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Berkeley, California Volume 15 July 1, 1972 to April 1, 1973 vs ee Lae enaninia ao te Sas Te Vol. 15; No. 4 TABLE or CONTENTS Additional notes on cephalopods from northern California TROT IRL, TALEMUOCH, cocceaseeebsee non uesn eme nme secon ecter 348 Additional notes on some Pacific coast Mollusca — geo- graphical, ecological, and chronological IROBER ie RGM lA TE MIAD GE) He eees natin pacacre getter 232 Additions to the opisthobranch mollusk fauna of Marin County, California, with notes on their natural history TERRENCE M. Gosuiner & Gary C. WILLIAMS ....... 352 A device for collecting free-swimming bivalve larvae from laboratory aquaria SEIN CIB TEBARGEReaerenta melee caterer cearencce: 256 Aerial and aquatic respiratory responses to temperature variations in Acmaea digitalis and Acmaea fenestrata SHaron Rose Doran & Donatp S. McKENZIE... 38 A field study on the clustering and movement behavior of the limpet Acmaea digitalis WIVERISWW es WALL OU GHIBY cco aces niacetnantee 223 A new species of Conus from Taiwan Epwarp JAMeEs PeTucH & GrorcE MENDENHALL 96 A new species of monoplacophoran from the abyssal North Pacific RANK MI MIROKOP te cell ici necien eeu Aeunaniede etre 91 A note on the anatomy of the circumesophageal ganglion complex of several doridacean nudibranchs ASD ONAUDREARTRIDGE |) Dalene sche ss. dtats mentisitents 349 Apertural barriers in Pacific island snails of the families Endodontidae and Charopidae PAINTS OTEE IMG) fee tate na ine IN Me ee SU 300 A preliminary list of known opisthobranchs from the Galapagos Islands collected by the Ameripagos Ex- pedition GaLe G. SpHON & Davip K. MULLINER 2.0.0 147. A Recent Oreohelix (Gastropoda : Pulmonata) from Baja California Sur, Mexico NWATSEPR VB SIMIIE DER js oe Ba lc 332 A report on cephalopods collected by Stanford Oceano- graphic Expedition 20 to the eastern tropical Pacific Ocean September to November, 1968 W. Gorpvon Fietps & VERONICA A. GAULEY 00.0. is) A systematic note on Ocenebra poulsoni Carpenter, 1865 (Gisopexena) 1B) IVA AONT eect noarteeeceatrecrenoneas eee ceeede 35 Authorship of a taxon RFU GENIE WV ACO AN see tie i ie ee teal Rea de, J abate VW 64 Biology of Okenia ascidicola spec. nov. (Gastropoda : Nudibranchia ) IMIESEATRIGIAWNIOR SE e2c0 cece clea cnce! a meme 2c He Of Comments on the authorship of some subfamilial names in the Turridae (Mollusca : Gastropoda) WALTER (Os CERNOHORSKYq cuenta cowed hank en 127 THE VELIGER Page III Comments on VoKEs’ paper MIGEVAET MD SELUBBARD! seamen tsnccnsincunias 360 Convergence in pulmonate radulae PNTDANT SOLE Mee treet ae cea M ara tin aati mir ath ais 165 Dentaliid taxa referred to the Siphonodentaliidae (Mol- lusca : Scaphopoda) with a description of a new species OEDND Ne pINRARUTER giant ah marin oinn ence uae 21 Description of a new species of the genus Latiaxis Swain- son, 1840 from the South Mozambique Channel, Indian Ocean (Gastropoda : Coralliophilidae) INDASAO) IAZU MAG arum aia cetera neni teutedeantitee Zon Embryonic and larval development in the New Zealand rock oyster, Crassostrea glomerata (Gould, 1850) IPD UNV ACCA TG es meetnE Ua talaga een mae sede 295 Embryonic development of the camaenid snail, Varohadra yeppoonensis ALEX S. TOMPA & JAMES N. CATHER ocsssssustseusnen 193 Evidence for a pheromone in the marine periwinkle, Lit- torina littorea Linnaeus INGRID DINTER & PETER J. MANOS urssmecscsnsnninnin 45 External description of a living Aranucus bifidus (Odh- ner, 1936) (Opisthobranchia : Dendronotacea ) Cue CARWSON | &:P JOBE p A enue eC 172 First recorded occurrence of Littorina tessellata Philippi, 1847, from the shores of North America ERASIERV OLA BING HA Man oma etnias a0 rc en nem 158 Food-preference of the nudibranch Aeéolidia papillosa, and the effect of the defenses of the prey on predation VIR GINTAGIEMIVVATERG eee Neto enn a nee ain 174 Further comments on deepwater Volutidae from off south- . east Africa, with descriptions of two new species of Volutocorbis ELAR ATED PAC INEETDER ean area Mien nese 11 Geographic distribution of Pinna rugosa Sowerby, 1835 (Mollusca : Bivalvia), and its occurrence on Clipper- ton Island IBUISAL VAT HSI OAL VAT: aro itanern tn. Ueh keay its Ga cher 43 Mantle changes in the pearl oyster Pinctada maxima in- duced by the pea crab Pinnotheres villosulus (REVORIGHD ix veer e sie oie se Nats ie ay ba 330 Microarmature and barriers in the aperture of land snails ITAA S SOULE Mga ee ME EEC ae NI ee a ae 81 Morum dennisoni Reeve (Gastropoda : Cassidae) and Strombus costatus Gmelin (Gastropoda : Strombi- dae) collected off the North Carolina coast EDVARD ROLE DU CE teueeas ni valli cone tone. ie asian sass 51 New name for Pyramidella (Triptychus) olssoni Bartsch, 1926 IPANIES PC CORG ANNI eet eraectenre eter eta 258 Page IV New records of Pleistocene marine Mollusca from Pacific Beach, San Diego, California MES PBISTHIOPE& 1 So) ey DISIELO Pyetteereee ster tetre meats 6 Nomenclatural notes on West Coast Odostomia (Gastro- poda : Pyramidellacea) JAMES POU CORGAN Heese titra sie themeertae ane eeeas 357 Note on secondary homonymy Enieysll VOKES) ne rnc se eue ee ae eee eee 102 Notes on abyssal gastropods of the eastern Pacific, with descriptions of three new species BRANKGRROKOP fico erate one ete niatie tr tote ate 15 Notes on Cypraea cinerea Gmelin and Cyphoma gibbos- um (Linnaeus) from the Caribbean Sea, and descrip- tion of their spawn TKGEAUSHMBAND EIA pote ween re ate nain Miser Reape ne ie 335 Notes on two endemic South African Cypraea 1, INL, IXanepyoieny Ge ID, WWE ANIESDINT ccomereettcommecrenomonmnenooadite 125 Observation of the glochidium, metamorphosis, and juve-- nile of Anodonta californiensis Lea, 1857 BETERYNMD EIS CU ee oe DER Oe lc Noreeetare 57 Observations of the feeding habits of Tochuina tetraquetra (Pallas) (Gastropoda : Tritoniidae) Mary K. WicksTEN & JoHN D. De Martin 1....... 195 Observations on growth, feeding, reproduction, and devel- opment in the opisthobranch, Fiona pinnata (Esch- scholtz) JOHNGIE THORERIAN (ie eal ei te Naru aten eters 142 Observations on Hexabranchus from the Australian Great Barrier Reef (Gastropoda : Opisthobranchia) Aaa MIO MPS ONG ace aii nee i tea rete eee 1 Observations on removal of spines by muricid gastropods during shell growth IMIBISR OW RIN EM Res C/ARRTKSER eee tenet 69 Odostomia minutissima Dall & Bartsch, 1909, a synonym of Odostomia raymondi Dall & Bartsch, 1909 PAMESPXUCORG AN ee See ete au tie oat ane rm amen 359 Opisthobranch mollusks dredged in San Francisco Bay during the period 1966 to 1971 JorNny HOLEEMAN neo ee eee 59 Oxidation of C'‘-glucose by the aestivating snail Pila glob- osa (Swainson ) S. RacHupatui Rami Reppy « R. RAMAMURTHI... 355 Polydora and related genera as borers in mollusk shells and other calcareous substrates (Polychaeta : Spion- idac ) JaMEs A. BLAKE & JOHN W. EVANS cocci 235 Preliminary note on hermaphroditism and embryonic stages in Diplodon variabilis CEMA GuuziwANEDE, LASCARY ) eee nena 213 Preserving terrestrial slugs by freeze-drying PLB CROWET Mie wren. alee ent ah geen ama Ee 254 THE VELIGER Vol. 15; No. 4 Range extensions of Conualevia alba Collier & Farmer, 1964 ANTONIO. J.. FERREIRA joss dis.cte nines one eee 53 Range extensions of several littorinids (Mollusca : Gastro- poda) in Florida FRASIER’ ©) BINGHAM) (20) cecsiecncnncuiticn eee 250 Review of the bathyal gastropod genus Phanerolepida (Homalopomatinae) and description of a new spe- cies from the Oregon Oligocene Carone’S) Hick MAN fin. ceeecde ee 107 Scanning electron micrographic study of the dorsal integ- ument of the land slug Lehmannia poirieri (Mabille, 1883 ) Joun A. Arcani & NORMAN HODGKIN ...secsnnee 338 Seasonal migration and population regulation in the lim- pet Acmaea (Collisella) digitalis PAUL A} BREEN 2). Gacotteee eee 133 Selective predation and prey location in the sea slug Navanax inermis Grec M. Bian & ROGER R. SEAPY ciccsssssanennnen 119 Settlement, growth rates and depth preference of the ship- worm Bankia setacea (Tryon) in Monterey Bay BG) HApERME & J.C; MELIOR =. nena 265 Some notes on the genus Teramachia (Volutidae : Callio- tectinae ) HarRALp: Az) REHDER: (iteci ch ccncacie cee ee 7 Some opisthobranchs (Mollusca : Gastropoda) from Oregon GALE G.) SPHON (1.0.00, Soe ae 153 Some records on West American Cenozoic gastropods of the genus A foria MADOKHT JAVIDPOUR) een 196 Soviet contributions to malacology in 1971 KENNETH J. Boss & Morris K. JACOBSON owen 362 Spawning and development of the eggs, in the laboratory, of Illex coindetu (Mollusca : Cephalopoda) S. v. BoLetzKy, L. Rowe & L. AROLES ween 257 Status of Obeliscus clavulus A. Adams, 1854 James UX; \CORGANS. ee eee ee 359 Stenoplax circumsenta Berry, 1956, in the Gulf of Cali- fornia ANTONIO YU BERREIRAG HI Gee a DS Systematics and distribution of western Atlantic Ervilia (Pelecypoda : Mesodesmatidae) with notes on the living Evvilia subcancellata JOHN Ds DAVIS) 2.2 use ee 307 Thecacera picta spec. nov. from Suruga Bay, Japan (Nudi- branchia : Doridoidea : Polyceridae) KiKUTARO! BABA ina. cee eee eee ne 88 The ecology and behavior of Nautilus pompilius in the Philippines Norint Haven Vol. 15; No. 4 The genera Chromodoris and Felimida (Nudibranchia : Chromodorididae) in Tropical West America: dis- tributional data, description of a new species, and scanning electron microscopic studies of radulae Hans Bertscu, ANToNIo J. FERREIRA, WESLEY M. FARMER & THOMAS L. HAYES cites 287 The genus Chelidonura from the Marianas Islands (O- pisthobranchia : Cephalaspidea ) CHER CARUSON & P. Je HOFF! 22.20 cca eetnntennee 20 The intertidal behavior of the bean clam, Donax gouldii Dall, 1921 PI TONOAS WETS ER WAN se sect sececcsae sentra sedettach tacsiebacienistine 206 The mucus holdfast of Littorina irrorata and its relation- ship to relative humidity and salinity ERSTE RG @ se BUN GWA eee eee eee 48 The northwest American Semelidae AU CINE RAN 5 CONN ee eres NUE eae te ae lle 314 The occurrence of Polycera zosterae O'Donoghue, 1924 in the Bodega Bay region, California, with notes on its natural history (Gastropoda : Nudibranchia) TERRENCE M. GosLINeR & Gary C. WILLIAMS ..... 252 Thermal and salinity effects on ciliary activity of excised gill tissue from bivalves of North and South Carolina PNIGAN AEs SIELO EWA KOERO oe nee meteors, 215 The role of wave impact and desiccation on the distribu- tion of Littorina sitkana Philippi, 1845 RSYPTLIYUN, LBV BTS DeQISIN IS Gaia stl ene 129 The use of the foot and the captacula in the feeding of Dentalium (Mollusca : Scaphopoda ) MO WISB ER GATINIE AM [ieee ent tem tenant 29 Two additions to the opisthobranch fauna of the southern Gulf of California IRAN SBE ERTES Cgc ie rene ee a est eee erste a 103 Unusual egg-deposit by a cuttlefish So Wo THONISIA SSC: 6 atten crcaneeemene sense rere ete ean 61 Zoogeography and ecology of seven species of Panamic- Pacific Scaphopoda VIE S Ee CAD IEING Sect teeter creme rae nme uO eet 340 AUTHOR INDEX AIKEN, D. W.see KiLpurn, R. N. AppicoTt, WARREN O. ....... (GO), (CIO), (OR), (A4e3) ARCADI, JOHN A. & NORMAN HODGKIN cece 338 ARoLes, L. see Boterzxy, S. v., L. Rowe & — Azuma, Masao Basa, KiKuUTARO BANDEL, KLAus REED RIES et OVA VITAN oe test sat Mee ee teat ecole et lenge ae 129 IB DRALS CHPRILAIN| Stee am Mersie) SPU seek Ore sean e el ease tec patet ieee 103 THE VELIGER Page V Bertscu, Hans, ANTONIO J. FERREIRA, WESLEY M. Far- MER NSM FEONAS Maa ELAVE SI muenne seen nnrne 287 IBINGEVAMEMERASTE RU ©) sient eet tated cee 48, 158, 250 BISHOP AVI meg Sane DISH OD sures ntin css cmsneitnrecienrctcis Briar, Greco M. & ROGER R. SEAPY usec BLAKE, JAMES A. & JoHN W. Evans BOGE DZKVAN Sony lo eer te cr pena nner tee Asai i ate ete 61 BoLeTzky, S. v., L. ROWE & L. AROLES .......00 Boss, KENNETH J. & Morris K. JAcoBSON Books, periodicals and pamphlets ........ 66, 161, 262, 370 IBREE N/R EAU Geert een recat eer Oe pen se hee 133 ChrrsonpiG He Pls HOnE eet neces 20, 172 CAR RTE ROS VUBIEB OURINIE ge eee en een nnn nee 69 CaTHER, JAMES N. see ALEZ S. TomPaA & — CERINOHORSKYA WN ATETERM © ieee teen ee ae ene 127 (COANAMENU GENIE WV eee ee 64, 314 CORGANANJANMES XG a: enue nie tet DX, By BOY) GROWER TET EM My ae Ao oie ec eer une ener nessa neues 254 DAVIS in] OUND ern eee 307 DAE TIScUAPEEDERUN Geers sree ee 57 De MartIN1, JoHN D. see WicksTEN, Mary K. & — TTB) uN ANN OAS gee ec ee ee ie sen San oeeere re eee ta 295 Dinter, INGRIp & PETER J. MANOS fooler 45 VTP oR NRE VOR Gree ei mete teal conti peels sue on ttc: 330 Doran, SHARON Rose & Donatp S. McKENZIE ........ 38 BCKEL BARGER WIGEVINGA Mire tenis een santa tattin satiate 256 Evans, JoHN W.see BLAKE, JAMES A. & — Farmer, WesLey M. see BertscH, Hans, and others BERREIR AW AINILONIOM Janes tet renee crt tintacnis BS, DD see also BertscH, Hans, —, and others FieLps, W. Gorpon & VERONICA A. GAULEY uisiccccon 113 GISUNE Veg OUIS UL ta) cee ener ene Len tinrtstoteere ces 29 GauLey, Veronica A. see Fietps, W. GORDON & — GosLINER, TERRENCE M. & Gary C. WiLuiAMsS 252, 352 VADER UTE ies Cre ups CoulVERBDOR MPa tents cense 265 TES VASA SIN INU ODSDENIT cay eect ee ee at eerec pointer ocr i) Hayes, Tuomas L. see BertscH, Hans and others FAUT @ MAIN GA RO TEE DSi cece eterna eran nats raare caters 107 Hopcxin, Norman see Arcap!, JOHN A. & — Horr, P J. see Carson, C. H. « — TLOMMEN CANE OEUNGM sree eases eesti recerectrmcer 59, 142 HUBBARD, MICHAEL D. ...ccccceee TRAIN Sg INET OMOAS WITS fete Metter ree tte stcecat ot tear sceatoen eats 206 Jacopson, Morris K. see Boss, KENNETH J. & — ANADEGURMIMIADOKGE iy een nnmncitcm rename sirarnteer atte: 196 IGE EIN GW ASS Vi RAG deere mnnun tei ects (163) Kitpurn, R. N. & D. W. AIKEN 125 TSGEYATEN OF EON Sat KODE OTs ING Hes eraser terete ere eer 21 Manos, Peter J. see DiInTER, INGRID & — INGOIPAD TIE Nia VEN S te ee cect ie kat nar etter e ane nantes seta 340 McKenzig, Donatp S. see Doran, SHARON ROSE & — Page VI ME Ltor, J. C. see HApERLIE, E. C. & — MENDENHALL, GEorGE see PeTUucH, Epwarp J. & — INITEDERE PO WiATSTE REIS se tee ete on cee needs mecca ere caea 332 INTORSEN Vey Ac CHA es eee erent natn e entesele re nena 97 MuLuiner, Davin K. see SpHON, GALE G. & — INGtesmandenewsme tence te Oil, WEY, Ba, Si) PARTRIDGE spe) O NATED al] geese eee nee eee are 349 PASGCAR, CELIA GLUZMAN DE oecsssssssssssnscsnsssssenssusetisssssnssiteens 213 PETUGH, EDWARD) iter eet ee Cait tee menace tae rsat ane oil Petucu, Epwarp J. & GeEorGE MENDENHALL ............ 96 IRVAD WWII GEORGE Eyes tie ea oc sores online eer ae ae DRL 35 RAMAMURTHI, R. see Reppy, S. R. R. & — Reppy, S. RAGHUPATHI Rami & R. RAMAMURTH ....... 355 IREHDER: IARAT DAK 28 isa yor ieee ehoM mnt east Ul ROKOP) PRANK iif. svc nd eeeen ee ree ear tae 5, Rowe, L. see BoLetzxy, S. v., — & L. AROLES THE VELIGER Vol. 15; No. 4 SATEVAT BS 6c ES SATE VA Taner aiar ret rene 43 Seapy, Rocer R. see Grec M. Biar & — SHOEMAKER, ALAN Hi iio) dea nusadacintin eee 215 SOE Ms GAGA Niji teers leer na 81, 165, 300 SPHON, Gate, G., decoction nena 153 SPHON, Gate G. & Davin K. MULLINER occ 147 STOHLER, R. (66), (67), (68), (162), (163), (164), BME tak (263), (264), (370) Ean ow) SWAT ADC ER BROBERT | Rem enrer te aerate ean 232, 348 IGHOMPSON IE, Bis 2 lea ae ee 1 Tompa, ALEX S. & JAMES N. CATHER ouesccssneninssneien 193 VOKES, EMItey: He. o.scccncsccicsisndsenccient ee ee 102 WATERS, VIRGINIA, L.. .c:c.c:ccrecngoscsanceicnae eee ee 174 WicksTEN, Mary K. & Joun D. De Martin 1.......... 195 WILLIAMS, Gary C. see GOSLINER, TERRENCE M & — ........ WILLOUGHBY; JAMES) Wi ciiceccecencnsneca cee eee 223 SECTIONAI DIVISION OF A Quarterly published by CALIFORNIA MALACOZOOLOGICAL SOCIETY, INC. Berkeley, California VOLUME 15 July 1, 1972 “NuMBER 1 CONTENTS Observations on Hexabranchus from the Australian Great Barrier Reef (Gastropoda : Opisthobranchia) . (2 Text figures) T. E. THomMPson 66 oat New Records of Pleistocene Manag Melee hoa Pacific Resch: San Diego, Cali- fornia. M. J. Bishop « S.J. BisHop . . 6) On) GL RE ROM ON ROUMSSe PO NORE SMD trOeieL Some Notes on the Genus Teramachia ete : a (1 Plate) Haracp A. REHDER . 3 ASie Oat cen wey / Further Comments on Dees oleae Genk off Sent Aftica, with Descriptions of Two New ae of Volutocorbis : es Haratp A. REHDER . . fs : ei eel Notes on Abyssal Gastropods Fe the ee Pacific, mth De npcons # Three Ne Species (2 Plates) Frank J. Roxop A ; . 15 The Genus Chelidonura Boe ae eae tases (Gemichanc: Gon: aspidea) . C.H.Cartsone PJ.Horr. . . . : - 20 Dentaliid Taxa Referred to the Sr sionaden aitdse etnies See AG a Description of a New ee (3 Text aay Joun N. KraEuTER sp tatNe . QI The Use of the Foot and the Capenune in ie Featns of Deetaleaa (uote. Scaphopoda). : 5 Text ae Louis F Gainey, Jr. . . : era Se Me eeler sa Mer icetineiiier Pe enre 2O A Systematic Note on Ocenebra ates Gos Ais (6 Text figures) GrorcE E.RapwIN . ... . MM Me Meee 1 ol fos AS yeh Wop eg) Aah) tom, ei ee OS [Continued on Inside Front Cover] Distributed free to Members of the California Malacozoological Society, Inc. Subscriptions (by Volume only) payable in advance to Calif. Malacozool. Soc., Inc. Volume 15: $18.- Domestic; $19.50 in the Americas; $20.- in all other Foreign Countries Single copies this issue $10.-. Postage extra. Send subscription orders to Mrs. JEAN M. Cate, Post Office Drawer R, Sanibel, Florida 33957. Address all other correspondence to Dr. R. STOHLER, Editor, Department of Zoology, University of California, Berkeley, California 94720 Second Class Postage Paid at Berkeley, California WILLIAM H. DALE! LIBRARY MOLLUSKS Contents — Continued Aerial and Aquatic Respiratory Responses to Temperature Variations in Acmaea digitalis and Acmaea fenestrata. (2 Text ae SHaron Rose Doran & Donato S. McKenzr.. . Se Bene Geographic Distribution of Pinna rugosa Sowerby, 1835 (Mollusca : Bivalvia), and its Occurrence on Clipperton Island. B. SALVAT & Fo SAL VAT 2 (opie eri Bro on Soetoro ile vat aN ool cata atn Vann Evidence for a Pheromone in the Marine Periwinkle, Littorina littorea Linnaeus. (1 Text figure) Incrip DinTER & PETER J. Manos Sic : elias iesiUle The Mucus Holdfast of Littorina irrorata and its Resco to nee Humidity and Salinity. (7 Text figures) Frasier ©: BINGHAMG 9 (Eo 3. Appa ura ne eat eit hoor Darter te Morum dennisoni Reeve (Gastropoda : Cassidae) and Strombus costatus Gmelin (Gastropoda : Strombidae) Collected Off the North Carolina Coast. (1 Plate) EDWARD J. /PETUGHD 1551/5) 62) 2) 7) er ia er tot notin OMe otaet Ina nt ae eRe Range Extensions of Conualevia alba Collier « Farmer, eee ANTONIO J. FERREIRA . Stenoplax circumsenta Berry, 058 in ee Gulf a California. (1 Plate) ANTONIO J. FERREIRA . . . ail och oui Uauehl ee ey anoal ach Salts tie aN Cog Observation of the Glochidium, hceseaene and Juvenile of Anodonta califor- niensis Lea, 1857. e Plate; 1 Text ae Peter N. D’Euiscu. . . Seren im ners Opisthobranch Mollusks mee in ers PANES Bay Duane ae ‘Period 1966 to 1971. (1 Text figure) orn) }-ELOLeE MAN) ac) meneame sit ial oe nei. Sarai atu eehestatth neh quelle geval tr olalKe NOTES & NEWS. . . og Selgin by Seri ea eagle [eo ean a ane Unusual egg-deposit Ge a cuttlefish. (1 Text figure) S. v. BoLeTzky INFORMATION DESK .. . . at. (ek | Sel eeu Ra What’s the Difference? —- Mutiontne of a Tagen’ EucEene V. Coan BOOKS, PERIODICALS & PAMPEMEEAS ioe cline. toy alin on) say me re arenmeniey ne . 38 ° 43 » 45 . 48 - 51 - 53 - 59 - 57 » 59 . 61 . 64 . 66 Note: The various taxa above species are indicated by the use of different type styles as shown by the following examples, and by increasing indentation. ORDER, Suborder, DIVISION, Subdivision, SECTION, SUPERFAMILY, FAmity, Subfamily, Genus, (Subgenus) New Taxa Vol. 15; No. 1 THE VELIGER Page 1 Observations on Hexabranchus from the Australian Great Barrier Reef (Gastropoda : Opisthobranchia) T. E. THOMPSON Zoology Department, University of Bristol, United Kingdom (2 Text figures) INTRODUCTION THE SWIMMING DISPLAY of Hexabranchus is one of the most splendid sights a malacologist may hope for. Despite the interest this has aroused there are great gaps in our knowledge of the genus. The normal diet is unknown, for instance, and the taxonomic situation is very confused, with dozens of proposed species. In order to help towards the solution of these problems, the present paper contains a description of the external features and anatomy of Australian specimens, together with notes on the gut contents and the swimming behaviour. These have been compared with observations on Hexabranchus by Morton (1964: Australia), GoHar & Sotiman (1963: Red Sea), ViceNTE (1963: Madagascar) and Epmunps (1968: Tanzania ). A suggested synonymy concludes the paper. Miss J. A. Langhorne prepared the drawings for pub- lication. SOURCE or MATERIAL Alive: One specimen, length 21 cm, creeping over coral sand near the reef crest at Heron Island, Capricorn Group, Australian Great Barrier Reef, June 1968. The specimen weighed 334 gr, and the pH of the skin was neutral. Preserved: Several specimens in the collections of the Queensland Museum and of Miss Isobel Bennett of the University of Sydney. Other Material: Kodachromes from life of Great Barrier Reef individuals, kindly given by Mr. D. Henderson and by Dr. L. Harris. DESCRIPTION A. External Features (Figures 1 and 2) The basic colour of the body was rich dark red, with irregular pale mottling. The rhinophoral tentacles were red-brown; the rims of the rudimentary pallial sheaths were bright red, with pale radiating markings. The pedal sole was paler in colour than the rest of the body. The oral tentacles took the form of a pair of flattened lobes (Figure 2C), with frilled edges. The gills, 7 in number, were ample and tripinnate, each being retractile into a separate pallial pit (7.¢e. phanerobranchiate). The gills twitched continuously. Within the ring of gills lay the conspicuous white anal papilla and the nephroproct (Fig- ure 2B). The colour pattern described above is that which can be seen in the creeping animal. If alarmed, however, the mantle edges are spread out and the animal takes on a vivid aspect, in marked contrast to the well camouflaged resting stage. The unrolling of the mantle margins exhib- its the white edges and brilliant purple sub-marginal zones, observable in both dorsal and ventral views. In the dorsal view can be seen an additional feature, where bril- liant red radial streaks penetrate the purple zones. There are also approximately bilaterally symmetrical slightly embossed patches of pink surrounding bright red spots; these are partially concealed when the animal is creeping (Figure 2A). Page 2 THE VELIGER Vol. 15; No. 1 fi hp, 7 Vol. 15; No. 1 THE VELIGER Page 3 B. Swimming Behaviour In swimming, the enrolled mantle skirt is spread out, dilated, and strong locomotor waves are propagated rear- wards from the anterior pallial margin. The waves are synchronous on the two sides of the body, and each wave takes about 4 seconds to travel its course. ‘Two waves are usually in progress along the sides of the body at any moment. At the same time, the body undergoes great dorso-ventral flexions, a full cycle of activity occupying about 4 seconds, Swimming may continue for many min- utes, and it is probable that this is more than a simple escape reaction. Certainly, a brilliant display of colour accompanies the unrolling of the mantle edge, and it may be that swimming here is the behavioural component of an aposematic or warning display. While swimming, the lateral edges of the foot are brought together in order to conceal the sole and the rhinophores are held back against the dorsal mantle. C. Anatomy The central nervous system was orange-pink in colour and pustulose like that of a pleurobranchomorph. The blood-gland (of uncertain function) was large and dark red, overlying the pallial nerves behind the nerve ring. A conspicuous pear-shaped gastric caecum was present. The penis was extremely large, 3 cm or more in preservative. The penial sheath was helically coiled around the narrow vas deferens. The penis was unarmed. The jaws were dark brown, lying one on each side of the oral canal. They exhibited antero-posterior wrinkles and were composed of minute rods of chitin. The radular for- mula was 48 X 91 -0-91. This is somewhat different from Red Sea specimens (40 X 60:0-60 to 60 X 78:0-78, according to GoHar « Soimman, 1963). The hooked simple teeth lacked subsidiary denticulations of any kind. D. Diet The hindgut was filled with fragments of greenish material which contained minute calcareous spicules. Dr. P. Kott kindly identified these remains as the ascidian Didemnum moseleyi Herdman. This is the first record of (< on facing page) Figure 1 Hexabranchus sanguineus A Swimming vigorously B_ The same, creeping over coral debris, Heron Island, Great Barrier Reef such a diet for Hexabranchus. Other authors have identi- fied the gut contents as sponges (Younc, 1969), or as foraminiferans, worm-tubes, and gastropod and echino- derm shells (EaLEs, 1938). DISCUSSION Many species of Hexabranchus have been proposed, but as long ago as 1909, Exior stated that “It may be doubted whether the species of Hexabranchus are for the most part more than colour varieties”. In the following year, this distinguished authority again made it clear that he doubted the validity of nearly all the claimed specific divisions (Euiot, 1910). Since that time, OsTERGAARD (1955) and Marcus & Marcus (1962) have added new proposed species of Hexabranchus but without seriously attempting to distinguish their specimens from previous described species. Indeed, apart from a minor difference in radular morphology, the only important feature distin- guishing H. morsomus Marcus & Marcus, 1962, from older described forms is the fact that it came from the Virgin Islands in the Atlantic Ocean, whereas other rec- ords had been exclusively from the Indo-Pacific. Only in GoHar & SOLIMAN’s (1963) paper is there an attempt to describe and illustrate the variations which may occur in the colour patterns within a particular sea-area. Their results support Eliot’s view that there may be only one valid species of Hexabranchus. Eymunps (1968) claimed to have detected differences in the swimming behaviour of Tanzanian specimens compared with published accounts of Australian material (Morton, 1964), but his illus- trations do not support this contention. His plate 1 (1) shows two waves on the mantle margin on each side, despite his assertion in the text of his paper that only one is present in Tanzanian material. There are thus no sub- stantial differences either in behaviour or colouration in Hexabranchus recorded from localities all over the Indo- Pacific Basin. The published records probably all refer to a single species. The name Doris sanguinea Riippell & Leuckart, 1828, appears to have priority. CONCLUSION List of Principal Synonyms of Hexabranchus sanguineus (Riuppell & Leuckart) Doris sanguinea Ruppell « Leuckart, 1828 (Red Sea) Hexabranchus proetextus Ehrenberg, 1831 (Red Sea) Doris flammulatus Quoy « Gaimard, 1832 (“fle des Amis”) Page 4 THE VELIGER Vol. 15; No. 1 Vol. 15; No. 1 THE VELIGER Page 5 Doris marginatus Quoy & Gaimard, 1832 (China, Madagascar, Red Sea, Ryukyu Islands, Japan, Caroline Islands, Mar- shall Islands, Australia [Great Barrier Reef to Abrolhos Islands], New Caledonia, Hawaii, Tonga, British Solomon Islands, Fiji, Ceylon) Doris cardinalis Gould, 1852 (Hawaii) Doris sandwichensis Eydoux « Souleyet, 1852 (Hawaii) Hexabranchus pulchellus Pease, 1860 (Hawaii) Hexabranchus pellucidulus Abraham, 1876 (unknown locality) Hexabranchus suezensis Abraham, 1876 (Red Sea) Hexabranchus aneiteumensis Abraham, 1877 (New Hebrides) Hexabranchus mauritianus Abraham, 1877 (Mauritius) Hexabranchus orbicularis Abraham, 1877 (Mauritius) Hexabranchus aneitus Bergh, 1878 (Philippines) Albania formosa Collingwood, 1881 (Formosa) Hexabranchus imperialis Kent, 1897 (Abrolhos Islands) Hexabranchus lacer Bergh, 1900 (not Cuvier, 1804) (unknown locality) Hexabranchus plicatus Hagg, 1901 (unknown locality) Hexabranchus digitatus Eliot, 1906 (Maldive Islands) Hexabranchus tinkeri Ostergaard, 1955 (Hawaii) Hexabranchus aureomarginatus Ostergaard, 1955 (Hawaii) ( Ae n> Ar 8 hour trial cs 63.23 3.91 1, 144 0.05 ST 10.84 2.67 3, 144 0.05 CT 3.00 2.67 3, 144 0.05 CST 2.63 2.67 3, 144 0.05 17 hour trial cs 84.93 3.91 1, 144 0.05 ST 17.86 2.67 3, 144 0.05 CT 6.03 2.67 3, 144 0.05 CST 10.43 2.67 3, 144 0.05 C - Condition S — Species T — Temperature (< adjacent column) Figure 2 Oxygen consumption of Acmaea fenestrata at temperatures between 10° C and 25° C. Average rates of oxygen uptake in air (OQ) and in water (@). Eight-hour trials are represented by broken lines and 17-hour trials by solid lines. Table 1 Mean Respiratory Rates for Acmaea digitalis and Acmaea fenestrata based on the pl of Oxygen consumed per gram (dry weight) per hour (pl/g/hr). The Means and Standard Deviations are included for each Temperature. 