rectangular plastic "mini- tanks" (18 X 25 X 10 cm). Each was sterilized with 95% ethanol and then rinsed thoroughly with tap water. Three liters of lake water from Rat Cove, filtered through a screen with a .5 mm filter mesh to remove macroinvertebrate grazers, were added to each tank to provide a potential snail grazing surface area of 1250 cm^ Three microscope slides, each with a surface area of 19 cm^ were placed in each container. Various population densities of snails (Table 1) were used, some with one species present and others with both species coexisting. A density of 10 in- dividuals of Physa and 4 individuals of Pro- menetus was considered an estimation of the population density of each respective snail population in Rat Cove. With this as a basis, we arrived at the densities shown in Table 1 by lowering or increasing the number of snails per tank proportionally. The complete series was duplicated and the control (no snails in a con- tainer) was repeated three times. Aquaria were arranged in rows 25 cm below continuously illuminated 20 watt naturescent and gro-lux fluorescent lights. Each tank was fur- nished with continuous aeration. Half the water was removed twice a week from each container and replenished with filtered lake water to pro- vide a regular turnover of nutrients. At these times dead snails were replaced with living in- dividuals from Rat Cove. To ascertain if conditions varied among the tanks and between natural and laboratory condi- tions, various chemical and physical charac- teristics of the water were determined in each aquaria and the snail collection site in Rat Cove. Water was analyzed for pH using a Beckman pH meter. Dissolved oxygen determinations (mg/1) employed the Winkler method-azide modification (APHA et al, 1970). Total alkalinity (as CaCo, in mg/1) was determined by titration with .02N H2SO4 using methyl orange as an indicator (APHA et al, 1970). Temperature and dissolved oxygen were utilized to determine oxygen satura- tion from a nomograph (Hutchinson, 1957). Dis- solved solids were determined by a Myron Dis- solved Solids Meter. Snails were allowed to graze two weeks in the tanks. At the end of that time all slides were removed. The three slides from each aquaria were collectively placed in flasks with 200 ml of 90% acetone for 72 hrs. at 5° C to extract chlorophyll. In a 2.54 cm spectrophotometer cell, chlorophyll transmittance was read at the 665 mn setting of a Bauch & Lomb (Spectronic 20) spectrophoto- meter. Results, expressed as a percentage of the 94 THE NAUTILUS July 1, 1977 Vol. 91 (3) transmittance exhibited by the chlorophyll ex- tracted from the controls, were utilized as measurements of the standing crop of periphyton. Thus, low values indicated that periphyton populations were greatly reduced by grazing snails. We consider these to represent efficient grazing abilities. The ^ig of chlorophyll a per m' was also utilized for comparative purposes because it is a potentially more definitive index. The results are given as fig Chi a/m' = 937.01 (Optical Density at 665 m/i), which assumes the absence of degredation products and interfering pigments in the chlorophyll extract. There was a significant size and weight dif- ference between specimens of Physa (.06 gm/in- dividual) and those of Promenetus (.01 gm/in- dividual). In order to give an accurate picture of the relative grazing abilities of the two species, total weight of the populations were used as a measure of population density. Since individuals of P. heterostropha weighed six times more than those of P. exacuous, it was assumed that six individuals of P. exaciunis would have grazing abilities comparable to one individual of P. heterostropha. PHYSICAL AND CHEMICAL PARAMETERS Limnological characteristics of the tanks con- taining Physa are illustrated in Table 1 as are characteristics of aquaria supporting populations of Promenetus and limnological features of tanks containing populations of both species. Also il- lustrated are physical and chemical characteris- tics of the water in Rat Cove at the time the snails were initially collected on August 4, 1974. The chemical and physical characteristics of the tanks containing P. heterostropha tend to ex- hibit reduced values as population density in- creases, except for oxygen saturation and the related parameters of temperature and oxygen concentration. All values peaked at intermediate population densities when only Promenetus was present. When the two species coexisted, the values appeared to remain stable as density in- creased. A series of t-tests indicated that signifi- cant differences between aquaria occurred in alkalinity and dissolved solids despite continual addition of lake water. All statistical analyses were performed at the 0.05 level. Water from Rat Cove and in the experimental aquaria differed greatly. Both environments were provided with the same amount of nutrients, but the tanks were completely enclosed and exhibited the characteristics of high eutrophy in a short time under continuous illumination. This is ap- parently related to the great surface area per unit substrate in Rat Cove that absorbs the nutrients, only slowly releasing them, compared Control Promenetus exacuoui Physa heterostropha Both species coexrsting .4 5 .6 Total snail weight per crisper FIG. 1. (ir(uing€fficie7Uiy of maik expressed as Log (Ckl a ^igrns/m^) ^ 2.550 - .297 Log (total snail weight per crisper). Vol. 91 (3) July 1, 1977 THE NAUTILUS 95 tx) their immediate availability in the tanks. The result is a buffering of the eutrophication process in Otsego Lake when enrichment is not too severe. Limnological parameters measured in each container were well within the limits for the two species measured by Harman and Berg (1971) in their survey of freshwater snails of central New York, indicating that the chemical conditions in the tanks were not atypical and the results can be applied to natural populations. SNAIL GRAZING Table 1 indicates the grazing efficiency of both mixed and pure cultures of P. heterostropha and P. exaxnious. The grazing efficiency of all snail populations was represented by the equation (Log Y = 2.550 - .297 Log X) where Y equals the chlorophyll a content in ^gm/m^ (extracted from slides placed in the aquaria) and X equals the total snail weight per tank, a measure of snail population density. The negative correlation, shown in Figure 1, clearly illustrates the fact that as snail population density increased, stand- ing crop of periphyton (chlorophyll a content) decreased. Physa heterostropha had a grazing ability effi- cient enough to reduce the standing crop of periphyton at all population densities studied (Fig. 1). The positive correlation between popula- tion density of P. exacuous and periphyton chlorophyll concentration illustrates the fact that this species is unable to limit growth of algae (Fig. 1). The increase in periphyton population density writh increase in snail population density may be due to the increased availability of nu- trients brought about by the presence of snails in the crispers. However, equally possible are effects of competitive interactions between algal species resulting from differences in the grazing char- acteristics of the snail species involved. The grazing ability of coexisting snail popula- tions is not significantly different from that of pure cultures of P. heterostropha (Fig. 1). This is what was expected, since P. exacuous added very little biomass in the experiments utilizing coex- isting populations. The sides and bottom of the snail-less control tanks were thickly covered with attached algae, but those with snails in them appeared relatively free. CONCLUSIONS It is an overgeneralization to state that periphyton standing crop is decreased by the presence of snail populations. Although this is often the case, as shown by our data collected form pure cultures of P. heterostropha and mixed cultures of P. heterostropha and P. exacuous, situations can arise when algal standing crops in- crease in size. When a particular species of gastropod grazes it undoubtedly alters competitive interactions between various species of algae by more effi- ciently cropping one species than another. In a natural environment these alterations could be extremely significant. In this study it was not determined whether this kind of phenomenon caused the periphyton standing crop to increase as the population density of P. exanwus in- creased. These results may have come about because of "inefficient" grazing of P. exacuous, in combination with the effects of continuous il- lumination and added nutrients associated with the presence of the snails. In many localities great effort has been ex- pended on the eradication of freshwater snail populations because they are intermediate hosts of economically important trematode parasites. The harvesting of rooted aquatic plants, with con- comittant removal of gastropods, is taking place in more and more situations where the plants have become nuisances. If snails have important effects on the standing crops of benthic algae in those ecosystems, studies such as this could deter- mine how well snails control algal population densities, and therefore, maintain the quality of natural waters. LITERATURE CITED APHA, AWWA, and WPCF. 1970 Standard metehods for the examination of water and wastewater. American Public Health Association. Beyers, R. J. 1963. The metabolism of twelve aquatic laboratory microecosystems. EcnI. Monagr. 33:281-.306. Castenholts. R. W. 1961. The effect of grazing on marine lit- toral diatom populations. Ecology A2(i): 783-794. 96 THE NAUTILUS July 1. 1977 Vol. 91 (3) Douglas. Barbara. 1958. The ecology of the attached diatoms and other algae in a small stony stream. J. EcoL 46: 295-32^ Harman. W. N. and C. 0. Berg. 1971. Tlie freshwater snails of central New York with illustrated keys to the genera and species. Search: Cornell Univ. Agr. Exp. Sta., Eiitomol., Ithaca my. 1-68. Herrman. S. A. and W. N. Harman. 1975. Studies on two populations of Physa heterostropha (Say). Ohio J. Sci. 75(2): 85-95. Hutchinson, G. E. 1957. A treatise on limnology. Volume 1. John Wiley and Sons. Inc. Kehde, P. M. and J. L. Wilhm. 1972. The effects of grazing by snails on community structure in laboratory streams. Amer. Mid. Nat. %7 {I): S-2i. A FURTHER NOTE ON GEOLOGIC CHANGES IN THE RELATIVE SIZE OF BIVALVE SHELLS Ralph W. Dexter Department of Biology Kent State University, Kent, Ohio 44242 At the 1965 meeting of the American Mala- cological Union, I challenged the conclusions of E. S. Morse who published various reports from 1879 to 1925 showing differences in the proportion (length-width) of bivalve shells between those found in native shell-heaps and living sjjecimens from the same locality. He believed that the dif- ference was due to climatic change. However, it was demonstrated that the ratio of Mya arenaria L. depends upon the nature of the substratum in which the clams developed. Without a knowledge of the substratum, comparisons cannot by made {Annual Reports, A.M.U. for 1965, p. 18). In studying the correspondence of naturalists at the Museum of Science, Boston, Massachusetts, I encountered a similar situation. Apparently, Sameul H. Scudder, Curator at the Boston Society of Natural History, believed he could detect a dif- ference in shell size between fossil and recent shells of the quahog (Mercenaria mercenana L.) and, like Morse, had assumed an evolutionary change. Addison E. Verrill, at Yale University, however, realized the differences could be due to local environmental conditions. He wrote to Scud- der 9 October 1875 as follows: "You are perfectly correct in regard to the peculiarities of the majority of the fossil quahogs with the average specimens seen in our markets. I had noted the same differences, but they are not constant in the fossils, for in my lot there are some of good size that are as thin and smooth as ordinary New Haven specimens of the same size and they have the same form also. We have a large number (50 or more) of good, large (3-4'/2 in.) Nantucket quahogs obtained from a native. They are remarkable for their massiveness, for their strong concentric rings and most of them are rather rounded and the disk violet color extends in a broad zone entirely across the shell (the same is true of some of the fossils that retain traces of color), and in the totality of their characters they are more like the average fossil quahogs than are those from any other locality yet examined, but in the same lot are some of the thin, elongated ones nearly smooth in the middle like the ordinary sort and others that are intermediate. I imagine that such differences as oc- cur are due to local causes and were in ancient times as now, inconstant. I presume that localities might now be found where the quahog would be precisely like the fossils." Permission to quote Verrill's letter was kindly given by the Museum of Science, Boston, Mass. Vol. 91 (3) July 1, 1977 THE NAUTILUS 97 BUOYANCY CHANGES AS RELATED TO RESPIRATORY BEHAVIOR IN AN AMPHIBIOUS SNAIL, POMACEA URCEUS (MULLER), FROM VENEZUELA Kathleen A. Burky' and Albert J. Burky' Instituto de Zoologi'a Tropical, Facultad de Ciencias, Universidad Central de Venezuela, Caracas, Venezuela ABSTRACT The ampullariid Pomacea urceus uses its ctenidium and lung in respiration. The snails reach the surface urith their siphon and ventilate their lung by urithdraunruj their head-foot in a pumping action. The lung gas also serves to change the buoyancy of the snails. After a ventilation a snail does not necessarily return to the same hioyancy level. They may achieve overall specific gravities of <1 to >1 after a ventilation. They may remain submerged (s.g. >1) or float (s.g. <1) for long periods. In the field many P. urceus are found floating during periods of low ox- ygen tension. Underwater weights were recorded over 2h hr and five day periods. Weight changes are representative of gas volume changes in the lung. The most rapid changes take place over the first six hours. Adult snails normally ventilate their lung within the first two hours of submersion. Juvenile P. urceus ventilate their lung more frequently than adults. Pomacea falconensis and P. luteostoma are similar to juveniles of P. urceus in size and show similar ventilation rates. The rate differences probably reflect the difference in lung capacity to total tissue in relation to metabolic rate. Considerable significance attaches to any obser- vations on the structural and functional adapta- tions shown by "primitive" lung-fish. This is also true for amphibious snails. Such observations, especially physiological data from whole animals, can be of interest in two ways. First, at the level of mechanistic physiology, they help establish our concepts of how such an "unlikely" animal ma- chine as one built on the basic molluscan plan — of great efficiency in an aquatic environment — can maintain itself on land. Secondly, it is possi- ble that hypotheses on the evolution of the major land stocks can be modified as a result of phy- siological investigation of amphibious stocks (whether they involve "partially adapted" or "doubly adapted" forms). The remarkable physiological plasticity shown by amphibious and freshwater snails of the major class Pulmonata has been discussed elsewhere (Russell-Hunter, 1964). The mantle-cavity con- verted as a "lung" can be used in rhythmic "div- ' Present address: Department of Biology, University of Dayton, Dayton Ohio 4&J69, U.S.A ing" (Russell-Hunter, 1953a, b, 1957), or be water-filled, or have its gas used as a "physical gill" for the underwater uptake of oxygen (Rus- sell-Hunter, 1953b; Henderson, 1963), or prin- cipally to provide buoyancy (Jacobs, 1941; Rus- sell-Hunter, 1953b; Henderson, 1963). Among the amphibious prosobranchs are sever- al genera and species in the family Ampulla- riidae (superfamily Viviparacea). It has long been known (Troschel, 1845; Pelseneer, 1895) that ampullariid snails possess unusually "amphib- ious" respiratory structures, one part of the mantle-cavity containing a ctenidium and ano- ther part being modified as a gas-filled lung cavi- ty. Significant anatomical studies on ampul- lariids have been reviewed (FYetter and Graham, 1962; Demian, 1965; Andrews, 1965a, b) and the physiology of aestivation has received attention (Meenakshi. 1956. 1957, 1964; Visser. 1965; Burky. Pacheco. and Pereyra, 1972). The behavior of lung ventilation has been discussed by Robson (1922). Prashad (1925, 1932), and Andrews (1965b), and examined in greater detail by McClary (1964) and Demain (1%5). Until recently there has been 98 THE NAUTILUS Julv 1, 1977 Vol. 91 (3) little modern physiological and ecological work on populations of ampullariids, but now there are extensive data on Fomacea urceits. which is abun- dant over vast areas of the Venezuelan savannah. These include data on growth and biomass turn- over (Burky, 1973, 1974) and on temperature, wa- ter, and respiratory regimes (Burky, Pacheco, and Pereyra, 1972). This paper reports work on buoyancy changes in relation to respiratory be- havior in Pomacea urceus (conducted by the senior author in Venezuela in 1970, along with some comparative notes on other aspects of respi- ration in P. urreua, and with limited comparative data on three other species of ampullariids. MATERIALS AND METHODS The snails were initially maintained in large outside tanks and then moved to aquaria in the laboratory. Caracas tap water was used but only after it had been allowed to stand for 24 hr or longer. When changing the water (at least twice a week), 25%-50% of the used "conditioned" water was usually retained. Snails were regularly fed lettuce. The weighing apparatus used in this investiga- tion (Fig. 1) was designed after that used by Balance eratlon FIG. 1. Weiyhiny apparatus. Henderson (1963). A triple-beam balance and a plastic weighing cage (made from a two liter bot- tle) with a volume of about 1.25 I were used. Lead weights were added to the naturally buoy- ant plastic cages until an underwater weight of 9-10 g was reached and this weight is referred to as the zero weight. This could easily ac- commodate the range of buoyancy changes in P. urceus. When the underwater weight of a snail is greater than the zero weight, it has an overall specific gravity of greater than one. It follows that underwater weights of less than or equal to the zero weight will correspond to specific gravities of less than one and one respectively. Snails were taken from aquaria at ambient room temperature (about 20-25° C) and placed in cons- tant temperature tanks (maintained near 29° C) two days before each experiment. Eighteen to 24 hr before an experiment, a snail was placed in an experimental cage with lettuce. The cage was suspended from the balance by coated copper wire a few centimeters below the water surface. On the morning of each experiment uneaten let- tuce was removed and the snail was observed un- til it ventilated its lung by reaching the surface with its siphon. It was immediately lowered to a depth of more than double its shell length so it could not reach the surface with its siphon to ventilate, and weighed. Subsequent weighings were made at various intervals depending on the experiment. The water was continuously aerated throughout each experiment; all snails were starved throughout each experiment; and all ex- perimental temperatures were in the range of 28.75-29.75° C, since this is near the natural field temperature during the rainy season (Table 1). The weight of a snail is reduced by a force equal to the mass of the water displaced when submerged. The submerged weight reduction in grams (without gas in the lung) is equal to the volume of water displaced (milliters), since one gram of water can be assumed to have a volume of one milliliter. It follows that the weight of a submerged snail will be further reduced by one gram per milliliter of gas (weight of the gas is disregarded) in the lung. Therefore underwater weight changes give an accurate picture of the gas volume changes in the lung. Since milliliters Vol. 91 (3) July 1. 