8 hour trial 17 hour trial Condition aerial aerial aquatic aquatic aerial aerial aquatic aquatic Species Acmaea digitalis Acmaea fenestrata Acmaea digitalis Acmaea fenestrata Acmaea digitalis Acmaea fenestrata Acmaea digitalis Acmaea fenestrata 10°C 413.45 + 49.98 307.84 + 85.38 293.08 + 79.23 341.88 + 65.92 332.94 + 30.01 308.93 + 60.06 262.21 + 80.12 313.71 + 69.80 15°C 561.35 + 64.36 430.66 + 90.49 361.85 + 113.14 378.39 + 77.09 494.64 + 39.92 431.76 + 64.04 333.68 + 121.16 388.56 + 85.48 20° C 718.96 + 112.09 404.41 + 92.81 404.29 + 121.86 396.14 + 108.60 621.38 + 49.92 350.37 + 106.27 326.44 + 106.66 374.83 + 75.25 25°C 730.86 + 96.82 331.44 + 103.35 437.24 + 102.42 361.36 + 86.05 695.56 + 63.77 273.26 + 104.63 309.20 + 98.36 301.11 + 42.37 Vol. 15; No. 1 THE VELIGER Page 41 to respire more actively during aerial conditions. The principal difference between trials of different time dura- tion was shown in the aquatic response (Figure 1). This difference could be influenced by a combination of tem- perature effect and duration of exposure (Orr, 1955). Acmaea digitalis may be exposed each day to desiccation and abrupt temperature changes (FRANK, 1965). This fact was the rationale for short acclimation periods. Harpin (1968) indicated 32°C as lethal for Acmaea digitalis, a value greater than our findings. However, its apparent heat coma temperature was consistent with our data (HarDIN, op. cit.). Evans (1948) observed normal metabolic activity in Patella sp. up to 30°C. Sanpison (1967) found littoral marine gastropods tolerant of 6.5° C to 22.5° C; however, between 22°C and 25°C, respiratory rates increased or became very irregular (NEWELL & NortHcrortT, 1967). Monodonta turbinata (MicaLLEF & BANNISTER, 1967), Patella aspera and P vulgata (Davies, 1966) show ir- regular respiratory rates between 25° C and 33°C. In contrast, Acmaea digitalis and A. scabra have greater oxygen consumption during aquatic conditions (BALDWIN, 1968). One factor that may explain the divergent results between Baldwin’s report and our findings is the differ- ence in experimental conditions. To simulate aerial con- ditions, Baldwin exposed his organisms to greater desicca- tion. Field observations indicate that the area under the limpets’ shells always retains sea water against the rock substrate. Thus, it seems that Baldwin’s procedure which eliminates this type of protection would surpass the nor- mal desiccation caused by exposed rock. Desiccation from exposure is an important factor for limpet survival in the mid-littoral zone (STEPHENSON & STEPHENSON, 1949). Because they are situated above the lower high tide line, many individuals are exposed twice as long per day as if they were below this level (SHort- WELL, 1950). High surf activity and a small amount of shade most accurately characterize their microhabitat. The thick shell with a high apex, narrow ventral aperture, and relatively large water storage capacity, enables Acmaea digitalis to withstand drying. Behavioral adaptations such as increased nighttime activity on submerged or dampened rocks, further facilitate existence in their harsh environment. Acmaea fenestrata, in contrast to A. digitalis, occupies a zone subject to shorter exposure periods and lower tem- peratures. Its thin, smooth shell has an almost circular ventral aperture. It follows the receding tide, and wedges its knife-like shell into the sand around and under smooth rocks where it remains moist until the return of the tide. Acmaea fenestrata is unique among limpets in this behav- ioral adaptation (Test, 1945). The data from Acmaea fenestrata concur with a state- ment by Prosser (1950) that the thermal properties of water protect and, at the same time, fix the temperature limits of aquatic animals. SUMMARY Mean respiratory rates of Acmaea digitalis were similar to those of A. fenestrata at 10°C and 15°C. Significant dif- ferences occurred at 20°C and 25°C. These higher tem- peratures appeared to exceed the tolerance of A. fenest- rata. Aerial and aquatic respiratory rates did not differ sig- nificantly for Acmaea fenestrata. Our results indicate that 15° C is the highest tolerable temperature which is within the average summer water temperature range of 8.5°C to 16°C (Kenny, 1968). ACKNOWLEDGMENTS We thank Dr. Michael C. Mix for reading the manuscript and Dr. Roger Peterson and Gerald Caton for statistical information in analysing data. Also, we wish to thank Janice Sivula and Martin Ikkanda for their aid in col- lecting animals. Various aspects of the research have been aided by a grant from the General Research Fund by the Graduate Council of Oregon State University. Literature Cited BALDWIN, SIMEON 1968. Manometric measurements of respiratory activity in Acmaea digitalis and Acmaea scabra. The Veliger 11 (Supplement) : 79-82; 3 text figs.; 2 tables (15 July 1968) Davies, PETER SPENCER 1966. Physiological ecology of Patella. I. The effect of body size and temperature on metabolic rate. Journ. Marine Biol. Assoc. U. K. 46: 647 - 658 Evans, Ronatp G. 1948. The lethal temperature of some common British littoral gastro- pods. Journ. Animal Ecology 17: 165 - 173 Frank, PETER WOLFGANG 1965. The biodemography of an intertidal snail population. Ecolo- ey 46 (6): 831 - 844; 8 figs.; 6 tables Giuson, W. E. 1963. Differential respirometer of simplified and improved design. Science 141: 531 - 532 Harpin, Dane D. 1968. A comparative study of lethal temperatures in the limpets Ac- maea scabra and Acmaea digitalis. The Veliger 11 (Supplement) : 83 - 87; 4 text figs. (15 July 1968) Jessee, WILLIAM FLoyp 1968. Studies of the homing behavior in the limpet Acmaea scabra (Gould, 1846). The Veliger 11 (Supplement): 52-54; 4 tables (15 July 1968) Page 42 THE VELIGER Vol. 15; No. 1 Kenny, Ron 1969. | Growth characteristics of Acmaea persona Eschscholtz. The Veliger 11 (4): 336 - 339; 4 text figs. (1 April 1969) Kineston, Rocer S. 1968. Anatomical and oxygen electrode studies of respiratory surfaces and respiration in Acmaea. The Veliger 11 (Supplement): 73 - 78; plt. 7; 6 text figs. (15 July 1968) Mica.tier, H. « W. H. BaNnniIsTER 1967. Aerial and aquatic O, consumption in Monodonta turbinata (Mollusca : Gastropoda). Journ. Zool. London 151: 479 - 482 Miirarp, Carot SPENCER 1968. The clustering behavior of Acmaea digitalis. The Veliger 11 (Supplement): 45-51; 4 text figs.; 1 table (15 July 1968) MILierR, ALAN CHARLES 1968. Orientation and movement of the limpet Acmaea digitalis on vertical rock surfaces. The Veliger 11 (Supplement): 30-44; 18 text figs.; 4 tables (15 July 1968) NeweE Lt, R. C. « H. R. NortHcRoFT 1967. A reinterpretation of the effect of temperature on the metabo- lism of certain marine invertebrates. Journ. Zool. London 151: 277 - 298 Orr, Pau R. 1955. Heat death. I. Time-temperature relationships in marine animals. Physiol. Zool. 27: 290 - 294 Prosser, Ciirrorp Lapp 1955. Physiological variations in animals. Biol. Rev. Cambridge Philosoph. Soc. 30 (3): 229 - 263 SANDEEN, M. I., G. C. StepHens & FE A. Brown, Jr. 1954. Persistent daily and tidal rhythms of oxygen consumption in two species of marine snails. Physiol. Zool. 27: 350 - 356 Sanpison, E. E. 1966. The oxygen consumption of some intertidal gastropods in rela- tion to zonation. Journ. Zool. London 149: 163 - 173 1967. Respiratory response to temperature and temperature tolerance of some intertidal gastropods. Journ. Exper. Mar. Biol. and Ecol. 2: 271-281 SHOTWELL, JESsE ARNOLD 1950. The vertical zonation of Acmaea, the limpet. Ecology 31 (4): 647 - 649; 3 figs. STEPHENSON, T. A. & ANNE STEPHENSON 1949. The universal features of zonation between tide-marks on rocky coasts. Journ. Ecol. 37: 289 - 305 Test, AvERY RANSOME 1945. Ecology of California Acmaea. Ecology 26 (4): 395-405 Vol. 15; No. 1 TEE VELIGER Page 43 Geographic Distribution of Pinna rugosa Sowerby, 1835 (Mollusca : Bivalvia ) and its Occurrence on Clipperton Island BY B. SALVAT ano FEF. SALVAT Ecole Pratique des Hautes Etudes, 55 Rue de Buffon, Paris, France WE HAVE RECEIVED from Mme. Bourrouilh (Laboratoire de Géologie historique, Université de Paris) some mollusks taken in the lagoon of Clipperton in 1968 by the Bougain- ville expedition organised by the Centre de Recherches du Service de Santé des Armées (C. R.S.S. A). The malacological fauna of Clipperton has been re- viewed in a previous paper (SALVAT & EHRHARDT, 1970), with a discussion of its composition and biogeographic affinities. Among the material recently received were three frag- ments of a representative of the family Pinnidae, which we were able to identify as Pinna rugosa Sowerby, 1835 because one fragment showed the characteristic muscle scar divided by a ridge inside, and the large undulation outside. Research on this species in our collection added further geographic information. The presence of a Pinna on Clipperton was indicated by HERTLEIN & ALLISON (1966: 138), who had incom- plete specimens. The mollusks known from the island (outer reefs and lagoon) number now 90 species (70 gastropods, 20 pelecypods). Pinna rugosa, as all other bivalvia collected in the lagoon of Clipperton, is only pres- ent as dead specimens. The type locality of Pinna rugosa is Isla Rey, Panama (SowerBy, 1835: 84). The species is known from Baja California to Panama; published records show it in the northwestern three-fourths of the Panamic province, where it has been cited by several authors, for example: Masitte (1895: 73); Lamy (1909: 226); HERTLEIN & Stronc (1943: 165; 1955a: 176) ; DurHAm (1950: 57); EMERSON & PurrFer (1957: 18); Keen (1958: 61; 1971: 75); OLsson (1961: 143); DuSHane et al. (1962: 42; 1967: 417; and 1968: 238). The record by Smrrit (1890: 305), cited with doubt, of P rugosa at Saint Helena Island in the eastern Atlantic probably refers to P. rudis Linnaeus, 1758. In their revision of the Pinnidae of the Atlantic, TURNER & RosEWATER (1958: 285 - 326) do not report this species at this locality. Among unidentified material in the Laboratory of Mal- acology at the Museum National d’Histoire Naturelle de Paris, we have recognized some specimens of Pinna rugosa collected in Baja California by Du Petit-Thouars in 1839 and by Leguillou in 1841, although labelled as “Cali- fornie.” In some collections of mollusks from Ecuador, made by Mr. Hoffstetter, we have found one right valve of Pinna rugosa, with a locality notation that indicates the occurrence of the species at both Manta and Salinas. This extends the range southward from Panama to lati- tude 2° S. It therefore actually ranges through most of the Panamic marine province. HorrsTETTER (1954: 23 to 24) recorded the presence of the genus Pinna, which we infer to be this species, in his list of subfossil material from the salt beds of Salinas. The offshore islands of west central America carry a predominantly Panamic molluscan fauna (EMERSON, 1967; SatvaT, 1967). This is the case with Guadalupe, the Tres Marias, and the Revillagigedo Islands (Stronc & Hanna, 1930), but no species of Pinnidae has been recorded on them. So also for the Galapagos Islands (HERTLEIN & STRONG, 1955b) and Cocos Island (HErt- LEIN, 1963). Thus, Clipperton is the only island of this group with representatives of the family Pinnidae or with Pinna rugosa. The molluscan fauna of Clipperton has an Indo-Pacific cast, for of the 90 species, nearly 50% of the 70 gastropods are Indo-Pacific, and of the 20 bivalve species 4 occur in the central Pacific, one both in the Pacific and on Panamic coasts, and 15 are exclusively Panamic in distribution. Page 44 THE VELIGER Vol. 15; No. 1 Literature Cited DuruaM, JoHN WyaTT 1950. The 1940 E. W. Scripps cruise to the Gulf of California. Part ITI. Megascopic Paleontology and marine stratigraphy. Mem. Geol. Soc. Amer. 43 (2): 1-216 DuSuane, HELEN 1962. A checklist of mollusks for Puertocitos, Baja California, Mexico. The Veliger 5 (1): 39-50; 1 map (1 July 1962) DuSuan_e, HELEN & Roy PoorMAN 1967. A checklist of mollusks for Guaymas, Sonora, Mexico. The Veliger 9 (4): 413-440; 1 map (1 April 1967) DuSuHane, HELEN & Gate G. SPHON 1968. A checklist of intertidal mollusks for Bahia Willard and the southwestern portion of Bahia San Luis Gonzaga, State of Baja Califor- nia, Mexico. The Veliger 10 (3): 223 - 246; plt. 35; 1 map (1 January 1968) Emerson, WILLIAM KEITH - 1967. Indo-Pacific faunal elements in the tropical eastern Pacific, with special reference to the mollusks. Venus 25 (3-4): 85-93; fig. EMERSON, WILLIAM KEITH & ELTON L. PUFFER 1957. Recent mollusks of the 1940 “E. W. Scripps” cruise to the Gulf of California. Amer. Mus. Novit. 1825: 1-57; 2 figs. HERTLEIN, LEo GEORGE 1963. Contribution to the biogeography of Cocos Island, including a bibliography. Proc. Calif. Acad. Sci. (4) 32 (8): 219-289; 4 figs. HerTiein, Leo Georce « Epwin C. ALLISON 1966. Additions to the molluscan fauna of Clipperton Island. The Veliger 9 (2): 138 - 140 (1 October 1966) HertLein, LEo Georce & ARCHIBALD McCLureE STRONG 1943. Eastern Pacific expeditions of the New York Zoological Society XXXII. Mollusks from the west coast of Mexico and Central America. Part IT. Zoologica 28 (19): 149 - 168; plt. 1 1955a. Marine mollusks collected during the “Askoy” expedition to Pan- ama, Colombia, and Ecuador in 1941. Bull. Amer. Mus. Nat. Hist. 107 (2): 159-318; plts. 1-3 (28 November 1955) 1955b. Marine mollusks collected at the Galapagos Islands during the voyage of the Velero III, 1931-32. pp. 111-145 in : D. Hatmos (ed): Essays in the natural sciences in honor of Captain Allan Han- cock. Univ. South. Calif. Press, Los Angeles, Califi: 1-345 HoFFSTETTER, ROBERT 1954. Moluscos subfosiles de los estanques de sol de Salinas (Pen de Santa Elena, Ecuador). Comparacion con la fauna actuel de Ecuador. Bol. Infor. Cient. Nac. Quito 62: 20-47; 2 figs. and 63: 137-170; 9 figs. Keen, A. Myra 1958. Sea shells of tropical West America: marine mollusks from Lower California to Colombia. i-xi+624 pp.; 10 col. plts.; 1700 text figs. Stanford Univ. Press, Stanford, Calif. (5 Dec. 1958) 1971. Sea shells of tropical West America: marine mollusks from Baja Stanford Univ. Press, Stanford, Calif. i- xiv+ (1 September 1971) California to Peru. 1066 pp.; ca. 4000 figs.; 22 color plts. Lamy EpovarpD 1909. Pelecypodes recueillies par M. L. Diguet dans le Golfe de Cali- fornie (1894-1905). Journ. de Conchyl. 57: 207 - 254 MasiLLE, JULES FRANGOIS 1895. Mollusques de la Basse Californie recueillis par M. Diguet. Bull. Soc. Philomathique Paris 7 (2): 54-76 Oxsson, AxeEL ADOLF 1961. Mollusks of the tropical eastern Pacific, particularly from the southern half of the Panama-Pacific faunal province (Panama to Peru). Panamic-Pacific Pelecypoda. Paleont. Res. Inst. Ithaca, N. Y, 574 pp.; 86 plts. (10 March 1961) Satvat, B. 1967. Importance de la faune malacologique dans les atolls polynésiens. Cahiers du Pacifique 11: 7 - 49; figs. 1-7; photo. 1-12 SatvatT, B. « J. RP EHRHARDT 1970. Mollusques de l’ile de Clipperton. (2) 42 (1): 223-231 Sowersy, GEorGE BRETTINGHAM 1835. Characters and observations on new genera and species of Mol- lusca and Conchifera collected by Mr. Cuming. Proc. Malacol. Soc. London: 84 - 86 SmitH, Epcar ALBERT 1890. Report on the marine molluscan fauna of the Island of St. Helena. Proc. Zool. Soc. London for 1890: 247 - 317; plts. 21 - 24 (August 1890) Bull. Mus. Nat. Hist. Nat. Stronc, ArcHIBALD McC.iure & G Dartias HANNA 1930a. Marine Mollusca of Guadalupe Island, Mexico. Proc. Calif. Acad. Sci. (4) 19 (1): 1-6 (4 June 1930) 1930b. Marine Mollusca of the Revillagigedo Islands. Mexico. Proc. Calif. Acad. Sci. (4) 19(2): 7-12 (4 June 1930) 1930c. Marine Mollusca of the Tres Marias Islands, Mexico. Proc. Calif. Acad. Sci. (4) 19 (3): 13-22 (4 June 1930) TurNeER, RutH Dixon & Jos—EpH ROSEWATER 1958. The family Pinnidae in the Western Atlantic. 3 (28): 285 - 326; pits. 149-171 Johnsonia Vol. 15; No. 1 THE VELIGER Page 45 Evidence for a Pheromone in the Marine Periwinkle, Littorina littorea Linnaeus INGRID DINTER anp PETER J. MANOS’ University of Massachusetts, Boston, Biology Department, 100 Arlington Street, Boston, Massachusetts 02167 Harvard University, The Biological Laboratories, 16 Divinity Avenue, Cambridge, Massachusetts 02138 (1 Text figure) INTRODUCTION A PHEROMONE IS A SUBSTANCE released by an animal which, if sensed by a second animal of the same species, causes a change in the probability pattern of the receiving animal’s behavior. For an excellent review of chemical communication in animals the reader is referred to an article by Witson, 1970. MATERIALS anp METHODS Specimens of Littorina littorea Linnaeus, 1758, were col- lected at the rocky shore of Nahant, Massachusetts. Fresh sea water was also collected. Experiments were performed within 3 days of the collection day. Our first attempts to set up a situation in which a specimen of Littorina littorea could “choose” to move toward another member of its species were failures due to the fact that the snail usually would not move at all. Then we took advantage of the fact that periwinkles are negatively geotropic in the dark (Kanpa, 1916). We placed the snails on plates of glass to which they adhered, set the glass at a vertical angle in an aquarium and covered the aquarium with a foil-covered, light-proof cardboard box. Under these conditions most snails moved upward. Five-gallon capacity aquaria were used for the ex- periments. Two glass test tubes (192X36mm) were at- " We wish to acknowledge the financial support of a United States Public Health Service Training Grant, 2 To1-GM 00036 (13) tached to a glass plate with waterproof electrical tape (Figure 1). A plastic platform taped 30 mm below the test tube openings served as a holder for the experimental animals. The glass plate was inserted into the aquarium and set at an angle of approximately 34° from the vertical. Figure 1 Apparatus for the demonstration of a pheromone in Littorina littorea Attracting snail is placed at top of right tube, test snail is placed on starting platform Page 46 THE VELIGER Vol. 15; No. 1 The tubes and aquarium were filled with seawater. Usu- ally an experiment was run with a series of 10 test snails. A snail was placed on the platform and allowed to move up the plate or into the left or right tube. Fifty-six percent of all snails run entered a test tube. All the data presented in this report are for snails which entered one tube or the other. At the beginning of the series the water tempera- ture was 7° C, at the end 14+2° C. All experiments were performed in darkness. EXPERIMENTS anp RESULTS Experiment 1 was intended to show if Littorina littorea demonstrated any preferred direction of movement with no guiding stimulus present. The tubes were filled with fresh seawater, a periwinkle placed on the platform by hand, and the aquarium covered. After 10 minutes the box was removed and the position of the snail recorded. The snail was then marked, measured, and its sex identi- fied (Linke, 1933; FrETTER & GraHaM, 1962). A new snail was placed on the platform and the experiment re- peated. Whenever a snail entered a tube, the glass plate and tubes were replaced with fresh ones in order to eliminate any possibility of build-up of substances within the tubes. The results showed that Littorina littorea has a strong tendency to move to the left side (Table 1). Of the females 84% (39 out of 46) and of the males 75% (24 out of 32) entered the left tube. Since periwinkles naturally tended to move to the left, we set up Experiment 2 in which an “attracting” snail was placed into the right tube and allowed to adhere. Both tubes were filled with seawater and rubber stoppers prevented convection currents from mixing the water in the tubes with that in the rest of the aquarium. The rationale was to allow any substance emitted by the “‘at- tracting” snail to become concentrated within the right tube. After one hour the stoppers were removed and the experiment conducted as before. Each time a snail entered a tube it was carefully removed by prying it loose with a spatula. If it went into the left tube, the water was blown out with rubber tubing and the test tube then re- filled. The results of this experiment showed that when a snail was present in the right tube other snails exhibited a strong tendency to enter that tube (Table 1). Of the females 62% (31 out of 50) and of the males 66% (26 out of 39) entered the right tube. To demonstrate the statistical significance of the difference between experi- ments 1 and 2 we assumed that there was no expected difference (the null hypothesis) and calculated the chi- square value on this assumption (Table 1). The probabil- ity that these results occurred by chance alone is less than 0.005. Experiment 3 was designed to eliminate the possibility that the test snail was being attracted into the right tube by other than chemical stimuli. A specimen of Littorina littorea was inserted into the right tube and left for 5 hours. Both tubes were stoppered. The snail was then re- moved from the tube to insure that only the pheromone, if present, would be attracting other snails. This experi- ment was then performed like Experiment 2. The results again showed that snails preferentially entered the right tube (Table 1). Comparing these re- sults with those of Experiment 1, using the null hypothesis, shows that this distribution of data would occur by chance with a probability of less than 0.005. Table 1 Preferential Entry of Left or Right Tube Number of snails entering left tube right tube Experiment 1 . 6, an Experiment 2 32 57 Experiment 3 3 11 for Experiments 1 and 2, X?=32.2, p< 0.005 for Experiments 1 and 3, X?=17.8, p<0.005 DISCUSSION Even a cursory glance at Table 1 gives the impression that snails are attracted into the right tube in Experi- ments 2 and 3. When these results are compared, using the null hypothesis, with the results of Experiment 1, the statistical significance of the results is even clearer. In both cases these results could be expected to occur by chance only 5 times in 1000 trials. The simplest hypothesis which explains these results is that Littorina littorea emits a substance (or substances) which attracts other snails. A total of 321 specimens of Littorina littorea were test- ed. It was demonstrated that periwinkles have a strong tendency to move up to the left in the dark. It is of interest to compare this observation with that made by Hayes (1929) on L. littorea moving on a horizontal sur- face: “It may be said that the individuals appeared to be totally indifferent as to which way they turned . The fact that the shells are dextral appears to have no effect in determining such activities.” Either an unequal Vol. 15; No. 1 THE VELIGER Page 47 distribution of weight or the snails’ inherent dextrality might explain why, in Experiment 1, 4 times as many snail moved to the left as to the right. We found no significant difference in the ability of males or females placed in the right tube to attract either males or females. We did note, however, a tendency for a higher percentage of snails to enter the right tube (in either Experiment 2 or 3) as the season changed from early March to early May. It is of interest that spawning takes place in March, April, and May, in this species (Linke, 1933; FrETTER & GRAHAM, 1952; WILLIAMS, 1964; 1970). After this period the reproductive organs of males and females are reduced to a minimum size and develop again the following spring. Snails ranging from 7.8mm to 13mm in height of shell never entered a right tube, seldom a left tube, instead usually moved to the right or the left of the glass plate. It has been shown that only rarely do specimens below 11 to 12 mm in shell height attain sexual maturity (WIL- LIAMS, 1970). Snails ranging from 13 to 26 mm in shell height entered the right tube in Experiment 2 and Ex- periment 3. These facts along with the observation that a higher percentage of animals moved into the right tubes as the mating season progressed indicate that a sex pheromone may be involved. Literature Cited FRETTER, VERA & ALASTAIR GRAHAM 1962. British prosobranch molluscs, their functional anatomy and eco- logy. London, Ray Soc. xvi+755 pp.; 316 figs. Hayes, FE R. 1929. Contributions to the study of marine gastropods III. Develop- ment, growth and behavior of Littorina littorea L. Contr. Canad. Biol. Fish. N. S. 4: 413 - 430 Kanpa, SAKYO 1916. Studies on the geotropism of the marine snail, Littorina littorea Ee Biol. Bull. 30: 57 - 84 LINKE, OTTO 1933. Morphologie und Physiologie des Genitalapparates der Nordsee- littorinen. Komm. Wissensch. Unters. deutsch. Meere 19: 1 - 60 (December 1933) WI.uiaMs, E. E. 1964. Growth and distribution of Littorina littorea L. on a rocky shore in Wales. Journ. Animal Ecol. 33: 413 - 432 1970. Seasonal variations in the biochemical composition of the edible winkle Littorina littorea L. Comp. Biochem. Physiol. 33 (3): 655 to 661 (4 April 1970) Witson, Epwarp O. 1970. Chemical communication within animal species. In: ERNEST SoNDHEIMER & JOHN B. Simeone (eds.): Chemical ecology. Acad. Press, London Page 48 THE VELIGER Vol. 15; No. 1 The Mucus Holdfast of Littorina irrorata and its Relationship to Relative Humidity and Salinity FRASIER O. BINGHAM Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida 33149" (7 Text figures) INTRODUCTION THE SALT MARSH PERIWINKLE, Littorina irrorata (Say, 1822), is common in salt marshes along the eastern coast of the United States from New York State to central Flor- ida, and along the northern coast of the Gulf of Mexico. The species shows a disinclination to remain submerged and is usually found attached, by dried mucus, to marsh grasses above the water level, or foraging on marsh floors exposed at low tide. Many other members of the family Littorinidae have, as well, been noted to employ a small amount of dried mucus (or holdfast) for attachment of the shell to sub- strates during periods of air exposure. During a recent study of the species’ behavior (BiNc- HAM, in press), the process of holdfast formation, and the relationship of holdfast formation to relative humidity and salinity were observed. HOLDFAST FORMATION The animal assumes a spire-down position (Figure 1) before secretion of the holdfast is begun and then, with the anterior end of the pedal sole, performs a single slow sweep of the uppermost interior portion of the shell lip. This action is depicted in various stages in Figure 2, and was completed in an average time of 94 minutes by 20 specimens. Re-orientation into the spire-down position, when the vertical substrate was inverted, was seen so long as the pedal lick had not begun. After the pedal lick had started, inversion of the substrate did not visibly affect " Contribution No. 1479 from the University of Miami, Rosenstiel School of Marine and Atmospheric Science, 10 Rickenbacker Causeway, Miami, Florida 33149 Figure 1 Normal spire-down position of Littorina irrorata holdfast formation, and an unstable position, as seen in Figure 3, resulted. The holdfast consists of 2 semicircular films of mucus attached to the substrate and joined along a line of shell attachment (Figure 4). This line is shown in Figure 5 to lie slightly within the shell lip. EFFECTS or RELATIVE HUMIDITY In studying the effects of various relative humidities on the latency of holdfast formation, 50 adult specimens were kept submerged in ambient sea water of 33%, salinity for 1 hour, dried with a paper towel, and 10 each placed in 5 jars of one gallon capacity containing stable relative hu- midities of 0%, 25%, 50%, 75%, and 100%. These hu- Vol. 15; No. 1 THE VELIGER Page 49 Figure 2 Stages in pedal sweep during holdfast formation foot operculum **%* region in which holdfast is formed Figure 4 Holdfast of Littorina irrorata Figure 3 Unstable attached position as viewed from above midities were created by placing in each jar a bowl con- taining sulphuric acid solutions of known concentrations and a known constant temperature (25° C), according to the method described by Satomon (1951). The length of time before each specimen was seen to complete a holdfast was noted and the average time in each group calculated. All of the specimens in relative humidities of 75% and below formed holdfasts, with each group forming them in a shorter average time than the group kept at the next higher level of relative humidity (Figure 6). None of the specimens kept in the 100% A as seen through a glass substrate B as seen with animal removed X line of shell attachment Figure 5 Holdfast of Littorina irrorata, cross section A shell B_ point of shell attachment Cc holdfast D substrate relative humidity atmosphere formed a holdfast during 3 days of observation. EFFECTS or SALINITY In the determination of salinity effects on holdfast forma- tion, 140 specimens which had been kept submerged in ambient sea water of 33%, salinity for one hour, were placed, 10 each, in 14 different salinities ranging from that of tap water to 75%. The solutions were aerated and ) Relative Humidity (% THE VELIGER Vol. 15; No. 1 Ot Bo Gye OPO 7 B QV M9 MT Latency in hours Figure 6 Latency of holdfast formation as related to relative humidity maintained at a temperature of 25+1° C. Plastic screen cages were used to keep the snails submerged. Low salinity solutions were prepared with sea water and distilled water. Solutions of higher than normal sea water salinity were prepared by evaporation of sea water. Salinity deter- minations were made with a Goldberg refractometer. 100 90 ) ©2)- Si (ee) S OC. © Snails Forming Holdfast (% wn o 0 5 Salinity (%) Figure 7 Occurrence of holdfast formation as related to salinity 12 13 14 15 16 10 15 20 25 30 35 40 45 50 55 60 65 70 75 In Figure 7, which illustrates the relationship of hold- fast formation and salinity, it may be noted that at only one salinity — that of tap water — did all of the snails form a holdfast; therefore, the percentage of snails form- ing holdfasts is presented rather than the latency of hold- fast formation. No holdfasts were formed (during 3 days of observation) by the specimens maintained in the 10 to 45%, salinity range. Above 45%, salinity, the percentage of specimens forming holdfasts increased as salinity increased. Below 10%. salinity the percentage of specimens forming hold- fasts increased as salinity decreased. DISCUSSION The holdfast is seen as a valuable adaptation to the supra- littoral environment in that it affords a means of main- taining position without continued exertion and leaves the snail free to withdraw into its shell to escape environ- mental stress conditions, such as low relative humidity or low and high salinities when such salinities cannot be avoided through upward movement. In this study, the holdfast was formed only during un- favorable conditions and was secreted under water as well as in the air. Upon appropriate stimulation, the holdfast was disposed of through feeding movements of the pro- boscis and radula. Literature Cited BincHaM, FRASIER O. In Press. The influence of environmental stimuli on the direction of movement of the supralittoral gastropod Littorina trrorata. Bull. Mar. Sci. Satomon, M. E. 1951. Control of humidity with potassium hydroxide, sulphuric acid, or other solutions. Bull. Entomol. Res. 42: 543 - 554 Vol. 15; No. 1 THE VELIGER Page 51 Morum dennisoni Reeve (Gastropoda : Cassidae) and Strombus costatus Gmelin (Gastropoda : Strombidae) Collected Off the North Carolina Coast EDWARD J. PETUCH Department of Zoology, University of Wisconsin — Milwaukee, Milwaukee, Wisconsin 53201 (1 Plate) Four ADULT SPECIMENS of Strombus costatus (Gmelin, 1791) and a juvenile specimen of the rare Morum denni- soni (Reeve, 1842) were collected off the North Carolina coast during the month of August, 1971. These exciting finds extend the ranges of these two Caribbean species well into the Carolinian Province. Previously, the northern limit to the range of S. costatus was fixed as southeast Flor- ida (Aszortt, 1954; 1961; Morris, 1951; WARMKE & AB- BOTT, 1961). From there it extends into the southern Gulf of Mexico and the Caribbean area where it is a common species. Morum dennisoni has been previously reported as far north as Great Inagua Island and Stranger’s Cay in the Bahamas, off Tarpon Springs and Pensacola, Flor- ida, and SSE of Freeport, Texas (DANCE & EMERSON, 1967). Its center of distribution appears to be the South- ern Caribbean (WaRMKE & ABzorTT, op. cit.). To find it in a dredge off North Carolina was quite a surprise. The 4 specimens of Strombus costatus were collected at two dredging stations by the Duke University Marine Laboratory research vessel Eastward on cruise number E-20-71. These stations were Eastward station no. 17663, with coordinates 33°31.8’N, 77°22.4’W, and Eastward station no. 17666, with coordinates 33°30.7’ N, 77°24.4’ W. The former took place at 11:50 pm on August 3, the latter at 1:30 am on August 4. Both stations were approx- imately 5.7 miles north of Frying Pan Light, off Cape Fear, North Carolina. The samples were dredged at a depth of 25 m, and the bottom temperature was 21-22° C. Judging from the dredge contents, the substrate appeared to be composed of marl heavily encrusted with living Arca zebra Swainson, 1845, the red alga Eucheuma sp., and occasional heads of the tropical reef corals Solen- astrea hyades (Dana, 1848) and Siderastrea siderea (Ellis & Solander, 1848). Two live specimens were taken at station 17663, while one live and one dead specimen were taken at station 17666. The first specimen collected at station 17663 was the largest, measuring 154 mm in length and 99 mm in width. It was an old adult, as the outer lip was heavy and thick with a silvery glaze. The other specimen, a mature adult, measured 125 mm in length and 77 mm in width. Of the specimens collected at sta- tion 17666, the largest one was a mature living adult, with a well-developed lip, and measured 128 mm in length and 78mm in width. The smaller one, measuring 110mm in length and 68 mm in width, was a dead specimen occupied by a hermit crab. This was a mature specimen with a well- developed but thin lip. The individuals collected con- formed to the general description of Florida and Carib- bean specimens and showed no apparent deviations from the typical Strombus costatus (Figure /). The Morum dennisoni collected measured 40 mm in length and 24 mm in width (Figure 2). It was taken at Eastward station 17663 along with the 2 live Strombus costatus and a live Cypraea cervus Linnaeus, 1771. Al- though it was a juvenile specimen, collected dead and occupied by a hermit crab, there can be no doubt as to its identity. It conforms to the descriptions and illustra- tions in the literature (DaNncE, 1966; DANcE & EMERSON, 1967), and shows no distinct differences from other re- corded specimens. Altogether, these 5 individuals represent a very inter- esting and important find. The North Carolina specimens of Strombus costatus and Morum dennisoni extend the range of these species northward by an appreciable dis- tance. At present, their extreme northern limit appears to be the Cape Fear area. However, future dredgings Page 52 THE VELIGER Vol. 15; No. 1 might extend the range further northward to off Cape Lookout and the Onslow Bay area. Here there are out- croppings of tropical reef corals offshore (MACINTYRE & Pitxey, 1969) where many tropical molluscan species such as C'ypraea cervus, C. spurca acicularis Gmelin, 1791 (D. Wore « N. Wotre, 1970); Cassis madagascariensis spinella Clench, 1944 (Apsott, 1954; Porter, 1965; D. Wotre & N. Wo tre, 1970), Conus juliae Clench, 1942, and Lyropecten nodosus (Linnaeus, 1758) (Assorrt, 1954, 1961; WarMKE & ApporT, 1961) are regularly taken. ACKNOWLEDGMENTS I would like to thank the following persons: Dr. Richard B. Searles, Professor of Botany, Duke University, for allow- ing me to take part in the R/V Eastward cruise; for critical reading of the manuscript and helpful suggestions I am indebted to Ronald Mollick, Christopher Newport College, College of William and Mary, and Kimberly Matthews, Duke University. I also acknowledge the sup- port of the Oceanographic Program of Duke University Marine Laboratory for use of the R/V Eastward on cruise E-20-71. The Oceanographic Program is supported by the National Science Foundation Grant no. GA-27725. Literature Cited AxpBotTT, Ropert TUCKER 1954. American seashells, Princeton, New Jersey. D. van Nost- rand Co., Inc.; xiv+541 pp.; 40 plts.; 100 text figs. 1961. How to know the American marine shells. New York. Signet Key paperback; 222 pp.; 12 plts. in color; 402 text figs. Dance, STANLEY PETER 1966. Shell collecting; an illustrated history. Univ. Calif. Press, Berkeley and Los Angeles: 344 pp.; 35 plts.; 31 text figs. Dance, STANLEY PETER & WittIAM KeirH EMERSON 1967. Notes on Morum dennisoni (Reeve) and related species (Gast- ropoda : Tonnacea). The Veliger 10 (2): 91-98; plt. 12 (1 October 1967) Macintyre, Ian G. & Orrin H. PILKEY 1969. Tropical reef corals: tolerance of low temperatures on the North Carolina Continental Shelf. Science 166 (3903): 374-375; 3 text figs. (17 October 1969) Morris, Percy A. 1951. A field guide to the shells of our Atlantic and Gulf coasts. Houghton Mifflin Co. Inc., Boston, Mass. iii+236 pp.; 45 plts. Porter, Hucu J. 1965. Cassis madagascariensis spinella off the North Carolina coast. The Nautilus 78 (2): 106 WarMkE, GERMAINE L. & RopertT Tucker ABBOTT 1961. Caribbean seashells; a guide to the marine mollusks of Puerto Rico and other West Indian islands, Bermuda and the lower Florida Keys. Livingston Publ. Co., Narberth, Pa. x+345 pp.; 44 plts.; 34 text figs. Wo tre, Douctas A. & Nancy WOLFE 1970. Molluscs of North Carolina. Beaufort, North Carolina; a check list published by Center for estuarine and Menhaden research. U. S. Bur. Comm. Fisheries, with regional marine sci. proj. 69 pp.; 1 fig. Plate Explanation Figures J and 2: Strombus costatus (Gmelin 1791) Figures 3 and 4: Morum dennisoni (Reeve, 1842) [PErucH] Figures / to 4 Figure 2 Figure 4 Figure 1 Tue VE LIcER, Vol. 15, No. 1 Vol. 15; No. 1 THE VELIGER Page 53 Range Extensions of Conualevia alba Collier & Farmer, 1964 BY ANTONIO J. FERREIRA Beta Research Oceanographic Laboratories, Inc., 2060 Clarmar Way, San Jose, California 95128 Conualevia alba Collier & Farmer, 1964, was first de- scribed from the rocky mud flats of Newport Bay (lat. 33°36’N, long. 117°54’W) where it was found to occur rather abundantly during the months of November and December. Lance (1966) reported finding this crypto- branch at Point Loma, San Diego County (lat. 32°40’ N, long. 117°14’W) and under stones at Bahia Tortuga, Baja California, Mexico (lat. 27°41’N, long. 114°53’ W) along the outer coast of Lower California. A range ex- tension north from Newport Bay was recorded by SPHON & Lance (1968) with the observation of C. alba at Taji- guas (lat. 34°20’N, long. 120°08’ W) and Coal Oil Point, Santa Barbara County, California, in 15 to 30 feet [4.5 to 9 m|] of water. The collections reported here extend the known range of Conualevia alba substantially both to the north and to the south, and to depths not hitherto indicated. The first specimen of C. alba was found under a fairly large stone in the intertidal zone on the northern side of Bahia de Banderas, Nayarit, Mexico (lat. 20°40’N, long. 105°17’ W) on March 21, 1971 while we were collecting at Man- zanilla. In all of its external features, this specimen con- formed well to the original description. However, the animal was 10-gilled-bipinnate (not 8-gilled-tripinnate, as indicated in the original description) ; also it was con- siderably larger than previously reported specimens, measuring 30 mm in length and 24 mm in width while at rest on a rock, whereas Collier & Farmer’s largest speci- man was said to have been 24X14mm while actively crawling. The notum of the Nayarit specimen was uni- formly papillose (Collier & Farmer noted that the notum of these animals is quite variable, in some entirely smooth, papillose in others) with papillae about 0.1 - 0.2mm in diameter. Around the margin of the notum there were several white glands in a row, more abundant on the right side. This specimen has been deposited with the Califor- nia Academy of Sciences, Department of Invertebrate Zoology (CASIZ) collection, together with 35mm color slides (CASIZ nos. 2573 - 2577, incl.). The northerly find occurred on August 19, 1971, at Cypress Point (lat. 36°35’N, long. 121°59’W), Pacific Grove, Monterey County, California. While SCUBA- diving with Gene Daily and Robert Western, Sr., from the R/V Kiwi, as part of the research activities of the Beta Research Oceanographic Laboratories, we came across a small white dorid that later was identified as Conualevia alba. The animal was found in 50 feet [15 m] of water on a rocky substratum covered mostly with coralline algae. The time was about noon, on a very calm but overcast day. The specimen measured 12*7 mm while crawling actively. However, when disturbed, the animal was observed to stop and contract, becoming virtually circular with dimensions of 9X9mm. The notum was papillose, with papillae closely set, uniform in appearance and size (0.1 - 0.2 mm). The body was quite translucent, and under appropriate tangential light it seemed as if light-catching white lines (spicules?) tended to converge towards the papillae, making for a star-like effect. The rhinophores were smooth, rounded at the tip, yellowish in color, and when fully extended about 1 mm in length and 0.3 mm in average width. Along the right border of the notum there were about 6 white dots (glands) in a row. In all respects, then, the specimen corresponded to the original description of Conualevia alba, with only one notable exception: the gill branches, 8 in number, were unipinnate instead of tripinnate. On August 22, 1971 a second specimen was found, in Monterey Bay. While SCUBA-diving from the Janss Foun- dation’s R/V Searcher, a specimen was found in 55 feet [16.5 m] of water on Chase Reef, slightly east of Aumen- tos Rock (lat. 36°38’ N, long. 121°55’ W) in Monterey Bay. The animal was motionless, clinging to the under- side of a rock. It was virtually identical with the one found at Cypress Point. In the laboratory it measured 13 mm in length, 7mm in width, and 3.5mm in height. It had numerous glands along the margin of the notum, on both sides, showing as conspicuous opaque white dots measuring as much as 0.3mm in diameter. The gills were 9-branched, unipinnate. Both specimens were kept alive in the laboratory for 4 days prior to being preserved. During this, time they were seen crawling about very slowly, their speed never ex- Page 54 THE VELIGER Vol. 15; No. 1 ceeding 1 cm per minute, They were also observed float- ing upside down, suspended from the water surface for long periods. Both specimens have been deposited in the California Academy of Sciences, Department of Invertebrate Zoolo- gy collections, together with 35 mm color slides (CASIZ nos. 2578 - 2582, incl.). Marcus & Marcus (1967) indicated that the genus Conualevia seemed to be restricted to the coast of Cali- fornia south of Point Conception. The observations here reported extend the range of Conualevia alba some 1000 miles [1600 km] to the south and 350 miles [560 km] to the north of the previously reported range (LaNcE, 1966; SPHON & Lance, 1968; Keen, 1971) to waters much colder and depths much greater than heretofore known. The specimens here reported did not quite completely conform to Collier & Farmer’s description as to the num- ber of branches and division of the gills. Whether these variations in the branching and pinnation of the gills are of taxonomic significance remains to be seen. ACKNOWLEDGMENTS The help and assistance provided by Hans Bertsch and Allyn G. Smith in the pursuit of this and other work is appreciated and hereby acknowledged. Literature Cited Couuier, Ciinton L. & WESLEY MERRILL FARMER 1964. Additions to the nudibranch fauna of the east Pacific and the Gulf of California. Trans. San Diego Soc. Nat. Hist. 13 (19): 377 - 396; plts. 1-6; 3 text figs. (30 December 1964) Keen, A. Myra 1971. Sea shells of tropical West America: marine mollusks from Baja California to Peru. Stanford Univ. Press, Stanford, Calif. i- xiv+ 1066 pp.; ca. 4000 figs.; 22 color plts. (1 September 1971) Lance, JAMES ROBERT 1966. New distributional records of some northeastern Pacific opistho- branchiata with descriptions of two new species. The Veliger 9 (1): 69-81; 12 text figs. (1 July 1966) Marcus, EvELINE Du Bots REyMonp & ERNST Marcus 1967. American opisthobranch mollusks. Studies in tropical oceano- graphy (Univ. Miami Inst. Marine Sci., Miami, Florida), no. 6: viii+ 256 pp.; figs. 1- 155 + 1-95 (December 1967) SpHon, Gate G. & James Rosert LANCE 1968. An annotated list of nudibranchs and their allies from Santa Barbara County, California. Proc. Calif. Acad. Sci. (4) 36 (3): 73 - 84; 1 text fig. (25 September 1968) Vol. 15; No. 1 THE VELIGER Page 55 Stenoplax circumsenta Berry, 1956, in the Gulf of California ANTONIO J. FERREIRA Beta Research Oceanographic Laboratories, Inc., 2060 Clarmar Way, San Jose, California 95128 (1 Plate) THE SAND FLATS west of Isla Concha, Scammon’s Lagoon (lat. 27°50’ N; long. 114°20’W), Baja California, were considered as type locality for Stenoplax circumsenta Berry, 1956. The holotype bears the number 13 602 in the Berry collection, and paratypes have the number 13 627 in the same collection. The Puritan-American Expedition of 1959 collected two more specimens from the east side of Isla Concha (Station P-5, at a depth of 4 feet [1.2 m]) which, preserved in alco- hol, now bear the number 10056 in the A. G. Smith collection at the California Academy of Sciences in San Francisco. To date, the species has never been illustrated. KEEN (1958, 1971) makes no mention of this species in either edition of “Sea Shells of Tropical West America.” On October 25, 1970, at Bahia de San Gabriel (lat. 24°26’N, long. 110°21’W), Isla Espiritu Santo, in the Gulf of California, I came across, on the underside of a rock in some 3 feet [90cm] of water, a specimen of Stenoplax decidedly different from the rather common S. limaciformis (Sowerby, 1832). The specimen was brought to the attention of Mr. Allyn G. Smith, Associate Curator, Department of Invertebrate Zoology, California Academy of Sciences, who identified it as Stenoplax circumsenta Berry, 1956. This particular specimen meas- ured in the dried state 25 X94 mm. The shell valves were a mottled dark gray; the girdle was characterized by the presence, in addition to minute scales, of numerous trans- lucent spinelets of triangular outline, sharply pointed, which give the girdle a rather rough appearance. On July 11, 1971, two more specimens of Stenoplax circumsenta were found, again under stones in two feet [60cm] of water at Pichilinque (lat. 24°15’N, long. 110°17’W) some 17 km east of La Paz, Baja California. Once dried, their sizes were 26X11 mm and 27X10 mm, respectively. At this point it became tempting to speculate that Stenoplax circumsenta was to be found only at shallow depths and in calm and very protected waters — the common features of the localities: Scammon’s Lagoon, Bahia de San Gabriel, Pichilinque, where the species had so far been found. The validity of this theory was put to a test on a sub- sequent collecting trip to La Paz and the Gulf of Cali- fornia. On September 1, 1971, an attempt was made to collect the species again in the Bahia San Gabriel (Isla Espiritu Santo), and in Pichilinque and adjacent coves. But an effort equivalent to 8 man-hours of search under rocks (mostly snorkeling) did not turn up any specimen of Stenoplax circumsenta among more than 200 chitons sighted. However, a few days later, while on a fish collecting expedition with the Steinhart Divers for the California Academy of Sciences aboard the R/V Marisla II a speci- men of Stenoplax circumsenta was found unexpectedly. Alone, under a turnable stone in 50 feet [15 m] of water, the specimen measured, when dried, 19X9mm. The locality was the reef that stretches out from the southwest corner of Isla Partida (lat. 24°32’N, long. 110°24’ W), some 20 nautical miles N of La Paz, Baja California. The waters over the reef, although calm and serene at the time of collecting, in no way evoked the image of being “protected” in the way it could be said of Scammon’s Lagoon, Bahia San Gabriel, or Pichilinque; and the depth at which the specimen was located was certainly much greater than for the specimens previously collected. The colors of the specimens reported here are varied: two specimens are creamy, speckled with brown and gray; one is mostly a rusty brown with minute whitish specks; another is a dark gray variously suffused with white. Inside, the valves are intensely pink and blue in 3 specimens; in the other specimen the inner surfaces of the valves are white with blue triangular areas in valves ii, iv, and v. The first specimen of Stenoplax circumsenta collected in the Gulf of California, at Bahia de San Gabriel, Isla Espiritu Santo, November 1970, was deposited with the California Academy of Sciences and is now part of the collection in the Department of Geology (loc. no. 45418). Page 56 THE VELIGER ACKNOWLEDGMENT I wish to express my gratitude to Allyn G. Smith for his invaluable help in the preparation of this report, and for the kind teaching with which he has so enriched my interest in invertebrates. Literature Cited Berry, SAMUEL STILLMAN 1956. Diagnoses of new eastern Pacific chitons. Leafl. Malacol. 1 (13): 71-74 (19 July 1956) Keen, A. Myra 1958. Sea shells of tropical West America: marine mollusks from Lower California to Colombia. i-xi+624 pp.; 10 col. plts.; 1700 text figs. Stanford Univ. Press, Stanford, Calif. (5 Dec. 1958) 1971. Sea shells of tropical West America: marine mollusks from Baja California to Peru. Stanford Univ. Press, Stanford, Calif. i - xiv+ 1066 pp.; ca. 4000 figs.; 22 color plts. (1 September 1971) Vol. 15; No. 1 THe VELIGER, Vol. 15, No. 1 [FERREIRA] Figures /, 2 Figure 1 Figure 2 Figure 1: Stenoplax circumsenta Berry, 1956. Pichilinque, Baja California, A. J. Ferreira, coll., July 1971. Length 27 mm Figure 2: Enlarged view of a portion of the girdle, showing the characteristic triangular spinelets photographs by A. J. FERREIRA Vol. 15; No. 1 THE VELIGER Page 57 Observation of the Glochidium, Metamorphosis, and Juvenile of Anodonta californiensis Lea, 1857 BY PETER N. D’ELISCU Department of Biological Sciences, University of Arizona, Tucson, Arizona 85721 (1 Plate; 1 Text figure) Anodonta californiensis Lea, 1857, is a bivalve inhabitant of freshwater ponds with muddy bottom substrates and lotic conditions. The specimens used in this study of its larval and juvenile biology were collected from Santa Ana Creek, a tributary of the Pajaro River, near Hollister, California. The observations were carried out at San Jose State College. The glochidia larvae of Anodonta californiensis possess teeth at each shell lip and a moderately long attachment thread. A single adductor muscle is also present. The 0.2mm larvae proved surprisingly hardy. Glochidia main- tained in unaerated, ice-bath cooled water at 15 to 16°C survived up to 36 hours. Infestation possibilities are surely enhanced by this long free-state viability of an eventual obligate parasite. When these larvae become attached to gill arches and filaments, fins, or barbules of a host fish, a chemical action is initiated. The usual response of the host to the parasite is tissue proliferation at the attachment site. Rapid growth of tissue at the site covers the parasite and a cyst is formed around it. Several mosquito fish, Gambusia affinis (Baird & Girard, 1839), were employed as artificial hosts in this study. LEFEVRE & Curtis (1908) found the Anodontinae not very host-specific. They found North American species of the bivalve subfamily able to utilize as hosts any number of common fresh-water fish, including various bass, trout, many perch-like fishes, and some catfish. Artificial infes- tation of the mosquito fish was accomplished by main- taining them for several hours in vigorously aerated water suspending many glochidia removed from a live, gravid female clam. Permanent attachment areas on this host included the gills, opercular edge, and all fins. Encyst- ment, measured from the time of attachment to cyst completion, required 3 to 44 hours at 20° C. The length of the parasitic period following excystment is variable, depending upon temperature. Anodonta cali- forniensis remained encysted on Gambusia affinis for 26 to 27 days at an average temperature of 20°C. The ex- cystment period for the juveniles ranged over two days, corresponding to the findings of LEFEVRE & Curtis, 1908. They showed that spring infections from winter-breeding Unionids, including Anodonta, often result in narrow-span excystment periods. Excystment marks the completion of a metamorphosis. The morphologically infective glochidium is transformed into an early juvenile clam, possessing some adult charac- teristics and organs. The structures evident at this stage include the paired, trilobed livers or “digestive glands;” two prominent adductor muscles; a mantle with a ciliated edge; a bilobed, ciliated foot possessing an adhesive struc- ture (byssal gland) ; and one pair of gills. The siphons and immature gonads noted by various observers were not evi- dent in the juvenile Anodonta californiensis. The glochid- ial shell teeth and attachment thread are lost during metamorphosis. The byssal gland is lost early in adult life, Howarp (1914: 46) mentions that the outer gills in Anodonta are not acquired until the second year of growth. This latter set of gills is important in the Anodontinae as female marsupia, holding many developing glochidia during reproduction. The long marginal shell hinge of the glochidium becomes more apical and concentrated in the early juvenile (Figure 1 and Figure 2). Behavior and growth of the juvenile stage was noted upon excystment. The foot of the young clam was long and ciliated. The foot could be extended more than twice the length of the clam shell. When the foot was extended, the antero-apical cilia began to beat. The ciliary activity ceased when the foot attached to the substrate. Rapid contraction of the foot after attachment caused the body Page 58 Figure 1 Early excysted juvenile — longitudinal view with left valve removed h — hinge; cf — ciliated foot; dg — digestive gland; g-gill; am — adductor muscle mass to be pulled forward. The valves were maintained open at an angle of about 45° during movement, but could be closed quickly when the animal was disturbed or overturned; the small clam righted itself with the aid of the cylindrical, adhesive foot. Juvenile growth studies revealed a very rapid rate. An average daily increase of 0.15mm (long axis) amounted to an 840% increase in size over a 14 day period. This growth rate correlates with the results of Howarp (1922: 69-70), investigating the growth rates of another Unionid, Lampsilis luteola Lamarck, 1819. The overall growth rates of the juveniles of both Anodonta californiensis and L. luteola were about 50 times that of the larger adults. Following the discovery that the larval stages of many fresh-water clams are parasitic on fish, many attempts were made to raise adults in captivity. These efforts were directed toward providing a food source, shell material for the once active “pearl button” industry, and informa- tion concerning the effects of glochidia on the fresh-water THE VELIGER Vol. 15; No. 1 fisheries. No particular difficulty was experienced in carry- ing certain species through the parasitic stage, but few investigators were able to maintain the clams through the juvenile stage to reproductive or harvestable adulthood. Artificial propagation experiments, in which fish were mechanically infested with glochidia and released, ap- peared ineffective. Survival of the juveniles depended solely on the chance that the host fish would be over the proper habitat conditions at the time of excystment. Studies by Isery (1911) and D’Euiscu (1970 MS) showed that few or no juveniles live in the observed adult habitat. Juveniles were difficult to collect for many species, in- cluding Anodonta californiensis. The juveniles of some species possess byssal glands and inhabit loose gravel, while the adults live in deep mud or sand (Howarp, 1914: 8). The morphology, physiology and difficulty of collection of the juvenile stage seem to indicate occupation of an en- tirely different habitat from that of the adult. This sepa- ration of different age groups may be similar to marine bivalve forms with motile larvae that do not compete directly with adults for food. Direct implantation of ex- cysted Unionid juveniles into their specific habitat re- quirements would greatly facilitate increased production in terms of individual survival rates. Literature Cited Howarp, ARTHUR Day 1914. Experiments in the propagation of freshwater mussels of the Quadrula group. U.S. Bureau Fish. Doc. 801; 1 - 52 1922. Experiments in the culture of freshwater mussels. Bull. U. S. Bur. Fish. 38 (916): 63-90 IseLy, Frep B. 1911. Preliminary note on the ecology of the early juvenile life in the Unionidae. Biol. Bull. 20: 77 - 80 LEFEvRE, GEORGE & WINTERTON C. Curtis 1908. Experiments in the artificial propagation of freshwater mussels. Bull. U. S. Bur. Fish. 28: 617 - 626 Tue VE IcER, Vol. 15, No. 1 [D’E.tscu] Figure 2 Figure 2 Several glochidia of Anodonta californiensis showing valves, single adductor muscle, and dark shell teeth Vol. 15; No. 1 THE VELIGER Page 59 Opisthobranch Mollusks Dredged in San Francisco Bay During the Period 1966 to 1971 BY JOHN J. HOLLEMAN Biological Science Department, Merritt College, Oakland, California 94619 (1 Text figure) INTRODUCTION BERG (1963) and MacFartanp (1966), while the occur- rence of nudibranchs in San Francisco Bay has been re- PREVIOUSLY UNREPORTED NUDIBRANCHS from San Fran- ported by GosLiNneR & WiLuiAMs (1970) and BEHRENS cisco Bay have been dredged from 1966 to 1971. Extensive (1971). Aptin (1967) reports that nudibranchs were accounts of the opisthobranch mollusks of the central Cali- dredged and collected intertidally during his study, but fornia coast have been given by Marcus (1961) ; STEIN- not identified. Angel Is. 6 10 @ 3 Treasure Is. 4,5€) 10 rs eas . 6, Be a BN TO Figure 1 San Francisco Bay from Red Rock Island on the north to South Bay. Insert shows San Francisco Bay. ‘ 1. Acanthodoris nanaimoensis; 2. Aeolidia papillosa; 5. Armina californica; 6. Dendronotus frondosus; 3. Anisodoris nobilis; 4. Archidoris montereyensis; 7. Diaulula sandiegensis; 8. Dirona ficta; 9. Hermissenda crassicornis; 10. Tritonia exsulans Page 60 THE VELIGER Vol. 15; No. 1 Biological samples were taken in San Francisco Bay using an Otter trawl and a bag dredge periodically from May 1966 to August 1971. Nudibranchs were encountered frequently during the summer months and rarely in winter months. DISTRIBUTION anp OCCURRENCE Acanthodoris nanaimoensis O’Donoghue, 1921 July 1971 North of Angel Island Aeolidia papillosa (Linnaeus, 1761) July, August 1969 South of Red Rock Island; south San Francisco Bay Anisodoris nobilis (MacFarland, 1905) May 1968 West of Treasure Island Archidoris montereyensis (Cooper, 1862) July 1966; August 1971 West of Treasure Island; south San Francisco Bay Armina californica (Cooper, 1862) July, August 1971 West of Treasure Island; South Hampton Shoal Dendronotus frondosus (Ascanius, 1774) June, July 1966; July 1968; July 1971 West and north of Treasure Island; South Hampton Shoal Diaulula sandiegensis (Cooper, 1862) July 1966; August 1969 South San Francisco Bay Dirona picta MacFarland in Cockerell « Eliot, 1905 December 1969 South San Francisco Bay Hermissenda crassicornis (Eschscholtz, 1831) July 1966; May 1968; July 1969; July 1971 South San Francisco Bay; west of Treasure Island; South Hampton Shoal; south of Red Rock Island Tritonia exsulans Bergh, 1894 May, June, July 1966; May, July 1968; January 1969; January 1970; July 1971 East, west, and north of Treasure Island; South San Francisco Bay; South Hampton Shoal The most frequently encountered and most numerous nudibranch was Tritonia exsulans which occurred in the northern and southern regions of San Francisco Bay and throughout the sampling period. During the summer months Dendronotus frondosus and Hermissenda crassicornis were dredged and maintained in the laboratory where numerous egg masses were laid. Occurring infrequently in summer months were Archi- doris montereyensis and Diaulula sandiegensis. Aeolidia papillosa, Anisodoris nobilis and Armina cali- fornica rarely occurred, but when collected, numerous individuals of each species were obtained. Acanthodoris nanaimoensis and Dirona picta were rep- resented by single individuals only. Literature Cited ApLin, J. A. 1967. Biological survey of San Francisco Bay 1963-1966. Calif. Dept. Fish & Game, Mar. Resources Oper. no. 67-4: 1-131 BEHRENS, Davin W. 1971. The occurrence of Ancula pacifica MacFarland in San Francisco Bay. The Veliger 13 (3): 297 - 298 (1 January 1971) GosLInER, TERRENCE M. & Gary C. WILLIAMS 1970. The opisthobranch mollusks of Marin County, California. The Veliger 13 (2): 175-180; 1 map (1 October 1970) MacFar.anp, FRANK MaAcE 1966. Studies of opisthobranchiate mollusks of the Pacific coast of North America. Mem. Calif. Acad. Sci. 6: xvit+546 pp.; 72 plt. : (8 April 1966) Marcus, ERNST 1961. Opisthobranch mollusks from California. (Supplmt. I): 1-85; plts. 1-10 STEINBERG, JOAN EMILY 1963. Notes on the opisthobranchs of the west coast of North America. — IV. A distributional list of opisthobranchs from Point Conception to Vancouver Island. The Veliger 6 (2): 68 - 73 (1 October 1963) The Veliger 3 (1 February 1961) Vol. 15; No. 1 NOTES & NEWS Unusual Egg-Deposit by a Cuttlefish BY S. v. BOLETZKY Laboratoire Arago, 66 Banyuls-sur-Mer, France (1 Text figure) IN AN AQUARIUM, a dead cuttlefish was observed with a few eggs attached to its pendent tentacles (Figure 1). They had been laid by a female living in the same tank. The common cuttlefish, Sepia officinalis Linnaeus, 1758, usually attaches its eggs, singly, to marine plants, branches of gorgonians, twigs or similar objects (Bott, 1938). In general, eggs are laid in great numbers, on the same spot, regardless of whether or not other supports are available (GrimpE, 1928). The eggs are attached to a support by two processes of the egg-case; these are fastened, by using the tips of the lateral arms, around the support so as to form a ring. In captivity, cuttlefish drop their eggs to the bottom if a suitable support is not available (GRIMPE, op. Cis) \e As Grimpe reported, it is rare that eggs are laid on non-sedentary animals such as crabs, brittle-stars or even sea-horses. The observation of eggs laid on the pendent tentacles of a dead (or moribund) cuttlefish might illustrate how stimulating these vertical structures, having an ideal diam- eter for fastening eggs, are for a female Sepia ready to spawn. However, under similar circumstances this mode of egg-deposit had never before been observed by the author. In view of the fact that only a few eggs were attached to both tentacles of the dead animal, it may be assumed that the female cuttlefish had started spawning at early dawn when, in the opaque concrete tank, the pendent tentacles became barely visible. With increasing light, the visual association of the egg-support with the fellow-cuttle floating at the surface (moribund and dead cuttlefish have strong positive buoyancy) may have inhibited further egg-fastening ; presumably, the numerous eggs lying on the bottom of the tank were then released. THE VELIGER Figure 1 Dead specimen of Sepia officinalis, with eggs attached to its tentacles Literature Cited Bott, RicHARD 1938. Kopula und Eiablage von Sepia officinalis L. Morphol. Oekol. d. Tiere 34 (1): 150-160 GrimPE, GEORG 1928. Pflege, Behandlung und Zucht der Cephalopoden fiir zoologische und physiologische Zwecke. Abderhalden Handb. biol. Arbeitsmeth. IX, 5: 331 - 402 Zeitschr. Page 62 The San Diego Shell Club Does It Again! For THE FOURTH YEAR in a row, the San Diego Shell Club has made a generous contribution to the Veliger. This latest donation has been added to the Veliger Endow- ment Fund, where it will help us to achieve our eventual goal: to keep membership dues to the lowest possible level without reducing either size or quality of our journal. Thus, all future members of our society will benefit from this repetition of the Club’s generosity. Tue CALIFORNIA MALACOZOOLOGICAL SoctETy, Inc. announces Backnumbers of ThE VERIGER and other publications Volumes 1 through 8: out of print Volume 9: $22.