1977 THE NAUTILUS 99 TABLE 1. Physical data from the natural habitat of Pomacea urceusduhng the rainy season. Time Tempemtun •c pH Water 0, ppm (mgO./I) Date Bottom Surface Water Water Air 11 Aug. 70 1100 29.2 30.1 28.3 6.8 1.7 1200 29.4 30.4 24.4 6.8 1.7 1400 29.6 31.5 25.2 7.1 4.5 1600 30.0 32.8 27.0 7.0 5.5 1800 31.2 31.5 26.8 7.1 4.1 2000 30.4 30.5 25.6 7.1 3.2 2200 30.2 30.3 24.5 7.0 2.1 2400 30.2 29.8 25.6 7.1 3.4 12 Aug. 70 0200 29.7 29.6 26.7 7.0 2.6 0400 29.5 29.4 25.6 7.0 1.6 0600 29.2 29.1 25.3 7.1 1.6 OBOO 29.0 28.8 25.0 7.1 1.1 1000 28.8 28.6 24.0 7.1 1.0 and grams are equivalent, the gas in the lung at the start of each exi)eriment can be estimated. The volume of a contracted snail in milliliters (determined by displacement of water) was sub- tracted from the weight of the snail (in air) in grams to give the underwater weight of the snail without any gas in the lung. It follows that the difference between the underwater weight with- out gas and the underwater weight of the snail immediately after ventilation will give the mil- liliters of air present in the lung. It is necessary to estimate the initial gas volume since it is not possible to force these snails to expel all gas for an underwater weight (without gas) at the end of an experiment. It also follows that the volume meaurement of a snail is not accurate and will include the volume of any retained gas. There- fore, initial gas volumes are underestimates but make reasonable comparisons between snails pos- sible. Observations on the interval between successive ventilations and the number of pumps per ven- tilation were made on adults and juveniles of Pomacea urceus, and on adults of P. falconensis and P. luteostoma (Swainson). Some general observations were also made on Marisa cor- nuarietis (Linne). Field measurments were taken hourly over a 24 hr period. Temperatures were recorded with a YSI Tele-thermometer; oxygen tensions were re- corded with a YSI portable oxygen electrode; and pH values were recorded with a portable pH meter. RESULTS It is important to know the weight and volume of body parts for Pomacea urceus. This informa- tion is partly based on the data of Burky, Pacheco, and Pereyra (1972) and is given for a hypothetical snail of lOOg in Table 2. Volume reductions over twenty-four hours of submersion— Ohservsitions of underwater weight changes were made over 24 hr periods of contin- uous submersion. Periods of submersion started immediately after ventilation of the lung. Under experimental conditions a snail usually reduces its overall specific gravity without becoming buoyant. The results of such an experiment are illustrated in Fig. 2 and given in Table 3. The weight increases (volume reductions) are brought about smoothly with time. The most rapid changes take place during the first six hours. The weight increase in the first hour is equivalent to a 6.7% reduction in the volume of gas. The rate decreases to Ll% of the initial volume in the sixth hour. In the first six hours, TABLE 2. Estimated weight and volume of body parts for a hypothetical snail with a maximum live weight of 100 g (shell length, abotit 85 mm). _ at€T Volume Reductxans on Successive Hoiin (mlAir) Total Volume Reduction .\fter h' Hourv Percentage Reduction After H Hours Total Volume Reduction After U Hours t^rrcntnge Rediu-tion .ifter a Hours /»( ..hid Jrrf ilh ,5(/i 67/l 1 (mm) 113 (ml) 73.38 7.88 3.87 1.91 0.96 0.74 0.43 (mil 15.79 21.5 (ml) 18.91 25.8 2 105 91.53 5.04 3.17 2.08 1.78 1.32 1.50 14.89 16.3 27.78 30.4 3 109 59.82 3.71 2.16 1.93 0.80 0.69 0.46 9.75 16.3 13.69 22.9 4 107 43.53 2.32 1.93 1.38 0.78 0.87 0.56 7.84 18.0 12.51 28.7 5 112 77.15 2.98 4.90 4.68 2.50 1.98 1.16 18.20 23.6 27.25 35.3 6 98 43.35 4.0fi 3.fi9 1.00 0.35 0.21 0.09 9.40 21.7 11.60 26.8 Mean 107 19.6 28.3 Vol. 91 (3) July 1, 1977 THE NAUTILUS 101 TABLE 4. Gas volume changes in the lung during a five day period of submersion. I'nderu'ater \ j/wmf Heductum <»n 7!.ta/ Percentage Eittimated Successive days Volume Reductwn Gas Vnlumr (mt/day) Reduction After Exp. SieU Length at Stan n/Erp ,5 Days No 1st Ind M Uh 5th 5 Days tmmj (ml) Imll 2 105 91,53 27.78 7.37 5.97 3.04 3.04 47.21 51.6 3 109 59.82 13.69 2.51 1.67 1.67 1.31 20.84 34.8 5 112 77.15 27.25 4.91 4.08 4.08 4.58 44.89 58.2 6 98 43.35 11.60 1.30 1.34 1.34 1.85 17.43 40.2 Mean 106 46.2 It should be pointed out that flotation is com- mon in these snails. On numerous occasions over 50% of these snails have been observed to float in laboratory tanks. At other times all are sub- merged. In the field most of the snails collected are those which are floating. Collecting snails is easiest in the early morning because of the large numbers which are buoyant. By mid-day condi- tions have changed and floating snails may be difficult to find. Pomacea urceus is either buoyant or has a specific gravity of greater than one after each ventilation. Therefore these snails do not always return to the same specific gravity after each ventilation. However, one must ask if a level is maintained while floating or while submerged. Figure 5 gives the results of a snail (specific gravity greater than one) which was allowed to ventilate at will. This individual may return to the same weight level; it may go to a much lower specific gravity; or it may decrease the total gas volume during the process of ventilation. On two occasions this snail ventilated three successive times before a smooth weight increase was re- corded. This type of ventilating activity has been observed frequently in laboratory tanks. Siphonal ventilation in Pomacea urceics, P. falconensis, P. luteostoma, and Marisa cor- nuarietis.— During ventilation the tip of the siphon is brought into contact with the surface to form an air tube to the lung. The head of these ampullariids is then observed to contract in a pumping action. Adults of P. urceus are gigantic and are capable of extending their siphon by at least 1.5 times their shell length. A large snail of 125 mm can easily extend its siphon about 200 mm and makes little effort to reach the surface of shallow laboratory tanks. The juveniles of P. urceus and the adults of P. falconerms, P. luteostoma, and Marisa comuarietis all had max- imum shell dimensions of about 30 mm. / 7^ 2400 2400 Tim* (hours) FIG. 4. Underwater weight changes of a snail which was buoyant after ventilation of its lung. Broken line indicates a decrease in weight when snail was allowed access to air after a period of nearly three days. 25 r- / / / / / / / / A / "5 c M «. 15 o _ //■ o J • 1/ X 10 ~~ Zaro ■fllaril Una 1200 laoo TImi (hours) FIG. 5. Undenrater weight changes after successive ventila- tions of the lung. Those weights marked by an X indicate the weight immediately after completion of a ventilation. Zero weight, 9.75 g. 102 THE NAUTILUS July 1. 1977 Vol. 91 (3) Adults of P. urceus ventilate their lung every 62 min with about 18 pumps per ventilation (Table 5). Juveniles of P. urceiw^ ventilate every 20 min with about eight pumps per ventilation (Table 5). The difference between the adults and juveniles of P. urceus undoubtedly reflect size. The adults of P. falconemns and P. luteostoma were similar to juveniles of P. urceus in the in- terval between ventilations and in the pumps per ventilation (Table 5). In addition to the snails of Table 5, Marisa comuarietvi was also maintained in aquaria. All the ampuUariids regularly surface and actively ventilate their lung by extending and withdrawing their head-foot. They have all been ovserved to release from the bottom and float to the surface. They may also float for pro- longed periods as well as release gas at the sur- face and sink to the bottom. DISCUSSION Unfortunately there are no published data on the underwater weights of ampullariids. There- fore many comparisons must be made with the extensive data of Henderson (1963) on freshwater pulmonate snails. This investigation has shown that Pomacea urceus regularly surfaces and ventilates its lung. This snail may become buoyant and float or maintain a specific gravity of greater than one. Ventilation normally occurs during the period of greatest weight change. This is also true of the pulmonates studied by Henderson (1963). For Henderson's pulmonates, the buoyancy level is apparently used as a very sensitive signal for sur- facing. This is not the case for P. urceus, which ventilates at various buoyancy levels (Fig. 5). En- vironmental oxygen tension is probably a more important signal for surfacing. McClary (1964) showed that the buoyancy in P. paludosa is reduced before surfacing, but believes that oxygen tension is probably the critical stimulus. Pomacea urce^ui maintains an overall specific gravity of greater than or less than one for periods of ac- tivity while continuously submerged or while floating. The apparent greater variability of sur- facing behavior in P. urceus may well be ac- counted for by the presence of a functional ctenidium. This provides an alternative: aquatic respiration with its gill or aerial respiration with its lung. Henderson (1963) points out that Lym- naea stagnalis and Planorbarius comev^ are very sensitive to disturbances and such will cause an increased amount of gas to be taken in at the surface. In P. urceus there is a sensitivity to vibration, movement near aquaria, and light changes. Such irritations may cause a snail to retract and remain inactive for long periods. However, there is no evidence that disturbances cause an increase in the amount of air taken in during ventilation. TTiis sensitivity increased as TABLE 5 Prpqiipnry and intensity of siphonal ventitation nf the Ivng in adultii nnd jiwenilfs o/ Pomacea urceus. and in P. falconensis and P. luteostoma. adult juvenile Description Pnmarea wrfpiw Pnmareft urcpus P falrnnrtuns P lutfoatfimo Number of .snails involved in observations 24 12 8 5 Shell len^h (mm) Mean — 28.3 32.8 28.0 Range about 90-125 22-32 15-53 17-35 Livewieghtig) Mean — 3.7 7.81 7.4 Range about 140-400 2.0-5.6 0.6-22.2 1.2-13.3 Interval between ventilations (min.) Number of observations 30 27 26 49 Mean 62.4 19.9 17.8 126 Range 3-190 2-78 1-54 1-42 Standard Error 8.413 3.069 2.545 1.519 Pumps per ventilation Number of observations 70 46 28 51 Mean 18.3 8.1 10.6 9.8 Range 3-36 4-16 4-22 5-19 Standard Error 0.762 0.433 0.690 0..551 Vol. 91 (3) July 1, 1977 THE NAUTILUS 103 the breeding season neared. During November when copulating pairs are common, experiments are impossible to perform. Therefore, these results are not representative of snails at all times. Further, P. urceits aestivates during the dry season and remains buried in the dry ground surface where aerial respiration is obligatory (Burky, Pacheco, and Pereyra, 1972; Burky, 1973, 1974). Over periods of 24 hours, Henderson (1963) reports that for L. stagnalis and P. comeus, 56.7% and 52.2% of the gas bubble has been lost, respectively. For P. urceus, only 28.3% of the gas bubble has been lost for the same period. At the end of five days these pulmonates have lost 93.5% and 91.5% of the gas respectively, while P. urceus has only lost 46.2%. The lower percentages for P. urceiis probably represents a lower respiratory rate for this large snail. However, the ratio of gas volume to body tissue, as well as the presence of a gill are also involved. On occasion the interface of the gas at the pulmonary opening was observed. However, this opening is relatively small in the genus Pomacea (Andrews 1965b) and is probably not suitable as a diffusion interface. Further, there is no evidence that P. urceus uses the pulmonary gas as a physical gill. After ventilation some snails have been observed to retract and remain inac- tive on the bottom until just before the next ven- tilation. In these snails the pulmonary gas must be used as an oxygen store. It is known that the rate of aquatic respiration of snails decreases with oxygen tension (Berg and Ockelmann, 1959). Similarly it follows that the volume reductions for P. urcevs represent reduced rates of gas consumption with time. This has also been claimed for pulmonates by Hender- son (1963) who points out that the weight changes, although representative of volume reduc- tions, cannot be converted to oxygen consumption rates. There is a constant loss of nitrogen and other gases to the surrounding water. However, the rates reported by Henderson are of the same order as oxygen consumption rates reported by others for pulmonates. In P. urceus the weight changes can be assumed to be even less represen- tative of oxygen consumption rates since apart from cutaneous respiration there is a functional gill. Regardless, the initial hourly volume change for P. urceus is of the same order as the oxygen consumption rates of active adults (Burky, Pacheco, and Pereyra, 1972). It was observed that juveniles of P. urceus ven- tilate their lung more frequently than adults. This probably reflects a higher metabolic rate in the smaller snails. Significantly, these juveniles show ventilation frequencies which are similar to those for adults of other species with the same approximate size (P. falconensis and P. luteostoma, from Table 5; P. paludosa from Mc- Clary, 1964; Marisa comuMrietis from Demain, 1965). The difference between juvenile and adult P. urceus may also reflect differences in the ra- tio of lung capacity to total tissue in relation to metabolic rate. It has been pointed out that more snails are observed to float during the morning in the field. Over vast areas of the savannah, greater than three meters of water may cover the savannah during the rainy season. Significantly the oxygen tension is lowest during the morning hours (Table 1). At times of high oxygen tension, in the aftemon and evening, there may be "less" de- pendency on aerial respiration. Andrews (1965b) points out that the ctenidium of ampullariids is relatively smaller that in other prosobranchs and that the genus Pomacea has a relatively large lung when compared to other ampullariids. The relative proportions of gill to lung support the field observations in relation to oxygen tensions and floating activity. Willmer (1934) studied the relation between the mode of respiration and the gas content of the water in a tropical fish, the yarrow. At low oxygen tension aerial respiration is used; at high oxygen tension and specific carbon dioxide ten- sions aquatic respiration is used; and at in- termediate gas concentrations both means of respiration are employed. It would be interesting to know the specific responses of Pomacea urceus to varying tensions of oxygen and carbon dioxide as well as the characteristics of its haemocyanin. Ampullariids possess a typical prosobranch ctenidium and it is unlikely that this could be of secondary origin (Andrews, 1965b). The develop- ment of the lung in ampullariids is unlike that of 104 THE NAUTILUS July 1, 1977 Vol. 91 (3) pulmonates (Ranjah, 1942) and is a new secon- darily derived structure (Ranjah, 1942; Demain, 1964 discussion and references therein). This sup- ports the primary ctenidial origin and the secon- dary pulmonary structure and physiological me- chanisms in ampullariids. As indicated in the in- troduction and above, more information on respi- ratory behavior and physiology will give a better basis to our concepts of the evolution of this pro- sobranch group and the structural-functional ba- sis for the colonization of amphibious-terrestrial habitats by these snails. ACKNOWLEDGMENTS We would like to thank Professor Jesus Pacheco for making facilities and equipment available; Eduardo Miranda and Oswaldo Tra- vieso for their assistance in collecting snails; Mr. T. Pain for the identification of the snails and Dr. W. D. Russell -Hunter for his continuing in- terest and constructive criticism of the manu- script. Voucher specimens are on deposit for future reference at the Delaware Museum of Natural History, no. 102235. LITERATURE CITED Andrews, E. B. 1965a. The functional anatomy of the gut of the prosobranch gastropod Pomacea canaliculata and of some other pilids. Proc. Zool. Soc. Land. 145: 19-36. Andrews. E. B. 1965b. The functional anatomy of the mantle cavity, kidney and blood system of some pilid gastropods (Prosobranchia). J. Zl Soc India 9: 62-71. Meenakshi, V. R. 1964. Aestivation in the Indian apple-snail Pila-l. Adaptations in natural and experimental conditions. Camp. Biochem. Physiol 11: 379-386. McQary, A. 1964. Surface inspiration and ciliary feeding in Pomacea paludosa (Prosobranchia: Mesogastropoda: Am- pullariidae). Ma/- i 300- 200 100 The others are insecticides. Dieldrin, designed to kill beetles, ants, grasshoppers, box elder bugs as well as "many other lawn and ornamental soil in- sects", is composed of dieldrin (see above) and an aromatic petroleum derivative solvent. Malathion 50 is designed "for use on evergreens, roses, or- namentals, shrubs, trees" and is meant to control red spiders, aphids, flies, mealybugs, scale insects as well as various other household pests. It is a choline esterase inhibitor. Active ingredients are 65 66 67 68 69 YEAR 70 71 72 73 FIG. 2. Population densities of V. ameghini in one 375 sq. meter area. Left column of each year represents a mid-July collec- tion, middle is mid-August, and right is mid-September. Vol. 91 (;3) July 1, H»77 THE NAUTILUS 1 1 1 25 NUMBERS SELECTING [ NOICATE THAT 1 5 3 1 24 3 3 23 INDIVIDUALS TEMPERATURE 1 i ^ \ 22 6 2 1 5 1 20 4 2 19 1 3 2,1 18 1 6 17 ' "1, 16 S,| lb 1 3 3 14 1 13 3 2 12 1 S 1 1 II 10 1 1 2 1' 4 2| u 9 33 1 8 5 l| 7 3 2 1 6 r 2 2 1 5 1 4 1 4 1113 3 222 2 3 3 1 2 112 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 ri 1 1 1 1 1 1 I I I I I I I I I I I I I I I I I I I I I I I I I I I 24 26 28 30 31 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 DEGREES FAHRENHEIT 54*- 82' TOLERANCE FIG. .3. Temperature tulerance in Veronicella ameghini. Bars indkate the temperature range tu which the slugs were exposed in each experiment. malathion (0, 0-dimethyl dithiophosphate of di- ethyl mercaptx)succinate) and an aromatic petro- leum derivative solvent. Cygon 2-E has as an ac- tive ingredient dimethoate (0, 0-dimethyl S-(N- methyl-carbamoylmethyl)phosphoro-dithioate). Although a much broader experiment with more variables such as size of area, moisture con- trol, would, of course, be more desirable, it is ap- parent from Table 1 that, even with these simple tests, these insecticides used for lawns (as well as the molluscicides which are for sale) are very quickly detrimental to the slugs. This could be a significant factor in population fluctuations. Temperature. Experiments patterned after Dainton(1954) were run numerous times to deter- mine temperature tolerance. The temperature measured was that of the air immediately above the substrate upon which the slugs were resting. In each trial, except one, 6 slugs were used. No difference in species behavior was found. Repeat- edly the results were shown in Figure 2 wherein the range of tolerance falls between 12 and 28°C (54-82°F) with the preference seeming to be 20-24T (68-75°F). When the temperatures fall below 12°C (34°F) inactivity prevails whereas if it rises beyond 28T (82°F) and remains even for a short period of time, death ensues. In relating these data to the situation in nature, one must remember that the soil temperature in the micro-habitat is modified by other factors not in- volved here: shade, wind, humidity. For example, we have collected active slugs when the air temperature was 10°C, but simultaneously the relative humidity was 92% and the slug substrate was approximately 23°C due to a warm water sewer close by (see section on relative humidities). Light. In another series of experiments involv- ing a combination of temperature and light several factors were discovered. When air temperatures have been