- Volume 10: $24.- Volume 11: $24.- Volume 12: $28.- Volume 13: $24.- Volume 14: $28.- Supplement to Volume 3: $6.-* plus $-.75 handling charge [Part 1: Opisthobranch Mollusks of California by Prof. Ernst Marcus; Part 2: The Anaspidea of California by Prof. R. Beeman, and The Thecosomata and Gymnosomata of the Cali- fornia Current by Prof. John A. McGowan] [The two parts are available separately at $3.- each plus a handling charge of $-.75 or as indicated above. If purchased separately, each part is subject to the Califor- nia State sales tax if mailed to California addresses. | Supplement to Volume 7: $2.-* plus $-.60 handling charge Pp g [Glossary of A Thousand-and-One Terms used in Conchology, compiled by Winirrep H. Arno.p] Supplement to Volume 11: $5.-* plus $-.75 handling charge. [The Biology of Acmaea by Prof. D. P. Aszortr et al., ed.] Supplement to Vol. 14: $5.-* plus $-.75 handling charge [The Northwest American Tellinidae by Dr. E. V. Coan] Items marked with * are subject to sales tax in the State of California; residents of that State please add the appropriate amount to their remittances. Prices subject to change without notice. THE VELIGER Vol. 15; No. 1 Send orders with remittance to: Mrs. Jean M. Cate, Manager, Post Office Drawer R, Sanibel, Florida 33957. Please make checks payable to C. M. 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Regarding UNESCO Coupons We are unable to accept UNESCO coupons in payment, except at a charge of $2.50 (to reimburse us for the ex- penses involved in redeeming them) and at $0.95 per $1.00 face value of the coupons (the amount that we will receive in exchange for the coupons). We regret that these char- Vol. 15; No. 1 ges must be passed on to our correspondents; however, our subscription rates and other charges are so low that we are absolutely unable to absorb additional expenses. Supplements Many of our members desire to receive all supplements published by the Society. Since heretofore we have sent supplements only on separate order, some members have missed the chance of obtaining their copies through over- sight or because of absence from home. It has been sug- gested to us that we should accept “standing orders” from individuals to include all supplements published in the future. After careful consideration we have agreed to the proposal. We will accept written requests from individuals to place their names on our list to receive all future sup- plements upon publication; we will enclose our invoice at the same time. The members’ only obligation will be to pay promptly upon receipt of the invoice. Requests to be placed on this special mailing list should be sent to the Manager, Mrs. Jean M. Cate, Post Office Drawer R, Sanibel, Florida 33957. General Notices REGARDING POSTAL SERVICE While increases in postal charges were anticipated, the actual amount involved could not be ascertained until 4 days before the effective date. Thus, we have been un- able to adjust our membership dues and subscription rates to cover these increases. Effective immediately, we must also raise our handling charges for backissues and other materials. Further, we will not acknowledge the receipt of manuscripts, unless an addressed envelope with the necessary postage is enclosed. We must call the attention of our Members and Sub- scribers to the fact that we mail our journal on the date stated on the cover of a particular issue. After we have delivered the journal to the Post Office, our control ends. Delays in delivery seem to become more and more com- mon. Needless to say that we regret this very much; we had hoped that when the salaries of the Postal Workers were increased, the service would improve. However, this seems not to be the case. THE VELIGER Page 63 In view of the ever increasing difficulties in the postal service, it is essential that members and subscribers not only give us prompt and early notice of address changes, but that proper arrangement for forwarding of our jour- nal be made with the local post office (at the old address). We are not able to replace lost copies free of charge but must charge single copy rates. There will, of course, be only the usual charge of $1.00 for re-forwarding a copy IF it has been returned by the post office to us. We also must urge our members and subscribers to place written complaints with the U. S. Post Office Department in case of loss, as every copy of our journal carries our guarantee for return postage. Thus, destruction of a copy of our journal by postal employees constitutes gross neg- ligence and the person concerned deserves an official reprimand, at least. Publication Date of THE VELIGER THE PUBLICATION DATE of The Veliger is the date printed on the index page; this applies even if the date falls on a legal holiday or on a Saturday or Sunday, days when the U. S. Post Office does not expedite second class mail matter. That the printed date is the actual date of pub- lication under the rules of the International Commission on Zoological Nomenclature is based on the following facts: 1) The journal is delivered to the Post Office on the first day of each quarter, ready for dispatch; 2) at least three copies are mailed either as first class items or by air mail; 3) about 20 copies are delivered in person to the mail boxes or to the offices of members in the Berkeley area; 4) two copies are delivered to the re- ceiving department of the General Library of the Univer- sity of California in Berkeley. Thus our publication is available in the meaning of the Code of the ICZN. The printed publication date, therefore, may be relied upon for purposes of establishing priority of new taxa. Moving? If your address is changed it will be important to notify us of the new address at least six weeks before the effective date, and not less than six weeks before our regular mailing dates. Because of a number of drastic changes in the regulations affecting second class mailing, there is now a sizeable charge to us on the returned copies as well as for our remailing to the new address. We are forced to ask our members and subscribers for Page 64 THE VELIGER Vol. 15; No. 1 reimbursement of these charges; further, because of increased costs in connection with the new mailing plate, we also must ask for reimbursement of that expense. Effective January 8, 1968 the following charges must be made: change of address -— $1.- change of address and re-mailing of a returned issue -— $2.-. We must emphasize that these charges cover only our actual expenses and do not include compensation for the extra work involved in re-packing and re-mailing returned copies. CALIFORNIA MALACOZOOLOGICAL Society, Inc. is a non-profit educational corporation (Articles of In- corporation No. 463389 were filed January 6, 1964 in the office of the Secretary of State). The Socicty publishes a scientific quarterly, the VELIGER. Donations to the Society are used to pay a part of the production costs and thus to keep the subscription rate at a minimum. Donors may designate the Fund to which their contribution is to be credited: Operating Fund (available for current production) ; Savings Fund (available only for specified purposes, such as publication of especially long and signi- ficant papers); Endowment Fund (the income from which is available. The principal is irrevocably dedicated to scientific and educational purposes). Unassigned dona- tions will be used according to greatest need. Contributions to the C. M.S., Inc. are deductible by donors as provided in section 170 of the Internal Revenue Code (for Federal income tax purposes). Bequests, lega- cies, gifts, devices are deductible for Federal estate and gift tax purposes under section 2055, 2106, and 2522 of the Code. The ‘Treasurer of the C. M. S., Inc. will issue suitable receipts which may be used by Donors to substan- tiate their respective tax deductions. Endowment Fund In the face of continuous rises in the costs of printing and labor, the income from the Endowment Fund would materially aid in avoiding the need for repeated upward adjustments of the membership dues of the Society. It is the stated aim of the Society to disseminate new infor- mation in the field of malacology and conchology as widely as possible at the lowest cost possible. At a Regular Membership meeting of the Society in No- vember 1968 a policy was adopted which, it is hoped, will assist in building up the Endowment Fund of the Society. An issue of the journal will be designated as a Memorial Issue in honor of a person from whose estate the sum of $5000.- or more has been paid to the Veliger Endowment Fund. If the bequest is $25 000.- or more, an entire volume will be dedicated to the memory of the decedent. INFORMATION DESK What’s the Difference? Authorship of a Taxon BY EUGENE V. COAN Department of Geology, California Academy of Sciences Golden Gate Park, San Francisco, California 94118 THERE HAS BEEN no little confusion about the interpre- tation and citation of the authorship of taxa. According to Article 51(a) of the International Code of Zoological Nomenclature (Srox1, et al., 1964), “The name of the author does not form part of a taxon and its citation is optional.” However, authors’ names are almost always cited in zoological publications for clarity, for bibliograph- ic purposes, to prevent confusion among homonyms, and for historic reasons. The Code establishes a clear basi: for decisions about the authorship of taxa, or put another way, the respon- sibility for taxa: “Article 50. Author of a name.—The author (au- thors) of a scientific name is (are) the person (per- sons) who first publish(es) it in a way that satisfies the criteria of availability ..., unless it is clear from the contents of the publication that only Vol. 15; No. 1 THE VELIGER Page 65 one (or some) of the joint authors, or some other person (or persons), is alone responsible both for the name and the conditions that make it available.” The key phrases in this part of Article 50 are: “the criteria of availability” and “the conditions that make it available.” If a species or other taxon is validated in a work, the author of that taxon is the author of the entire work or of some subunit of the work containing the taxon and the features that validate the name. This person is not necessarily the person who first recognized the taxon to be new and who first thought up the name. Sometimes we may choose to add to our citation of the “official” authorship of a taxon additional biblio- graphic information, either about the larger work of which a subunit is a part or about who thought up the new name. In either case, the main criterion for doing so is Clarity. For instance, information about the person who in- vented the name is often included to clear up past or potential confusion about a taxon’s authorship. This is generally done only in major revisions or systematic reviews. For example: Macoma inflata Dawson, 1872, ex Stimpson MS This species was described by an author, Dawson, in his own work, but the species was first recognized and its name invented by another person. The courtesy refer- ence “ex Stimpson MS” is optional, but I would include it because it clarifies an often confused authorship. Information about the author of a larger, encompas- sing work is especially useful and is often added if some subunit of a larger work is not a formal and easily or generally cited part in a Bibliography or Literature Cited section. For example: Macoma orientalis Scarlato, in Golikov « Scarlato, 1967 This is a species described by only one author in a work by two authors. The description of this species is not a formal and easily cited section of the entire article, so the more complicated combination is neces- sary to key a reader to a Literature Cited section. Another example: Choristes Carpenter, in Dawson, 1872 The description of this new genus was the only part of the article by Carpenter. On the other hand, workers rarely do the following: Tellina rotundata Sowerby, in Reeve, 1867 Sowerby’s monograph on Tellina is in Reeve’s “‘Con- chologia Iconica,’ the parts of which are generally cited alone. “Sowerby, 1867,’ would be sufficient. De- tails about the location of Sowerby’s monograph in Reeve’s set, like details about an article in a journal, can be reserved for the Literature Cited section. A further example: Tellina proxima Sowerby, in Gray, 1839, ex Brown MS Here the section by Sowerby includes more than just the description of this one species, but the section is small and not generally cited by itself; therefore a full citation is given. The “ex Brown MS,” on the other hand, is not essential and would be given only in a major revision. More difficult problems of interpretation arise in the case of works published anonymously. If the true au- thor of a work is known or later becomes known but was not indicated in the original, the author’s name is cited in square brackets following Recommendation 51A of the Code. An example: Conus araneosus [Lightfoot, 1786],ex Solander MS Not only was the “Portland Catalogue” an anony- mous publication by Lightfoot, but it was largely based on previous work by Solander. The citation “ex Solan- der MS” is not essential. When a species is transferred from an original genus to another, the square brackets should be placed inside the resulting parentheses, al- though some workers prefer to drop them to avoid clutter. The principle of responsibility also applies in the case of posthumous publication. If a work is published sub- stantially as the deceased left it, even after a consider- able passage of time, then the deceased remains the author of the taxa therein. Two examples: Tegula eiseni Jordan, 1936 Eubranchus occidentalis MacFarland, 1966 If, on the other hand, a work is much edited, rewrit- ten, and otherwise changed, the author is the person responsible for the actual publication. For example: Distorsio Roding, 1798, ex Bolten MS This book was partly the work of Bolten, including the creation of the new names, but it was so substan- tially rewritten by Roding that he is now considered to be the author. Literature Cited Stoitt, Norman Rupo.pH et al., (editors) 1964. International code of zoological nomenclature adopted by the XV International Congress of Zoology, ed. 2. London (Intern. Trust for Zool. Nomencl.) i- xx+1-176; 5 appendices & glossary Page 66 THE VELIGER Vol. 15; No. 1 BOOKS, PERIODICALS, PAMPHLETS Tertiary Molluscan Fauna from the Yakataga District and Adjacent Areas by SaBuro Kanno. Paleontological Society of Japan, Special Paper No. 16, pp. 1 - 154; 18 plts. Paleontological Society of Japan, % Department of Geology, Kyushu University, Fukuoka (Hakata), 812, Japan. $15.00. De- cember 25, 1971. This is the first thoroughly illustrated modern treatment of Tertiary molluscan fauna from the Gulf of Alaska. Emphasis is on Miocene molluscan assemblages from the Poul Creek and Yakataga Formations. Included among the 104 molluscan taxa are several new species and many western Pacific species previously unknown from Alaska. The bulk of the report consists of a thorough taxonomic treatment of these mollusks including detailed analysis of species of the extinct nautiloid Atwria and the deep water bivalve Calyptogena. Of particular interest are the author’s biogeographic and paleoclimatic inferences. Early Miocene assemblages from the Poul Creek Formation are of warm water aspect and have strong affinities with faunas from lower latitudes in the eastern North Pacific. Middle Miocene assemblages from the overlying Yakataga Formation, however, are of cold water aspect and are characterized by species from Miocene faunas of Hokkaido and Kamchatka of the western North Pacific. This will be an extremely useful reference for anyone interested in the origin and migration of shallow water Tertiary faunas of the North Pacific. It is superbly illus- trated and is written in English. W. O. Addicott Molluscan Digest the International Publication for Malacological Research. Steven J. Long and Jack Brookshire, eds. Sample copies are available at US$0.75 each from Steven J. Long, 110 Cuyama Avenue, Pismo Beach, California 93449. Number 3 of the second volume has just reached our desk. It is gratifying to see the steady development into an ever more useful publication of this monthly magazine. In view of the ever increasing - in spite of price freezes and Phases - one is astonished at the modest price of the publication ($4.50 for private individuals in the Unit- ed States, Canada and Mexico and $5.50 in other count- ries). In addition to the “Current Citations,” a list the editors endeavor to make as complete and as up-to-date as possible, there are usually about 2 pages of “Personal Notes” with information on current research or “Current Events” with information on recent and future meetings of interest to malacologists. RS Malacological Review vol. 3, continued. Pages 103 to 192; illustrated. Five research papers and several brief communications are contained in this, the concluding number of the third volume of the periodical. Its delivery was delayed partly by difficulties in obtaining the necessary permission and by the prolonged dock strike on the Pacific Coast of the U.S.A. vol. 4, no. 2: pp. 121 to 290; illustrated. In addition to several research papers and brief com- munications, this issue provides information on the publi- cation dates of the earlier issues of “Malacological Review.’ It also contains a number of book reviews as well as the reproductions of the tables of contents of various mala- cological publications. This latter feature, as far as we are aware, was an innovation by this publication and is of great help to all serious workers who may not have ready access to a first-rate private or public library subscribing to the many journals. In view of the very great service this review provides, the subscription rate of $5.00 for private subscribers in North America and $5.50 for non- North American private subscribers is unbelievably mod- est. Institutional subscriptions are $8.00 if placed directly and $9.00 if placed through subscription agents. This differential is made to compensate for the extra handling required. In our own experience we would conclude that this is really an inadequate difference. Subscriptions can be entered at Post Office Box 801, Whitmore Lake, Mich- igan 48189. RS Vol. 15; No. 1 Australian Shells Illustrating and Describing 600 Species of Marine Gastropods from Australian waters by B. R. Witson & Kerru Gittett. 168 pp. of which about half are full-page color plates. Charles E. Tuttle Company, Rutland, Vermont. $21.50. Published in 1972. We could express our impression of this book in a single word: Magnificent! However, there is more to it than just the exquisite photography and the extraordinarily fine color reproductions. There is also the text which is of equally high quality, both in ‘literary style’, if such a term may be applied to a work of this sort, and its truly schol- arly approach. In the introduction, Dr. Wilson gives some information on classification and names of Australian shells as well as a good outline of the biology of gastropods in general (anatomy, reproduction, etc. ). The main body of the book is, of course, devoted to the illustration and description of the 600 species. Especially spectacular are the photographs of many living animals, showing that the body of a snail may be as spectacularly colored and patterned as the shell. This aspect may come as a welcome surprise to many shell collectors who never had the opportunity to ‘get their feet wet’ and who have been limited in their efforts to purchase and exchange of the empty shells. It may be worth mentioning that the number of pages is no real indication of the size of the book: the pages are approximately 22 by 28.5 cm (8.5 by 11 inches). If our readers gained the impression that we like the book -— they are quite correct. RS Opisthobranchia (Mollusca) from the Mediterranean Waters of Israel by A. Barasu & Z. Danin. Israel Journal of Zoology, vol. 20, pp. 151 - 200; 2 maps; 3 plates. 1971. This work, dealing with a portion of the Mediterranean Sea heretofore little explored, is based on collections made during the past 20 years or so. The authors stress the fact that the Pyramidellidae are not included in this report. There are 70 species of opisthobranchs, of which 43 are reported from this area for the first time. In an extensive table the authors present information also on the distribu- tion of the species outside of Israel. In the text part, under the entry of each species, are given collecting localities with benthic and substrate data, as well as localities re- THE VELIGER Page 67 ported in the literature with bibliographic references. This paper is of importance to the student of opistho- branch distribution and of Zoogeography in general. RS A Catalogue of Living and Fossil Cowries Taxonomy and Bibliography of Triviacea and Cypraeacea (Gastropoda Prosobranchia) by Maria ScHILDER & FRANZ ALFRED SCHILDER. Mémoires, Institut Royal des Sciences Naturelles de Belgique, 2" series, part 85: 246 pages; with a preface by Maxime Gurpert. Published in 1971. The number of pages is scarcely an indication of the great wealth of information presented in this work. It is based on about 80 years of combined study by the two authors. In their efforts to organize the immense amount of detailed information, the authors have, over the years, developed an ingenious system of symbols and special abbreviations. The most recent innovation, perhaps, is their method of identifying literature citations which, in their system, will always remain the same, no matter where published in connection with what other papers cited. Instead of using the letters a, b, etc. for distinguish- ing different papers by the same author published in the same year, they use a capital letter taken from an initial of an important word in the title of the paper. Some of the other symbolism employed by the authors can be learned easily enough by the constant user of the works by the Schilders. In these days of the ever mounting costs of publication, the possible slight inconvenience of having to familiarize oneself with this system is amply justified. The present work was completed only after the death of Dr. Franz Schilder. However, Dr. Maria Schilder was more than just qualified to see the work through its final stages. The entire work can be described essentially as three lists: a systematic list of all sufficiently characterized taxa, arranged according to the authors’ view at the time of the preparation of the manuscript; an alphabetical list of all 3720 names proposed for cowries with exact references and a bibliography of 3650 titles of books and papers concerning cowries. It is impossible, without going into lengthy details, to give an adequate idea of the wealth of information packed into these relatively few pages. It is a case of ‘seeing is believing.’ RS Page 68 Studies in Tropical American Mollusks Edited by FrepEricK M. Bayer & GILBERT L. Voss. Coral Gables, Florida 33124: University of Miami Press, 236 pages, illustrated. Cloth, $12.50. 1 November 1971. This book contains four papers: Cephalopods collected in the Gulf of Panama by Gilbert L. Voss (included are descriptions of 3 new species of Octopus and a new genus, Euaxoctopus with the new species E. panamensis; in ad- dition to the discussion of previously known species collect- ed in the Gulf of Panama, of which 11 species are new records for the area) ; Mollusks from the Gulf of Panama by Axel A. Olsson (2 new species of Bivalvia and 13 new species, 1 new genus and 1 new subgenus of gastropods are described) ; The Conidae of the Pillsbury Expedition by James Nybakken (11 species were obtained; of these Conus poormani Berry, 1968 is here illustrated for the first time) ; and New and unusual Mollusks collected, by Frederick M. Bayer (55 species of gastropods are reported, of which 15 are new; 1 new genus and 2 new subgenera are also established; 4 species of bivalves, of which 2 are new, including 1 in a new genus, are discussed). The illustrations are of high quality throughout and the collection of these four papers constitutes an important contribution to malacology. RS Le Monde Vivant des Atolls Polynésie frangaise Tuamotu-Gambier published by Société des Océanistes, Musée de l Homme, Paris XVI*, 28: v+ 148 pp.; 1 map; 43 plates, some color. This beautifully illustrated book contains various chapters contributed by different specialists. Of special interest to our readers is Chapter 5 on the molluscan fauna, pages 37 to 56 with plates 12 to 17. According to the preface, this book contains a collection of articles presented in a way to transmit to the reader THE VELIGER Vol. 15; No. 1 a coherent picture of an atoll and its flora and fauna. No claim is made that it contains important new discoveries. It is, however, a charmingly compiled and very well writ- ten collection of essays in a easily understandable vein. We regret that we cannot inform our readers what the book costs; however, this information may be obtained, no doubt, from the Société des Océanistes in Paris. RS Kelp Habitat Improvement Project Annual Report, 1 July, 1970 — 30 June, 1971. WHEELER J. Nortu, Principal Investigator. W. M. Keck Laboratory of Environmental Health Engineering, California Insti- tute of Technology, Pasadena, California. ix+150 pp.; illustrated ; published in 1972. This is the 8™ of these annual reports. Evidence present- ed indicates that the investigators seem to be well on the way to the finding of a solution of the problem of re- establishing the once plentiful kelp beds off the coast of Southern California. RS of Sea and Shore Vol. 3, No. 1: 50 pages, illustrated; color pictures of shells on front and back covers. Published by ‘of Sea and Shore’ Publications, Post Office Box 33, Port Gamble, Washing- ton 98364. With this issue the separately published book by Glenn and Laura Burghardt, entitled ‘West Coast Chitons’ is being reprinted, one portion at a time. The color plates from that work are inserted separately and loose, so that at the conclusion of volume 3 of ‘of Sea and Shore’ the subscribers will have the complete book. Various articles, all well illustrated, complete this issue. RS THE VELIGER is open to original papers pertaining to any problem concerned with mollusks. This is meant to make facilities available for publication of original articles from a wide field of endeavor. Papers dealing with anatomical, cytological, distri- butional, ecological, histological, morphological, physiological, taxonomic, etc., aspects of marine, freshwater or terrestrial mollusks from any region, will be considered. Even topics only indirectly concerned with mollusks may be acceptable. It is the editorial policy to preserve the individualistic writing style of the author; therefore any editorial changes in a manuscript will be submitted to the author for his approval, before going to press. Short articles containing descriptions of new species or other taxa will be given preferential treatment in the speed of publication provided that arrangements have been made by the author for depositing the holotype with a recognized public Museum. Museum numbers of the type specimens must be included in the manuscript. Type localities must be defined as accurately as possible, with geo- graphical longitudes and latitudes added. Short original papers, not exceeding 500 words, may be published in the column “NOTES and NEWS”; in this column will also appear notices of meetings of regional, national and international malacological organizations, such as A. M. U., U. M. E., W.S.M., etc., as well as news items which are deemed of interest to our Members and subscribers in general. Articles on “METHODS and TECH- NIQUES” will be considered for publication in another column, provided that the information is complete and techniques and methods are capable of duplication by anyone carefully following the description given. Such articles should be mainly original and deal with collecting, preparing, maintaining, studying, photographing, etc., of mollusks or other invertebrates. A third column, entitled “INFORMA- TION DESK,” will contain articles dealing with any problem pertaining to collecting, identifying, etc., in short, problems encountered by our readers. In contrast to other contributions, articles in this column do not necessarily contain new and original materials. Questions to the editor, which can be answered in this column, are invited. The column “BOOKS, PERIODICALS, and PAMPHLETS” will attempt to bring reviews of new publications to the attention of our readers. Also, new timely articles may be listed by title only, if this is deemed expedient. Manuscripts should be typed in final form on a high grade white paper, not exceeding 814,” by 11”, at least double spaced and accompanied by a clear carbon or photo copy. A pamphlet with detailed suggestions for preparing manuscripts intended for publication in THE VELIGER is available to authors upon request. A self-addressed envelope, sufficiently large to accommodate the pamphlet (which measures 514,” by 81”’), with double first class postage, should be sent with the request to the Editor. EDITORIAL BOARD Dr. Donatp P. Asgort, Professor of Biology Hopkins Marine Station of Stanford University Dr. Jerry DonouueE, Professor of Chemistry University of Pennsylvania, Philadelphia, and Research Associate in the Allan Hancock Foundation University of Southern California, Los Angeles Dr. J. Wyatr Duruam, Professor of Paleontology University of California, Berkeley, California Dr. E. W. Facer, Professor of Biology Scripps Institution of Oceanography, La Jolla University of California at San Diego Dr. Cavet Hanp, Professor of Zoology and Director, Bodega Marine Laboratory University of California, Berkeley, California Dr. JoeL W. Hepcretu, Resident Director Marine Science Laboratory, Oregon State University Newport, Oregon Dr. Leo G. HERTLEIN, Curator of Invertebrate Paleontology, Emeritus California Academy of Sciences, San Francisco Dr. A. Myra KEEN, Professor of Paleontology and Curator of Malacology, Emeritus Stanford University, Stanford, California Dr. Victor LoosanorrF, Professor of Marine Biology Pacific Marine Station of the University of the Pacific Dr. Joun McGowan, Associate Professor of Oceanography Scripps Institution of Oceanography, La Jolla University of California at San Diego Dr. Frank A. Pitre.xa, Professor of Zoology University of California, Berkeley, California Dr. Ropert Rosertson, Chairman and Pilsbry Chair of Malacology, Department of Malacology Academy of Natural Sciences of Philadelphia Mr. Attyn G. Situ, Associate Curator Department of Invertebrate Zoology California Academy of Sciences, San Francisco Dr. Ratpu I. Smiru, Professor of Zoology University of California, Berkeley, California Dr. Cuarces R. StasEx, Associate Professor of Zoology Florida State University, Tallahassee, Florida EDITOR-IN-CHIEF Dr. RupotF STOHLER, Research Zoologist, Emeritus University of California, Berkeley, California ASSOCIATE EDITOR Mrs. JEAN M. Cate Los Angeles, California A Quarterly published by CALIFORNIA MALACOZOOLOGICAL SOCIETY, INC. Berkeley, California VOLUME 15 October 1, 1972 NUMBER 2 CONTENTS Observations on Removal of Spines by Muricid Gastropods During Shell Growth (3 Plates) MELBOURNE R. CaRRIKER.. .. na) Ween ae dven. al, OG The Ecology and Behavior of Nautilus Ligon pitts in he Philippines. (2 Plates; 2 Text figures) INORINE MEVAVEINE( ei yeti oe Weel eae NR ee ne alee a PS Microarmature and Barriers in the Apertures of Land Snails (5 Plates) INEANT SOLEMN. cre ie a tete) ee ae ; : SSG MULE Miato | Thecacera picta spec. nov. from Suruga Ba Japan ivauibeenia Derndoiden Polyceridae) . (1 Text oa, KrkuTarO BaBA . . .. Bude ered doucise cs hOO A New Species of eae enaee oe the Aes North Pacific. (2 Plates; 5 Text figures) RUNNIKGg INO KORE hy Sete ae ete Oe eh ad le et he ey eh ay “QE A New Species of Conus from Taiwan. (1 Plate) Epwarp JAMEs PeTtucH « GEorcE MENDENHALL .. . Se eerie tee serene. (OO, Biology of Okenia ascidicola spec. nov. (Gastropoda : Nudibranchia) (5 Text figures) MES PATRICIAMNIORSE aimee ich tem sirg cl iveAl get ah iC sire ve) peice dite stehe sites OY Note on Secondary ae EmiryH. Vokes. . . 102 Two Additions to the Cae Fauna of the Southern Gulf of California. (@ Plate; 3 Text oe Hans BERTSGH Be eee a el re Un asian ac Glaee eile eng CNA Neue.» daran ge LOB [Continued on Inside Front Cover] LES IEA a aS Distributed free to Members of the California Malacozoological Society, Inc. Subscriptions (by Volume only) payable in advance to Calif. Malacozool. Soc., Inc. Volume 15: $18.- Domestic; $19.50 in the Americas; $20.- in all other Foreign Countries Single copies this issue $10.-. Postage extra. Send subscription orders to Mrs. Jean M. Care, Post Office Drawer R, Sanibel, Florida 33957. Address all other correspondence to Dr. R. SToHER, Editor, Department of Zoology, University of California, Berkeley, California 94720 Second Class Postage Paid at Berkeley, California ConTENTs — Continued Review of the Bathyal Gastropod Genus Phanerolepida (Homalopomatinae) and Description of a New Species from the Oregon Oligocene. (1 Plate; 1 Text figure) CaroLe S. Hickman. . 5 HOF A Report on Cephalopods coneced i Seal Gee Pee 20 to the Eastern Tropical Pacific Ocean September to November, 1968. W. Gorvon EIErDS, & VERONICAVAs) | GAULEY)) (0) ye -la) soe oe eee Tere Selective Predation and Prey Location in the Sea Slug Navanax inermis. (2 Text figures; 1 Map) Gree M. Bram & ROGER RSEAPY, eye) bat eo een ee OT Notes on Two Endemic South African Cypraea. (1 Text figure) RoN. ISIEBURN & 1D) WicATKEN 2003 86 eh ere) oe eee deems Comments on the Authorship of Some Subfamilial Names in the Turridae (Mollusca : Gastropoda) Water ©; CERNOHORSKY) 020 he ies ee eT 7 The Réle of Wave Impact and Desiccation on the Distribution of Littorina sitkana Philippi, 1845 (1 Text figure) SyLvIA BEHRENS . . . . a el come aoe 5 1 129 Seasonal Migration and BepMON Renulnaen in the Limpet meee ( Collisella) digitalis (7 Text figures) Pau A. BREEN. . . LS Be Saleen hate 2 > LER Observations on Growth, Foe Renreduc cnn aa Becoeneen: in the Opie: branch, Fiona pinnata (Eschscholtz) 5 Text figures) Joun J. HoLteman . . . . 142 A Preliminary List of Known Gane From the Cae fat Goilested by the Ameripagos Expedition. (1 Map) Gare GUSPHON, & DAVID) KIMIUELINER yey 2) cee en eee een Some Opisthobranchs (Mollusca : Gastropoda) from Oregon (1 Text figure) Gate G.SPHON® 1325s See. ees ae ieee eal anagem eT NO TESUSINE WS 00sec eee TE ye ae ea weet Ss Sees hat ene aM First Recorded Occurrence of Littorina tessellata Philippi 1847 from the Shores of North America (1 Text figure) Frasier O. BINGHAM BOOKS, PERIODICAWS & PANIPEIU EMS 8 lee) i ee eee eo Note: The various taxa above species are indicated by the use of different type styles as shown by the following examples, and by increasing indentation. ORDER, Suborder, DIVISION, Subdivision, SECTION, SUPERFAMILY, Famity, Subfamily, Genus, (Subgenus) New Taxa Wolk IaENowZ THE VELIGER Page 69 Observations on Removal of Spines by Muricid Gastropods During Shell Growth BY MELBOURNE R. CARRIKER Systematics-Ecology Program, Marine Biological Laboratory, Woods Hole, Massachusetts 02543 (3 Plates) INTRODUCTION WHILE INVESTIGATING the comparative functional mor- phology of the boring mechanism of muricacean and naticacean gastropods (CarrRIKER, 1961), we had an oppor- tunity to observe the behavior of many of the snails closely. Two species of Muricidae, Murex brevifrons La- marck, 1822 and Murex fulvescens Sowerby, 1834, whose shells are ornamented with conspicuous varices and spines which run the breadth of the whorls, particularly drew our attention because of the possible role of the accessory boring organ (CarrIKER, 1969; CarRIKER & VAN ZANDT, 1972) in removal of the spines during shell growth. As pointed out by FRETTER & GRAHAM (1962) and by Rogpertson (1965), in the process of spiral growth of the helicocone, the snail has to remove the older spines which come to lie along the inner lip of the aperture in order to make room for the new shell of the enlarging body whorl. If the spines were not removed, they would block the aperture and interfere with the movements of the snail in and out of its shell. In the case of Murex bre- vifrons, blockage would be almost complete; in that of /. fulvescens, only partial. How snails remove these spines has not been reported. Since the molluscan mantle has the capacity to secrete shell as well as to remove what it has deposited (FRETTER & GraHam, 1962; Smiru, 1969; Sottman, 1969), Fretter and Graham postulated that the spines and varices may be resorbed by the mantle. Ropertson (1965) hypo- thesized that the spines may be broken or rasped off, or may be removed chemically, possibly by the same means that boring snails use to excavate holes in the shell of prey. In Murex brevifrons and M. fulvescens a strong thick varix is formed at the edge of the outer lip of the body whorl at regular intervals. Each varix represents a resting period in the growth of the shell. The intervarices of the shell represent active periods of shell deposition. Little is known about how long it takes snails to lay down the spines or the shell between the varices. ABBoTT (1954) suggested less than two days for growth from one varix to the next in Muricidae. This paper reports the results of observations in the laboratory on the deposition of shell and the removal of spines during growth of the body whorl from one varix to the next in Murex brevifrons and M. fulvescens. ACKNOWLEDGMENTS John W. Blake and Langley Wood assisted in the investi- gation. Dr. Juan A. Rivero had Murex brevifrons sent from Puerto Rico, and Paul Shave later collected snails of the same species in the same area. Dr. Virginia Peters collaborated in the use of the scanning electron micro- scope. The research in 1959 was supported in part by a grant from the U. S. Fish and Wildlife Service; that in 1968 and thereafter by Public Health Service Research Grant DE 01870 from the National Institute of Dental Research. This assistance is gratefully acknowledged. Systematics-Ecology Program Contribution No. 268. MATERIALS anp METHODS The specimens of Murex brevifrons were collected in the vicinity of Mayaguez, Puerto Rico, packed moist, and shipped by airmail. The snails survived the flights in good condition, fed actively, grew new shell, and deposited egg capsules in our running seawater trays. We collected spe- cimens of M. fulvescens on a rock jetty off Shackleford Banks, North Carolina. These individuals likewise accli- matized readily to laboratory conditions. Both species were fed oysters, Crassostrea virginica (Gmelin, 1791). Page 70 Principal observations were made at the Institute of Fisheries Research, University of North Carolina, More- head City, during the period August 1 to September 11, 1959. Salinity of the seawater ranged from 31 to 35%, and the temperature from 24 to 29°C. Both species came from high salinity, partially sheltered habitats. Supple- mentary observations were made on individuals of Murex brevifrons at the Marine Biological Laboratory in 1968. Salinity of the seawater in running seawater trays was approximately 32%, and the temperature ranged from 20 to 21°C. In both laboratories snails were illuminated by daylight coming through the laboratory windows, and during the early part of the evening by standard overhead artificial light. For the observations in 1959, five Murex brevifrons, ranging in shell height from 64 to 95mm, were placed in an aquarium 30 < 30 < 60cm in size; and six M. fulves- eens, ranging in shell height from 95 to 100mm were set in a similar tank. A stream of seawater about 7mm in diameter ran into and overflowed from each aquarium. he tanks had wooden ends and glass on two sides, and were placed with one glass side against the wall so that the back was partially shaded. Position and feeding activ- ity of the snails were watched through the front glass and top of the aquaria. To examine the amount of deposition of new shell and progress in removal of spines, we lifted snails off the bottom without taking them out of the water. To photograph them, we removed them from the water for brief periods. Frequency of examinations varied from daily to weekly, depending upon the rate of shell deposition and proximity of the mantle edge to the base of the spines. We marked M. brevifrons by tying fine red plastic twine of various lengths to one of the large dorsal spines. Individual M. fulvescens were identified by shell form. THE VELIGER Vol. 15; No. 2 Microscopic examination of shell spines was done with a JEOLCO scanning electron microscope, JSM-U3, in Woods Hole, Massachusetts. Spines which were partly eroded at the base in living Murex brevifrons were broken off, rinsed in distilled water, dried quickly, coated with gold in a vacuum evaporator, and studied at magnifica- tions ranging from 45 to 5000 x. OBSERVATIONS During the varix periods (Figure 7) when no shell growth was taking place, snails crawled actively about the aquar- ia, bored oysters, and fed voraciously through their bore- holes. At the onset of the intervarix period and deposition of new shell, they crawled to the shaded parts of the aquaria and remained there with little or no movement, the foot firmly appressed to the substratum. They re- mained relatively stationary until the end of the intervarix period. During this period they were difficult to dislodge from the bottom. When placed at the lighted side of the aquaria, snails returned to the more shaded spots. Dis- lodgment from the bottom caused them to retract within the shell, generally drawing the operculum into the aper- ture. In the hope of watching the normal activity of the mantle edge at the base of the spines under water, we had placed squares of clean glass plate on the bottom of the aquaria; glass on which a snail might settle could then be upended to bring the aperture into view without dis- turbing the snail. Unfortunately, the snails avoided the glass plates. We were able to follow closely the cleaning of the pari- etal area, removal of spines, and deposition of new shell by several Murex brevifrons. Observations on one individ- ual (Table 1) were confirmed by those on others. During Explanation of Figures / to 6 Figure 7: Apertural view of Murex brevifrons in the varix stage. To the snail’s right (bottom of photograph) is the most recently formed varix and row of spines along the edge of the outer lip, and to the left (top) is an older varix and row of spines which will be removed as the body whorl grows 1.5 X Figure 2: Apertural view of Murex brevifrons in an early phase of the intervarix stage. A thin layer of new shell is being deposited on the outer lip, and the base of the spines and shell surface on the inner lip are being eroded 2X Figure 3: Apertural view of Murex brevifrons at the end of the intervarix stage. The old row of spines has been completely re- moved. The thin new intervarix shell of the body whorl has been formed, and the lacy, convoluted, outturned flanges of the lip mark the location of the new varix and new row of spines 2X Figure 4: Apertural view of Murex fulvescens in an early phase of the intervarix stage (comparable to that in Figure 2). Thin new shell is being added to the outer lip, and the base of the spines and parietal shell surface are being eroded 1.2X Figure 5: Close view of a spine of Murex fulvescens on inner lip of aperture whose base has been almost completely eroded. The pari- etal surface in front of and between the spines has also been eroded. Mid intervarix stage 4X Figure 6: Apertural view of Murex fulvescens at the beginning of the varix stage, photograph taken 10 days after that in Figure 4. The row of new spines on the outer lip is almost completely formed, the inner lip has been coated with a glaze of new shell, and a zone of new shell, 11mm in width, has been added to the outer lip 1.5 X Tue Ve icErR, Vol. 15, No. 2 [CarrIkKER] Figures 1 to 6 Figure 2 Figure 3 Figure 4 ia. aad Vol. 15; No. 2 THE VELIGER Page 71 Table 1 Rate of deposition of shell on body whorl and removal of spines by Murex brevifrons during one intervarix period, August 7 to September 11 Days Shell Height Snail Activity 0 64 mm End of feeding period 12 Inactive 18 Inactive 31 69 mm Inactive 35 74mm End of inactive period and flaring base of new spines Width of New Shell Added to Outer Lip Fate of Spines on Inner Lip None Spines intact (Figure /) Trace Inner lip eroded to base of spines 4mm Base of spines being eroded (Figure 2) 26 mm Spines removed and stumps covered with new parietal shell 30 mm, including new varix _ Position of removed spines now almost on the level with new varix at posterior base of aperture (Figure 3) the intervarix period which lasted about 35 days, this snail grew from 64 to 74mm in shell height, and added a maximum width of 30mm of new intervarix shell to the outer lip, most of the new varix, and the accompanying row of spines. As accurately as we could determine, it took this snail about 8 to 10 days to remove a single row of spines. Incom- pletely removed spines showed conspicuous evidence of erosion at the base just above the level of attachment to the parietal area of the aperture and on the side facing the mantle edge (Figure 2). The area of erosion was restricted to the parietal area and to the base of the spines. Spines were removed close to the surface of the inner lip so that after the new coat of shell had been deposited over the newly cleaned parietal area, there was no trace of them (Figure 3). The freshly deposited inter- varix shell on the outer lip was extremely thin (Figure 2). During the following varix period this was thickened by deposition of more shell interiorly by the mantle, result- ing in the characteristically thick valve of the species. The manner and time for removal of spines by Murev fulvescens was approximately similar to that by M. brevi- frons (Figures # to 6). The snail in Figure 4, for example, had deposited a rim of thin new shell 12mm wide on the outer lip, and dissolution of the parietal area and the base of the spines had begun. Ten days later (Figure 6) the spines had been completely removed and the parietal wall had been coated with a smooth layer of shell which completely hid the site of the original row of spines. The advancing edge of erosion of the surface of the shell in the inner lip was more or less uniform up to the spines. As the base of the spines was attacked, areas of shell removal extended between the spines and slightly beyond (Figures 2, 4). After the spines had been removed, the border of erosion again straightened. Study by scanning electron microscopy of the partially eroded base of the spines of Murex brevifrons clearly re- vealed a delicately etched shell surface, and exposed a strikingly variegated pattern of complexly oriented shell prisms (Figures 7 to 10; 11 to /4). Figures 7 and 8 are low magnifications of the area of solution of the shell at the base of two spines. The topography of the eroded areas was divisible into an upper portion with conspicuous vertical striae, and a lower portion in which the striae were much less prominent and ran horizontally. Two prominent keels on each side of each spine separated the front from the sides. No radular rasp marks were visible on the eroded sur- faces of the spines. When rasping hard surfaces, muricid snails employ mainly the tricuspate rachidian teeth (Car- RIKER & VAN ZANDT, 1972). The width of rachidian teeth in Murex brevifrons ranged from 200 to 300m, and the distance between the points of adjacent cusps varied from 65 to 75. Thus had rasp marks been present, the inter- val between the individual cusp traces would have ranged between 65 and 75. At a magnification of 45 « (Figures 7, 8) the traces would have been about 3mm apart; at a magnification of 100 « (Figure 9), about 7mm apart. At low magnifications (Figures 7, 8) the striae, but for their branching, did resemble rasp marks; at higher magnifications (Figure 10; Figures // to 13), however, the striae resolved into differentially dissolved strata of shell prisms. The ridges of the vertical striae (Figures /0; 11, 12) were comprised of slender prisms whose long axes Page 72 came close to paralleling the general plane of dissolution, whereas the narrow depressions represented similar prisms whose ends abutted more nearly at right angles to the plane of dissolution. In the horizontal striae the differ- ence in elevation between the layers of prisms was slight, and the long axes of the prisms in the ridges and the valleys, though appearing at approximately right angles to each other, formed nearly similar angles with the plane of dissolution (Figures /3, 14). DISCUSSION anp CONCLUSIONS These observations demonstrated that removal by Mu- rex brevifrons and M. fulvescens of spines obstructing the aperture during growth of the shell is done by chemical dissolution at the mantle edge. After the base is eroded through, the spines fall away. This conclusion is based on the pattern of the advancing edge of dissolution over the parietal area to, and past, the spines, the ultrastructural appearance of the eroded surface, and the absence of rasp marks on the eroded area. The remarkable capacity of the gastropod mantle to function both in shell dissolu- tion and deposition is mentioned briefly by FRETTER & GraHAm (1962). What portion of the complex mantle border secretes the dissolving substance, and what por- tion deposits shell, or whether the same tissue functions alternately in shell formation and shell dissolution, are not known. If the latter were the case, it would be inter- esting to speculate on the nature of the snail’s integrating mechanism which brings this about, and what triggers the change from dissolution to deposition. Related aspects of the problem of shell deposition were treated by BEvEL- ANDER & NAKAHARA (1970), Dicspy (1968), SALEUDDIN (1970), and Wirpur (1964). Because of the active role of the radula in boring holes in shell of prey (CarrIKER & SmiTH, 1969; CarrIKER & Van ZANDT, 1972), we anticipated when the study was begun that the radula might be involved in removal of THE VELIGER Vol. 15; No. 2 the spines. There is no apparent anatomical barrier to such a possibility as the proboscis of these snails is long enough to permit rasping around the inner lip of the aperture. Although we found no evidence of rasp marks on the eroded portion of the spines, even with the scan- ning electron microscope, the possibility may exist that we examined the snails at a time when only chemical activity was taking place. Since, however, the mantle edge dissolves the surface of the parietal area as well as the base of the spines, it is more likely, as our observations suggest, that the operation of cleaning the shell surface and removing obstructions as the body whorl enlarges is done entirely by the mantle. Furthermore, the hardness of the shell of these snails would suggest, as is the case with Urosalpinx cinerea (CARRIKER & VAN ZANDT, 1972), that radular cusps, if used, would have only minor im- pact on the surface of the spines anyway. Examination with the scanning electron microscope of the dissolved surface of the spines revealed an unexpect- edly complex organization of strata of shell prisms. Inter- digitation of the strata in the spines undoubtedly contrib- utes to the strength of these structures. MacCiintocKk (1967) described the light microscopical structure of the shell of patelloid and bellerophontoid gastropods in de- tail, and illustrated crossed layers similar to those in the spines of Murex brevifrons. Prisms whose long axes tended to parallel the surface of dissolution comprised the ridges of the striae, and those ending most nearly at right angles to the surface of dis- solution formed the depressions. This pattern suggests that the sides of the prisms were slightly less soluble to the secretion of the mantle than the ends of the prisms. Differ- ential dissolution may have resulted from the orientation of the molecules in the prisms, or from more protection afforded the sides of the prisms than the ends by the organic matrix. The matter needs experimental verifi- cation. Whether the prominent keels on the base of the partially dissolved spines resulted irom the way the mantle edge Explanation of Figures 7 to 10 Figure 7: Scanning electron micrograph of the base of a spine in the mid intervarix stage of Murex brevifrons showing the three faces of the eroded region 45 X Figure 8: Scanning electron micrograph of a second spine in the mid intervarix stage of the same Murex brevifrons showing the right, middle, and part of the left faces of erosion and the fracture surface where the spine was attached to the body whorl 45 X Figure 9: The juncture on the middle face of the planes of erosion illustrated in Figure 8. Vertical striae are at the top portion and the horizontal striae are at the bottom portion of the micrograph 100 < Figure 10: Vertical striae shown in Figure 9. Scanning electron micrograph 500 X [CarrIKER] Figures 7 to 10 THE VELIcER, Vol. 15, No. 2 vee! nite Figure 70 Vol. 15; No. 2 THE VELIGER Page 73 surrounded the spines, possibly creasing at the line of the keels, or from the presence in the keels of less soluble shell, is not known. Because of the major role of the accessory boring organ of muricid gastropods in boring the shell of prey (Car- RIKER & VAN ZANDT, 1972), we wondered if this organ might also aid in the removal of shell spines. All Murici- dae which have been studied to date are shell borers, and all possess an accessory boring organ (Carriker, 1961; CaRRIKER & YOCHELSON, 1968). Contrary to WELLS’ (1958) report, this also includes Murex fulvescens which bores holes primarily between the edges of the valves of its prey (CARRIKER & YOCHELSON, op. cit.). The “halo” which Wells observed at the inner site of entry was dissolu- tion of shell by the accessory boring organ. From a purely functional point of view, it is difficult anatomically to visu- alize a muricid snail moving the extended accessory boring organ over the full length of the inner lip of the shell while cleaning the parietal area and removing the spines. Fur- thermore, it is questionable whether the delicate micro- villar surface of the organ could withstand the abrasion, or whether the organ could produce enough secretion to accomplish the task. The mantle, on the other hand, effec- ting continuous close contact over the area to be dissolved, would function smoothly and economically. Not all mur- icid borers (Thais lapillus, for example), possess spines, and then there are gastropods which possess conspicuous spines (for example, some forms of Melongena corona corona) but are not borers (CLENCH & TURNER, 1956). The latter are likewise faced with the problem of spine removal during shell growth. It does not seem likely, there- fore, that the accessory boring organ is employed in spine removal. The practice of secreting a thin layer of shell onto the outer lip of the body whorl during the intervarix phase which is later reinforced on the inside during the varix phase, has also been reported for other muricid snails. Mackenzie (1961), for example, observed that in Eu- pleura caudata the intervarix stage lasted about 3 weeks, and the varix stage, about 4 weeks. This is a smaller snail than the two species of Murex reported in this paper, and may account for the shorter intervarix period. ABBOTT’s (1954) suggestion of 2 days for growth from one varix to the next in Muricidae seems too brief, but he may have re- ferred to a species of much smaller size. Spiny gastropods are widely distributed and in tropic and semi-tropic waters, occur in abundance. Whether all species use the mechanism for removal of spines employed by Murex brevifrons and M. fulvescens, has yet to be determined. It is likely that they do. A good subject for study with extremely long spines is the beautiful 17. cabri- tii from the Gulf of Mexico and the West Indies (RoBERT- son, 1965). Some muricids lacking spines, like Urosalpinx cinerea, add new shell to the body whorl gradually (BLAKE, 1966). It would be instructive to determine if individuals of U. cinerea could remove artificial calcare- ous spines imposed experimentally on the inner lip in advance of the mantle edge, and what effect artificial removal of the spines of M. brevifrons would have on growth of the body whorl. Not all gastropods solve the problem of obstructing shell ornamentation in the path of the growing body whorl by its removal. In the genus Epitonium, for example, prominent costae are simply covered over by new shell. resulting in a more widely coiled univalve than in Muri- cidae (CLENCH & TurNER, 1951). Muricids with long spines have no recourse than to remove the offenders if the shell is to grow and the animal is to survive; snails with short spines could cover them as do individuals of Epitonium. What determines which of the two courses is followed, is not known. SUMMARY The prosobranch gastropods, Murex brevifrons and M. fulvescens, were maintained in captivity for observations on the removal of spines and the deposition of shell during growth of the body whorl from one varix to the next. Spine removal is necessary to eliminate blockage of the aperture and to permit easy movement of the snail in and out of its shell. Snails fed voraciously on oysters during the varix stage after boring holes in them, and then crawled to a quiet shady spot in aquaria to clean the parietal area and remove old spines on it, and to add new shell and spines to the outer lip. The parietal area was cleaned and the spines were removed at the base by the mantle by chemical dissolution. The mantle likewise secreted the new intervarix shell and spines. Scanning electron micro- scopy revealed a complex organization of strata of shell prisms in the dissolved surface of the spines. No radular marks were evident. The accessory boring organ was prob- ably not employed in removal of spines. Literature Cited Assott, RoperT TUCKER 1954. American seashells. Princeton, New Jersey. D. van Nost- rand Co., Inc.; xiv+541 pp.; 40 plts.; 100 text figs. BEVELANDER, GERRIT & HtrosH1 NAKAHARA 1970. An electron microscope study of the formation and structure of the periostracum of a gastropod, Littorina littorea. Calc. Tiss. Res. 5: 1-12; 11 figs. Page 74 BLAKE, JOHN WILSON THE VELIGER Wolk Iss ING. 2 1966. Inherent differences between populations of the oyster drilling gastropod, Urosalpinx cinerea, reared under laboratory conditions. Second Internat. Oceanogr. Congr., Abstr. of Papers, Moscow, 30 May-9 June, 1966. No. 45 - SlIIc., Ip. CarrIKER, MELBOURNE ROMAINE 1961. Comparative functional morphology of boring mechanisms in gastropods. Amer. Zool. 1 (2): 263 - 266; 1 fig. 1969. Excavation of boreholes by the gastropod Urosalpinx: an an- alysis by light and scanning electron microscopy. 9 (3): 917-933; 31 text figs.; 2 tables Amer. Zool. (August 1969) CarrIKER, MELBOURNE RomaINE « EDMUND HosBarT SMITH 1969. Comparative calcibiocavitology: summary and conclusions. Amer. Zool. 9 (3): 1011-1020; 1 table (August 1969) CarrIKER, MELBOURNE ROMAINE & Dirk VAN ZANDT 1972. Predatory behavior of a shell-boring muricid gastropod. Chapt. 5 in Behavior of marine animals: Current perspectives in research, vol. 1, Invertebrates. H. E. Winn & B. L. Oxra (eds.), Plenum Press, New York, N. Y., pp. 157 - 244; 37 figs.; 7 tables CarrikER, MELBOURNE ROMAINE & ELLIS LEON YOCHELSON 1968. Recent gastropod boreholes and Ordovician cylindrical borings. Contr. Paleont., Geol. Surv. Prof. Paper 593-B: B1 - B26; 5 plts. CiencH, WILLIAM JoHN & RutH Dixon TurNER 1951. The genus Epitonium in the Western Atlantic (Part I). Johnsonia 2 (30): 249 - 288; plts. 108 - 130 (28 September 1951) 1956. The family Melongenidae in the Western Atlantic. John- sonia 3 (35): 161-188; plts. 94-109 Dicpy, PETER S. 1968. The mechanism of calcification in the molluscan shell. Symp. Zool. Soc. London, no. 22: 93 - 107; 6 figs. In: Studies in the structure, physiology and ecology of molluscs, VERA FRETTER & J. FE PEAKE (eds.), Acad. Press, London FRETTER, VERA & ALASTAIR GRAHAM 1962. British prosobranch molluscs, their functional anatomy and eco- logy. London, Ray Soc. xvi+755 pp.; 316 figs. MacCuintocx, CopeLaNnp 1967. Shell structure of patelloid and bellerophontoid gastropods (Mol- lusca). Peabody Mus. Nat. Hist., Yale Univ. Bull. 22: i- ix+1 - 140; 128 text figs.; 32 plts. Mackenzie, Crype Leonarp, Jr. 1961. Growth and reproduction of the oyster drill Eupleura caudata in the York River, Virginia. 