higher than 3rC (88°F) and begin decreasing, the slugs begin activity whereas when temperatures have been lower than 25°C (77°F) and are increasing, activity does not begin to occur until 25°C is reached even though this is above the preferred range (20-24°C) as demonstrated in the substrate studies. Since these temperatures approximate 112 THE NAUTILUS Julv 1, 1977 Vol. 91 (3) the summer season daily temperature range (21-30T) here, this leads us to superimpose light as a factor directing slug behavior. We discovered that slugs (in our experimental chamber) moving towards a cooler area, will, if a light (anywhere from 44 to 260 foot candles) is directed at their anterior ends, go in the reverse direction even if the temperature is intolerably high there. Several such experiments lead us to believe that temperature controls time of activity but that light determines the area of activity. All of these factors together could account for noc- turnal activity which is seen normally. But, the further problem of desiccation must also be con- sidered. Wi-nd. A series of experiments to test for ef- fects of wind upon the slugs was done. Superim- posed upon these experiments were additional conditions of heat, light and temperature. The method of procedure was as follows: a clear, plastic box 25 cm wide X 17.5 cm high X 15 cm deep, with moist paper toweling on its floor and sides, was used as the light chamber. A similar box with all sides painted black served as the dark chamber. A partial barrier (15 cm high X 5.5 cm wide) was taped upright in the right front side of each box. The box was turned so that the top faced frontwards to the path of the air from a small electric fan. Screen covered the top (front) of each box. Twenty slugs (the ex- periments involved each species) were placed in each chamber approximately 2.5 cm abeam of the plastic wind barrier. Exposure time was planned to be fifteen minutes per experiment; however, under certain conditions the animals were dying sooner so that results were obtained more quickly. The animals were observed and responses recorded. A control set was maintained in a similar box for each experiment but without the variables (wind, hot, cold)— simply at room condi- tions. No behavior similar to that observed in the experiments was seen. Terminology used was as follows: barrier area: that portion of the box behind the plastic barrier (the area sheltered from the wind) exposed area: the rest of the box aggregation: animals close together so as to form a group; characterized by a mound-like ap- pearance and complete or near complete absence of motion random orientation: any motor activity not specifically directed towards the barrier area; includes extension -retraction of tentacles, mo- tion of anterior body and/or actual movement into the barrier area sheltered activity: activity occurring after the animal had reached the barrier area but which was not directed towards the outside of that area temperature: room temperature was 22°C (72°F). Heat was introduced into the boxes by placing a hot-plate directly in front of the fan. Temperatures as high as 33°C (92°F) could be attained by this method: however, tem- peratures between 23 and 29°C (74-84°F) were used since it was determined that the animals would not survive above 28°C (84°F); again this verified previous experiments. A summary of results follows: Experiment 1 (repeated ten times with each species): light box— room temperature— wind (fan) 1. Animals initially stationary; no motion for first five minutes. 2. Random orientation on the part of three animals; others motionless or with only slight movement. Lasted 6-15 minutes. 3. By the end of twenty minutes, most animals had migrated to the barrier area. 4. Remaining animals aggregated. Note: Attainment of barrier area did not necessarily indicate cessation of movement. On a number of occasions sheltered activity con- tinued. In some cases, animals having attained the barrier area early would return to the ex- posed area to any clustered group. One time when a single slug attained the barrier area and the others clustered in the exposed area, that individual returned to the cluster. Under conditions of exposure all animals secreted mucus heavily unless clustered. This occurred in both the light and the dark. Experiment 2 (repeated ten times with each species): Dark box— room temperature— wind (fan) Vol. 91 (3) July 1, 1977 THE NAUTILUS 113 1. The same absence of activity for the first five minutes. 2. Much less activity for the first ten minutes than in the light. 3. Some random orientation leading to clustering by most; in some of the ex- periments several slugs had, by the end of fifteen minutes, attained the barrier area and ceased activity. Note: There was much less activity in the dark than in the light when wind was applied. Experiment 3 (repeated ten times with each species); Light box— heat— wind (fan) 1. Motion often leading to aggregation in first five minutes. 2. Random orientation leading to signs of shriveling accompanied by increase in ac- tivity for next ten minutes. Those reaching the barrier area often returned to the ex- posed area. Appearance of general discom- fort; the higher the temperature, the greater the appearance of discomfort (in combination with wind) Experiment 4 (repeated ten times with each species); Darkbox— heat -wind (fan) 1. Aggregation was the response within the first five minutes with no other behavior oc- curring. Experiment 5 (repeated ten times with each species); Light box— cold (whole experiment placed in 3T (;38°F)-wind (fan) 1. Immediate shriveling. 2. Moved into an aggregate within two minutes; appear "pinched"; very heavy mucus secretion. Experiment 6 (repeated ten times with each species); Dark Box— cold— wind (fan) 1. Aggregation close to point of release followed by inactivity; same appearance and mucus as in light-cold. Several interesting results were obtained from these experiments. First, it is obvious that veronicellids have a negative response to wind and either seek shelter or aggregate in the presence of it. The temperature of the wand seems to be of no more importance than temperature alone (based upon a comparison of these ex- periments with the previously-discussed tem- perature experiments). The reason for less activi- ty in the dark than in the light is as yet unex- plained; it is the reverse of the situation without wind. pH: the range in soil pH in areas where slugs are common is 7.2-7.8. LIFE HISTORY There are two periods of egg deposition by Veronicella ameghini in the Gulf Coast area. One is from March through June and another from September through mid-November. The same tim- ing prevailed in the laboratory despite different experimental conditions. E^s are normally deposited in a shallow con- cavity which the slug makes in the soil. This usually occurs under leaf litter where a higher moisture level is likely to be maintained. The egg mass is coiled and the eggs are attached together by a gelatinous, fecal-containing strand. The slug deposits the strands while it is curled in the form of a circle. The curve of the body apparently helps form the coil-shaped egg mass. A single slug may deposit from one to five masses during each breeding season. Five to fifteen eggs are laid in this manner and the period of deposition is known to be at least five hours. Each egg is oval, 6 mm in length 3 mm wide, gelatinous without a hard cover. Once deposited, the eggs are not covered over with soil but are merely left to hatch. Hatching occurs in approximately 20-28 days depending on the temperature. The average in- cubation period in the laboratory with a room temjjerature averaging 24°C was 21.4 days. The late spring masses hatch sooner than those laid in early spring, probably due to a higher temperature; likewise, the later fall eggs require a longer period to hatch. Length of newly hatched slugs is about 3-4 mm. It is impossible to accurately measure living slugs; therefore, weighing was employed. Average weight of a newly hatched slug .016 g. Grovrth rate in the laboratory is slow. Here they were maintained at room temperature (ap- proximately 24°C or 76°F with air condition- ing) and fed lettuce. The average rate was 0.28 g in six months. The average weight of hundreds of THE NAUTILUS .Julv 1. 1977 Vol. ;»1 (3) slugs collected at random throughout the year was 0.523 g. It is suspected that the average growth rate in laboratory is well under that in the field. The largest adult captured weighed 2.94 g. If the alx)ve-mentioned growth rate does occur in nature the calculated age would be approximate- ly five years for this individual. Longevity is more likely around two years as it is with many other land molluscs. Laboratory maintenance is difficult for periods longer than six months. One has a constant die-off as time goes by. The prob- lem is one which is being investigated in more detail— namely, that of a blistering phenomenon wherein the slugs become pitted, form blisters and gradually become weak and die. It is thought that the disease is caused by either a yeast or a bacterium (DeGravelle, 1971). SIGNIFICANCE OF THE INTRODUCTIONS Repeated checks in nature and in greenhouses of our local colonies of Veronicella ameghini and Veronicella floridana reveal no significant damage from them to native vegetation, crops, or property. The latest finding of veronicellids in southern Texas is new enough that no informa- tion is available on their activities. USDA does rep(jrt that damage has been done to greenhouse plants by these slugs. The author has received a picture of damage done to bananas in Honduras by V(ujmuhis olivaceous (courtesy of Div. of Trop. Res., Dept. Entomology, La Lima, Honduras). It shows holes and browm spots where the slugs have rasped the banana "peel", thus making the banana unmarketable. With more introductions being reported recent- ly, it is well that we stay alert and be prepared with knowledge in case of any major problems such as have been associated with introductions of Achatinafidica, the giant African snail (Mead, 1961). LITERATURE CITED Dainton. B. H. 1954. The activity of slugs. ./ Erp. Biul. 31: 165-197. DeGravelle. L. 1971. An investigation of a blistering condition in the slug. Vcrdiiici'lla amcyhDu. MS Thcsix: Louisiana State University in New Orleans. Dundee, D. S. 1970. Introduced Gulf Coast Molluscs. Tulane Studies inZool. andBot. 16(3): 101-115. Dundee. D. S., B. S. Stutts. and P. W. Hermann. 1965. Preliminary survey of a possible molluscan pest in the southern United States. Ecol 46(1&2): 192-193. Mead. A. R. The Giant African Snail: A pmhlem in economic nialiu-dliyi/. Univ. Chicago Press. 1961. Petrellis, L.. and D. S. Dundee, 1969. Veronicella ameghini (Gastropoda): Reproductive. Digestive and Nervous Systems. Trans. Amer. Micr Soc. 88(4): 547-558. V(.l. 91 (:?) July 1. 1977 THE NAUTILUS 115 USE OF EMPTY GASTROPOD SHELLS (POLYGYRIDAE) BY PSEUDOSCORPIONS Ralph W. Taylor, Michael P. Sweeney, and Clement L. Counts, III Department of Biological Sciences Marshall University Huntington, West Virginia 25703 Pseudoscorpions are noted for their phoretic associations with many living vertebrates and in- vertebrates (Muchmore, 1971). However, their associations with non-living animal remains for a survival advantage has not been documented. Specimens of Chthonitis tetrachelatus (Preyssler) and Apochthonius moestus (Banks) have been col- lected by us from the empty shells of the ter- restrial gastropods Diodopais alholahri.'^ (Say and Mesodon thyroidvs (Say) from Cabell, Kanawha, Putnam, and Wayne Counties, West Virginia. The empty shells were collected from mid- February to May, 1976, and the pseudoscorpions were collected in them up to April. The use of gastropod shells by arthropods is not an uncommon occurrence in the marine and littoral environment, as demonstrated by several species of hermit crab. Indeed, the use of ter- restrial gastropod shells by pseudoscorpions may have the same survival advantage in protecting the animal's soft parts during molting. However, this behavior may have other implications. The shells may offer protection from excessive cold, heat and desiccation. We would like to thank Drs. Sigurd Nelson, Jr., SUNY at Oswego, New York, William B. Muchmore, University of Rochester, and C. Clayton Hoff, University of New Mexico, for their advice and assistance. Voucher mollusk speci- mens are in the Marshall University Malaco- logical Collection and the Delaware Museum of Natural History. LITERATURE CITED Muchmore. William B. 1971. Phoresy by North and Central American pseudoscorpions. Proc. Rochester Acad. Sci 12: 79-97. VERONICELLA OCCIDENTALIS IN LOUISIANA Steven T. Malek 826 Fern Street New Orleans, Louisiana 70118 A comprehensive review of introduced mollusks in eastern North America (North of Mexico) was recently published by Dundee (1974). The tropical veronicellid slugs introduced in the above area received attention in the review. In the summer of 1975 I collected veronicellids in New Orleans, in the uptovm region of the city. These slugs fit the description of Veronicella nccidentalis (Guilding). This is a new record for this slug in Louisiana. About twenty slugs were found under logs, garbage cans and leaves, and on side-walks. Veronicella occidentalis was reported by Dundee (loc. cit.) to have been introduced into Oklahoma and Texas. The slug is believed to have originated in southern Mexico, northwestern South America and the Antilles. I have seen and examined specimens collected on the Caribbean Island of St. Lucia (E. A. Malek, 1976, in press), and the Louisiana material is quite identical to those from St. Lucia. These tropical slugs were probably introduced into the United States on several plants, judging from interceptions by the 116 THE NAUTILUS Julv 1, 1977 V.)l. 91 (3) U. S. Department of Agriculture, at ports in Florida, Louisiana, New York and Texas. Among the plants are bromeliad, caladium, Dracaena sp.. Funis, orchid, palm, pineapple, and philodendron. Another veronicellid previously introduced in Louisiana, circa 1960, is Veronicella ameghini (Gambetta), and was reported upon by Dundee and Herman (1968). The latter slug occurs now in small numbers, that it is rarely encountered in New Orleans. It did, however, occur in large numbers in New Orleans in the early 1960's. I am grateful to Dr. Dee Dundee of the Univer- sity of New Orleans for having e.xamined the slugs which I collected in New Orleans, and having confirmed my identification. LITERATURE CITED Dundee. D. S. 1974. Catalog of introduced molluscs of eastern North America (North of Mexico). Sterkiana No. 55: 1-37 Dundee. D. S. and Herman, P. W. 1968. New records for in- troduced molluscs. NautUus. 82: 43-45. Malek, E. A. 1976. Land and freshwater snails of St. Lucia, the West Indies. Tidane Studies ZooL Bot. (in press). NATIONAL MUSEUM OF NATURAL HISTORY Department of Invertebrate Zoology— Mollusca Several changes have occurred recently in the malacological staff of the Department of In- vetebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560 (formerly known as Division of Mol- lusks, U.S. National Museum). Dr. Arthur H. Clarke joined the staff in Janu- ary, 1977, as Associate Curator of freshwater and land mollusks in the position created by the retirement of Dr. J. P. E. Morrison (1975). Dr. Clarke formerly was curator of Molluscs and later Head, Invertebrate Zoology Division at the National Museum of Natural Sciences, National Museums of Canada, Ottawa. Dr. Richard S. (Joe) Houbrick became an Asso- ciate Curator in marine mollusks in March 1977, transferring from the Smithsonian Oceanographic Sorting Center (NMNH), where he supervised the benthic invertebrate sorting program. Dr. Hou- brick occupies the vacancy created by the retire- ment of Dr. Harald A. Rehder (1976). Dr. Rehder remaines in mollusks as Zoologist Emeritus, Department of Invertebrate Zoology. Dr. C. F. E. Roper and Dr. Joseph Rosewater continue to serve as Curators in cephalopods and marine mollusks, respectively. Each department of the National Museum of Natural History (Anthropology, Botany, Eii- tomology. Invertebrate Zoology, Mineralogy, Paleobiology and Vertebrate Zoology) is ad- ministered by a chairman. The Departmental chairmanship is a rotating position so that no in- dividual Curator need have his research program permanently curtailed. Curatorial staff are ad- ministratively responsible to the Department Chairman, as divisional Head Curators no longer exist. The subject areas within the Department of Invertebrate Zoology are Crustacea, Echinoderms, Lower Invertebrates, Mollusca, and Worms. Ad- ministrative requirements within a subject area are attended to by a Supervisor, a position rotated among the curatorial staff every year or two. Requests should be directed to the Super- visor or to a specific curator.— C. F. E. Roper. Vol. 91 (3) July 1, 1977 THE NAUTILUS 117 PUBLICATIONS RECEIVED Thompson, Fred G. 1977. The Hydrobiid Snail Genus Marstonia. Bull. Florida State Mus., Biol. Sci., vol. 21, no. 3, pp. 113-158. Eight species, of which five are new, are treated systematically. The genus, limited to Southeast and Central United States, is placed in the sub- family Nymphophilinae Taylor, 1966. $1.75, Florida State Nuseum, Gainesville, Fl. 32611. Thompson, Fred G. and Richard Franz. 1976. Some Urocoptid Land Snails from Hispaniola. Rev. Biol. Trop., vol. 21, no. 1, pp. 7-33, 9 figs. Allocoptis ne6rms,new genus and species, and three new species of Autocoptis are described. Hickman, Carole S. 1976. Bathyal Gastropods of the Family Turridae in the E^arly Oligocene Keasey Formation in Oregon . . . Bull. Amer. Pa- leontology, vol. 70, no. 292, 119 pp., 7 pis. Iversen, E. S. 1977. Farming the Edge of The Sea. 436 pp., 202 text figs. Fishing News Books Ltd., 1 Long Garden Walk, Famham, Surrey, England. $23.00. This is a greatly improved and enlarged second edition of a very in- formative and accurate book on the mari- culture of marine organisms, including mol- lusks. Marincovich, Louie, Jr. 1977. Cenozoic Nati- cidae (Mollusca: Gastropoda) of the North- eastern Pacific. Bull. Amer. Paleontology, vol. 70, no. 294, 494 pp., 42 pis. An excellent systematic, paleontological and biogeographical treatment of 18 genera, 87 species, of Cenozoic naticids from the Eastern Pacific. The family Choristidae Verrill 1882 is now synomymized with Polinicinae Finlay and Marwick, 1937. Cain, A. J. 1977. Variation in the spire index of some coiled gastropod shells, and its evolu- tionary significance. Philos. Trans. Royal Soc. London, Biol. Sci., vol. 277, no. 956, pp. 377-428. Yonge, C. Maurice 1977. Form and evolution in the Anomiacea—Pododesmus, Anomia, Patro, Enigmonia (Anomiidae): Placunanomia, Pla- cuna (Placunidae Fam. Nov.). A magnificent anatomical analysis of a complex group. The family name, Placunidae, however, dates from J. E. Gray, 1840. Placunanomiinae Beu, 1967, is a synonym. Habe, Tadashige. 1977. Systematics of Mollusca in Japan. Vol. 1, Bivalvia and Scaphopoda. 372 pp., 72 pis. of drawings. A much-expanded and up-dated checklist, with synonyms, English to Japanese glossary, and index. About $20.00 FOR SALE Several complete original sets of Johnsonia, vol. 1 to vol. 5, no. 50 $130 each; | postpaid (unbound). Several incomplete sets (pt. 5 absent) of Dall's Tertiary Fauna of Florida, 1890-1895 (Gastropods and some bivalves). Send for price list. Write: Dept. G., The Nautilus, Box 4208 Greenville, Delaware 19807. Rare and Exotic Specimen Shells for the discriminating collector Free price list Janowsky's MAL DE MER ENTERPRISES 946 Ralph Avenue Brooklyn, New York 11236 USA (212) iS5-S550 -^----'-^-"^'-'*--^' J978 >ovoe:^°' daN^ Order your copy today ^3.00 each No orders will be accepted after August 1. 