15 tables RospertTson, ROBERT 1965. A spiny murex. SALEuppDIN, A. S. M. Ecology 42 (2): 317-338; 12 figs.; (April 1961) Frontiers 29 (4): 101-103; 4 figs. 1970. Electron microscopic study of the mantle of normal and re- generating Helix. SmitH, EpmMunp HoBArT Canad. Journ. Zool. 48 (3): 409-416; 33 figs. 1969. Functional morphology of Penitella .conradi relative to shell- penetration. Sotiman, Gamiv N. Amer. Zool. 9 (3): 869 - 880; 7 figs. 1969. Ecological aspects of some coral-boring gastropods and bivalves of the northwestern Red Sea. We tts, Harry WILSON 1958. Feeding habits of Murex fulvescens. Wizsur, Kart MILTON 1964. Shell formation and regeneration. YonceE (eds.) Physiology of Mollusca. Y. 1: 243 - 282; 14 figs.; 3 tables Amer. Zool. 9 (3): 887 - 894; 5 figs. Ecology 39 (3): 556 - 558 In K. M. Wizsur & C. M. Acad. Press, New York, N. Explanation of Figures I/ to 14 Figure 17: Juncture of vertical and horizontal striae shown in Figure 9. Scanning electron micrograph 500 Figure 12: Higher magnification of the juncture of vertical and horizontal striae shown in Figure 1/. Scanning electron micro- graph 1000 Figure 13: Horizontal striae shown in Figure 9. Scanning electron micrograph 500 < Figure /4: Higher magnification of a portion of the layers of prisms shown in Figure 73. Scanning electron micrograph 2000 X Tue VE.icER, Vol. 15, No. 2 [CarRIKER] Figures 11 to 14 Figure 11 Vol. 15; No. 2 THE VELIGER Page 75 The Ecology and Behavior of Nautilus pompilius in the Philippines NORINE HAVEN Department of Biological Sciences, Simon Fraser University, Burnaby 2, British Columbia, Canada (2 Plates; 2 Text figures) INTRODUCTION OBSERVATIONS WERE MADE on various aspects of the eco- logy and behavior of Nautilus pompilius Linnaeus, 1758, during the course of a study of reproduction of the animal where it occurs in the Philippines. There have been few previous studies of living N. pompilius, studies on living animals in the field having been done on only two pre- vious occasions. WILLEY (1902) worked in the New Heb- rides for 3 years, and Dean (1901) did a much shorter study in the Philippines. Observations on aquarium spe- cimens of a different species (N. macromphalus) have been made by Biwper (1962) and Catata (1964). Mose- LEY (1879) described the activities of a single specimen of N. pompilius in a bucket, while Biper (1962) observed one specimen of N. pompilius “immediately after it was brought to the surface”, but did not further differentiate its activities from those described for N. macromphalus. The present observations were made on animals trapped and kept in holding cages in the ocean, as well as on animals held in an aquarium. Studies were made in the water with the aid of SCUBA gear. Field studies were done from June until mid-October, 1971. MATERIALS anp METHODS Specimens were caught in traps set in Tanon Strait, which lies between the islands of Negros and Cebu (Figure 1), and were kept for months at a time in holding cages at 60m. Some animals were also kept for as long as 2 weeks in holding cages set at 10m and at 25m, where observations were made by SCUBA diving. Observations of free swimming animals were also made by SCUBA diving. Animals kept in aquaria with a continuous flow of sea- water remained healthy and reactive so long as the water was cooled to 23° C, but field conditions precluded cooling for more than 48 hours. All animals were fed at least every other day. GEOGRAPHICAL DISTRIBUTION Two coastal areas of the island of Negros were surveyed in an attempt to ascertain the distribution of Nautilus pompilius in the area. Along one, on the northern coast of Negros Occidental between Escalante and Cadiz (Fig- ure 1), N. pompilius is seldom, if ever, encountered alive. Empty beach washed shells are occasionally found but the animal is never trapped alive. Stories were persistent among the fishermen of frightened animals deserting their shells. These same fishermen brought in the pelagic octo- pus, Tremoctopus violaceus della Chiaje, 1830, caught near Bantayan Island, saying this was the animal which lived in Nautilus shells. It is interesting to note that the fishermen call this octopus by the local name for Nautz- lus (“lagang’’), instead of by the name they usually use for an octopus (“‘cogeta”). From extensive questioning, and our own field search, it appears that if N. pompilius occurs in these waters at all, it is certainly rare. The southern coast of Negros was also surveyed from Bais City on the east, to Bayawan on the west coast (Fig- ure 1). Here Nautilus pompilius is encountered as an incidental catch in the local fish traps. These bamboo fish traps are not baited, and are left. in place at a depth of 60 to 120m for a period of 1 to 3 weeks. Estimates given by the fishermen of the frequency of N. pompilius catches in the fish traps show that it may be more abundant on the southwest coast of Negros around Bayawan, where an average of 20 per year are caught, than in the southeast portion of the coast from Dumaguete to Siaton ( Figure 1), where an average of 7 specimens were encountered per year per trap. Animals purchased in this region were Page 76 = a g 33 9 S & VER ae (os (GF a) R < A Negros Island, the Philippines, where work on Nautilus pompilius was undertaken. Shaded areas of coast represent survey areas. Inset shows Negros and Cebu (black) in relation to rest of Bayawan THE VELIGER Bindoy @ Bais @\ Dumaguette @ Siaton —@—r SS : Figure 1 Philippine Islands Vol. 15; No. 2 Vol. 15; No. 2 positively identified as N. pompilius. There were no stories here of N. pompilius abandoning its shell. Four fishermen who trap exclusively for Nautilus pom- pilius were eventually located. Philippine fisheries biolo- gists, university scientists and shell collectors had indicated no knowledge of living N. pompilius being taken anywhere in the islands, and the finding of these fishermen marked the discovery of a good supply of N. pompilius for the first time in 70 years. DEAN (1901) had worked with fishermen near Bais, where N. pompilius is no longer known as a commercial animal. TALAvERA & FAUSTINO, writing in 1931, state that at that time there was no longer any commercial fishing of N. pompilius in the Philippines. At present, 4 fishermen from Negros Oriental set traps near Tinaogan Reef, north of Bindoy (Figure 1) (9°48’ N, 123°10’E). Bobos — traditional bamboo fish traps similar to those described by DEAN (1901) — are baited with fresh chicken, fish or pork and set on the bottom, from 60 to 240 m deep. The traps are pulled each morning, and although catches may range from 0 to 19 Nautilus pompilius per trap, the average daily haul is 5 specimens per trap. The meat of the animal is sold in the local market, and shells are shipped to Cebu City where they are wholesaled by shell dealers. However, the overwhelm- ing majority of N. pompilius shells shipped from the Phil- ippines each year have been found during the typhoon season washed up on shore in regions such as the island of Bohol. Bohol lies southeast from the island of Cebu. ECOLOGICAL DISTRIBUTION eo The bobos used by the nautilus fishermen are set near coral reef areas where the bottom drops from 40m to ap- proximately 240m within a mile from shore. The Tanon Strait deepens to 400-600m a short distance beyond. It is likely that Nautilus pompulius could be found in the deeper regions, but the physical effort of hauling up traps from these depths precludes any trapping there. Fishermen in the area report the bottom environment on the north side of Tinaogan Reef to be rocks and coral heads to about 90m, and mud to limits of their trapping there (approximately 150m). The bottoms of traps brought up sometimes drip a grey mud. In experimental trapping at various depths, no Nautilus pompilius were ever captured shallower than 58m. Experiences with the animals in holding cages, aquaria, and experimental release observed with SCUBA gear, as well as in their transport from the field, strongly suggested that temperature limits vertical distribution. THE VELIGER Page 77 Table 1 summarizes trapping data for a 6-week period between August 8, 1971 and September 15, 1971. Most traps are set between 80 and 180m where catches are Table 1 Records of Nautilus pompilius caught in traps near Bindoy, Negros Oriental from August 8 to September 15, 1971 Depth Number of Nautilus per haul Number of (meters) average range hauls 58 - 70 1 0-3 3 71-90 4 0-10 17 91-110 6 0-19 20 111 - 130 5 0-12 48 131 - 150 3 1-9 12 151-170 7 0-15 13 171 - 190 5 0-10 13 191 - 210 4 0-7 2 211 - 230 6 4-8 4 231 - 250 5 0-9 7 260 2 1 Co) 40 80 An 120 = 160 as ray o A 200 240 280 320 20 22 24 26 28 30 32 Temperature (° C) Figure 2 Morning temperatures at holding cage sites (*) and trapping areas, Tafion Strait, September 2 and 3, 1971 Page 78 consistently good, and the depths convenient for working. Figure 2 shows temperatures taken at various depths during a 2-day period in early September 1971. The data indicate that Nautilus pompilius lives at depths where water temperature may be as much as 9° C lower than in the more shallow waters adjoining. ANOMALOUS DISTRIBUTION or SEXES In the 6-week period between early August and mid-Sep- tember, 1971, 534 specimens were caught in baited traps, and less than 5% of these were females. Eight chance catches (7. e., from an ordinary fish trap or hook and line) were brought in from the southern coast of Negros during July and August. Five of these, or over 60%, were females. Baited traps were set 3 times in one of these loca- tions just south of Dumaguete that had yielded most of the females, in an attempt to determine whether the com- position of the population differed there, but no Nautilus pompilius at all were caught on these occasions. Wittey (1902) experienced a similar, though less dras- tic, reduction of females in the animals he trapped in New Britain. Approximately one-third of the Nautilus pompi- lius he trapped there over a period of 9 months were females. Trapping data covering an entire year are being ob- tained in the present study. These data will show if the low percentage of females caught is a seasonal phenom- enon. COMMENSALS Commensal copepods, identified as Anchicaligus nautil (Willey, 1896), were numerous on the interior aspect of the ala infundibulae, that is, the mantle flaps that lie at the rear of the hood area dorsolaterally and which regulate water intake. Anchicaligus nautili were also com- monly found in the posterior dorsal portion of the funnel. Although the vast majority of Nautilus pompilius shells are free of settled animals, 2 living specimens were found THE VELIGER Vol. SNe with attached barnacles. One had a balanoid type bar- nacle on the rear of its shell. Another had a stalked bar- nacle attached about midline ventrally. These shells were accidentally discarded, so further identification of the bar- nacles was not possible. ; The kidneys of freshly killed animals were examined at 500 < magnification under a dissecting microscope, and no evidence of mesozoan infestation was found. DIURNAL ACTIVITY Experimental trapping near Bindoy, Negros Oriental, confirmed the observation that activity is diurnal (WiL- LEY, 1902). Baited traps placed out during daylight hours (7 AM to 5 PM) at depths from 110 to 180m, caught no Nautilus pompilius, while those similarly placed for 24 hours produced average yields. Nautilus pompilius kept in holding cages in the ocean at 10 and 25m and observed with SCUBA gear, were occasionally seen eating dead fish placed in the cage during the day. However, most feeding activity was during the night. In the aquarium, Nautilus pompilius usually rested quietly during the day, attached by the distal portion of one or more tentacles to the wall of the aquarium (Figure 3). In the holding cages, where chicken wire provided little support, animals often attached their tentacles to one another’s shell. Where portions of the holding cages were lined with burlap, the animals frequently hid in the folds during the day. It is highly likely that the normal daytime activity of Nautilus pompilius is to remain attached to coral rubble or crevices in its natural habitat. Not only did animals usually remain attached during the day when in captivity, but field experiments lent further support to this hypo- thesis. A healthy N. pom pilius was released above a sloping coral reef, and swam slowly down at an angle until it came to rest on the reef, where it fastened itself to a coral head and rested quietly, much as it had been ob- served to do in the aquarium. This behavior was elicited each time it was removed by a diver and released again Explanation of Figures 3 to 6 Figure 3: Nautilus pompilius in daytime resting pose, one tentacle fastened to wall of aquarium Figure 4: Nautilus pompilius beak compared to contour of break in shell of young male Nautilus pompilius Figure 5: Comparison of normal shell of female Nautilus pompilius, left, with a similar shell whose contour has been severely altered by bites Figure 6: Nautilus pompilius in aquarium with shortened tentacles Tue VE IcER, Vol. 15, No. 2 [Haven] Figures 3 to 6 iy ee ae Figure 3 Figure 4 Figure 5 Figure 3: Nautilus pompilius in daytime resting pose, one tentacle fastened to wall of aquarium Figure 4: Nautilus pompilius beak compared to contour of break in shell of young male Nautilus pompilius Figure 5: Comparison of normal shell of female Nautilus pompilius, left, with a similar shell whose contour has been severely altered by bites Figure 6: Nautilus pompilius in aquarium with shortened tentacles Vol. 15; No. 2 THE VELIGER Page 79 at progressively deeper depths. At 20m the released N. pompilius landed about 2 feet from a cave that was ap- proximately 4 feet long and 2 feet deep, formed by coral overhang on the slope. Upon landing, N. pompilius turned, swam forward, and fastened itself to the coral rubble back in the darkened recess, with the rear of its shell facing outward. Here it remained until removed by the diver, and pieces of coral rubble had to be forcibly re- moved from its tentacles. It should be particularly noted that N. pompilius was never observed to swim forward at any other time except when feeding (see subsequent section). Such purposive behavior suggests that N. pompi- hus preferred a sheltered spot during the daytime. SPEED or SWIMMING Animals released in the ocean were never found to swim quickly, although here, as elsewhere (see BrppER, 1962), the local people claimed the animals could swim very fast. A diver could keep up with a Nautilus pompilius by swim- ming with a slow breast stroke. Animals may give fairly strong jerks in an attempt to wrench themselves free from a restraining grip, and these sudden movements may give rise to the erroneous belief that the animal is a speedy swimmer. Attempts were made to frighten free-swimming ani- mals by swimming directly at them, or by touching the hood or an eye. When so annoyed, Nautilus pompilius made no attempt to escape or clamp shut, but merely turned the rear of the shell to the source of irritation. Similar behavior was elicited when pictures were taken of animals in the aquarium, even though flash bulbs were not used. I would view with caution statements belittling the intelligence of this animal. FIGHTING Irregular breaks are common along the anterior margins of shells of both male and female Nautilus pompilius. When a young male kept in a holding cage with several other adult males received a bite in its hood and a clean V-shaped break in its shell, the break was found to con- form closely in contour to the upper beak of N. pompilius (Figure 4). Comparison of breaks along the edge of other adult N. pompzlius shows that fighting within the species — for whatever reason — is fairly common. Both males and females are bitten and some so severely as to alter the contour of the shell (Figure 5). TENTACLE POSITIONS The tentacles of Nautilus pompilius are structurally di- vided into two parts, with a thick sheath at the base, into which a slender cirrus can be withdrawn. The cirri are highly distensible and the tentacles can be held in a vari- ety of positions that seem to lend themselves to categori- zation, although the function of these positions is not al- ways Clear. (a) Shortened Tentacles (Figure 6): The cirri are well retracted into the fleshy base. This position was common when the animals were in an apparently stressful situation, such as being in warm water or water containing abund- ant plankton. (b) Trailing Tentacles (Figures 7, 8): All of the ten- tacles are fairly well retracted with the exception of one or two of the lowermost outer pairs. These trail during ocean swimming, as in Figure 7, or may extend forward or down on more stationary specimens respiring in the aquarium (Figure 8). (c) Moderately Extended Tentacles (Figure 9): These may be combined with trailing tentacles, as in Figure 9, or are seen when the animal is attached and resting (Fig- ure 3), usually when specimens are in aquarium water with a temperature close to that of their normal environ- ment. (d) “Cat’s Whiskers” Pose (Figure 10): Three to 4 pairs of tentacles radiate outward as in Figure /0. In the aquarium, Nautilus pompilius would pump itself to the surface and drift downward with tentacles splayed out in this position. The increased ability to become aware of objects close by seems obvious, thus the name of “cat’s whiskers” for this position. (e) Extended Feeding Tentacles (Figure //): The ten- tacles are extended to apparently the maximum length during feeding (Figure //). The tentacles are arrayed in Bidder’s “cone of search” during the search for food and their use during feeding appears to correspond to that of Nautilus macromphalus (Bwper, 1962). A more detailed description of feeding can be found in the next section. FEEDING When dead fish or chicken is given to Nautilus pompilius in captivity, small pieces approximately 5mm square are neatly bitten off by the beak. Large amounts may be stored in the esophagus, to await processing by the gizzard. The esophagus is thin-walled, but highly distensible. Spe- cimens removed from baited traps usually had 20 to 30ml Page 80 THE VELIGER Vol. 15; No. 2 of bait in the esophagus, but one specimen had stored 100 ml of bait. Little information was obtained on the natural food of N. pompilius, but pieces of decapod crustacean carapaces were occasionally found in the gizzard, and ap- peared to come from crabs with a carapace | cm in width. Specimens kept in holding cages were fed both live and killed crabs and fish. There was no clear evidence that the crabs or fish were ever taken alive. The fish, however, had to be large enough so as not to escape through the chicken wire mesh of the cage and were 9 - 13cm long. Observations with SCUBA gear showed that dead fish and crabs placed in the cages were sometimes eaten during the day, but the greatest feeding activity occurred in the night. Aquarium specimens would search for food during the night. The cirri of the tentacles were stretched out ap- proximately 9cm and Nautilus pompilius would cruise forward with the tentacles extended downward (BmwpEr’s “cone of search”, 1962) with the tips touching the bot- tom. These tentacles moved quite rapidly, exploring the bottom and trailing a short distance behind. When food was offered for the first time and dropped in the aquarium 2 feet away, it was located within one minute. The for- ward swimming did not cease until the tentacles touched the food, which meant that for a moment, the main body of the animal would continue ahead, leaving the tentacles trailing behind, wrapped around the food. Thus, in the aquarium, although the stimulus that initiated the food search was chemosensory in nature, food was definitely located by touch. It is of particular interest that Nautilus pompilius swam forward when searching for food, since this was the only time the animals were ever observed to swim forward, with one exception, when one moved to a hiding place (see “Diurnal Activity”). It makes sense adaptively that with sensory tentacles in the front N. pompilius moves forward and makes use of these tentacles as an exploratory apparatus when searching for food, rather than always swimming backwards. The searching-touch phenomenon of feeding in the aquarium, coupled with the relatively slow swimming movements strongly suggests that Nautilus pompulius is a bottom feeder. It is possible that in addition to feeding on small crustaceans, N. pompilius is a scavenger. Lack of predation on live food in the holding cages plus the highly distensible esophagus would suggest this as a possible way of life. The method of trapping with dead bait is also evidence for this argument, which needs to be further tested in the field. ACKNOWLEDGMENTS I am indebted to Robin Coulon for much of the field work and many original observations, and to Wilson Vailoces for his part in collecting data and animals. I am grateful to the Biology Department of Silliman University, Dumaguete City, for research space and particularly to Mr. Daniel Sycip who offered invaluable field research facilities and help. I thank Dr. Gilbert L. Voss, School of Marine and Atmospheric Sciences, Miami, Florida, for identification of the octopus, and Dr. Paul Illg of the Zoology Department, University of Washington, Seattle, Washington, for identifying the commensal copepod. This project was supported in part by a grant from the Penrose Fund of the American Philosophical Society. Literature Cited Bipper, ANNA M. 1962. Use of tentacles, swimming and buoyancy control in the pearly Nautilus. Nature 196: 451 - 454 Catata, Rene L. A. 1964. Carnival under the sea. figs.; 27 plts. Dean, BASHFORD 1901. Notes on living Nautilus. Mose ey, Henry NotrTipce 1879. Notes by a naturalist on the “Challenger.” Macmillan & Co., London: xvi+620 pp.; col. frontisp.; illust.; col. plts.; fold. map TALAVERA, FLoRENCIS & L. A. FAUSTINO 1931. Industrial shells of the Philippines. 45 (3): 344 - 347 WILLEyY, ARTHUR 1898-1902. Contribution to the natural history of the pearly Nautilus in Zoological results based on material from New Britain, New Guinea, Loyalty Islands, and elsewhere collected during the years 1895, 1896 and 1897. Pt. 6: 691 - 827 Ed. R. Sicard, Paris: 141 pp.; 48 Amer. Natural. 35 (418): 819-837 Philipp. Journ. Sci. Explanation of Figures 7 to 11 Figure 7: Nautilus pompilius descending after release in ocean, with lowermost pair of tentacles trailing Figure 8: Nautilus pompilius in aquarium with lower pair of ten- tacles trailing Figure 9: Moderately extended tentacles on Nautilus pompilius in aquarium Figure 10: Nautilus pompilius in aquarium displaying “cat’s whis- kers” arrangement of tentacles. Specimens pump to surface and drift down in this attitude Figure 11: Nautilus pompilius with tentacles extended in feeding position. Piece of fish is being grasped by tentacles next to beak Tue VELIGER, Vol. 15, No. 2 [HaAvEN] Figures 7 to 11 Figure 7 Figure 9 P Figure 10 Figure 17 Vol. 15; No. 2 THE VELIGER Page 81 Microarmature and Barriers in the Aperture of Land Snails BY ALAN SOLEM Department of Zoology, Field Museum of Natural History Roosevelt Road and Lake Shore Drive, Chicago, Illinois 60605, (5 Plates) DEVELOPMENT OF VARIOUS FOLDS, ridges, calluses, tuber- cles, constrictions or lamellar plates that effectively narrow the shell aperture is a common phenomenon in non-oper- culated land snails. With the obvious exception of slugs or taxa with partly (Succineidae, Vitrinidae) to drastically (some Helicarionidae, Testacellidae) reduced shells and visceral humps, most families show at least a few species with apertural narrowing caused by such constrictions. There is no agreed nomenclature for these structures, which have most frequently been cited as “teeth”. Since this has obvious gustatory connotations, a better term for general usage would be to refer to these as ‘barriers’. This generic term can be modified to indicate the form of the structure by use of the more traditional terms as modifiers. The general assumption has been that these barriers are effective in reducing predation by arthropods (see CooKE, 1895: 63). Along with the production of distasteful mu- cus by slugs, an offensive odor (as in Oxychilus, see Lioyp, 1970), issuing an irritating froth or liquid (as in Ligwus, see EISNER & WILSON, 1970), and self amputation of the posterior tail (as in Prophysaon, see Pitspry, 1948: 680), such barriers are a basic defense mechanism of pul- monate snails. They are partial substitutes for the oper- culum of prosobranchs, which forms a nearly impregnable defense against small predators. The number, position, shape and size of these barriers frequently has been used as identification or diagnostic features for both genera and species, particularly in such groups as the Clausiliidae, ‘Tornatellinidae, Urocoptidae, Endodontidae (s./.) and Pupillidae (s./.) where the shell is rather uniform in appearance. Virtually no attention has been paid to their structure and formation. ‘The develop- ment of ‘prickly nodes” on apertural lamellae in Strobi- lops (Pitspry, 1948: 862, fig. 466), calcareous hooks that point towards the outside of the aperture on the lamellae in Thaumatodon multilamellata (Garrett, 1872) (see Pitspry, 1893-1895: plt. 4, fig. 38), plus numerous obser- vations on the internal ridges in various Urocoptidae are among the few exceptions. Scanning Electron Microscope (hereafter SEM) exam- ination of barriers and apertural surfaces in several land snail families has shown that a high percentage of species have microarmature, not just on the barrier edges, but over much of the lip surface, particularly the columellar and parietal regions of the aperture. This report is con- cerned with the basic pattern of such microarmature, its probable function, and how more sophisticated micro- armature could have evolved from the generalized condi- tion. As necessary background information, a brief survey of barrier types is presented. A second report (SOLEM, in press) will discuss structural differences in the armature found on the barriers in species of Charopidae and Endo- dontidae. ACKNOWLEDGMENTS The photographs illustrating this paper were taken on both Cambridge and Jeolco SEM!’s over the past two years. For assistance in SEM operation and photography, I am indebted to Mr. Akira Kabayaand Dr. John Russ of Jeolco (USA), Inc.; Miss L. Marchant of Franklin Institute Re- search Laboratories, Philadelphia; and to Dr. Harvey Lyon, Mr. John Lenke, and Mr. George Nayarian of the American Dental Association Research Institute, Chicago. Mr. Fred Huysmans, Photographer at Field Museum of Natural History prepared the published prints, and Mrs. Dorothy Karall mounted the figures. Part of this work was sponsored by National Science Foundation grant GB- 6779. Their support is gratefully acknowledged. Page 82 Patterns of Apertural Narrowing There is no single strategy for barrier formation, but rather a great variety of experiments. Most involve deposi- tion of calcareous ridges, inward lip edge growth, or a com- bination of both. Large and complex barriers can be present in early and mid-juvenile stages, then become greatly reduced to absent in the adults. The Tornatel- linidae (see Cooke & Konno, 1960: 113, figs. 50, a, d, e), Cerionidae (see Pirspry, 1946: 161, fig. 76), and zonitoid taxa such as Ventridens (see Pitspry, 1946: 438, fig. 235) exemplify this approach. These barriers are formed early, added to anteriorly and resorbed posteriorly during juve- nile growth, and then mostly resorbed before or when the animal reaches terminal size. In other groups, such as the Urocoptidae, Strobilopsidae, Charopidae and Endodon- tidae, the barriers may be formed early, growth follows the same pattern as in the first type, but then the barriers are retained at essentially full size during the adult stage. Perhaps most common is for the juvenile shell to totally lack any barriers or constrictions of the aperture, with the adult animal secreting complex barriers upon reaching maximum size. Such families as the Pupillidae (s./.), Strep- taxidae, Odontostominae and Polygyridae (especially Polygyra, Stenotrema and Triodopsis) have a majority of ‘species with well developed barriers. Frequently only a few genera in a family will show this development. Buli- mulid genera such as Auris, Eudolichotus and Otostomus, camaenid genera such as Labyrinthus, Traumatophora, Moellendorffia and most of the West Indian derivatives from Pleurodonte, bradybaenid taxa such as Metodontua, Semibuliminus, Pseudaspasita and Odontotrema, and various European helicid taxa have greatly developed apertural barriers although most taxa in these families have not or only slightly constricted apertures. Even in the helicarionid taxa, genera such as Brazieria and Sesara depart from the normal open aperture by developing high, transverse lamellae. Occasionally as in some pupillids, THE VELIGER Vol. 15; No. 2 juveniles will have one form of barriers and adults a totally different set. A few taxa build barriers at regular intervals. In Heli- codiscus (see Pitspry, 1948: 626, fig. 339, b) there are tubercles at about quarter-whorl intervals. Apparently these are not resorbed, or only resorbed after several new barriers have been erected. Members of the Corillidae have carried this approach to its logical conclusion. Highly complex barriers are ‘... formed on the completion of each half of a whorl, after which the previous set is ab- sorbed by the animal. I have observed several specimens which contained two sets of barriers at a distance of half a whorl; in some cases the older set had almost vanished . . .” (GupeE, 1914: 55). Finally, the clausilium and barriers found in members of Clausiliidae and the most unusual apertural closing attributed to Thyrophorella from Sao Thome, a hinged flap (see Girarp, 1896), are additional strategies for aper- tural narrowing. All of these barriers should be viewed as representing structures partly compensatory for the absence of the prosobranch operculum. That is, they hinder possible predators from reaching the animal after it retreats behind the barriers. This was perhaps suggested first by GUILDING (1829: 168) in an oft quoted sentence—‘I know not whether the use of the teeth and laminae of the Pupadae (=Pupillidae, s. /.) has been explained; they may answer the purpose of an operculum to keep out enemies, while they afford no obstacle to the motions of the soft and yield- ing body of the animal.” Subsequently Gopwin-AUSTEN (1874: 611) reported finding small insects stuck between the barriers in two specimens of the corillid genus Plecto- pylis. While not frequently observed, anybody who has sorted field collections of small land snails that have large and complex apertural barriers can attest to the reality of this phenomenon. - At times the barriers come so close to filling the aperture of the shell that it is dificult to conceive how the buccal Explanation of Figures / to 6 Tornatellina plicosa Odhner, 1922 Figures 1 to 3: Southwest slope at 500 - 530 m elevation, Portazuelo, Masatierra, Juan Fernandez Islands. Field Museum of Natural History number 167976. Figure /: partial view of shell aperture at 76 showing columellar (upper center), parietal (lower right center), and lower palatal (bottom center) lamellae. Figure 2: lower side of outer edge of columellar lame!la at 880 X showing con- centration of microdenticles on sides of lamellae. Figure 3: part of a cluster of denticles from same area at 4230. Tekoulina price: Solem, 1972 Figures 4 to 6: Station R-11, summit of Mt. Te Kou, Takuvaine Valley, 1930 feet elevation, Rarotonga, Cook Islands. Field Museum of Natural History number 153414. Figure 4: Palatal (upper with serrations) and columellar (lower and smooth) lamellae near pos- terior end of palatal (upper left) at 139X. Figure 5: Surface of palatal lamella at 826X showing positioning of denticles on upper surface. Figure 6: Details of denticle shape and relation to surface of lamella at 4646X. Tue VELicER, Vol. 15, No. 2 [SoLeM] Figures 7 to 6 Vol. 15; No. 2 mass and muscular foot can be successfully withdrawn and protruded. In the polygyrid genus Stenotrema (Figure 23), for example, the aperture is effectively narrowed to a thin slit by lip extensions and a parietal lamella. In such Florida species as Polygyra uvulifera (Shuttleworth, 1852) and P. auriculata Say, 1818 (see Pitssry, 1940: 595, fig. 384) the degree and complexity of constriction is even greater. In many of the minute Tornatellinidae (for example, CooKE & Konpo, 1960: 107, fig. 47, a—c), Pupillidae (for example, see Pitssry, 1948: 897), and endodontoid taxa (SOLEM, in press, figs. 1-6) high lamellar barriers come close to over- lapping in the middle of the aperture. Such structures are not limited to minute or medium sized land snails. Laby- rinthus otis (Lightfoot, 1786) is a South American cama- enid ranging from 39-54 mm in diameter. A combination of a raised parietal lamella and a huge palatal tubercle that shows on the outside of the shell as a deep indentation combine to grossly restrict the shell opening (see SOLEM, 1966: 110, fig. 30, b). The internal barriers of the 10- 25mm Plectophylis are equally effective (see GupE, 1914: Sy Es OB))o There is no simple relationship between relative size of the barriers and the size of the organism. In the Polygy- ridae, small sized genera such as Polygyra and Stenotrema (see ARCHER, 1948) do have large barriers, while the larger Triodopsis and Mesodon have reduced or vestigial den- ticles. However, the small Praticolella whose distribution overlaps that of Polygyra and Stenotrema, totally lacks such barriers. In the Pupillidae (s. /.) the minute Vertigo and relatively large Pupilla lack barriers or have very small ones, while the extremely complex barriers occur in the medium sized Gastrocopta. In contrast, the larger species of Labyrinthus have proportionately larger barriers than do the small species (SOLEM, unpublished data). What is needed before relative barrier size can be interpreted func- tionally is hard data on the predators of particular species. Unfortunately, this is mostly unavailable. Arthropod Predators and Barrier Effectiveness While it is a text book statement that snails are preyed upon by carabid beetles, larval fire flies, silphid beetles, and various sciomyzid flies, we know nothing concerning the identity of predators on micro-species. Essentially all published records are about larger insects feeding on Euro- pean or North American helicoid and zonitoid taxa. Pre- daceous mites, the smaller staphylinid beetles, plus a huge variety of less familiar groups belonging to the litter fauna are potential suspects. Until these receive more study, THE VELIGER Page 83 analogies will have to be drawn from data on the larger snail-eating insects. Carabid beetles, both adult and larval stages, are active predators on medium to large sized land snails. Indeed, one tribe, the Cychrini, is almost exclusively malaco- phagous. Data concerning both adult and larval feeding patterns in Carabus have been given in a recent review (SturANI, 1960). The larva or adult enters the snail’s aperture (STURANI, 1960: 94, fig. 6), gradually consuming the occupant. In some cases, pieces of the shell are broken off to facilitate feeding (STURANI, 1960: 123, fig. 14; p. 136; p. 140, fig. 23). Similar patterns are shown by the snail- eating Silphidae. Both narrowing and elongation of the head and thoracic region are associated with this habit. In an elegant paper, BorTTcER (1921) demonstrated coevolu- tion between predator and prey, with increasing size of palatal aperture barriers in the North African helicid snail Otala (Deserticola) tigri (Gervais, 1857) countered by decreased width of head and thorax in the carabid beetle Carabus morbillosus Fabricius, 1792. Considerable information about larval feeding on snails in the lampyrid beetles Lampyris and Phausis is given by SCHWALB (1961: 456-470), including experimental tests concerning prey location and method of attack. The significant feature in both the carabid and lampy- rid method of feeding is that efficient utilization of the food source requires the predator entering or breaking the shell at some point. If a crawling snail is caught and the head and extended foot bitten or pulled off, considerable volume of the snail still remains inside the shell. For a small predator that cannot crush the shell, only entry into the aperture permits utilizing this part of the prey. If the snail is retracted into the shell, then it is available to the predator only by entering the aperture. Hence the evolu- tion of barriers behind which the snail can retreat would be an effective means of defense. Even if the snail lost a tentacle to an initial grab by a predator, a quick retreat behind the barriers would be effective, if the opening that remained was too small for the predator to gain entry and the predator could not crack the shell. The utility of such barriers to a particular land snail would depend upon the local predators. Most predators have a size range of objects that are recognized as possible “prey”, while things that are smaller or larger than this size are ‘‘non-prey’’. It is also well established that for many predators, the food sources will differ according to the season of the year. Hence the patterns of apertural barriers in land snails that vary from present in adult but absent in juveniles to the exact opposite situation would reflect selective pressure under particular circumstances. Page 84 Ornamentation on Apertural Surfaces With the above background information on the occur- rence, age correlation, and function of barriers in larger species of land snails, it becomes possible to discuss the ornamentation found on the surface of these barriers in smaller species. While in some taxa the barriers have shown an absolutely smooth surface even at 2000x magni- fication, in most of the small species there have been marked protuberances. These are particularly well de- veloped in the Endodontidae and Charopidae (Solem, in press). The data reported on here represent only a tiny sampling of the world fauna. It is too early to say that this is an almost universal phenomenon, but the discovery of these structures in more than 85% of the species examined to date suggests that it is very widespread. Tornatellina plicosa Odhner, 1921 (Figures 1-3) is a very small species, found on ferns or under leaves, from Masatierra, Juan Fernandez Islands. The maximum re- corded adult size is 5.1 mm in height. The photographed individual is a 2.47 mm high subadult. Optical measure- ment of the distance from the outer edge of the basal lip to the upper margin of the parietal lamella (left part of Figure 7) is 0.69 mm. When the surfaces of the major barriers, both top and sides, are examined at 880 x (Figure 2) and 4230x (Figure 3), they are seen to be covered with scattered to densely clustered calcareous hooks and tu- THE VELIGER | Vol. 15; No. 2 bercles. The hooks do not form a clear pattern, but lie at a variety of angles from the vertical and point in almost any direction. Tekoulina pricei Solem, 1972 (Figures 4-6) from Rarotonga, Cook Islands also is a tornatellinid. It reaches 9.1 mm in height and is a much more elongated species than the Tornatellina. Apertural armature is much less complex, with only single parietal, columellar and palatal apertural barriers. The columella (Figure 4, lower left) is smooth, but the palatal lamella (Figure 4, upper right) and parietal (not shown) have the top and upper side covered with raised denticles that point towards the outside of the aperture. Inspection at higher magnifica- tions shows that these denticles have their anterior fifth free of the surface (Figure 6 at 4646x) and their outer margin slopes back to the surface at about a 30° angle (left side of Figure 5 at 826x). From a broad base, each denticle narrows to an elongated, spear-like tip. Please also note that the surface of the columellar wall (Figure 4, extreme lower left) has vague irregularities. Barriers in the Tornatellinidae are present when the young hatch, grow anteriorly as the shell grows, and are absorbed posteriorly. The resorption margin on the pala- tal lamella in Tekoulina can be seen at the upper left of Figure 4. Both in structure, orientation and distribution, there are major differences between these two tornatel- linids, indicating that variation within family units can be extensive. Explanation of Figures 7 to 12 Vertigo milium (Gould, 1840) Figures 7 to 10: Menard County, Illinois. Field Museum of Natural History number 18776: Figure 7: Aperture and body whorl at 74X. Figure 8: Lateral view of parietal lamella edge at 2450. Figure 9: View from lower side of parietal lamella at 1879. Figure /0: Vertical view of denticles on parietal lamella at 5980. Virpazaria adrianae Gittenberger, 1969 Figures 11, 12: “Velika jama,” near Soko Mt., near Dupilo, west of Virpazar, Montenegro, Jugoslavia. Rijksmuseum van Natuur- lijke Historie, Leiden. Figure 17: Aperture of shell at 79X. Figure /2: Edge of palatal barrier at 935 X. Explanation of Figures 13 to 18 Strobilops labyrinthica (Say, 1817) Figures 13 to 15: Below Esterville, West Fork, Desmoines River, Emmet County, Iowa. Field Museum of Natural History number 154121. Figure 13: Parietal lamellae at 195X. Figure 14: Lat- eral view of small denticles at 2090. Figure 15: Detail of a single denticle at 6250 showing relationship of denticle and parietal lamellar surface. Phrixgnathus erigone (Gray, 1850) Figure 16: Waitakere Range, north of Auckland, North Island, New Zealand. Field Museum of Natural History number 135477. Den- ticles on columellar wall at 2485 x. Dentherona bairnsdalensis (Gabriel, 1930) Figures 17, 18: Jemmy’s Point, Lakes Entrance, Victoria, Australia. National Museum of Victoria, Melbourne. Figure 17: Aperture of shell with outer lip partly broken off at 73X. Figure 18: Low angle view towards posterior of parietal lamellar surface at 2435 X. THE VELIGER, Vol. 15, No. 2 [SoLEM] Figures 7 to 12 Tue VELIGER, Vol. 15, No. 2 [Sotem] Figures 13 to 18 1D ‘s . Vol. 15; No. 2 Vertigo milium (Gould, 1840) is a common North American pupillid. The aperture (Figure 7 at 74x) has several high and prominent lamellae. In this group the lamellae only form at adulthood, while the young lack these denticles. On most apertural surfaces there are ex- tremely small, roughly triangular denticles. On the pari- etal lamella edge (Figure 9 at 1879) they point partly towards the narrow central opening of the aperture and partly towards the outside of the aperture. When viewed almost horizontally from an anterior position looking diagonally backward (Figure 8 at 2450 x), they are seen to weakly: denticulate the surface. A more vertical view (Figure 10 at 5980x) shows that they have a triangular point coming from a nearly square base. Despite their minute size, these are equivalent to the clear hooks and scales of the tornatellinids. Virpazaria adrianae Gittenberger (1969: 298, fig. 4) has a large transversely situated parietal lamella combined with an inwardly elevated palatal and basal lip to effec- tively narrow the aperture. The specimen shown in Figure 11 has been tilted so that the edges of both the parietal (lower right) and palatal (upper right) barriers are visible. Tops and sides of these barriers are covered with dense pustulations (Figure 72 at 935x). These lack the sharp definition of the structures found in the previously dis- cussed species. They are comparable to the irregularities seen on the columellar wall of Tekouwlina (extreme lower left of Figure 4). Another orthurethran, Strobilops labyrinthica (Say, 1817) (Figures 73-15), has lamellae that show the same basic growth pattern as in Tekoulina, that is, anterior growth and posterior resorption. Instead of a continuous cluster of scale-like denticles, there are single rows of denticles at regular intervals. A low magnification picture (Figure 13 at 195x) provides orientation for the view of a single row of denticles (Figure 74 at 2090) and of a single denticle (Figure 15 at 6 250x) found on the parietal lamel- lae. The individual denticles are sharply elevated with only slight anterior inclination, restricted to the upper edge of the lamella, and formed of the same type crystals as the lamellar surface. he bands of denticles only start about one-quarter whorl behind the apertural lip and extend to the posterior edge of the lamella. These photo- graphs were made of the upper parietal (large lower la- mella in Figure 73) and the small interparictal (upper lamella in Figure 73) at a point about one-third of a whorl behind the apertural lip. Please note the irregular “peb- bling” of the parietal wall surface lying between the lamellae in Figure 13. Such structures are not limited to orthurethrans. The huge dagger-like denticles that line the edges of the main parietal Jamella in the New Zealand charopid, Ptychodon THE VELIGER Page 85 microundulata (Suter, 1890), have been figured previously (SoLeM, 1970: plt. 60). Illustrations of more typical endo- dontid and charopid taxa will be presented elsewhere (SOLEM, in press). Here I show only two aulacopod ex- amples. Phrixgnathus erigone (Gray, 1850) (Figure 16) isa New Zealand punctid without barriers, although other species in the genus (as presently defined) have well de- veloped ones. Particularly on the columellar wall, but toa lesser extent on the other surfaces of the aperture, there are small raised denticles that point towards the outside of the aperture (Figure 16 at 2485). These are irregular in form. They look like slanted flecks of mica crystals in rock and do not show a regularly defined shape. Similarly, the Australian charopid, Dentherona bairnsdalensis (Gabriel, 1930) (Figures 77, 18), has the surface of the barriers and the callus covered with fine irregularities that denticulate the surface (Figure 18 at 2435x). The same type of microarmature covers the apertural surfaces in the Malayan streptaxid Oophana diaphano- pepla van Benthem Jutting (1954: 105, fig. 13). Apertural narrowing is effected by three structures—a high sinuated parietal lamella, inward deflection of the outer palatal lip, and inward extension of the basal lip. SEM examination of the surfaces shows sharply defined elevated plates. In vertical view at 800x (Figure 19) and 4345x (Figure 20) their shape and spacing is seen to approximate that of Phrixgnathus (Figure 16) and Vertigo (Figures 9, 10) al- though quite different in size. Viewed laterally from a low angle at 1585x (Figure 21) and 6345x (Figure 22), the sharp anterior edge (left side of photographs) and gradual posterior slope of the denticles is obvious. At times the size of such platelets becomes very large. In Stenotrema barbatum (Clapp, 1904), a common polygyrid land snail of eastern North America (see ARCHER, 1948), they can be detected with optical equipment at relatively low magnification. Even at 27.5x (Figure 23) their pres- ence over all apertural surfaces is obvious. Viewed at 3100x (Figure 24) they are seen to be a series of overlap- ping ‘‘shingles’” that point towards the outside of the apertural opening. While not yet viewed under the SEM, 100x optical examination of various clausiliid, bulimulid, camaenid, helicid and enid taxa shows that equivalent structures are present on the lip and barrier surfaces in many species of these families. DISCUSSION What at first would seem to be a confusing mass of dif- ferent structures can be classified into two types. First, it is evident that the presence of partly elevated platelets, gen- erally very small in size, is almost the normal situation. Page 86 These occur on lip edges, calluses and barrier surfaces. They have been observed in species, such as Phrixgnathus erigone, that lack any apertural barriers. Where high, lamellar barriers that extend posteriorly for a fair distance are present, as in the Tornatellinidae, Strobilopsidae, En- dodontidae and some Charopidae, these can be partly or completely replaced by hook-like denticles, the second type of structure. In all cases the sharp edge or point of the microstructure faces towards the apertural opening. While the probable function of the hook-like structures is easy to hypothesize, their origin and the utility of the platelets is not immediately obvious. Barriers function to hinder or deny access by predators to the retreated animal. Addition of barbules that point towards the exterior and are located on top of the barriers as in Tekoulina (Figures 4-6), Ptychodon (SoLeM, 1970: plt. 60), and the Endo- dontidae (SOLEM, in press) reinforces and complements this protection. A small arthropod attempting to crawl between the lamellae could get setal hairs, antennal parts, or tarsal fringes caught under the free edge of the denti- cles. These could be freed most easily by backing out. Forward motion would most likely result in further en- tanglements, while retreat would bring liberation at the price of continued hunger. The platelets do not have an incised anterior that could entangle these arthropod parts (see Figures 16, 21, 22, 24). Their anterior margin is vertical. They do, however, have this vertical margin on the outside facing edge of the plate- let. I suggest that they function as an aid to the snail in extending its body from the shell. Contractions of the free muscle system and shift of the body fluids into the pallial cavity enable the foot and head to be withdrawn into the shell, but the problem of regaining the outside is more difficult. Increased turgor will cause swelling and relaxing the free retractor muscles will help extrude the foot and head, but, in particular, the parietal and columellar margin of the visceral hump would have difficulty in mov- ing forward after a deep retraction. Just as sand or cinders on an icy sidewalk improve traction for a human walking, so the provision of a rough surface on the columellar and parietal walls could aid the snail to pull its body forward. If a snail is prodded to retreat deep within its shell, then Explanation of Figures 19 to 22 Oophana (Haploptychius) diaphanopepla van Benthem Jutting, 1954 Figures 19 to 22: South face of Bukit Serdam, near Raub, Pahang, Malaya. Field Museum of Natural History number 147666. Figure 79: Vertical view of microdenticles on palatal lip of shell at 800. Figure 20: Details of microdenticles on palatal lip at 4345. Figure 217: Lateral view of microdenticles at 1585 x. Figure 22: Detail of microdenticles on palatal lip at 6345. THE VELIGER Vol. 15; No. 2 left alone, the edges of the mantle region are moved for- ward to near the lip edge before the head and foot are un- folded. The anterior vertical edges of these platelets would provide micro gripping surfaces for the mantle collar. Current techniques of SEM specimen preparation are not adequate to allow effective study of the cellular sur- faces on the mantle collar. When preparation technique catches up with the viewing capabilities of the SEM, then a study to test the validity of this hypothesis becomes pos- sible. That these platelets are not restricted to land snails has been demonstrated by RoBErTsoN (1971: plt. 9, figs. 32-34). The larval shell of Pedicularia decussata Gould, 1855 has these platelets on the columellar and basal lip edge. Hence it may well be that these platelets are a basic structure of snail shells that was not detected previously because of the limits inherent to optical viewing. SEM study of species without apertural barriers and comparisons of barrier and non-barrier species in the same genus must be undertaken. Since the aperture of Steno- trema is far more constricted proportionately than is the aperture of Oophana, for example, the large size of the platelets in the former could result from selection for rougher surface. If increasing platelet size is selected for when the aperture is narrowed, then this can be viewed as a pre-adaptation for development of hooks or points to entangle micro-arthropods. Once the anterior plate edge is elevated, then any mutation that incises the anterior margin would tend to discourage crawlers. The deeper the incising, the greater the discouragement, hence the selec- tive pressure leading to the change from a plate-like ridge to a pointed hook. Once the hooked points are present, the functional use of the platelets would be less important, and a degeneration to the irregularities seen in Tekoulina (Figure 4) and Strobilops (Figure 13) becomes probable. Thus the complex denticles in the Tornatellinidae and endodontoid taxa can be derived quite simply from the micro-platelets that are found in many taxa, first by selec- tion pressure for better sripping by the snail’s mantle during extension of the body from a retracted position, then by selection for indenting the elevated anterior edge as a means to discourage predators. Explanation of Figures 23 and 24 Stenotrema barbatum (Clapp, 1904) Figures 23, 24: Medora, Jackson County, Indiana. Field Museum of Natural History number 61296. Figure 23: View of shell aper- ture at 27.5X. Figure 24: Lateral view of platelets on parietal barrier at 3100X. [SoLEM] Figures 19 to 22 Tue VELIGER, Vol. 15, No. 2 Tue VELIGER, Vol. 15, No. 2 [SoLEM] Figures 23, 24 Vol. 15; No. 2 SUMMARY Many land snails are shown to have a dense microarmature of platelets on the inner surfaces of the shell aperture. These are visible at low magnifications when the shell aperture has been greatly constricted by barrier formation, but mostly at 900-3000x magnification in more typical species. It is hypothesized that this microarmature aids the snail when it extends the body after being retracted into the shell. The microplatelets would become larger when the aperture became more constricted, since the snail would have more difficulty in squeezing its foot and buccal mass through the narrowed opening. The various patterns of barrier formation in land snails are reviewed and the presence of hook-like denticles, gen- erally on the barrier edges, that point towards the outside of the aperture is documented. These can be evolved from the common platelets by progressively deeper in- cision of their anterior margin and narrowing from a broad anterior margin to a point. The function of these hooks is to hinder the attempts of small arthropod preda- tors to enter the snail shell by providing crevices (the under edges of the hooks) in which setae, antennae or tarsal fringes can become entangled. Literature Cited ARCHER, ALLAN F 1948, Land snails of the genus Stenotrema in the Alabama Region. Geol. Surv. Alabama, Mus. Pap. 28: 85 pp.; 10 plts. BorTTcEr, Caesar R. 1921. Carabus morbillosus Fabr. und Otala tigri Gerv., eine Studie gegenseitiger Anpassung. Abhdl. Senckenberg. Naturforsch. Gesell. 37 (4): 319 - 326; plts. 30, 31 Cooke, ALFRED Hanps 1895. Molluscs. figs.; 4 maps Cooke, C. MontacuE & YosHio Konpo 1960. Revision of the Tornatellinidae and Achatinellidae (Gastropoda, Pulmonata). Bernice P Bishop Mus., Bull 221: 303 pp.; 123 text figs. (30 December 1960) E1sner, T. & E. O. WiLson 1970. Defensive liquid discharge in Florida tree snails (Liguus fas- ciatus). The Nautilus 84 (1): 14-15; 1 text fig. (16 July 1970) Cambridge Nat. Hist. 3: xiit+t1-459; 311 text THE VELIGER Page 87 Girarp, ALBERT ALEXANDRE 1896. Sur le “Thyrophorella thomensis”, Greef, Gastéropode terrestre muni d’un faux opercule 4 charniére. Jorn. Sci. Math., Phys. e Natur., Acad. Real Sci. Lisboa (2) 4 (13): 28-32; 1 plt. GITTENBERGER, E. 1969. Beitrage zur Kenntnis der Pupillacea I. Die Spelaeodiscinae. Zool. Meded. 43 (22): 287 - 306; plt. 1; 8 text figs. (16 July 1969) Gopwin-AusTEN, H. H. 1874. Description of five new species of Helicidae of the subgenus Plectopylis, with remarks on all the other known forms. Proc. Zool. Soc. London 1874: 608 - 613; plt. LX XIII (17 November 1874) Gupe, Gerarp K. 1914. Mollusca. — II (Trochomorphidae-Janellidae). of British India. pp. xii+520; 164 text figs. Gui.piInc, LaNsDOWN 1829. Observations on the zoology of the Caribaean islands. Zool. Journ. 4 (14): 164-175 | G5 co’ vay Da OF 1970. The function of the odour of the garlic snail Oxychilus alliarius (Pulmonata: Zonitidae). Malacologia 10 (2): 441-449; 1 text The fauna fig.; 2 tables Pirspry, HENry AUGUSTUS 1893 - 1895. Manual of conchology. Second series: Pulmonata. 9: xlviiit+366 pp.; 71 plts. (16 November 1893 to 2 February 1895) 1940. Land Mollusca of North America (north of Mexico). Acad. Nat. Sci. Philadelphia, Monogr. 3, 1 (2): vii, 575-994; text figs. 378 to 580 (1 August 1940) 1946. Land Mollusca of North America (north of Mexico). Acad. Nat. Sci. Philadelphia, Monogr. 3, 2 (1): vi, 1-520; text figs. 1 - 281 (6 December 1946) 1948. Land Mollusca of North America (north of Mexico). Acad. Nat. Sci. Philadelphia, Monogr. 