1977 handsomely bound, gold stamped— full color photographs — fine engrav- ings and space enough to keep a record of everything you plan to do in 1978 Winner of many mapr awards, the 1978 diary will again emphasize shells as a constantly recurring theme in the culture of mankind^ 'Plus appropriate stale and local sales taxes I enclose $_ . __ lor _ .copy(ies) of me 1978 Shell Desk Diary Mail your order to Stiell Oil Company, One Stiell Plaza, Houston, Texas 77001 room 1 536 The Diary will be mailed to you in November (2) City _ State _ Zip LIVING MARINE MOLLUSCS Contents Introduclion 1 Historical hy C. M. Yonfie 2 The nature of molluscs by C. M. Yonge 3 Classihcation by C. M. Yonge 4 Chitons by C. M. Yonge 5 The first gastropods by C. M. Yonge 6 Limpets and top shells by C. M. Yonge 7 Mesogastropods hy C. M. Yonge 8 Mesogastropods — burrowers and drifters by C. M. Yonge 9 Neogastropods — scavengers and predators by C. M. Yonge 10 Opisthobranch sea-snails hy T. E. Thompson 1 1 Sea slugs hy T. E. Thompson 12 Origin and nature of bivalves hy C. M. Yonge 13 Evolution and adaptation of bivalves by C. M. Yonge 14 Ark shells, mussels, fan and file shells, scallops and oysters hy C. M. Yonge 15 Shallow and deep burrowing bivalves by C. M. Yonge 16 Borers in rock and timber hy C. M. Yonge 17 Anomalous bivalves and scaphopods by C. M. Yonge 18 Cuttlefish, squids and octopods hy C. M. Yonge Epilogue by C. M. Yonge Selected book list BEHAVIOUR y C. M. Yonge and T. E. Thompson An Understandable Biology Text "The first modem book on the biology of marine mollusks that is oi textbook quality, yet so beautifully written and illustrated that the legions of amateur conchologists will readily absorb its wealth of information"—/?. Tucker Abbott. Ph.D. VirV-^,.!^ REPRODUCTION \/ I Cldthbound, 288 pp., 162 text figures. 16 plates with 18 marine molluscs. Only $13-96 glorious color photographs of Send check or money order to Amenam Matacotogisti. Publ P 0 Box 4206 Greenville. De 19807 USA INFORMATION FOR SUBSCRIBERS The anmud subscription rate for The Nau- tiius is $8.00 for individuals and $12.()0 for in- stitutions (domestic or foreign). Subscriptions may begin in January. Send check or money or- der to "The Nautilus" to Mrs. Horace B. Baker, Business Manager, 11 Chelten Road, Haver- town, Pa. 19083. Back issues from volume 72 to date are ob- tainable 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 Sci- ences, 1401 Wilson Boulevard, Arlington, Va. 22209. Manuscripts should be typewritten and doublespaced; original and one copy are required, to facilitate revievre. 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 trans- lucent 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, in- formation 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 sam- pling 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 modem facilities and equipment for the housing and curating of voucher specimens. Material 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. OCTOBER 27, 1977 THE NAUTILUS Vol. 91 No. 4 A quarterly devoted to malacology and the interests of conchologists o 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. Division of Mollusks National Museum of Natural History Washington. D. C. 20560 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 1 0024 Mr. Morris K. Jacobson Department of Living Invertebrates The American Museum of Natural History New York, New York 1 0024 Dr. Aurele 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 Woods Hole Biological Laboratory National Marine Fisheries Service Woods Hole, Mas.sachusetts 02543 Dr. Donald R. Moore Division of Marine Geology School of Marine and Atmospheric Science 1 0 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. GUbert L. Voss Division of Biology School of Marine and Atmospheric Science 1 0 Rickenbacker Causeway Miami, Florida 33149 Dr. Charies B. Wurtz 3220 Penn Street Philadelphia, Pennsylvania 19129 EDITOR-IN-CHIEF Dr. R. Tucker Abbott American Malacologists, Inc. Box 4208. Greenville, Delaware 19807 Mrs. Horace B. Baker Business and Subscription Manager 1 1 Chelten Road Havertown, Pennsylvania 19083 OFFICE OF PUBLICATION American Malacologists, Inc. 429 H Arthur Drive, Hockessin, Delaware Mail : B' of North American land pulmonates. Index to vol. 1. Published May 22, 1977. Jewell, ('. B. 1977. 'Hie Inception and A.'ircnsion if Man. 93 pp. Hardback. Vantage Press, N. Y. Mentioned only because the author theorizes that man descended from mollusks. This should make malacologists feel special. Powell, A. W. B. Shelh of New Zealand. Fifth revised edition. 153 pp., 45 pis. (2 in color). Hardback. Whitcoulls Ltd., N. Z. Checklist of 2256 New Zealand mollusks, with 555 now il- lustrated. Leading guide, up-dating Suter's Manual $12.00 N. Z. Obtainable in U. S. from Seashell Treasures, P. 0. Box 73l). Uakhurst,CA 93644. Tlie costs of publication of certain articles in thi.s journal (labelled "Page charges paid" on the title page) were defrayed in part by the payment of voluntary page charges. These ar- ticles are thercfure and hereby dwlared "advertisement" in accordance with 18 U.S.C. .section 1734 solely to indicate this fact, and do not count as true advertising as far as computa- tion of sea)nd-class postal rates. Vol. 1)1(1) October 27, 1977 'Hie Nautilus Uil SMALL SPECIES OF NUCULIDAE (BIVALVIA) FROM THE TROPICAL WESTERN ATLANTIC Donald R. Moore University of Miami, Rosenstiel School of Marine and Atmospheric Science ABSTRACT Three small species of NucuMae, two of which are the smallest known bivalves, are described from tropical western. Atlantic sediments. Nucula calcicola n. sp. is a small, less than 2.0 mm, clam found in calcareous sediments over much of the Caribbean region. The other two species are placed in a new genus. Condylonucula, with C. cynthiae n. sp. as the tvpe. C. cynthiae, matnre^ at around 600 /i, is found in the western Caribbean on atolls off the coast oj Nicaragua. C. maya n. .sp., mature at around 500 /a has been found at Cozumel and Arrowsmith Bank at the northwestern extremity of the Caribbean. Recent and Upper Cenozoic Nuculidae of the area are listed, and some are discussed. A very small shallow-water species of Nucula is widely distributed throughout much of the Caribbean region. Specimens, when found, have apparently been identified as juvenile N. prorima Say or as A^. aegeensis Jeffreys. However, N. proxima is a temperate species with a distribu- tion from New England to Texas, and is a much larger species reaching a size of 10 mm. The small tropical species does not reach, at least in the material at hand, more than a length of two mm. A^. aegeensis. in the western Atlantic, was identified by Dall in 1886, and this identification has not been challenged even though A^. aegeeyisis was described from the Mediterranean. While most of the material ascribed to the species came from depths of more than 200 m, Dall (1889) gave a depth range of 5-464 fins (9-849 m). Later, Dall and Simpson (1901) reported a single worn juve- nile valve from Mayaguez Harbor (Puerto Rico). The American specimens of A'^. aegeensis. ac- cording to Dall, are fairly large, reaching a length of more than 10 mm. Dall did not give size or locality for the shallow water specimens, and apparently no one has studied them recently. Dall apparently considered small Nucula from shallow water to be either A^. proxima or A^. 'Contribution from the University of Miami. Rosenstiel School of Marine and Atmospheric Science, and Contribution No. .5 from the West Indies Laboratory, Fairleigh Dickinson University. aegeensis. This was probably due to the amount and condition of the material that he had to study. He apparently did not have any of the rather distinctive species from northern South America at the time. South Caribbean shallow water species are Nucula dalmasi Dautzenberg 1900, N. Surinam ensis Altena, 1968, and A''. venezuelana Weisbord, 1964. OBSERVATIONS I first found the new species in a bottom sam- ple collected at a depth of two m in Lameshur Bay, St. John, U. S. Virgin Islands (Moore, 1970). Thinking that these were very young specimens, I did not attempt to identify them at the time. Several years later, I found more specimens in bottom samples from Serrana Bank (Bock and Moore, 1971), an atoll in the western Caribbean (Milliman, 1969). It was not until I found that I had 72 specimens from two stations made at Courtown Cays, a small atoll east of Nicaragua, that I became convinced that I had a small shallow-water-dwelling species. The largest specimen measures 1.90 mm. By this time I had also found several specimens of a much smaller species with a peculiar prodissoconch. This nuculid gave every indication of having attained full growth at a length of about 600 ji. Naturally, I wanted more material before attempting to describe either 120 The Nautilus October 27, 1977 Vol. 91(1) species as there have been many cases of im- mature mollusks described as adults, often badly misclassified (Moore, 1966, Pilsbry, 1949). Search- ing through sediment samples from St. Croix, Virgin Islands, Key Largo in the Florida Keys, and from Bermuda all provided more material of the larger species. Bottom samples from Chancanab Lagoon, Cozumel, Mexico, collected in November, 1971. provided a large suite of the largest species and over 30 specimens of another, very small species. The latter species was also found in sediments from Arrowsmith Bank, a flat topped bank about 34 km NNE of Cozumel. Since I now had well over 300 specimens of the largest species, and 52 of the two smaller ones, I felt that there was lit- tle doubt that all three species matured at a very small size. In the following descriptions, the largest species is assigned to Nucula. and a new genus is erected for the smaller two. DESCRIPTIONS Genus Nuada Lamarck, 1799 Type species by monotypy, An-a nucleus Lin- naeus Nucula calcicola new species Description: A small species of Nucula matur- ing at a length of about 1.5 mm. The pro- dissooinch is about 220 ^ long, somewhat flat- tened, pitted, and has a small knob near the posterior edge. The dissoconch is about 25% longer than high; thickness of an adult specimen is about one half the length. The anterior end is extended and rounded; posterior end truncate. The posterior margin forms a straight or nearly straight line. The ventral margin is well-rounded and weakly dentate. Both concentric and radial sculpture are present, but are exceedingly weak. A thin brownish periostracum is present on fresh specimens. The resilifer is internal, short, and nearly at right angles to the hinge line. The anterior limb of the hinge is broad, and is widest distally be- tween the la.st two teeth. Mature specimens us- ually have seven anterior teeth in the left valve, six in the right. The posterior limb of the hinge is short and broad with four teeth in the left valve, four in the right. The adductor muscle scars are located at each end of the hinge. Shell structure in fresh specimens is transparent; there is no nacre, or at most, an extremely thin wash of this material. Material: Holotype. Specimen collected alive, 1.74 mm long and 1.38 mm high. U. S. N. M. No. 75&5a5. Type locality: Chancanab Lagoon, depth 2 m, Cozumel, Quintana Roo, Mexico. Paratyj)es and other localities: Courtown Cays, western Caribbean, Lagoon, depth 11 m, 59 separate valves. North end of the atoll, depth 2 m. 13 separate valves. Serrana Bank, western Caribbean: Lagoon, 14 valves, 2 complete spe- cimens. St. John, Virgin Islands: Lameshur Bay. depth 2 m, 15 separate valves. St. Croix, Virgin Islands: West side of Cottongarden Point, depth 1 m. one valve. Tague Bay, depth 3 m, 3 valves and one complete specimen; depth 4 m, one com- plete specimen; station at inside edge of outer reef, 4 m, 3 valves and one complete specimen. Glovers Reef, Belize (British Honduras): depth 2 m, 3 valves, 2 complete specimens. Cozumel, Quintana Roo, Mexico: Chancanab Lagoon, depth 2 m, 74 complete, 98 separate valves, and 14 identifiable fragments: depth 5 m, one valve. Key Largo, Florida: Harry Harris Park, depth 2 m. 2 complete, 17 separate valves, some badly broken. Andros Island, Bahamas: one mile east of Wax Cut. depth 3 m, one complete specimen. Har- rington Sound, Bermuda: notch at 4.6 m, 2 com- plete, 3 separate valves. The paratypes range in length from 0.38 mm. for a complete specimen from Cozumel to 1.90 mm for a single valve from the same locality. One typical complete mature specimen from Cozumel measured 1.60 long by 1.24 mm high by 0.86 mm thick. Paratypes have been placed in the following institutions: National Museum of Natural His- tory. Smithsonian Institution (USNM 7585;?7); Delaware Museum of Natural History (DMNH 120581); Academy of Natural Sciences Phil- adelphia (ANSP 344387); American Museum of Natural History (AMNH 18:^57); Museum of Comparative Zoology (MCZ); British Museum (Natural History); Rijksmuseum van Natuurlijke Historie, Leiden; Laboratoire de Malacologie. Vol. 91 (4) October 27, 1977 The Nautilus 121 Museum National d'Histoire Naturelle, Paris: University of Miami Marine Laboratory Museum (UMML 28-2812). Name: From calcis. lime, and cnla. dweller in, referring to the calcareous sediments the new species seems to prefer. Remarks: At first I thought that A^. calcicola should go into Pronucula Hedley, 1902, but I could not find any character in the new species, except lack of nacre, that was actually distinct from other species of Nucula. The one character that seems to set Pronucula off from other genera is the large smooth area surrounding the um- bones, with the sculptured area coming in relatively late. Both N. venezuelana Weisbord, 1964, from the lower Caribbean and A^. eiigua Sowerby, 1833, in the eastern Pacific, have this feature, but no one has assigned these species to Pronucula. Furthermore, a species dredged by me in 45 m off Abidjan, Cote d'lvoire, looks like a Promicula with a size of 1.0 to 1.5 mm. The large prodissoconch, the arched hinge, and the teeth distant from the resilifer are all characters used by Hedley in forming his new genus. However, the largest specimen is 17 mm long, and has the characters of a typical Nucula. The above men- tioned characters for Pronucula thus appear to be juvenile characters, at least in some species. Whether P. decorosa Hedley and its allies in Australian waters are described from immature specimens or are adults, I do not know. The collection of 330 specimens of A^. calcicola with a maximum size of 1.90 mm from nine localities in the western Atlantic left little doubt this was a distinct small species of Nucula. The only locality where a different Nucula was col- lected along with the new species was at Glovers Reef, Belize, where two specimens of another, perhaps undescribed, species were collected. Large specimens of N. calcicola (1.4 to 1.9 mm) were examined for signs of maturity, and in this material a thickening on the inside of the valves was noted as well as some irregularity of the in- ner surface. 'Rie adductor muscle scars were sunken, indicating that shell material had been deposited on the inner surface after growth had been completed. However, this is not the smallest species of Nucvla. For instance, Powell (1939) described Austronucula schencki whose length was 1.15 mm, and recently Marincovich (1973) described a 1.12 mm species as Nucula interfluc- ta. Marincovich had more than 2,(XX) specimens. The range of A', calcicola now extends from Courtown Cays and Serrana Bank, atolls off the coast of Central America, to Belize, to C^izumel off the east coast of Yucatan, and the Florida Keys. Far to the eastward, it is found in the Virgin Islands, and it almost certainly must live in the Greater Antilles between the two areas. It has also been collected at Bermuda. This appears to be a very shallow-water- dwelling stenohaline species. All of the known localities are around coral reefs, in lagoons behind reefs, or where at least a few corals are living. Chancanab Lagoon, where N. calcicola was most abundant, is a small shallow landlocked hjdy of water, Moore (1973), but it is connected with the open sea by a short underground pas- sage. Several coral colonies were observed grow- ing on rocks in the lagoon, and the other animals observed were all marine in habitat. The greatest depth of any of the material of A^. calcicola was 11 m in the lagoon of Courtown Cays. All of the specimens taken at this locality were rather worn separate valves making it a distinct possibility that the clams had been car- ried to that depth by water movement from near- by shallows. Live material was only collected in 2 m at Chancanab Lagoon; the depth range for empty valves is one to 11 m. Some of the Key Largo material (2m) was very fresh in appearance, but none were alive when collected. N calcicola has apparently been considered in the past to be young A'^. aegeensis Jeffreys. Our knowledge of this species in the western Atlantic stems mainly from Ball's (1886) discussion. There is a brief description of N. aegeensis in Dall and Simpson (1901), but it is based on the "one young left valve" found at Mayaguez, Puerto Rico, or on larger specimens in the U. S. National Museum. There is also a brief description and figure of a 2.7 mm specimen ascribed to N. aegeensis in McLean (1951), and another very brief description and figure in Warmke and Abbott (1961) of a specimen collected in a shallow dredging at Puer- to Rico. It is not certain what species these specimens represent. It is interesting to note that Dall first (1886) reported A^. aegeensis at a depth 122 The Nautilus October 27, 1977 Vol.!) 1(4) range of 175 to 464 fathoms (320 to 849 m). I^ter. he dec-ided that shallow water material from the shelf off North Carolina also was A^. aegeensis. Probably this material should be reexamined. At least a dozen Recent species of Nwula have been described or reported, from the Caribbean region. In the following list, the ma.ximum reported size of the species is given, and also the known depth range in the Caribbean area. No at- tempt has been made to arrange the species ac- mrding to the latest classification, or to provide a synonymy. Recent species of western Atlantic Nuculn from northern South America to the southeastern United States. Nucida aegeensis Jeffreys, 1879 10.7 mm 9-849 m A^. tenuis Montagu. 1808 10 mm 320-82.3 m A', cremdata k. Adams, ia56 6 mm .5,5-805 m A', prorinia Say, 1822 10 mm 2-183 m N.cipiii'lhU-dUAmy 5 mm .37.5-2013 m N. vemlli Ilall. 1886 5 mm .5.38-.3084 m N.femnndimie Dall, 1927 4 mm .5.38 m A', didmasi Dautzenberg, 19(X) 6 mm 22-67.5 m A^. surinamenxif: Altena, 1968 4.5 mm shallow water A^. venezuelana Weisbord. 196'1 2.4 mm shallow water A^. canceUata .Jeffreys, 1881 4 mm 1610 m A', callieredemmi Dall, 189(J 12.5 mm 1610 m A', calriaitd n.sp. 1.9 mm 1-11 m A', ndelrrens-is Smith. 188.5 (i mm 715 m There are also more than twenty Cenozoic fossil species described from various formations from Trinidad to the southeastern United States. The list as it stands may not be complete as the paleontological literature is now enormous. Again, no effort was made to revise the classifica- tion, but maximum size and presumed age are listed. N. venezuelana is listed again since it was originally described from the Pliocene, but the other species are apparently known only from the fossil record. Cenozoic fossil species of Nucula from lands bordering the Caribbean and Gulf of Mexico are: Nucida venezuelana Weisbord, 1964 2.7 mm Pli(X-ene N. mareana Weisbord, 1964 4.4 mm Pleistocene N. limonenais C,-Ahh. 1881 3 mm ? Miocene N. moenensvt Cabb, 1881 3.5 mm '.' Miocene A^. /»fcpra//a/uGabb, 1873 7 mm Miocene N. teniiisndptn Gabb. 1873 4 mm Miocene A', trieta (iuppy. 1867 4.9 mm Miocene N. hacrata (Iuppy, 1867 7 mm Miocene N. orbicetla Olsson, 1922 11 mm Miocene N. cahuitenMx Olsson, 1922 3.5 mm Miocene N. chipolana Dall, 1898 4 mm Miocene .V. chipiitana waltonia Gardner. 1926 A', mmria Dall, 1898 Af.fap/ina Dall, 1898 A', pntniaila Dall. 1898 A', tampae Dall. 1915 A', dma Gardner, 1926 A', defuniak Gardner, 1926 ■V. g(uLsdenensi.< Mansfield. 1937 A', miiratensis Woodring, 1925 A'. /iiHi Woodring, 1925 4 mm Miocene 4.75 mm Oligocene& Miocene .3.8 mm Miocene (fig.sp.) 6 mm Miocene 7.3mm L.Miocene 3.5 mm Miocene 5 mm Miocene 3 mm Miocene 4.8 mm Miocene 8.9 mm Miocene All of the 32 other species enumerated in the two lists are distinctly larger than A^. calcicola. The only Recent species close in size is A^. venezuelana, but this species is only known from the northern coast of South America, is heavily sculptured, and lives in a muddy environment. However, immature specimens of one or more species could be confused with N. calcicola. Material of the unidentified species found with N. calcicola at Glovers Reef consists of two right valves, 2.2 and 2.64 mm long. This was the only station where a similar species was found along with A^. calcicola. However, the Glovers Reef material, a 4.16 mm right valve from Hook Bank (Belize), 13 valves from 19° 14' N., 9r20' W (max. size 2.0 mm), and six valves (max size 4.0 mm) from a depth of 113.5 m (east of Port Aransas, Texas), all agree with N. proxima in having a narrow elongate resilifer directed anteriorly. The shape and sculpture is similar to that of A^. calcicola. but the resilifer of A^. calcicola is quite different from A^. proxima and its allies. A record of Nucula proxima from Panama, based on material collected by Olsson and McGinty, ap- f)ears to be an undescribed species. A specimen donated to the Academy of Natural Sciences of Philadelphia is a single valve measuring about 2.3 mm in length. There are many species in the ancient family Nuculidae, and most of these are small simple clams without strong characters setting them off from other species. Perhaps the most divergent of the genera is Acila with divaricate external sculpture. Acila is not known from the Atlantic. Species in the tropical western Atlantic range from smooth to somewhat sculptured, and have little diversity of form. Thus identification is often difficult, and this is especially true for the smaller species. Vol. 91 (4) October 27, 1977 The Nautilus 123 The other new species of Nuculidae herein con- sidered are distinctive for several reasons; their extremely small size, few hinge teeth, and com- paratively large sculptured and pitted prodis- soconchs. They appear to be so different from other nuculids that a new genus is hereby erected to contain them. Condylonucula newgenus Extremely small nuculids wath a large caplike prodissoconch. The valves are inflated, well- rounded, and have concentric sculpture. The anterior end is longer than the posterior; the pro- dissoconch is pitted and sculptured and as much as 40% of the length of the dissoconch. Hinge teeth few in number, while the resilifer is small and more or less normal to the hinge line. There is no nacre on the interior of the shell. TTie ad- ductor muscle scars are paired, roughly equal in size, and the valve margins are smooth. T)ff)e species: Condylonucula cynthine, new species Name: from condylus, a knob on the end of a bone, referring to the prodissoconch, and nucida. a small nut. Gender: feminine. The genus is erected for a pair of species, both new, from the western Caribbean. They are characterized by the relatively enormous pitted and sculptured prodissoconch, few hinge teeth, concentric sculpture, and smooth ventral margins. TTiey are also smaller than any other species in the family. (Condylonucula cynthiae new species Description: An extremely small species maturing at a length of about 600 ^i (0.6 mm). The shell is compact, a little longer than high, and is rather thick. The prodissoconch is large, about 210 fi long, and has a large knob centrally located adjacent to the hinge line. There are two concentric ridges, an inner one about half way to the edge of the prodissoconch, and an outer ridge forming the projecting outer edge. Both ridges are best developed in the anterior and posterior areas, the inner ridge especially so on the pos- terior side. The surface of the prodissoconch is pitted. The anterior end of the dissoconch is well-developed, the posterior end short. The ven- tral margin is well rounded. About ten to twelve concentric ribs are present on the adult. There are fine concentric striae between the ribs. The interior of the shell is without nacre. Two oval adductor muscle scars are present, the ventral margin is smooth, and the hinge plate is short and broad. There are four anterior, three pos- terior hinge teeth in the right valve, four an- terior, two posterior in the left valve. There is a slight depression or notch on the inside at either end of the hinge. The resilifer is short and almost normal to the hinge. Name: named for Cynthia Moore, wife of the author. Material: Holotype. Complete specimen 600 ^^ long, 480 M high. USNM No. 758534. Type locality: About 800 m west of outer reef (lagoon) Courtown Cays (Cayos del E.S.E.) in the western Caribbean off Nicaragua. Depth, 7.5 m. Paratypes: (specimens are complete unless otherwise noted). Courtown Cays, depth 1.5 m, one 350 m long, one (bored) 600 m long, one 460 f^ long, one 460 n long, one 6.30 m long, one broken right valve, one fragment, USNM No. 758538. Courtown Cays, depth 1.5 m, one 620 ^ long, one right valve 560 ^^ long, ANSP No. 344388. Cour- town Cays, depth 1.5 m one 570 n long, one left valve 620 ^ long DMNH No. 120580. Courtown Cays, north end, about two m, one 465 n long, one left valve 600 m long, one left valve 580 n long, MCZ No. Unknown. Courtown Cays, outer reef, one m, one 630 ^ long, one left valve 590 ^i long. Serrana Bank, lagoon, one 590 ^ long, UMML No. 28-2811. Two specimens from Serrana Bank, one com- plete, one a left valve, both 600 ^ long, were lost after being photographed with the Scanning Elec- tron Microscope at the University of Illinois. Hence there were originally eighteen good specimens available for this study. Remarks: TTie minute size of C. cynthiae makes it unlikely that it would be confused with any other species of Nuculidae except another new species (C. maya) described in this paper (for comparison of the two species, see remarks after the description of C. maya). The young of other species such as C. calcicola may look super- ficially like C. cynthiae, but do not have the 124 The Nautilus October 27, 1977 Vol.91 (4) strongly sculptured prodissoconch or show signs of maturity. Maturity is always a problem when studying very small mollusks. TTiere have been many cases of a larval or immature shell being described as an adult. Externally, one should look for a dif- ferentiated prodissfX'onch or protoconch to be cer- tain that the sf)ecimen is beyond the larval stage. In bivalves, indications of maturity should be looked for on the inside of the valves. The shell is usually thickened internally after reaching max- imum growth, and this is often accompanied by irregularities of the inner surface. Adductor mus- cle scars become sunken while changes in the hinge line may also occur. One other species in the family, Nunda calcicola, has been found at both Courtown Cays and Serrana Bank. At present, these two atolls (Milliman, 1969), some 250 km apart, are the only known localities for C. cynthiae. A number of islands, islets, and shallow banks, however, are located off Nicaragua and Honduras, and prob- ably have other populations of the species. There is also very little information on the vertical range of C. cynthiae. All of the specimens were collected in quite shallow water 1 to 7.5 m deep. Condylonucula tnaya new species Description: 1^ is is an extremely small species maturing at a length of about 500 n. The shell is compact, oval in shape when viewed from the side, and moderately thick. The prodissoconch is large, 220 fi long, and has a small knob centrally located next to the hinge line. The edge of the prodissoconch is somewhat raised above the adult shell, but does not form a distinct ridge. An inner concentric ridge is ex- tremely weak or absent on the anterior and me- dian area of the prodissoconch, but becomes an upright projection on the posterior part. This pro- jecting ridge is about the same height as the cen- tral knob. The surface of the prodissoconch is pit- ted. The dissoconch is oval in side view, and has most of the prodissoconch confined to the pos- terior half The anterior end is more elongate than the posterior; both ends are rounded to about the same degree. The ventral margin is moderately well rounded, and there are about 10 to 12 weak concentric ribs. The shell is transparent when fresh. Two oval adductor muscle scars are present; the ventral margin is smooth; and the hinge plate rather narrow. Ilie hinge teeth number three anterior, two posterior in both valves. The resilifer is a short triangular notch beneath the prodissoconch. Name: Named for the inhabitants of the Yucatan Peninsula. Material: Holotype. Complete specimen 500 ji long, 380 M high. USNM No. 758536. Type locality: Chancanab Lagoon, Cozumel, Quintana Roo, Mexico. Paratypes: Chancanab Lagoon, depth 2 m. Seven complete, 365, 270, 430, 530, 480, 500, and 480 ^i long; one right valve 500 (i long. USNM No. 758536. One 540 ^*, one 520 /i, and a right valve 480 /i long, MCZ No. Unknown. One 460 n, one 520 fi, one 325 ji, and a left valve 500 fi long. ANSP No. 344389. One 460 ^i. one 425 n. and a left valve 445 m long, AMNH No. 183858. One 500 M. one 490 m, one 380 ^, and 510 n long. DMNH No. 120579. One 490 m long. Fm (Field Museum) No. 198080. Five complete sjjecimens ranging from 470 to 510 fi long, and three separate valves ranging from 370 to 465 ^ long have been kept by the author. Arrowsmith Bank, "Gerda" Sta. 899, September 10, 1967, depth 110 to 220 m, two specimens both 520 fi long, UMML No. 28-2810. Remarks: C. maya is clearly closely related to C. cynthiae. The chief differences are: in C. maya the prodissoconch is not as strongly sculptured, the central knob is weaker, and the dissoconch is FIG. 1. Interior view of right valve of holotype of Nucula calcicola. FIG. 2. Exterior view of left I'olve of holotifpe of Nucula calcicola. length for both isl.7J,mm. FIG. 3. Interior mew of left valve of paratypc of Nucula calcicola. This was a large specimen, 1.9 mm long, and s/ioxvs signs of old age. irregvlar shelly deposits on the inteior and strongly deveUrped hinge. Thissperimen waslaterlost. FIG. 4. Ejcterior mew of right vali'e of holotype of Condylonucula maya. FIG. 5. Interior view of left valve of holotype of Con- dylonucula maya, both 500 ^ in length. FIG, (i. Exterior view of left valve of holotype of Con- dylonucula cynthiae. FIG. 7. Interior view of right valve of holotype of Con- dylonucula cynthiae, both 600 jj in length. Vol. 91 (4) October 27, 1977 The Nautilus 125 ^ 6 5 -^-^— / New NucuMae—D. R. Moore (see explanation on opposite page) 12fi Tlie Nautilus October 27, 1977 Voi.yi(i) more elongate. Two representative adult speci- mens had the following measurements: (In each case, the percentage refers to the length of the specimen). C.cynthiae Length Height Th ichness 600 pi 480 ,i 380 1* 100% 80% 63% .520 p, .390 >/ 280 p< IW/O 7,5% .54% C. maya Another comparative feature is the concentric sculpture. It is stronger in C. cynthiae, and this species also has fine concentric striae between the ribs. C. maya is presently known only from Cozumel and Arrowsmith Bank, some 34 km to the NNE of Cozumel. The examples from Cozumel are all from a depth of two m. The Arrowsmith Bank specimens were collected dredging up the steep slope of the side of the bank. They were probably in sediment that poured over the edge of the bank, and, if so, must have been living at a depth of25to35m. It is interesting that all known specimens of the two species have been found at atolls or shallow banks, and not on the continental shelf. I have recently examined reef sediment samples from Belize. These samples were taken from con- tinental shelf reefs, and while rich in micro- mollusks, did not contain any Condylonucula. Other species of bivalves slightly less than a millimeter in length have been described. Usual- ly, these descriptions have been based on very scanty material, often dredged, and little has been done since to ascertain whether these are truly mature specimens or only partially grown. The smallest of these appears to be Cuna gem- mula Turton, 1932, from South Africa described as fully grown at 0.5 mm. There was only one quite transparent valve which was supposed to be quite similar to C. concentriea Bartsch, 1915, but not so pointed at the top! It is hardly necessary to point out that the validity of this species is ex- tremely doubtful. There are signs of maturity to look for in bivalves. These are: thickening of the shell, sunken adductor muscle scars, rugosity of the in- terior surface, thickening of the hinge line, and, sometimes formation of denticles along the ven- tral margin. Even with these guides, one must ex- ercise caution, as there is considerable variation in the appearance of the adult from one species to another. It is best to have a series of spe- cimens, preferably from more than one locality, so that morphological changes from sub-adult to adult can be observed. These changes are some- times dramatic although the maximum dimen- sions of the shell may be almost unchanged. SUMMARY Tlie three species herein described present quite a contrast. Nucula calcimla is ubiquitous in the Caribbean and adjacent areas, while the two species of Condylonucula appear to be confined to two small areas in the western Caribbean. All three species, however, have only been found in calcareous sediments. Information is usually lack- ing on ecological requirements of species, but Hampson (1971) has shown that A^. proiima Say lives in fine to medium quartz sand, and that the similar appearing A'^ annulata Hampson lives in muddy areas. N. calcicola has been found in back reef to stenohaline inshore areas in quite shallow water. The depth range of the present material is one to 11 m. but live or fresh material has only been found at two meters. C. cynthiae has been found only in back reef and lagoonal deposits from one to 7.5 m in fairly coarse sediments. C. maya has been found in 2 m in quiet water and at 25 to 35 m (dead material from steep slope). It may well be a deeper water species that shuns the turbu- lent water of shallow reefs. Chancanab Lagoon, however, provides a quiet environment with oceanic water, and this seems to prove an ac- ceptable niche for C. maya. Chancanab sediments are much finer than those in which C. cynthiae are found. The three species have a number of character- istics in common. They are very small (two are the smallest known bivalves), and are rather similar in appearance. They are stenohaline and tropical in distribution. TTiey live in quite shallow water, and in areas with calcareous sediments. Thus their ecological requirements are similar to those of hermatypic reef corals. The Vol. 91(1) October 27, 1977 The Nautilus 127 two species of Condylonuctda especially seem to be confined to a very narrow range of physical conditions. Their very limited geographic range may signify a very brief planktonic larval stage, or none at all. ACKNOWLEDGMENTS I would like to thank Gray Multer for the op- portunity to collect and study Virgin Island raicromollusks. It was because of this material that I started working on the small Nuculidae. I also thank John Milliman for his invitation to take part in the Caribbean Atoll cruise in 1966. Thanks are due to Wayne Bock for sorting part of the Serrana Bank material in which the first two C. cynthixie were found. To Jon Staiger, thanks also for the opportunity to participate in the Arrowsmith Bank cruise of September, 1967. To Peter Supko, thanks for two bottom samples from Bermuda. Thanks are also due to Donald Marszalek for bottom material from Belize. I also thank my wife Cynthia for the trip to Cozumel as she discovered the bargain tour that made it possible to visit the island. Acknowledgment is made to the donors of the Petroleum Research Fund, administered by the American Chemical Society, for partial support of this research (PRF No. 5063-AC2). This work was also supported in part by National Science Foun- dation Grant GB-8684. LITERATURE CITED Adams, A. 1856. Descriptions of thirty-five new species of bivalve mollusca (Leda. Nucula, and Pythina) from the Cuming collections. Proc. Zool. Soc. London. 185.5: 47-.5.3. Altena, C. 0. 1968. The Holocene and Recent marine bivalve Mollusca of Surinam. Stud. Fauna Curacao 10: 153-179. figs. 145-152. Bergmans, W. 1968. A survey of the species of the genus Pro- nucida in New South Wales. J. Malae. Soc. Aiist. 11: 71-78. figs. l-6c. Bock, W. D. and D. R. Moore 1971. The Foraminifera and micromollusks of Hogsty Reef and Serrana Bank and their paleoecological significance. Trans. Fifth Carib. Geol. Conf., Geol. Bull. No. 5: 143-146. 2 figs. Dall. W. H. 1886. Report on the Mollusca. Part I. Brachiopoda and Pelecypoda. Report on the results of dredging. . . in the Gulf of Mexico (1877-78) and in the Caribbean Sea (1879-1880), by the U. S. Coast Survey steamer "Blake". Bull. Mus. Comp. Zool. Harv., 12(6): 171-318, pis. 1-9. Dall, W. H. 1889. Report on the MoUusca. Part II. Gastropoda and Scaphopoda. Reports on the results of dredging ... in the CuU of Mexico (1877-78) and in the Caribbean Sea (1879-1880) by the U. S. Coast Survey steamer "Blake". Bull. A/!«. Comp. Zool. Harv., 18: 1-492, pis. 10-40. Dall, W. H. 1890. Preliminary report on the collection of Mollusca and Brachiopoda obtained in 1887-88 (Albatross). Ptm: U. S. Nat. Mtis. 12(773): 219-.36a pis. 5-14. Dall, W. H. 1898. Contributions to the Tertiary fauna of Florida. TVon.s. Wagner Free Inst. Sci.. PhUa. 3(4): .571-947, pis. 23-a5. Dall. W. H. 1915. Monograph of the molluscan fauna of the Orthaulax pugnax zone of the Oligocene of Tampa, Florida. Bull. USNMW. 1-173, pis. 1-26. Dall, W. H. 1927. Small shells from dredgings off the southeast coast of the United States by the United States Fisheries Steamer "Albatross" in 1885 and 1886. Proc. U. S. Sat. Mus. 70(18): 1-134. Dall. W. H. and C. T. Simpson. 1901. The Mollusca of Puerto Rico. Bull. U. S. Pish Comm. 20: .351-516, pis. 53-58. Dautzenberg, Ph. 1900. Croisieres du yacht Chazalie dans I'Atlantique. Mollusques. Mem. Soc. Zool. France 13: 145-265, pis. 9-10. Gabb, W. M. 1873. On the topography and geology of Santo Domingo. Trans. Amer. Philos. Soc.. new series, 15: 49-259, 2 maps. Gabb. W. M. 1881. Descriptions of new species of fossils from the Pliocene clay beds between Limon and Moen, Costa Rica, together with notes on previously known species from there and elsewhere in the Caribbean area. J. Acad. Nat. Sri. Phila, 2nd series, 8: 349-380. pis. 45-47. Gardner, J. 1926. The molluscan fauna of the Alum Bluff Group of Florida. Part I. Prionodesmacea and Anomalo- desmacea. U. S. Geol. Surv. Prof. Pap. 142A: 1-64. pis. 1-15. Guppy. R. J. L. 1867. On the Tertiary fossils of the West In- dies with special reference to the classification of the Kainozoic rocks of Trinidad. Proc. Sri. Assoc. Trinidxid. Part 3: 145-176. Hampson. G. R. 1971. A species pair of the genus Nucula (Bivalvia) from the eastern coast of the United States. Proc. Malac. Soc. London 39(5): .3.33-342, 1 pi.. 3 figs. Hedley, C. 1902. Scientific results of the trawling expedition of H.M.C.S. "TTietis" off the coast of New South Wales in February and March 1898. Mollusca, Part I, Mem. Aust. Mus. 4: 287-321. figs. .39-60. Jeffreys. J. G. 1879. On the Mollusca procured during the "Lightning" and "Porcupine" expeditions. 1868-70. (Part 2). Prw. Zool. Soc. London, 1879: 553-588, pis. 45-46. Mansfield, W. C. 1937. MoUusks of the Tampa and Suwannee limestones of Florida. Bull. Flo. Ceol Surv. 15: 1-.3.34. pis. 1-23, 10 figs. Marincovich, L. 1973. Intertidal mollusks of Iquique, Chile. Los Angeles Co. Mus. Nat. Hist. Sri. Bull. 16: 1-49, 102 figs.. 1 map, 1 table. McLean. R. A. 19.51. The pelec>T»ds or bivalve mollusks of Puerto Rico and the Virgin Islands. Sclent. Sun: P. Rico. N. Y. Acad. Sci. 17(1): l-ia3, 26pls. Milliman, J. D. 1969. Four southwestern Caribbean atolls: Courtown Cays, Alburquerque Cays, Roncador and Serrana Bank. Atoli Res. Bull. No. 129: i-iv. 1-26, 29 figs. 128 The Nautilus October 27, 1977 Vol. 91(1) Montagu. G. 1808. Testacea Britannica: or an account of all the shells hitherto discovered in Britain. Suppl. i-iv, 1-18;3. pis. 17-30. Moore, D. R. 1966. The Cyclostremellidae, a new family of pro- sobranch mollusks. Bull. Mar. Sci. 16(3): 480-484. 6 figs. Moore. D. R. 1970. A new Caecum from Pureto Rico and the Virgin Islands. Bull. Mar. Sa. 20(2): 368-373. Moore. D. R. 1973. Mollusks from a small landlocked Mexican lagoon. Bull. Amer. Malac. Unwn 1972: 5-6. Olsson. A. A. 1922. The Miocene of Northern Costa Rica, with notes on its general stratigraphic relations. Rilt. Amer. Pa/po,9(.30): 1-310. pis. 1-32 Olsson. A. A and T McGinty 1958. Recent marine mollusks from the Caribbean coast of Panama with the description of some new genera and species. Bull. Amer. Paleo. 39(177): 1-58, 5 pis. Pilsbry. H. A. 1949. Dissentnma. the embryonic stage of Cymalium martuiianum {Orh.) The \autilus 62Hy. 142. Powell. A. W. B. 19,39. The Mollusca of Stewart Island, Rec. Auckland hist. & Mu^ 2: 211-238, pis. 48-.50. Say, T. 1822. An account of some marine shells of the U. S. J. Acad. Nat. So. PkUa.. 1st ser., 2: 257-276. Turton, W. H. 1932. The marine shells of Port Alfred. S. Africa. Oxford Univ. Press, i-.wi. \-Xi\. 70 pis. Warmke, G. L. and R. T. Abbott 1961. Caribbean Seashelts. Livingston Publishing Co.. Narberth. Pennsylvania, 348 pp, 44 pis.. 34 figs. Weisbrod, N. E. 1964. Late Onozoic pelecypods from northern Venezuela. Btdl. Amer Paleo. 45(204): 1-.564. pis. 1-.59. Woodring. W. 1925. Miocene mollusks from Bowden. Jamaica. Carnegie Inst., Washington Publ. No. 366; 1-222. pis. 1-28. VARICORBULA CHOWANENSIS A NEW SPECIES (BIVALVIA: MYACEA) FROM THE PLIOCENE OF NORTH CAROLINA Richard H. Bailey Dept. of Earth Sciences Northeastern University Boston, Mass. 02115 ABSTRACT Varicorbula chowanensis n. sp. occurs in the late Pliocene deposits along the Chowan River of northeastern North Carolina. This i,s the first report of the genus in the Neogene Chesapeake Group of Virginia and North Carolina. Late Pliocene deposits along the Chowan River in northeastern North Carolina contain diverse molluscan assemblages that are indicative of shallow shelf and estuarine environments. Within these assemblages the family Corbulidae is rep- resented by Caryocorhida inequalis (Say), C. cf. conradi Gardner, and Varicorbula chowanensis n. sp. The genus Varicorbula has not been reported from well-exposed late Miocene and Pliocene strata of the Chesapeake Group of Virginia and northern North Carolina; however, specimens of Varicorbula, labeled V. caloosae (Dall), from the Pleistocene Waccamaw Formation of south- eastern North Carolina are in the collections of the United States National Museum. Varieorbula is unique in that it exhibits the in- equivalved condition of the Corbulidae to a very high degree. Tlie right valve is extremely convex and bears coarse concentric rugae. The smaller left valve is flatter and bears concentric growth lines crossed by irregular radial riblets. Yonge (1949) demonstrated that Varicorbula gibba (Olivi) lives with the plane of the commissure vertical despite the asymmetry of the valves. He suggests that the large overlap of the valves may allow the animal to compress water in the man- tle cavity periodically to expel pseudofeces. The inhalent siphon of V. gibba is flush with the sedi- ment surface so that when the clam is actively pumping, large quantities of fine sediment, along with diatoms, bacteria, and organic detritus are carried into the mantle cavity (Yonge, 1949). In order to utilize such a food resource Varicorbula needs an effective mechanism to dispose of the sediment accompanying the food. Varicorbula chowanensis also lived in bottoms consisting of Vol. 91 (4) October 27. 1977 The Nautilus 129 % FIG. 1. Exteriw of hohtype (USNM m806) of Varicorbula chowanensis n. sp.. right valve, length 7.2 mm (a): left valve, paratype (USNM 2i 1807), length 6.9 mm (b); interior of right valve (c): interior of left valve (d). Interior of right valve with a very faint pallial line and small pallial sinus; with well-developed marginal groove for insertion of left valve; ad- ductor scars small, slightly impressed and closest to dorsal valve margin; single conical cardinal tooth below and slightly anterior of beak; deep subumbonal resilial pit. Interior of left valve shows pallial line; adductor scars poorly-de- veloped; small thick chondrophore immediately beneath and posterior of beak is firmly fused to hinge plate; immediately anterior of chondro- phore and beneath beak is a large socket for the cardinal tooth of the right valve. very clayey and silty fine sands. It is likely that the function of the valves hypothesized by Yonge (1949) also operated for the extinct species, V. chowanensis. Family Corbulidae Lamarck, 1818 Genus Varicorbula Grant and Gale, 1931 Varicorbula chowanensis new species (Figs. 1, 2) Description: Shell small, very strongly ine- quivalve; right valve convex and inflated with high prosogyrate umbo, rounded anterior, trun- cate posterior, flat corselet separated from rest of valve by poorly defined posterior diagonal ridge and abrupt anterior turn of concentric ribs; left valve flatter and smaller than right, narrow well defined umbo, rounded low posterior ridge defines irregular corselet, rounded anterior, sub-truncate posterior. Sculpture of right valve consists of regularly- spaced, rounded concentric ribs, becoming higher and wider near ventral margin; prodissoconch devoid of sculpture. Exterior of left valve with ir- regular concentric grooves parallel to the growth lines; distinct but frequently irregular growth lines are crossed by faint discontinuous riblets that converge toward the umbo; riblets 3 to 8, with highly variable spacing, and are more distinct on ventral portion of valve. FIG. 2. Valve outlines of Neogene species o/ Varicorbula; V. caloosae (Doll), early Pleistocene Caloosahatchee Formation, (a) right valve, length 10.lt mm, fb) left valve, length 8.6 mm, after Olsson arid Harbison (1953); V. chowanensis n. sp., late Pliocene "Yorktown" Formation, (c) right valve (USNM 21,1812). length 7.0 mm, (d) left, valve (USNM 21,1815), length 7.0 mm; V. waltonensis (Gardner), middle Miocene Shoal River Formation, (e) right valve, length 7.5 mm. (f) left valve, length 6.5 mm, after Ckirdner (1928); V. chipolana (Gardner), lower Miocene (Jhipola Formation, (g) right valve, length 6.5 mm, (h) left valve, length 5.8 mm. after Gardner (1928). 130 The Nautilus Measurements Valve Holotype (USNM 241806) R Paratypes (USNM ail8fl7) L (USNM 2-1 MIX) R (USNM msm) R (USNM 241810) R (USNM •211811) R (USNM 211812) R (USNM 241813) L (USNM 211814) L (USNM 211815) L October 27, 1977 Vol.91 (4) H (mm) 5.7 5.0 6.4 6.6 5.4 5.0 5.4 4.4 5.4 5.0 ;, (mm) 7.2 6.9 8.4 8.9 6.9 6.6 7.0 6.3 7.8 7.0 No. No. Ribs Riblels 18 22 21 21 18 20 tion, 2.0 kilometers upstream (north) of bridge where U. S. Route 17 crosses Chowan River, Ber- tie County, North Carolina, locality 27 of Bailey (1973). Twes: Holotype, right valve, USNM 241806, ventral margin partially broken; figured para- type, left valve, USNM 241807, measured and/or figured USNM paratypes, 241808-241815; undes- ignated paratypes, 3 fragmentary valves. USNM 241816. DISCUSSION Varicorbnla chowanends is most similar in shape to V. caloosae (Dall, 1898). However, it may be distinguished from the latter by its smaller size, more gently sloping anterior and posterior dorsal margins, narrower umbonal region, and its broader, more distinct posterior region (Fig. 2). The Vancorbida lineage of the Neogene of the Atlantic and Gulf Coastal Plains is represented by at least four species (Fig. 2). Varicorbula chipolana from the lower Miocene Chipola For- mation is the earliest reported member of the lineage. The evolutionary relationships of these species remains to be clearly demonstrated. T]ff)e locality: Pliocene deposits along the west bank of the Chowan River, "Yorktown" Forma- LITERATURE CITED Bailey, R. H. 1973. Paleienviriinment, paleoecology and stratigraphy of molluscan assemblages from the Yorktown Formation (upper Miocene— lower Pliocene) of North Carolina. Ph.D. dissertatmn. University of North Carolina. 110 pp. Gardner, J. 1928. The molluscan fauna of the Alum Bluff Group of Florida. Part V. U. S. Geological Survey Prof. Paper 142 E. pp. 185-249. Dall. W. H. 1898. Contributions to the Tertiary fauna of Florida. Part IV. Trans, of the Wagner Free Inst, of Sri.. PhUadelph m. pp. 511-947. Olsson, A. A. and Harbison, A. 19.53. Pliocene mollusca of Southern Florida. Acad. Nat. Sci. Phila. Man. 8. 4.57 pp. 65 pis. Yonge, C. M. 1946. On the habits and adaptations of Ahidis (Corbulaj gibba. Jour. Marine Biol. Assoc. United Kingdom 26: :358-376. TWO NEW RABDOTUS (PULMONATA: BULIMULIDAE) FROM BAJA CALIFORNIA, MEXICO Carl C. Christensen and Walter B. Miller Department of General Biology University of Arizona Tucson, Arizona 85721 ABSTRACT Tira ncir speri.ps of the land snail genus Rabdotus are described from Baja (alifiiniia Siir. Mr.riro. R. gigantensis is reported from the Sienv de la (riganta and R. laevapex is reported from Isla Cerralvo. The bulimulid genus Rabdotus contains most of the larger land snails of Baja California Sur, Mexico. Although snails of this genus also inhabit much of mainland Mexico and of the southern Vol. 91 (4) October 27, 1977 The Nautilus 131 FIG. 1 and 2. Rabdotus gigantensis Christensen arid Miller, neir species. San Javier. Baja California Sur. Mexico. Holotj/pe. CASGTCNo. 57937. Shell height 19.7 mm. FIG. 3. Rabdotus gigantensis Christensen and Miller, new species. Shell opened to show columellar lamina. Paratype. CASGTCNo. 579U. Shell height 20.5 mm. FIG. 4 and 5. Rabdotus laevape.\ Christensen and Miller, new .species. Isla Cerraho, Baja California Sur, Mexico. Holotype. CASGTCNo. 579J,2. Shell height 27.8 mm. FIG. 6. Rabdotus laevapex Christensen and Miller, new species Shell opened to show cohimellar lamina. Paratif})e. CASGTCNo. .5794.3. Shell height 28.J, mm. and southwestern United States, about three quarters of the over thirty known species are con- fined to the southern half of the Baja California peninsula and nearby islands. Tliis report con- tains descriptions of two new species from this region, one recorded from several localities in the Sierra de la Giganta, the principal mountain range of the central part of the peninsula, the other known only from Isla Cerralvo, the southernmost island in the Gulf of California. Rabdotus gigantensis Christensen and Miller, n. sp. Descriptwn. Shell (fig. 1-3) solid, 16.9-21.3 mm in height (mean height of twenty adult shells from type lot 19.2 mm), 7.8-10.2 mm in diameter (mean 8.8 mm), ratio of height to diameter 1.85- 2.36 (mean 2.17), ratio of shell height to aperture length 2.18-2.62 (mean 2.44), whorls .5-7/8 to 6-7/8 (mean 6.42); spire convex in outline; em- bryonic whorls 2 to 2-1/4 in number, rounded, 132 The Nautilus October 27, 1977 Vol.91 (4) I with strong regiilar axial riblets the interstices of which are crossed by fine spiral threads; post- nuclear whorls convex, sutures moderately im- pressed; surface of shell weakly shining, sculp- ture of early postnuclear whorls of numerous weak growth wrinkles which may bear minute hyphen-like granules arranged in spiral rows, this sculpture becoming obsolete in later whorls; color of shell light brown except peristome and narrow subsutural band sometimes whitish; last whorl slightly inflated, flattened at periphery, often ascending slightly at aperture; columellar margin of peristome reflected, basal and palatal margins weakly reflected, not revolute; termina- tions of peristome joined by a thin to moderately thick parietal callus; columella with a well- developed sinuous lamina located deep within the aperture; basal region of shell deeply rimate. Soft parts unknown. Ti/pe Locality. Baja California Sur, Mexico, at San Javier, in a large lava rockslide immediately south of the mission, elevation 350-450 m. Holotype. California Academy of Sciences Geology Type Collection No. 57937. Height 19.7 mm, diameter 9.3 mm, length of aperture 8.2 mm, whorls 6-5/8. Collected by W. B. Miller, 25 Oc- tober 1972. Paratypes. 46 specimens collected by W. B. Miller, 24 October 1971; 53 specimens collected by C. C. Christensen, P. N. D'Eliscu, W. B. Miller, R. L. Reeder, and D. B. Richman, 25 October 1972. Paratypes in the collections of the California Academy of Sciences and Delaware Museum of Natural History (No. 112458) and in the private collections of R. L. Reeder and the authors. Additional Paratype Material. Specimens have been examined from the following additional localities in Baja California Sur; inland of San Jose de Magdalena on the road to Guadalupe, 43.3 km west of the Transpeninsular Highway, C. Church, 11 December 1970; 11.3 km north of San Jose Comondu, C. Church, November 1969; San Jose Comondu, R. J. Drake, July 1953, and V. Roth. 15 February 1966; 1.0 km east of San Javier, C. Church, 11 December 1970; 15.7 km west of San Javier on the road to Santo Domingo, C. Church. 12 December 1970; 72.4 km south of Loreto and 49.9 km northeast of Villa Insur- gentes on Transpeninsular Highway, in lava rockslides on south side of arroyo, elevation 275 m, W. B. Miller. 23 October 1971; road between El Obispo and Rancho Tinajitas. I. L. Wiggins, 20 November 1959. Remarks. Rahdotus gigantensis is distinguished by its small size, weakly reflected peristome, col- umellar lamina, and coloration. R. leins (Dall) is similar in overall dimensions and form but lacks a columellar lamina; its shell is usually marked with dark axial streaks. R. dentifer (Mabille) and R. chamberlini (Hanna) are small snails each with a columellar lamina but with the peristome strongly reflected or revolute. Rahdotus giganterms is most often found in large talus slides of volcanic rock and is known to occur over nearly the entire length of the Sierra de la Giganta. Although dead shells of this species are common in some localities, no living specimens have yet been collected. The species is named for the mountains in which it lives. Rahdotus laevapex Christensen and Miller, n. sp. Description. Shell (fig. 4-6) solid, 24.8-28.6 mm in height (mean height of eight adult shells from type lot 27.7 mm), diameter 11.8-13.4 mm (mean 12.6 mm), ratio of height to diameter 2.10-2.29 (mean 2.19), ratio of shell height to aperture length 2.08-2.25 (mean 2.18), whorls 5-7/8 to 6- 3/8 (mean 6.12); spire weakly convex in outline; embryonic whorls not readily distinguishable from postnuclear shell; first two whorls rounded, smooth or with subobsolete axial wrinkles; later whorls convex, sutures weakly impressed, surface of shell shining or dull, sculpture of weak growth wrinkles; color of shell light brown except peris- tome and narrow subsutural band sometimes whitish, shell sometimes with light axial streaks; last whorl inflated, rounded at periphery, not ascending or descending at aperture; columellar margin of peristome reflected, basal and palatal margins reflected and revolute; terminations of peristome joined by a thin white or clear parietal callus; columella with a strong spiral lamina which is prominently visible within the aperture; basal region of shell deeply rimate. Pulmonary veins and pallial roof between veins and hindgut light brown; mantle not marked with dark spots. Vol. 91 (4) October 27, 1977 The Nautilus 133 FIG. 7. Rabdotus laevapex Christensen and Miller, new species. Genitalia of halotype. Abbreviations: ec epiphallic caeaivi; ep epiphallns: pe upper portion nf penit; ps penial sheath and lower portion o/ppnis; sd spermathecal diwt: sp spemiatheca: va vagina: vd vas deferens. Scale line 10 mm. Genitalia (fig. 7) typical of the genus in general structure, epiphallus usually greater in length than penis or epiphallic caecum, comprising over 40% (average of 6 specimens) of the combined length of these three structures; penis and epiphallic caecum approximately equal in length, vagina much shorter than penis; dimensions of genitalia of holotype (figured): penis 9 mm in length, epiphallus 16 mm, epiphallic caecum 9 mm, vagina 3 mm, spermathecal duct 26 mm. T]fpe Locality. Baja California Sur, Mexico, on west side of Isla Cerralvo, approximately 0.5 km inland of the beach at El Limona anchorage, in a small rockslide on the south slope of a narrow ar- royo, elevation 50-100 m. Living snails were found sealed to small rocks. Holotype. California Academy of Sciences Geology Type Collection No. 57942. Height 27.8 mm, diameter 12.2 mm, length of aperture 12.8 mm, whorls 6. Collected by C. C. Christensen, 8 August 1974. Paratyjns. 7 adult and 5 immature specimens collected with the holotype. Paratypes in the col- lections of the California Academy of Sciences and Delaware Museum of Natural History (No. 112457) and in the private collections of the authors. Remarks. The sculpture of the embryonic whorls is the outstanding character of Rabdotus laevapex and distinguishes it from all other members of the genus. In other Rabdotuj^ these whorls bear regular axial riblets; in R. laevapex these are smooth or bear only weak wrinkles which do not resemble the riblets of other species. This condition is not the result of wear, as it is found in the shells of live-collected immature specimens of 2-1/2 whorls. The name assigned to this species refers to its smooth apex. Although the shells of Rabdotus lamellifer (Pilsbry), R. rimatus (Pfeiffer), and R. spirifer (Gabb) resemble that of R. laevapex in size and general form, these species differ from the new species anatomically; in each of them the penis is greater in length than either the epiphallus or epiphallic caecum, and the length of the vagina is more nearly equal to that of the penis than is the case with R. laevapex. ACKNOWLEDGMENTS We wish to thank the individuals named above who collected specimens used in this study and Mr. Barry Roth of the California Academy of Sciences for the loan of material, as well as Dr. D. A. Thomson of the University of Arizona and Sr. Felipe Maldonado, captain of the yacht La Sirena, who provided transportation to Isla Cer- ralvo. We also wish to thank Judith A. Chris- tensen for assistance with the preparation of the figures which accompany this report. 134 The Nautilus October 27, 1977 Vol. 91 (1) STUDIES ON FOULING INVERTEBRATES IN THE INDIAN RIVER. FLORIDA 2: EFFECT OF MODULUS MODULUS (PROSOBRANCHIA: MODULIDAE) David Mook Johnson Stience Laboratory Harbor Branch Foundation, Inc. Ft. Pierce, Florida 33450 ABSTRACT The buildup of fouling invertebrates on tiles placed among seagrass blades is considerably less than on tiles placed in adjacent areas devoid of scagi-ass. Snail counts and the results of caging experiments suggest that the grazing action of Modulus modulus may retard the buildup of folding organisms on surfaces within the gr-ass bed,"!. Observations on fouling patterns on the Indian River lagoon of eastern Florida indicate that the accumulation of fouling invertebrates on tiles placed among seagrass blades is considerably less than on tiles placed in adjacent areas devoid of seagrass. The processes responsible for this are not know^n but the following mechanisms were suspected: (1) large predators may graze more ac- tively among the grass blades (a large predator is operationally defined here as one which cannot go through a 12 mm mesh); (2) rubbing of grass blades on the tiles due to wave action may mechanically remove newly settled organisms: and (3) survival of newly settled fouling organisms may be affected by small animals such as Modulus modulus Linne, 17-58, a snail that often is found locally on grass blades. The research presented in this paper was designed to experimentally test whether any of these mechanisms are responsible for the retarda- tion of fouling in the grass beds. MATERIALS AND METHODS The study area was located in a seagrass bed north of Link Port on the west bank of the In- dian River lagoon near Fort Pierce, Florida (31.r27' N; 20.9°80' W) (Young et d.. 1976). The site consisted of subtidal dense stands of Halodule urrightii Ascherson, 1868, interspersed with large sandy patches devoid of grass. Small .stands of Tfii I: i^i^-'ZW Badman, D. G. and S. L. Chin. 1973. Metabolic responses of the fresh-water bivalve, Pleurobema cnccineum (Conrad), to anaerobic conditions. Comp. Biuchem. Physiol. 44B: 27-32. Calvin. D. B. 1931. Glycogen content of fresh-water mussels. Proc. SrK. Erp Biol. Med. 29: 96-97. Dietz, T. H. 1974. Body fluid composition and aerial oxygen consumption in the freshwater mussel, Liqumia s^ibrostrata (Say): Effects of dehydration and anoxic stress. Biol. Bull_ 147: .560-572. Foster. T. D. 1932. Observations on the life history of a finger- nail shell of the genus •Sp/i.fK'nMm. J. Morphol. 53: 473-497. Gale, W. F. 1976. Vertical distribution and burrowing behavior of the fingernail clam, Sphaerium transversum. Malacologia 15: 401-409. Gilmore, R. .1. 1917. Notes on reproduction and growth in cer- tain viviparous mussels of the family sphaeriidae. The .Vnwn/iw 31: 16-30. Heard, W. H. 1964. Litter size in the Sphaeriidae. The Sautibu^n-.M-A^. Heard, W. H. 1965. Comparative life histories of North .American pill clams (Sphaeriidae: Pisidium). Malacologia 2: 3X1-411, Horst, T. .]. and Costa, R. R. 1975. Seasonal migration and density patterns of the fresh water snail. Amnicola limosa. 77icAnM(i7)is 89: 56-59. .I(iy. .]. E. and L, E. McCoy. 1975. Comparisons of shell dimen- sions and vi.scera mass weights in Corbinda manilenMs (Philippi. 1844). The Nautilus 89: 51-.54. l/)wry, 0. H., N. J. Rosebrough, A. L. Farr, and R. .J. Randall. 1951. Protein measurement with the folin phenol reagent. J. Biol. Chem. 193: 265-275. Mackie. G. L, S. U. Qadri and A. H. Clarke. 1976. In- traspecific variations in growth, birth periods, and longevi- ty of Musndium securis (Bivalvia: Sphaeriidae) near Ot- tawa. Canada. Malacologia 15: 433-446. Montgomery. R. 1957. Determination of glycogen. Arch. Biochem. Biophys. 67: 378-386. Stickle, W. B. 1975. The reproductive physiologj- of the inter- tidal prosobranch Thais lamellosa (Gmelin). II. Seasonal changes in biochemical composition. Biol. Bidl. 148: 448-460. Thomas. G. .J. 1959. Self-fertilization and production of young in a sphaeriid clam. The Nautilus 72: 131-140. Van Cleave, H. J., A. G. Wright and C. W. Nixon. 1947. Preliminary observations on reproduction in the molluscan ^envis Muscidium. The Nautilus 6\: 6-11. Webber, H. H. 1970. Changes in metabolite composition dur- ing the reproductive cycle of the abalone Haliotis cracheroidii (Gastropoda: Prosobranchiata). Physiol. Zool. 43:213-231. De Zwaan, A. and D. I. Zandee. 1972. Body distribution and seasonal changes in the glycogen content of the common sea mussel Mytilits edulis. Comp. Biochem. Physiol. 43A: 53-58. INTRODUCED LAND SNAILS OF TRAVIS COUNTY, TEXAS Raymond W. Neck Pesquezo Museum of Natural History 6803 Esther Austin, Te.\as7S752 Currently a survey of the land snails of Travis County, Texas, has turned up ten non-native land snails. Only one of these, Rumina decollata, has been previously reported in this county. Report of the other nine species has only been in a simple preliminary checklist (Neck, 1976b). Previous records exist for all these species in other parts of Texas (see Dundee, 1974). Vol. 91 (4) October 27, 1977 The Nautilus 141 Helicidae Helve aspersa Miiller. Native of western and southern Europe. This species has been found in several home gardens in the Austin residential areas. This species is known as the European Brown Snail or European Spotted Snail. Occur- rence is spotty; populations are characteristically of low density and restricted to urban areas. H. aspersa is widespread in California but invasion of natural areas is quite restricted due to the an- nual summer drought (Potts, 1975). Frequently hot, dry summer months in central Texas are a severe obstacle to the establishment of thriving fwpulations of this species in other than artifical garden habitats. Otala lactea (Miiller). Native of southern Spain and northern Africa. Individuals of this species are known from home gardens as well as self- sustaining feral colony which contained both banded and unhanded snails. Banded snails have very dark brown, distinctive bands. Individuals of this feral colony were commonly seen estivating on the trunks of mesquite, in the same manner as Rabdotm altematus Say (as illustrated by Pilsbry, 1946:2(1): p. 5, fig. 2). Individual snails in gardens are relatively common but probably represent short-lived occurrences. Self-sustaining colonies may exist in small (one-fourth acre) plots in urban areas. This species is known as the Milk Snail or Spanish Snail (Dundee, 1970). Otala vermiculata (Miiller). Native of the Mediterranean area. In Travis County this spe- cies is knovm only from a single urban residen- tial locality. Feral colonies undoubtedly could survive as one such colony is knovra in Bastrop, Bastrop County, Texas, approximately thirty miles south-southeast of Austin. All shells seen have been banded; bands vary in their distinct- ness from light background color. Limacidae Lehmannia poirieri (Mabille). Native of western and southern Europe. Extremely dense populations of this slug occur in ubran garden areas which receive supplemental watering. With one exception, it is unknown in rural areas. This population occurs on a seepage slope in the flood- plain of Onion Creek. Urban natural areas ap- pear able to support only smaller population levels. Limaa- flavxis Linnaeus. Native of temperate Europe. This slug is much less commonly encoun- tered than the preceding species. Although Pils- bry (1948: 529) described this species as a "slug of cultivated places," most Austin localities of L. flavus are semi-natural islands in urban areas. In fact, L. flavus is more likely to be found in semi- natural urban islands than L. poirieri although this latter species is much more common on an overall scale. Milax gagates (Drapamaud). Native of western Europe including Britain and Ireland. This slug is rarely encountered and has been found only along the banks of watercourses and urban gar- den situations. Only a single collection (and that one an urban garden) is knovm since before the short but severe drought of 1970-71. Feral pop- ulations of this species should be considered perilous although areas of previous collection do not receive supplemental water. Even in the moist Pacific Northwest of North America, e.g. British Columbia, M. gagates is generally associated with greenhouses (see references in Rollo and Wellington, 1975). Polygyridae Polygyra septemvolva volvoxis Pfeiffer. Native to southeastern and coastal Texas and other coastal plains areas outside the state. In Travis County, this species has not been found under natural conditions; two localities are known— a greenhouse and a residential backyard which con- tained potted plants from this greenhouse. The nearest natural occurrence reported is Burleson County (Pilsbry 1940: 1(2):591. The Travis County population originated from Cameron County. This species is most common in warm, humid coastal areas. No successful reproduction was observed in the residential locale. Travis County may be too cold and/or dry for this species to survive under natural conditions. Achatinidae Rumina decollata Linnaeus. Native of southern Europe and northern Africa. TTiis is by far the 142 'Ilie Nautilus October 27, 1977 Vol. 91 (4) most abundant non-native snail in Travis County as well as much of the southern United States (Dundee, 1970). This species is probably the most familiar snail for most of the general public, be- cause it is the most abundant urban snail in Austin. R. decollata, however, is also able to col- onize rural areas via downstream transport. It is the only non-native snail species commonly found in rural areas. The first literature report of this species in Travis County was by Strecker (1935:23). Suhm (1957) reported that this species had burrowed in- to sediment at the Smith Rockshelter, a famous archeological site in southeastern Travis County. Branson (1959) later reported it from Zilker Park, an Austin municipal park. It has also been reported from Austin Caverns (cave now used as a storm sewer) and the Barton Springs archeo- logical site (in Zilker Park) by Reddell (1965). Approximate time of introduction of R. decol- lata in this area can be determined. The publi- cation by Strecker (1935) appeared posthumously following Strecker's death in January 1933; therefore, initial Travis County collections were made no later than 1932. The time of initial in- troduction into Travis County is unknown, but it is probably no earlier than the late 1880's as Singley (1893) did not record this species from the state. Introduction probably came later, as Pilsbry (1905) reviewed the world range of this snail but did not list any collections from Texas. The first Texas report of this species was by Camp (in Ferriss 1914) from Brovmsville. No other Texas localities were mentioned although Ferriss compared the Brownsville specimens to those in his collection from Louisiana and South Carolina. At this point, arrival in Travis County would most likely have been between 1915 and 1932. Archeological investigations of historic sites of the last and early twentieth centuries are poten- tially important sources to pinpoint when R. decollata became established in various areas. However, there is an inherent problem. Even if the layer from which the deep)est shells are found could be dated accurately, the burrowing habit of this snail would complicate the situation. In Travis County alone, this species has been found in several archeological excavations of pre- European sites (see references in first paragraph). Estimates of time of arrival of this snail would most likely be on the early side. Oppas pyrgula Schmacker & Boettger. Native of Japan and China. This small snail has been found living in two residential localities. Some individual dead shells have been found in urban natural areas which are downstream from resi- dential areas. These shells indicate further urban colonies. No feral colonies have been established by such downstream dispersal of living snails, however. Colonies observed occur in areas pro- tected from cold winter winds and dry, hot sum- mer weather conditions. Cedlioides Ojcicula (Muller). Native of central and western Europe. This minute species is known from the banks of a creek running through a residential area. Only a single living specimen was found, but this blind species is generally subterranean in habit (Pilsbry, 1909) which would reduce collecting chances. This species has been reported feeding on grass roots to a depth of 40 cm while preferring "soils rich in lime" (Likharev and Rammal'meier, 1952). Report of this snail in Travis County at this locality has been previously mentioned (Neck 1976a). No sub- sequent collections have been made, even at the original collection site. CONCLUSIONS Introduced snails may occur in rural, urban natural or residential areas. A species occurring in a residential area may be totally dependent upon human activites for maintenance of a viable population. Occurrence in urban natural islands indicates an ability of the species to survive under natural conditions. Occurrence in rural natural areas would indicate an ability to col- onize new habitats on their own. Significantly, the most successful non-native snail of Travis County, Texas, R. decollata, is from the Mediterranean area. Central Texas does not have a Mediterranean-type climate, but the summers are often very dry. R. decollata is well- adapted to survive arid periods. The ability to produce offspring parthenogenetically (Selander, et al., 1974) is also very important in its ability to rapidly populate newly colonized areas. Vol. 91 (4) October 27, 1977 The Nautilus 143 Non-native snails are introduced by a variety of means, either accidentally on ornamental plants or deliberately as fish bait. Almost all of the introduction to Travis County were probably accidental. The feral colony of Otala lactea could have been a deliberate introduction. LITERATURE CITED Branson. B. A. 19.59. Riinmm decollata in Oklahoma. The Naulihis 73: 37. Dundee. D. S. 1970. Introduced Gulf Coast molluscs. Tidane Studies Z00I.& Bat. 16: 101-115. Dundee. D. S. 1974. Catalog of introduced molluscs of eastern North America (North of Mexico). Sterkiana 55: 1-37. Ferris, J. H. 1914. Rumina decollata in Texas. The Nautilus 28:11. Likharev, I. M. and E. S. Rammel'meier. 1952. Terrestrial mollusks of the fauna of the U.S.S.R. Trans Y. Lengy and Z. Kraut hamer. 1962. Isreal Prog. Sci Tran., Jenisaiem. Neck, R. W. 197()a. Cecilundes acicula (Miiller): Living colon ies established in Texas. Sterbmia 61: 19-20. Neck, R. W. 1976b. Preliminary checklist of land snails of Travis County. In A bird finding and naturalist's guide for the Austin. Texas, area. E. A. Kutac and S. C. Caran. pp. 124-129. Oasis Press, Austin. Texas. Pilsbry, H. A. 1905. Rumina decollata L. Manual of Con- chologyn: 212. Pilsbry, H. A. 1909. Caecilimles. Glessula and Partulidae. MaunalofCom-holtonensis, /(. sp.. x 5. Fig. 2. Gastrooipta debilis, n. sp.. i 10. Fig. S, Gastrocopta arena, «. sp.. x 10. Magnifications approximate. Lymnaea claytonensis, n. s-p. Fig. 1 Dinqnoiii.'i: A slender l>Tnnaeid shell, having 5 to 6 rounded whorls, shouldered above, and hav- ing a laterally compressed, elliptical aperture, oc- cupying about one-half the total length of the shell. Description of holoti/pe: Shell of slender lym- naeid form; whorls a little more than 5 in num- ber, rounded and somewhat shouldered; suture well-impressed, slanting obliquely forward; aper- ture elliptical, outer peristome simple and thin, parietal wall adnate upon body whorl, and twist- ed upon the umbilicus reducing that opening to a narrow chink; nuclear V2 whorls having granu- lar surface, remaining whorls with distinct, slightly oblique, vertical ridges, crossed by fine spiral lines, producing a satinlike surface tex- ture; total length, 7.0 mm, diameter, 2.80 mm, a- perture length, 3.64 mm, aperture width, 2.10 mm. The specific name, claytonensis. derives from the name of the section, in turn derived from the nearby town of Clayton, Union County. New Me.xico, Holotype in NM 52-75-1; paratypes in NM 52-75-12. Comparisons: Some paratypes are larger than the type (but damaged), reaching an estimated length of nearly 11 mm. The ultimate whorl on these older shells is often characterized by revolv- ing ridges, about 5 in number; or the last whorl may be irregularly malleated. None of these features is judged to have taxonomic significance. Lymnaea claytonensis, although differing from them in its more slender shape, and compressed, elliptical aperture, seems to relate best to the Lymnaea kumilis-truncatula-cubensis complex, because of the general proportions and size of the shell, and the fine spiral sculpture. Its closeness to the circumcaribbean cubensis may indicate a southern element in the lymnaeid fauna at this site. Gastrocopta debilis, n. sp. Fig. 2 Diagnosis: Shell small, bearing the characters of the genus, about 2.5 mm in length; whorls five, rounded; aperture irregularly rounded, peristome reflected, lip thin, having well-developed crest behind, separated from the lip by a well-devel- oped trough; denticles 4, the two palatals weakly developed to almost absent. Description of holotype: Shell minute, subcylin- dric, tapering slightly toward blunt apex; whorls five, rounded, bearing surface sculpture of fine, irregularly disposed diagonal striations, except for finely granular apical I'z whorls; suture im- pressed; aperture about as high as wide, peris- tome reflected, thin, but bearing a callus within; margins of peristome approaching, but connected by no more than a thin wash across parietal wall; a strong crest parallels outer peristome separated from it by a trough; no impressions behind palatal folds; denticles 4: angulo-parietal simple in all views, inclined slightly toward the right; columella lamella simple horizontal, nei- ther entering nor ascending; two palatal folds, lx)th weakly developed, the lower more elongate and more deeply entering than the upper; basal fold absent. The name debilis refers to the weakly developed palatal folds. Holotype deposited in NM 52-76-1; paratypes in NM 52-76-5. Compansons: There is a minimum of variation among the numerous paratypes. but what occurs is related to the strength of the two palatal folds. Among a hundred shells, four of them have palatal folds more than weakly developed, and in another four of them, the two palatal folds are essentially absent. G. debilis superficially resembles G. pellucida parvidens of Sterki but differs from that species in the simple angulo- parietal fold, and the prominent crest behind the Vol. 91 (4) October 27, 1977 The Nautilus 145 peristome. G. debilis differs from G. cortu-aria in that the latter lacks the crest behind the peristome, the angulo-parietal is not simple, and the two palatals in corticaria are strongly developed. Gastrocopta arean. ii. xp. Fig. 3 Diagnosis: A small ovoid gastrocoptid, little more than 2.0 mm in length, having five rounded whorls, flared aperture with crest behind the peristome, and four denticles: angulo-parietal, columellar and 2 palatals. Description of holotyve: Shell elongate, ovoid, imperforate; 5 convex whorls, smooth nuclear whorl forming bluntly conic apex the granular surface texture extending to last half of ultimate whorl but beyond first IV2 nuclear whorls, over- lain by fine diagonal striations, aperture having flared, simple peristome, with crest behind, the right margin extending toward, but not reaching opposite margin, to which it is connected only by thin callus; denticles 4: angular limb of angulo- parietal extending from parietal limb and joining with margin of peristome, parietal limb elevated, elongate, extending deeply within aperture; col- umellar lamella nearly vertical; basal lamella ab- sent; upper palatal lamella conic and rising from a thick callus, the tip closely approaching pa- rietal lamella; lower palatal nodular, very deeply inserted in aperture and smaller than upper pa- latal lamella; the palatal lamellae producing an elongate impression behind the peristome. Total length, 2.38 mm; diameter, 1.2 mm, aperture length, 0.77 mm, aperture width, 0.84 mm. Gas- trocopta arena is known only from the holotype (NM 52-76-21) and three paratypes (NM 52-76-5) the shells of the paratypes are variously damaged. Tlie name arena refers to the fine sandy matrix from which this and other taxa of mol- lusca were recovered. Comparisons: Similar in form and in the general configuration of the denticles to G. ar- mifera, from which it differs by its small size, about half that of annifera, by the simple, un- twisted columella lamella, and by the deeply im- mersed, nodular lower palatal lamella. The sur- face texture is also unique, as the granular al- most waxy surface sculpture extends to the last half of the ultimate whorl, where diagonal stria- tions suddenly begin. G. arena bears no resemblance to any of the small gastrocoptids known to me. The three taxa of gastropods described above are known only from the type locality, given earlier. The total molluscan fauna recovered from the Clayton South locality includes 25 taxa, listed as follows in generic alphabetical order: AQUATIC Fcirissiaparallela (Haldemian) Ferrissia shimeki (Pilsbry) Ferrissia tarda. (Say) Gyraulus cxrcumstriatus (Tyron) G. parviLS F. C. Baker Lynmaea bulimoides Lea L. claytonensis. n. sp. L. ddli F. C. Baker L. parva F. C. Baker Physa anatirui Lea Pisidium casertanum (Poll) Terrestrial Evjconuiusfidms (Muller) Gastrocopta arena n. sp. G. cristata (Pilsbry & Vanatta) G. debilis. n.sp. G. pUsbryana (Sterki) Hawaiia mimiscida (Binney) Pupilla blandi Morse Pupoides albilabris (C. B. Adams) P. hordaceus (Gabb) P. inomatus Vanatta P. modicus (Gould) Suiccinea grosvenori Lea Sucdneagelida F. C. Baker Valloniaperspectiva Sterki Vertigo milum (Gould) 146 The Nautilus October 27. 1977 Vol. 91 (J) RADIODISCUS HUBRICHTI BRANSON, 1975. A SYNONYM OF STRIATVRA (S.) PUGf7rp:NSlS {DALL, 1895) (PULMONATA: ZONITIDAE) Alan Solem Department of Z<)ol()g>' Field Museum of Natural History Chicago. Illinois 60605 ABSTRACT A pamtifpp of Radiodiscus hubrichti Brnnsori. 1975. compares exactly inth material of Striatura (S.) pugetensis (Dall, 1895). The tiro taxa are considered to be Hynonyms. Scanning electron microscope photographs of shell sculpture in the two distinct species. S. (S.) pugetensis and S. (S.) milium (Morse. 1S59J. show that they have basically identical sculpture. The minute (1-3 mm) shells of such genera as Striatura, Punctum. Radiodvictis. and Planogyra are easily confused. They have a common pattern of decoiling and spire protrusion, all have radial ribbing interspaced with microribs, and in each group the apical and post-apical sculpture are markedly different. Even the best illustrations published previously (Pilsbry, 1946, 1948) suggest that there are more similarities than differences. Use of the scanning electron microscope permits showing that the shell sculpture in these genera, although very similar in gross appearance, is formed quite differently. TTiis paper reports on the basic sculpture of Striatura, s. s., while a subsequent contribution (Solem, in this issue of The Nautilus) will illustrate the same features as found in Striatura (Pseudohyalina). Punctum, Radiodiscus and Planogi/ra. Comparative remarks are included in the second paper. SHELL SCULPTURE Although much of the surface in the paratype of Radindiscus hubrichti (FMNH 175456) is coated with debris (figs. 4, 5). sufficient clean areas remain so that details of the microsculpture could be studied (figs. 6, 7). The apical sculpture for the first l-3/8ths whorl con- sists of crowded spiral ridges (fig. 5). There is an intrusion of weak radials on the remaining slightly more than one-eight apical whorl. A con- striction at the suture marks the end of this region. The post-nuclear sculpture consists of pro- minent radial ribs and weak .'spiral elements. Tliis continues to the lip edge. Viewed at intermediate magnification (fig. 6), the radials are seen to be narrow thread-like elevations on top of weakly raised ridges. At high magnification (fig. 7), the inter-rib area shows "pits and swirls". There are distinctive mirco-folds on the pit edges as well as the surface of the radial ribs (upper left). The apical sculpture of Striatura milium (fig. 1) is the same as that found in S. pugetensis. Ti\e post-nuclear sculpture (figs. 2, 3) of S. milium ap- pears different at first glance, since the raised radial threads of 5. pugetensis (fig. 6) are absent. When viewed at comparable high magnification (fig. 3), the "pits and swirls" found in inter-rib areas of 5. piigetensis (fig. 7) are seen to be inten- sified in S. milium and represent the only post- nuclear sculptural element. At the highest magnification (figs. 3, 7), both species show a very peculiar pattern of micro- folding. This folding is very similar to stress marks seen in dried paint or plastic films. It is interpreted as the result of periostracal shrinkage drying. This "folding" also is characteristic of many zonitoid (Solem. unpublished) and pupillid taxa (see also Gittenberger. 1975. pi. I, fig. 4 and Solem. in this issue of The Nautilus. SYNONYMY AND DISTRIBUTION Striatura (S) pugeten.vs (Dall, 1895) has a sporadic distribution from Vancouver Island south to Guadeloupe Island. Baja California, and the Palomar Mountains near San Diego (Pilsbry, 1946: 492). It is quite common near Seattle and Voi.;»i(i) October 27, 1977 The Nautilus 147 FIGS. 1-3. Striatura (S.) milium (Morse, mn)- FMNH mnHH. Near Minden. Halliburton Co.. Ontario. Canada. P. M. Oughton! FIG. 1. Nuclear sculpture. 560X. FIG. 2. S<-ulpture on body whorl near aperture. 56.5X. FIG. 3. Detail of two "ribs" m body whorl. 1.670X. FIGS. 4-7. Striatura (S.) pugetensis (Ml. 1895). FMNH mU56. Paratype "f Radiodiscus hubrichti Branson, wr.:. Ml. Storm King. Olym- pic Penhmda. Washington. FIG. 4. Sid^ mew of shell. S6X. FIG 5. Top view of shell. S6X. FIG. 6. Sculpture on body whorl showing the raised "ribs" on top of the same pattern .^een m Fig. 2. 370X. FIG. 7. Detail oftuv radial ribs shownng shrinkage pattern and inter-rib pits and swirls. 1.510X. 148 The Nautilus October 27, 1977 Vol. 91 (4) on the Olympic Peninsula, from which Radw- discus hubrichti was described. TTie dimensions cited by Branson (1975), his description, and his figures, all agree with the information concerning S pugetevsis given by Pilsbry (1946). Direct com- parison of a paratype of I\iiv 1^ FIGS. 1-3. Striatura (Pseudohyalina) exigua (Stimpsim. 1850). Ohin. FMNH 110-20. FIG. 1. Apical (left.) and poi^t- miclear fright) sculpture. 1S5X. FIG. Z Sculpture on body whorl shouing one major radial rib. 620X. FIG. 3. Mail of penoMmad snrfarr on major nb. l.HmX. FIGS. 4-6. Punctum minutissimum (Lea. mi). Cedar bog on Woodburn Road. J, miles southwest of Urbana. Champaign Co.. Ohm. October 20. 1969. E. Keferl! FMNH 151102. FIG. 4. Entire shell (hp broke II) (iSX FIG. .5. Sculpture on bod,j whorl. 1.5t>0X. Broken ends of major radial (left) and two microradiak (center and right). 5.mX. 152 The Nautilus October 27, 1977 Vol.itl (1) % FIGS. 7-10. Radiodiscus (R.) millecostatus Pihhry & Ferriss. 1906. Wickerxham (iulch, Huachuca Mts.. Cochise Co.. Arizona. James Ferriss! FMNH U6619. FIG. 7. Apical sculpture. 195X. FIG. 8. Detail of late apical sculpture. 1.900X. FIG. 9. Tu'o major ribs on body whorl. 630X. FIG. 10. Detail of a major rib and mirrorihlets on body irhorl. ilKXlX. FIGS. 11-12. Punctum minutissimum (Lea, mi). FMNH 1H1W2. FIG. 11. Sculpture on body whorl. 2.()i»)X. FIG. 12. TktaU of microsculptwre on body whorl. 6.700X. Vol. 91 (4) October 27, 1977 The Nautilus 153 FIGS. 13-15. Planogj-ra asteriscus (Morse. 1857). FVaserdalf, Cochrane Dist.. Ontario. Canada. S. D. Downing! June 1938. FMNH 1,6T8S. FIG. 13. Apical view of siibadidt specimen. 36X. FIG. 14. Major rib and microsadpture on body tvhorl. 355X. FIG. 15. Apical sculpture and early post'uuclear scidpture. .W.5.V. FIGS. 16-18. Planog>Ta clappi (Pilsbry. 1898). Quamicham. Vancouver Id.. British Columbia. FMNH U0588 ex W. J. Eyerdam. FIG. 16. Apical I'iew ofsubadult specimen. 37.3X FIG. 17. Scidpture on body whorl. 373X. FIG. 18. Broken edge of body whorl shouintj major rib and detaih of mierosculpture. 792X. 154 The Nautilus October 27, 1977 Vol.91 (4) tween these "major" spiral elements are vague sprial corrugations (fig. 10; Solem, 1970, pi. 59, figs. 10, 11) that resemble those found on the spiral ridges in Punctum (fig. 12). Planoyyra asterifscus (Morse, 1857) (figs. 13-15) from the boreal areas of Extern North America and P. clappi (Pilsbry, 1898) (figs. 16-18) from Oregon to British Columbia differ from each other in major rib spacing (compare figs. 13 and 16) and umbilical width. They both have very high, lamellar periostracal ribs that stand erect when the live animal is in the moist litter, but warp and twist (fig. 11) in the dry museum cab- inets (H. B. Baker, 1928a: 122). Seen at a broken edge (fig. 18), the periiKstracal nature andthinness of the ribs is obvious. Similarly, the microradial riblets are formed by the f)eriostracum (fig. 17) and are fewer in number in P. chtpiii (fig. 17) than in P. asteriscus (fig. 14). Both species have a weak microspiral sculpture that shows most clearly in figs. 14 and 18 because of the oblique angle of view. The microspirals blend into the raised radial ribs, but do not buttress them as in many CTiaropids. The apical sculpture in Plan- ogyra usually is eroded, but in unworn examples (fig. 15) it can be seen to form a series of cor- rugated wrinkles and pits with a vague diagonal- ly radial pattern. At the highest magnification (fig. 18) there are evident irregularities on the periostracal surface. These appear homologous to the structures on the spiral microribs of Rndio- discus (fig. 10) and Punctum (fig. 12), and quite different from the stress drying marks in .S7n- atum (fig. 3; Solem, 1977: figs. 3, 7). COMPARATIVE REMARKS Under optical examination, the spiral apical sculpture and post-nuclear sculpture with both major radials and usually microradials found in the four genera appear quite similar, but at the higher magnifications of the SEM, major dif- ferences appear. In both Striatura and Planogyra, the shell sculpture appears to be totally periostracal in nature. The raised major ribs are simple lamellar protrusions from the surface. They are scarcely wider at their base than at their midsection (figs. 2, 18). In Punctum and Radindwcu.% the microradial riblets are purely periostracal, but the major radial ribs are underlaid and partly formed by a swelling in the calcium layer. Punctum (fig. 6) differs in that the periostracal ribs are simple lamellae, while in the Charopidae (Solem, 1974: 199. fig. 8b) the basal portions of the periostracal ribs are distinctly wider than the middle sections, with tapering continuingto the topof the ribs. Microspiral sculpture is present, but differs greatly. In Striatum (fig. 2; Solem, 1977: figs. 2, 3, 6, 7) the spiral elements initially are short diagonals, becoming coalesced into wavy spiral cords only in S. eodgua (fig. 2). In both Planogyra (fig. 18) and Punctum (figs. 11. 12) ' the microspirals are basically independent of the radial ribs and riblets, but in Radiodiscus (figs. 9, 10) they serve to buttress the apical edge of each riblet. In Punctum and Radiodiscus, weak spiral corrugations are associated with the sprial ridges. All four genera have spiral sculpture on the nuclear whorls. In Radiodisciis (figs. 7, 8) this consists of short interrupted threads arranged serially in spiral rows, although other charopids (Solem, 1970: pi. 58, fig. 1) normally have promi- nent, narrow spiral cords, such as are seen in both Punctum (Giusti, 1973; pi. 5, fig. 1) and Striatura (fig. 1). Planogi/ra (fig. 15), in contrast, has a less well defined, almost punctate sculpture. The most striking difference is the peculiar micro-folding pattern found in Striatura (fig. 3; Solem, 1977: figs. 3, 7). This effect is lacking fi-om the other taxa, although having analogous struc- tures in some other Orthurethra (see Solem, 1977). The sculpture of these four taxa, although "macroscopically" veiy similar and functionally probably serving an identical purpose, is com- posed of quite different elements. On the basis of this and other data available now, primarily a review of Pacific Basin endodontoid taxa, it seems possible that certain of these differences are consistent for at least family units. TTie total periostracal nature of the shell sculpture in Stivatura and Planogyra contrasts with the com- bination of calcareous and periostracal sculpture in Punctum and Radiodiacus. At the other ex- treme the Endodontidae, as restricted by Solem, has a uniformly thin periostracum, with even Vol. 91 (4) October 27, 1977 The Nautilus 155 the microsculpture on the apical whorls formed mainly by the calcareous layers. Except where the sculpture is secondarily reduced in the Charopidae, the combination of periostracal and calcareous elements is consistent, as is the use of microspiral ridges to buttress the riblets. In the valloniids, species of Vallonia with regularly spaced ribs do have calcareous extensions into the ribs, and some of the punctids from Australia and New Zealand lack the calcareous swellings underneath the main ribs. The tapered and buttressed ribs in the Cliaropidae are quite unlike the simple lamellar ribs of the other taxa, while the stress folds and "pit and swirl" microsculpture of the zonitid Striatura separate it from the other three. A study of the physical chemistry of the peri- ostracum in Striatura as compared to the other taxa might yield highly significant information. In conclusion the grossly similar shell sculpture of these four taxa show several signifi- cant differences in mode of formation and com- position. Ebdended studies on the ribbed pu- pillids, small polygyrids, streptaxids, and helicids might yield equally interesting results. ACKNOWLEDGMENTS Figures 1 through 12 were taken during a fac- tory demonstration of a JEOLCO SEM, and fi- gures 13 through 18 were taken on a Cambridge S4-10 provided Field Museum of Natural History by NSF grant BMS72-02149. I am grateful to Mr. Fred Huysmans for the excellent photographic prints, to Dorothy Karall for mounting them into prints, and to Sharon Bacoyanis for help with manuscript preparation. LITERATURE CITED Baker, H. B. 1927. Minute Mexican Land Snails. P>-iic. Acad. Nat. Sci.. Phiiadelphia 1927: 223-246. pis. 15-20. Baker. H. B. 1928a. Planogi/ra asti'risciix (Morse). The NwitUu.-i. 41(4): 122-123. Baker. H. B. 1928b. Minute American Zonitidae. Pruc. Acad. Nat. Sci.. Philadelphia. 1928: 1-44, pis. 1-8. Baker. H. B. 19.3.5. Review of the Anatomy of the Pupillidae and Related Groups. In Manual of Conchology, (2) 28: 191-209. Giusti, F. 1973. Notulae Malacologicae XVIII. I Molluschi ter- restri e salmastri delle Isole Eolie. Lavori Delia Sac. Italmna Biogeog.. n. s.. 3: 113-306, pis. 1-16, 2 tables, 39 text figs. Pilsbry, H. A. 1946. Land Mollusca of North America (North of Mexico). Acad. Nat. Sci.. Philadelphia. Monog. 3, 2(1): i-vi, 1-.520, figs. 1-281. Pilsbry. H. A. 1948. Land Mollusca of North America (North of Mexico). Acad. Nat. Sci.. Philadelphia, Monog. 3, 2(2): i-x- Ivii, 521-1113, figs. 282-585. Solem. A. 1970. Malacological Applications of Scanning Elec- tron Microscopy. I. Introduction and Shell Surface Features. ne Veliger 12: 394-400, pis. 58-60, 1 table. Solem. A. 1974. The Shell Makers: Introducing Mollusks. New York: John Wiley, pp. xii. 289. Solem, A. 1977. Radiodiscus hubrichti Branson, 1975, a synonym of Striatura (S.) pugetensis (Dall, 1895) Mollusca: Pulmonata: Zonitidae). Vie Naiitilm 91(4) in this issue. Solem, A. hi Press. Systematics of non-marine gastropods. other than Basommatophora. /« Pulmonata, vol. 2, Systematics, Evolution and Ecology. Academic Press. FOR SALE Several complete original sets of Johnsonia, vol. 1 to vol. 5, no. 50 $130 each; postpaid (unbound). Several incomplete sets (pt. 5 absent) of Dall's Tertiary Fauna of Florida, 1890-1895 (Gastropods and some bivalves). Send for price list. Write: Dept. G., The Nautilus. Box 4208 Greenville, Delaware 19807. 156 The Nautilus October 27, 1977 Vol. 91 (4) We deeply regret to announce the tempo- rary suspension of the Department of Mollusks at the Delaware Museum of Natural History effective November 15, 1977. Public exhibits at the museum will remain open. However, the Curator and Assistant Director of the Museum, R. Tucker Abbott, and the Assistant Curator of Mollusks, Russell H. Jensen, as a consequence, will be leaving their positions. Professional malacologists are invited by the Director to continue to use the facilities of the museum. Those wishing malacological informa- tion may address Dr. Abbott at P.O. Box 4208, Greenville, Delaware, 19807 and Mr. Jensen at R.D. 1, Box 55, Chadds Ford, Pennsylvania, 19317. These events will not adversely affect the publication of The Nautilnfi. Indo-Pacific Mdlhi.'^cn, The Standard Catalog of Shells or publications of American Malacologists, Inc. DEATHS We regret to announce the sudden death of George E. Radwin, Curator of Mollusks at the San Diego Museum of Natural History. George was born August 20, 1940, at Far Rockaway, N.Y., and died of a heart attack at the age of 37, on September 30, 1977, in San Diego. Most of his research was on the ta.xonomy of the Muricidae and Columbellidae. He was senior author of the recent book, Murex Shells of the World. He received his Ph.D. in 1968 from The George Washington University, and went to San Diego in 1970. He is survived by his wife, Rodda, to whom all malacologists send their sincere con- dolences. Henning M. Lemche, former head of the Department of Mollusks, of the Zoological Museum, University of Copenhagen, Denmark, died August 4, 1977, after a brief illness. Dr. Ivemche was an outstanding malacologist, well- known for his works on nudibranchs and NcopilllKl. Isabelle E. Welch of Fails Church, Virginia, an ardent shell collector and partner in The Shell Cabinet, died on August 15, 1977. She was a former employee of the U.S. Navy, a member of the A.M.U. and several shell clubs. Miss Welch produced several taped travelogs of her shelling experiences in the Bahamas and the Galapagos. NEWS Stanford University Collections Ti'ansferred to the California Academy of Sciences The moUuscan shell collection, the type specimen collection, and a major part of the in- vertebrate fossil collection of the Department of Geology, Stanford University, have been trans- ferred on indefinite loan to the Department of Geology, California Academy of Sciences. All enquiries regarding these Stanford collections should be directed to the Academy. The com- bined Academy and Stanford collections are now available for study. The shell and fossil collections are housed separately, and both col- lections have work space and other facilities for visitors. The combined Academy — Stanford shell col- lection, containing an estimated one million specimens, is of world-wide scope, but is especially rich in marine species from the Eastern Pacific and land snails from Western North America. The fossils transferred from Stanford to the Academy include the Cenozoic stratigraphic collection and the systematic col- lection of fossil cephalopods and echinoids. The combined Academy — Stanford fossil collection contains about one million specimens (mostly mollusks), principally from Cenozoic and Late Mesozoic rocks of the Pacific Coast of North America (Alaska to Mexico), The combined Aca- demy — Stanford type collection, housed in a separate room, contains several thousand spe- cimens including primary and secondary' types of living mollusks, and fossil invertebrates (mostly mollusks), vertebrates and plants. Peter U. Rodda C(illfonii(t Academy of Sciences San Francisco. Califoniia 9J,11S INFORMATION FOR SUBSCRIBERS The annual subscription rate for TJie Nau- Wf/.s' is $8.00 for individuals and $12.00 for in- stitutions (domestic or foreign). Subscriptions may begin in January. Send check or money or- der to "The Nautilus" to Mrs. Horace B. Baker, Business Manager, 11 Chelten Road, Haver- town, Pa. 19083. Back issues from volume 72 to date are ob- tainable from the Business Manager. 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All authors or their institutions will be charged 50 cents per line of tabular material and taxonomic keys. TTie 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, in- formation about ordering reprints will be given. They are obtained from the Ek;onomy Printing Co., Inc., R. D. 3, Box 169, Easton, Mar id 21601. MOLLUSK VOUCHER SPECIMENS It is becoming increasingly important for future research purposes that an identified sam- pling of species mentioned in publications be deposited in a permanent, accessible museum specializing in moUusks. This is particularly true of mollusks used in physiological, medical, parasitological, ecological, and experimental projects. Several museums of natural history have ex- tensive modern facilities and equipment for the housing and curating of voucher specimens. Material should be accompanied by the identifica- tion, 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. I Mill. WIK" .V'lIi'iMiMIl' yH 17XX -.w «• . '^'If