3; 2 (2): xlvii, 521-1113; text figs. 282 - 585 (19 March 1948) RoBERTSON, ROBERT 1971. Scanning electron microscopy of planktonic larval marine gastro- pod shells. The Veliger 14 (1): 1-12; plts. 1-9 (1 July 1971) Scuwacs, Hans HEeLtmMutT 1961. Beitrage zur Biologie der einheimischen Lampyriden Lampyris noctiluca Geoffr. and Phausis splendidula Lec. und experimentelle Analyse ihres Beutefang- und Sexualverhaltens. Zool. Jahrb., Syst. 88 (4): 399-550; 100 text figs. SoL_eM, ALAN 1966. The neotropical land snail genera Labyrinthus and Isomeria (Pulmonata, Camaenidae). Fieldiana: Zool. 50: 226 pp.; 61 text figs.; 16 tables (31 May 1966) 1970. Malacological applications of scanning electron microscopy I. Introduction and shell surface features. The Veliger 12 (4): 394 to 400; plts. 58-60; 1 table (1 April 1970) 1973. Apertural barriers in Pacific island land snails of the families Endodontidae and Charopidae. In press, The Veliger SturANI, Mario 1962. Osservazioni e ricerche biologiche sul genere Carabus Linnaeus (sensu lato). Mem. della Soc. Entomol. Ital. 41: 85 - 202; 59 text figs.; plt. 9 vAN BENTHEM JuTTING, W.S. S. 1954. The Malayan Streptaxidae of the genera Discartemon and Oo- phana. Bull. Raffles Mus. Singapore 25: 71-106; 13 text figs. (December 1954) Page 88 THE VELIGER Vol. 15; No. 2 Thecacera picta spec. nov. from Suruga Bay, Japan (Nudibranchia : Doridoidea : Polyceridae) KIKUTARO BABA Shigigaoka 35, Minami-11-jyo, Sango-cho, Ikoma-gun, Nara-ken, Japan (1 Text figure) Tue GENuS Thecacera Fleming, 1828 was established on the type Doris pennigera from Devon, England. But the original description of this species by Montacu (1815) was poor. Also, it is unfortunate that ALDER & HANcocK’s (1855) figures of T: pennigera were based on an animal “in a sickly state,” and so deformation presumably oc- curred by contraction at certain parts of the body of that animal. According to one of the color photographs taken in 1956 by Dr. A. Inaba of the Mukaishima Marine Biological Station on the Inland Sea of Seto, Japan from a very active specimen of T: pennigera and shown to me, the rhinophorial and branchial appendages are found to terminate altogether in an acutely pointed tip, not forming a blunt end as appeared in Alder & Hancock’s figures. The main species of Thecacera of the world are: 1. Thecacera pennigera (Montagu, 1815) Distribution: England; France; the Mediterranean; Brazil; Australia; Japan 2. Thecacera darwini Pruvot-Fol, 1950 Distribution: Chile 3. Thecacera maculata Eliot, 1905 = T. lamellata Barnard, 1933 Distribution: Karachi, India; South Africa 4. Thecacera inhacae Macnae, 1958 Distribution: Inhaca, South Africa The present new species is evidently distinct from the forms listed above by having (1) a different coloration of the body, and (2) a crescent-shaped ridge at the outer base of each rhinophorial appendage. Thecacera picta Baba, spec. nov. (Japanese name: Tsunozaya-umiush1) (Figure 1) Type: Collected by Mr. K. Suzuki, Curator in the Marine Science Museum of Tokai University and his assistants, SCUBA-divers of the Museum, from Uchiura-coast (35° 02’N; 138°53’E) near Osezaki, NE of Suruga Bay, Japan, in 35m, on 17 November, 1971. Description: The living animal, when fully extended, at- tains a length of 10mm. The external form of the body is essentially as in Dr. Inaba’s Thecacera pennigera (see above). The rhinophore is long, cylindrical, and perfoli- ated above. The rhinophorial appendage or sheath is incomplete (cf. ABRAHAM, 1877: 231) ; it takes the form of a triangular valve more or less narrowed and tapering to the tip. The anterior margin of the valve at its base is folded back to the stalk of the rhinophore. In this new species there is a crescent-shaped ridge situated at the outer base of each rhinophorial appendage. The gill is formed of 7 bipinnate plumes, set around the anus. The branchial appendage or post-branchial process is elonga- ted conical and pointed to the tip. The foot-corners are horn-like. The genital orifices are located immediately below and behind the right rhinophorial sheath. In the preserved state, the rhinophorial and branchial appendages of the animal become markedly shortened, (on facing page >) Figure 1 Thecacera picta Baba, spec. nov. A, C, and D: Living animal in dorsal, lateral, and ventral views; length tromm B: Copulatory organ in extruded state E: Paired jaws from outside (X 40) F: Right half-row of radula (xX 100) a — rhinophorial sheath b — male orifice c — female orifice d-—post-branchial process e—crescent-shaped ridge f — hollowed space g — penis h — hooks i—jaw proper j- wing 1 to 2—inner laterals 3 to 4-—outer laterals THE VELIGER Page 89 Vol. 15; No. 2 Page 90 and rounded as well, at their extremity. The rhinophores are completely retracted within sheaths. The ground color of the body above is translucent yel- lowish white. In this new species a conspicuous band of chocolate brown appears: (1) on the mid-dorsal line in front of the gill; (2) along the lateral margin of the head and back, including the lower half of the rhino- phorial and branchial appendages; (3) on the crescent- shaped ridge at the outer base of the rhinophorial sheath; (4) on each side of the length of the body, and (5) on the foot-brim. The tip of the rhinophorial and branchial appendages, foot-corners and tail are vividly tinted orange yellow. The rhinophore is orange yellow on the perfoliated portion, and yellowish white on the stalk. The gill is yel- lowish white, the largest plumes of it being provided with orange yellow pigmentation on the tip and a longitudinal chocolate brown vein on the rachis on the outside. The sole is uniformly yellowish white. The shape of the jaws and radula is typical of the genus. Each jaw is accompanied by a wing. The radula formula is 10 & 2°2:0:2:2. The inner laterals are hamate (the first is smaller than the second), and the outer ones simply scale-like. In Thecacera darwini a wing is absent from the jaws; also, this species is unusual in having a median tooth of the radula (Marcus, 1959: 58). The penis is armed with chitinous hooks as usually found in the genus. ACKNOWLEDGMENTS I wish to thank Mr. Katsumi Suzuki and his assistants for supplying the type collection for my taxonomic study. THE VELIGER Vol. 15; No. 2 Acknowledgment also is made to Dr. Akihiko Inaba for a photograph referred to for comparison. Literature Cited ABE, TAKEO - 1964. Opisthobranchia of Toyama Bay and adjacent waters. Tokyo. Hokuryu-Kan: ix+99 pp.; 36 plts. ABRAHAM, PHINEAs S. : 1877. Revision of the anthobranchiate nudibranchiate Mollusca, ‘with descriptions or notices of forty-one hitherto undescribed species. Proc. Zool. Soc. London 1877: 196 - 269; plts. 27-30 (August 1877) ALDER, JOSHUA & ALBANY Hancock 1844-1855. A monograph of the British nudibranchiate Mollusca, with figures of all the species. London, Ray Soc. prts. 1-7: 438 pp.; 84 plts. ALLAN, Joyce K. 1957. Some Opisthobranchia (class Gastropoda) new to Australia or otherwise of interest. Journ. malacol. Soc. Australia 1 (1): 3-7; figs. 1-3 Basa, KikuTARO 1960. The genera Polycera, Palio, Greilada and Thecacera from Japan (Nudibranchia - Polyceridae). Publ. Seto Mar. Biol. Lab 8 (1): 75 - 78; plt. 6 BARNARD, KEPPEL HARCOURT 1933. Description of a new species of Thecacera. London 19 (9): 294 - 295; fig. 1 Exvrot, CHares N. E. 1905. Nudibranchs from the Indo-Pacific: I. Notes on a collection dredged near Karachi and Maskat. Journ. Conchol. London 11 (8): 237 - 256; pit. 5; 1 text fig. Macnae, WILLIAM 1958. The families Polyceridae and Goniodoridae (Mollusca, Nudi- branchiata) in southern Africa. Trans. Roy. Soc. South Africa 35 (4): 341-372; plts. 17, 18; text figs. 1 - 23 Marcus, ERNST 1959. Lamellariacea and Opisthobranchia. University Chile Expedition 1948-49, No. 36. N. E (2) 55 (9): 1-133; figs. 1- 196 MontTacu, GEORGE 1815. Descriptions of several new or rare animals, principally marine, discovered on the south coast of Devonshire. Trans. Linn. Soc. Lon- don 11 (1): 1-26; plts. 1-5 Pruvot-Fo., ALICE 1950. Le genre Thecacera Fleming 1828 et une espéce nouvelle, The- cacera darwint. Journ. Conchyl. Paris 90 (1): 48-52; figs. 1-4 Journ. Conchol. In: Reports of the Lund Lunds Univ. Arsskr. (20 March 1959) Vol. 15; No. 2 GE RVERIGER Page 91 A New Species of Monoplacophoran from the Abyssal North Pacific FRANK J. ROKOP Scripps Institution of Oceanography, University of California, San Diego — La Jolla, California 92037 (2 Plates; 5 Text figures) INTRODUCTION SEVERAL RECENT species of Monoplacophora belonging to the subgenera Neopilina and Vema have been reported since the initial discovery of N. (N.) galatheae Lemche, 1957, by the Galathea Expedition in 1952. A total of ap- proximately 60 specimens, representing 5 species, have been collected from 19 stations in the Eastern Tropical Pacific (FILATOvA & ZENKEVICH, 1969). Only 3 specimens have been recorded from other regions: the Gulf of Aden in the Indian Ocean (TrEBBLE, 1967) ; the South Atlantic off the tip of South America (Rosewater, 1970); and the Central Pacific southwest of Hawaii (FiLatova et al., 1968). All have been recorded in depths ranging from 1650 to 6350m. With the exception of the Central Pacific monoplaco- phoran, all have been collected in relatively close proxim- ity to continents. Soxotova (1969) described these oce- anic regions near the continental land masses where primary production is high as “eutrophic”, in contrast to the sterile central “oligotrophic” areas. The Central Pacific specimen was collected by the R/V Vityaz from 2000 m on the slope of a guyot in the Marcus-Necker Sub- marine Mountains. Since the associated macrofauna was relatively diverse and abundant, Fitatova et al. (1968) concluded that the feeding conditions on the raised guyot were more favorable thanon the more characteristic, deep- er oligotrophic regions that surround it. They further pos- tulated that the distribution of monoplacophorans was restricted to eutrophic areas or to environments within otherwise oligotrophic regions with favorable feeding conditions. However, on Leg 7 of the Scripps Institution of Ocean- ography Expedition Seventow in the North Pacific a species of monoplacophoran was obtained from a depth of more than 6000m underlying the sterile, central water mass. The collection site is located in the center of the oligotrophic region where the estimated biomass of the bottom fauna (0.01 to 0.05 g/m?) is extremely low (Fia- Tova, 1969). Thus, contrary to previous information, monoplacophorans are able to survive in nutrient-poor, oligotrophic environments. This Central North Pacific species of monoplacophoran is distinct from other known species and is described in this report as a new species of the genus Neopfilina. In addi- tion, a series of scanning electron micrographs illustrating the details of the elaborate shell sculpture of the new spe- cies is included. SYSTEMATICS MONOPLACOPHORA Wenz in Knight, 1952 TRYBLIDIOIDEA Lemche, 1957 TRYBLIDIACEA Pilsbry in Zittel, 1899 Tripiipmpaer Pilsbry in Zittel, 1899 Neopilina Lemche, 1957 Neopilina (Neopilina) oligotropha Rokop, spec. nov. (Figures 1 to 5 and 6 to 9) Description of Holotype: Shell small, thin, patelliform and semitransparent. Shell sculpture of concentric and ra- dial elevated threads. Radial threads increasing in num- ber abapically from approximately 40 near the apex to 135 - 140 peripherally. Concentric threads 12 in number anterior to the apex and 32 in number along the midline from apex to posterior margin. The intersection of radial and concentric threads producing raised nodes and delim- iting quadrate depressions (150 -200/mm’). Aperture Page 92 THE VELIGER Vol. 15; No. 2 T.omm Figure I Dorsal view of the shell of Neopilina (Neopilina) oligotropha Rokop, spec. nov. Holotype, USNM no. 723796 ovate, slightly longer than wide. Apex prominent, disc- oidal, positioned slightly posterior of anterior margin. Peri- ostracum pale yellowish and transparent, noticeable only along the margin where it projects beyond the shell. The external morphology of the animal is exposed in ventral view. The prominent subcircular foot is surrounded laterally by the marked depression of the pallial area. Along each side is a row of 5 small, lobate gills. The oral region is bound anterolaterally by the velum and posteri- orly by numerous postoral tentacles. The gut, with 4 SM 1.0mm Figure 2 Ventral view of the holotype of Neopilina (Neopilina) oligotropha Rokop, spec. nov. MVR — median velar ridge M — mouth V— velum PT — postoral tentacles PM — pallial margin F— foot G — gills A — anus SM — shell margin distinct coils, terminates posteriorly at the anus, located at the base of the foot. Dimensions: Shell length 3.0mm, width 2.5mm, maxi- mum height (depth) 0.9mm, apex height 0.7mm, apex to anterior margin 0.1mm. Comparisons: On the basis of gill number, the present new species has been placed in Neopilina s. s. rather than Explanation of Figures 6 and 7 Scanning electron micrographs of the shell surface features of Neopilina (Neopilina) oligotropha Rokop, spec. nov. Figure 6: Oblique view of the entire shell fragment showing the overall pattern of the radial and concentric sculpture. x 40 Figure 7: Portion of the fractured edge of the shell fragment illus- trating the relief of the sculpture and the granular, porous nature of the shell structure. sm — shell margin c — concentric thread x 510 r— radial thread fe — fractured edge Tue VELIGER, Vol. 15, No. 2 [Roxop] Figures 6, 7 Vol. 15; No. 2 THE VELIGER Page 93 1.0mm Figure 3 Lateral view of the holotype of Neopilina (Neopilina) oligotropha Rokop, spec. nov. the subgenus Vema. Members of Vema, of which N. (V.) ewingi Clarke « Menzies, 1959, is the type, possess 6 pairs of gills in contrast to the 5 pairs present in the subgenus Neopilina. Of the other members of the subgenus Neopilina, the present new species most closely resembles N. (N.) veler- onis Menzies & Layton, 1962. Both N. (N.) veleronis and N. (N.) oligotropha are small (1 - 3mm), distinctly ovate in outline, and have small lobate gills. However, the post- oral tentacles are simple, unbranched projections in N. (N.) veleronis and the shell apex characteristically extends beyond the anterior margin; N. (N.) oligotropha differs in having multiple postoral tentacles and a shell apex which does not extend anteriorly over the margin of the aperture. Collection: Scripps Institution of Oceanography Expedi- tion Seventow, Leg 7, Station H-30. Central North Pacific, approximately 680 miles N of Hawaii (30°05/N, 156°11’ 48” W ), 6065 - 6079m, 8 July 1970, R/V Thomas Wash- ington. Gear: Epibenthic Sled (HESSLER & SANDERS, 1967) equipped with a 0.5mm mesh trawl bag. One spe- cimen (holotype) and 1 shell fragment. Holotype Deposition: National Museum of Natural His- tory (U.S. N.M.), Smithsonian Institution, Washington, D. C. USNM No. 723796. Key to the Species of the Subgenus Neopilina 1. Specimens large (10- 36mm); shell almost circular in outline; gills branching, with 5 - 8 lamellae .......... 2 — Specimens small (1-3mm); shell longer than wide, ovate in outline; gills with 1 - 4 small lobes ................ 4 2. Postoral tentacles well developed and numerous; gills WO Oo B WAGON ANS crt ccrrcdrcrmcianraanncoanrcecotemenaxiberonarco eo 3 — Postoral tentacles reduced; gills with 5 lamellae ........ Arann eee Neopilina (N.) bruuni Menzies, 1968 3. Shell apex almost immediately over the anterior margin I Ne een S| N.(N.) galatheae Lemche, 1957 — Shell apex set back from the anterior margin ............. bes te ee Ne Ne badenensisslebblesl 967 4. Postoral tentacles simple, unbranched; shell apex pro- jectmpabeyondstheshelliimanginge er rere eee cache ee area N. (N.) veleronis Menzies & Layton, 1962 — Postoral tentacles multiple; shell apex not extending beyoncdaithte esiielllesiai cinerea peer ete eres Dette econ 3 Lee N. (N.) oligotropha Rokop, spec. nov. REMARKS Size: Members of the benthic fauna of oligotrophic areas of the deep-sea are characteristically very small in size. All the gastropods and pelecypods from the same epi- benthic sled lowering (Station H-30) were under 6mm in maximum dimensions and the majority were smaller than 3mm. Hence, Neopilina (Neopilina) oligotropha is not unusually small but rather of moderate size for this par- ticular environment. Furthermore, the size range of the 14 specimens of N. (N.) veleronis collected by the R/V Velero IV off Baja California was 1.1 to 2.6mm and those close to 2mm in length had mature ova (MENZIES & Layton, 1962). Thus, there is no compelling reason to suspect that the type of N. (N.) oligotropha is an imma- ture growth stage of a larger form. Protoconch: The apex of Neopilina (Neopilina) oligo- tropha is smooth and discoidal, displaying no distinct coiled protoconch. A small dark area, however, is present a short distance behind the apex center (Figure 4). This mark possibly indicates one of the places of contact of a lost protoconch as in N. (N.) galatheae (LEMCHE & WING- STRAND, 1959: plt. 10, fig. 35). Figure 4 Apical portion of the shell of Neopilina (Neopilina) oligotropha Rokop, spec. nov. Page 94 THE VELIGER Vol. 15; No. 2 Shell Sculpture and Structure: The concentric threads on the shell of Neopilina (Neopilina) oligotropha are not all continuous. The posterior-most threads do not continue completely around the shell anteriorly; instead, they dis- appear abruptly along the lateral margin. In addition, several short threads are interspersed between longer ones, particularly along the midline. Thus, these concentric laminations cannot be considered as growth increments, but only as structural and sculptural aspects of the shell de- sign. In addition to the intact holotype of Neopilina (Neo- pilina) oligotropha, a fragment approximately 2mm long was obtained in the same epibenthic sled sample. This fragment had fresh mantle tissue adherent to its undersur- face indicating that another complete specimen was dam- aged during collection. Judging from the shell sculpture and curvature of the margin, the fragment originated from the left postero-lateral portion of a specimen nearly equal in size to the holotype (Figure 5). Figure 5 Diagrammatic representation of the relative position of the shell fragment of Neopilina (Neopilina) oligotropha Rokop, spec. nov. This fragment was utilized for detailed shell sculpture studies employing a scanning electron microscope (Cam- bridge S4 Stereoscan). The advantages of the scanning electron microscope over conventional optical methods of examination of shell surface features are numerous (SOLEM, 1970). Particularly with regard to depth-of-field at high magnifications, the scanning electron microscope is far superior. The entire shell fragment is shown in Figure 6. Of par- ticular interest are the radial threads which are seen to mcrease numerically abapically maintaining nearly equal quadrate depressions upon intersection with the concentric threads. The radial threads usually originate and termi- nate in contact with the concentric sculpture, thereby re- taining the integrity of the quadrate depressions. At the intersection of the radial and concentric threads, raised nodes are produced which are nearly twice as high as either thread alone (Figure 7). These nodes are not dis- tinct, independent features of the shell design, but merely the result of the overlap of the radial threads over the concentric sculpture (Figures 8, 9). Also, the radial threads are seen to be slightly wider than the concentric threads, both of which are separated by interspaces one to three times as wide. The shell structure of Neopilina (Neopilina) galatheae and three species of fossil monoplacophorans has been de- scribed (ScHmipT, 1959; ERBEN et al., 1968). Neopilina (N.) oligotropha seems to differ in having a much more irregular type of shell construction. As shown in the frac- tured edge view of Figure 7, the shell wall appears spongy and porous, consisting of minute, variable sized calcare- ous granules having irregular contacts with their neigh- bors. This appearance may, however, be due to partial dissolution and recrystallization of the shell fragment during preservation and storage of the sample. Ecology: At this time very little can be stated conclusively about the ecological aspects of Neopilina (Neopilina) oli- gotropha. Such information can only be inferred from the contents of the trawl, bottom type, and the morphology of the animal. Direct observations of the living animal under natural conditions are of course not available. The habitat of Neopilina (N.) oligotropha is that of a red clay, manganese nodule bottom. Most of the nodules in this region are buried (MENARD, 1964), the exposed nodules covering only a small percentage of the sea floor. The importance of these manganese nodules as a possible substrate for this species is uncertain. Neopilina (N.) gala- theae has been collected from muddy clays which con- tained no hard objects suitable as substrates (LEMCHE & WincstrAnp, 1959). Similarly, N. (Vema) ewingi is con- sidered a soft-bottom animal (Menzies et al., 1959). On the other hand, the Vityaz monoplacophoran was firmly Explanation of Figures 8 and 9 Figure 8: Surface view of the shell sculpture showing the arrange- ment of the radial and concentric threads. x 200 Figure g: Surface view of the shell sculpture illustrating the details of radial and concentric thread intersection, < 525 r— radial thread c — concentric thread THe VELIcER, Vol. 15, No. 2 [Roxop] Figures 8, 9 Vol. 15; No. 2 attached to the surface or a basalt block that was covered with a ferromanganese crust (Fiatova et al., 1968). Al- though N. (N.) oligotropha was not attached to any hard substrates in the trawl sample, the specimen may have been dislodged during collection. The coiled intestine of the holotype of Neopilina (Neo- pilina) oligotropha is clearly visible through its thin shell. The intestine appears to be filled with dark-colored sedi- ment, indicating a deposit-feeding mode of life. Deposit feeding seems to be characteristic of the monoplacophor- ans. Sediment-filled guts were also found in N. (N.) gala- theae (LEMCHE & WINGSTRAND, 1959; WotrFr, 1961), N. (V.) ewingi (Menzies et al., 1959), and in the Vityaz specimen (Fitatova et al., 1968). ACKNOWLEDGMENTS This study is part of a continuing program at Scripps In- stitution of Oceanography involved in the investigation of the structure of open-ocean, deep-sea benthic communities supported by the National Science Foundation Grants GB 14488 and GA 31344X. I wish to express my gratitude to Ronald T: La Borde, Staff Research Associate at Scripps Institution of Oceano- graphy, for taking the scanning electron micrographs and to Bryan R. Burnett, also at Scripps Institution, for his assistance in preparing the text illustrations. I thank Dr. Joseph Rosewater, Curator of Mollusks at the Smith- sonian Institution, for loaning the South Atlantic mono- placophoran specimen for comparison and study. I par- ticularly wish to acknowledge Dr. Robert R. Hessler, Asso- ciate Professor of Biological Oceanography at Scripps In- stitution of Oceanography, for the opportunity to report the present new species and for his critical reading of the manuscript. Literature Cited Crarke, ARTHUR H., Jr. « Ropert J. MENzIES 1959. Neopilina (Vema) ewingi, a second living species of the Paleo- ozoic Class Monoplacophora. Science 129: 1026 - 1027; 1 text fig.; 1 table (17 April 1959) THE VELIGER Page 95 Ersen, H. K., G. Frays « A. SIEHL 1968. Uber die Schalenstruktur von Monoplacophoren. Akad. Wiss. Lit. Abhandl. Math.-Naturwiss. K]., Mainz 1968 (1): 1 - 24; plts. 1-17 Firatova, Z. A. 1969. Quantitative distribution of the deep-sea benthic fauna. In V. G. Korr (ed.), The Pacific Ocean, vol. VII, Biology of the Pacific Ocean, prt. 2, The deep sea bottom fauna. Pleuston, pp. 202 - 216 [in Russian]. Moscow (‘“‘Nauka” Publ. House) Firatova, Z. A., M. N. Soxo.tova # R. YA. LEVENSTEIN 1968. Molluscs of the Cambro-Devonian Class Monoplacophora found in the Northern Pacific. Nature 220: 1114-1115; 3 text figs. (14 December 1968) Firatova, Z. A. & L. A. ZENKEVICH 1969. Present distribution of ancient primitive Monoplacophora in the Pacific Ocean and the fossilized Pogonophora in deposits of Cambrian seas. {in Russian] Okeanologia 9: 162-171; 1 plt.; 2 text figs.; 1 table Hessver, Ropert R. & Howarp L. SANDERS 1967. Faunal diversity in the deep-sea. 3 text figs.; 6 tables LemcHE, HENNING 1957. A new living deep-sea mollusc of the Cambro-Devonian Class Monoplacophora. Nature 23: 413 - 416; 4 text figs. (23 Feb. ’57) LemMcHE, HENNING & Kari G. WINGSTRAND 1959. The anatomy of Neopilina galatheae Lemche, 1957 (Mollusca, Tryblidiacea) . Galathea Reprt. 3: 9- 71; 56 plts.; 1 text fig.; 1 table MeEnarp, H. W. 1964. Marine Geology of the Pacific. McGraw-Hill, San Francis- co, Calif. pp. 1-271; 121 text figs.; 10 tables MeEnzizEs, RosBeErT J. 1968. New species of Neopilina of the Cambro-Devonian Class Mono- placophora from the Milne-Edwards deep of the Peru-Chile Trench, R/V Anton Bruun. Mar. Biol. Assoc. India, Proc. Sympos. Mollusca, held at Cochin from January 12 to 16, 1968, Mandapam Camp, India. Symp. Ser. 3: 1-9; 4 plts. Menzies, Ropert J. & WititAm Layton, Jr. 1962. A new species of monoplacophoran mollusc Neopilina (Neo- pilina) veleronis from the slope of the Cedros Trench, Mexico. Ann. Mag. Nat. Hist. 5: (55): 401-406; pits. 7-10 Menziges, Rospert J., Maurice Ewinec, J. LamMaAR WorZEL & ARTHUR H. CvarKE, Jr. 1959. Ecology of the Recent Monoplacophora. to 182; 10 figs.; 2 tables ROSEWATER, JOSEPH 1970. Monoplacophora in the South Atlantic Ocean. Science 167: 1485 - 1486; 1 text fig. (13 March 1970) ScumuptT, W. J. 1959. Bemerkungen zur Schalenstruktur von Neopilina galatheae. Galathea Reprt. 3: 73-77; 2 plts. So_em, ALAN 1970. Malacological application of Scanning Electron Microscopy I. Introduction and shell surface features. The Veliger 12 (4): 394 to 400; plts. 58 - 60 (1 April 1970) Soxotova, M. N. 1969. Distribution of deep-sea benthic invertebrates in relation to their methods and conditions of feeding. In V. G. Kort (ed.), The Pacific Ocean, vol. VII, Biology of the Pacific Ocean, prt. 2, The deep sea bottom fauna. Pleuston, pp. 182-201 [in Russian] Moscow (“Nauka” Publ. House) TEBBLE, NoRMAN 1967. A Neopilina from the Gulf of Aden. Deep-Sea Res. 14: 65 - 78; (February 1967) Oikos 10 (2): 168 Nature 215: 663 - 664; 3 text figs. (5 August 1967) WotrF, ToRBEN 1961. Animal life from a single abyssal trawling. Galathea Reprt. 5: 129-164; plts. 7-10 (28 December 1961) Page 96 THE VELIGER Vola INow2 A New Species of Conus from Taiwan EDWARD JAMES PETUCH Department of Zoology, University of Wisconsin - Milwaukee, Milwaukee, Wisconsin 53201 GEORGE MENDENHALL 416 Bayview Avenue, Millbrae, California 94030 (1 Plate) A LARGE SPECIMEN of a new species of Conus was trawled from deep water off the Taiwan coast during December, 1970. It was quite distinct from any other species found in that area. Because of the possession of several unique morphological characteristics, the following taxon is being proposed. GASTROPODA — PROSOBRANCHIA NEOGASTROPODA ConmaeE Linnaeus, 1758 Conus fletcheri Petuch & Mendenhall, spec. nov. Description: Shell glossy, elongate and sharply tapered towards the anterior end; body whorl incised with 25 deep spiral sulci which become wider apart toward the shoulder and closer together at the anterior tip; between each 2 of the major sulci there are less depressed spiral grooves which become coarser and more numerous near the columella; shoulder smooth, rounded and faintly coro- nated; spire relatively sharp and elevated, comprising 11 whorls and encircled with 3 spiral threads; spire angle approximately 40° ; first 6 spire whorls showing faint cor- onations; protoconch broken off on the holotype; aperture narrow and more or less equal in width throughout its length. Ground color white with 2 broken bands of brown flammules. The band near the shoulder covers half the body whorl while the other is only half as large. Scattered small brown flammules are also found on the spire. Holotype: Length 105mm; width 44.5mm Occurrence: The type was trawled from a depth of ap- proximately 300 feet (90m), southwest of the Penghu Island Group, Taiwan, Republic of China. Type Depository: California Academy of Sciences, Ge- ology catalog no. 48862. Remarks: At first glance, this species appears to be re- lated to the Conus profundorum Kuroda, 1957 complex mainly in shape. However, it can easily be separated out of this group by its lacking a well-stepped spire and by possession of heavy incised spiral grooves. The latter char- acteristic would suggest a relationship to the subgenus Asprella Schaufuss, 1869, but its general shape, large size and high polish point to a relationship with the subgenus Chelyconus Morch, 1852. The holotype was collected dead, and unfortunately none of the soft parts could be studied. The lip was also badly broken and the shell was stained in places from being buried in mud. Still, the remaining morphological characteristics are so distinct that this species cannot be readily confused with any other member of the genus. ‘This species is named in honor of Dr. Louis R. Fletcher, M.D.,now Research Associate in the Geology Depart- ment, California Academy of Sciences, San Francisco. Tue VELIcER, Vol. 15, No. 2 [PeTucH & MENDENHALL] Figures 1, 2 Figure 2 ei Vol. 15; No. 2 Biology of Okenia ascidicola spec. nov. THE VELIGER Rageson I (Gastropoda : Nudibranchia ) M. PATRICIA MORSE Marine Science Institute, Northeastern University, Nahant, Massachusetts 01908 ' (5 Text figures) IN THE EARLY SUMMER of 1968, two nudibranchs were collected at East Point, Nahant, Massachusetts. They were placed in an aquarium at the Marine Science Institute where feeding behavior, mating, depositing of eggs and subsequent development were observed. It was determined that the specimens represented a new species of the genus Okenia Menke, 1830. The name Okenva ascidicola spec. nov. is based on their habit of feeding on solitary ascidi- ans followed by taking up temporary residence in the empty ascidian test. This work was supported by the Northeastern Office of Research Administration Grant No. 8024. I wish to ex- press my appreciation to Dr. N. W. Riser, Mrs. Eveline Marcus, Dr. William Clench and Dr. Tucker Abbott for their help in the preparation of this paper. Okemia ascidicola Morse, spec. nov. Species Diagnosis: Length 12mm, width 5mm; branchi- al plumes 11, anterior one bifid, thus displaying 12 free tips; mantle forms pallial ridge with 14 tentacular ap- pendages, anterior 4 elongate and equal, 8 smaller on lat- eral edges and a single bifid posterior pair; single small mid-dorsal appendage just anterior to branchial plumes; ground color of red-brown with dark and light yellow blotches; radula, 24 rows, formula 1-1-0°1-1, inner lateral tooth 0.16mm with 14 - 16 prominent denticles on the cusp, outer marginal 0.09 mm and smooth; incomplete labial armature of 3 paired units containing stout and slender elements. Penial spines small, scale-like with broad bases. Type Locality: Nahant, Massachusetts ' Contribution No. 16, Marine Science Institute, Northeastern University Type Date: June 1968 Type: Holotype, USNM 577681 Paratype — Radular preparation, labial armature and dissected specimen in author’s collection Description: Both of the living nudibranchs measured 12.0mm in length and 5.0mm in width. The mantle is drawn out into a veil which surrounds the notum and has 14 tentacular extensions (Figure 1). There are 4 elongate anterior appendages of equal length, 8 smaller tentacular extensions on the dorso-lateral ridges and a longer postero- lateral pair of bifid tentacular extensions, one on either side of the branchial plume. A single small appendage is found just anterior to the branchial plume in the mid-line of the body. In the holotype this appendage is pyramidal in shape as in the living specimens but in the preserved paratype it is now a blunt papilla. In both cases the single appendage is smaller than any other extensions of the mantle. In the holotype the partially retractile branchiae num- ber 11. The anterior branchia is bifid and on first glance gives the impression of 12 branchiae. The posterior pair is more slender and slightly shorter than the others. The branchiae are simply bipinnate with alternating lamina from the central stem. Their tips are pointed and they form a complete circle around the anus. The branchiae number 10 in the paratype with bifid anterior and poste- rior ones resulting in 12 free tips. They are more uneven in size in the circle than in the holotype. It is difficult to tell how much of this latter variation is due to fixation. The rhinophores are laminated on the posterior side for about } of their length. The laminae are rounded, slightly concave and number about 25. In an undisturbed crawling nudibranch, the rhinophores are held upright with a slight posterior bend at the half-way point. They are stout, being twice as thick and slightly longer than the tentacular ex- tensions of the anterior mantle veil (Figure 1). When the Page 98 THE VELIGER Vol. 15; No. 2 Figure 1 Okenia ascidicola Morse, spec. nov. (drawn from the living type specimen) nudibranchs are disturbed, they go through a character- istic reaction. The branchiae are partially retracted, the rhinophores lie back flat against the mantle, the lateral mantle extensions fold toward the mid-dorsal line (the most posterior ones folding over the branchiae), and the anterior 4 tentacles curl dorsally inward. From a ventral aspect, the foot is transparent with parallel sides, rounded anterior angles, and an obtusely pointed posterior end. The upper portion of the posterior end of the foot fuses with the mantle behind the branchiae and forms a slight ridge posteriorly to the tip. In sections, the foot is seen to be ciliated with a greater concentration of cilia at the anterior end. Epidermal and subepidermal gland cells are particularly abundant at the anterior end of the foot. The head is rounded, giving a bilobed appear- ance in the living animal and the reduced oral tentacles form a thick fleshy veil surrounding the antero-posterior slit which is the entrance to the mouth. A groove separates the foot from the oral veil; the latter two structures lie in a similar plane in the crawling nudibranch. The overall coloration of the living animal (Figure 1) is red-brown with 2 distinct hues of yellow forming epi- dermal blotches on the tentacular extensions and dorsal surface of the nudibranch. The lemon-yellow coloration forms a line on the mid-dorsal mantle from the rhino- phores to the branchiae and from just posterior to the branchiae on the ridge of the tip of the “foot”. There are additional smaller blotches on the sides between the pallial ridge and the foot. A darker yellow, canary yellow color, is found in large blotches on either side of the mid-dorsal region. Smaller blotches occur dorsad on either side of the posterior portion of the “foot”, and on the tips of the tentacular extensions of the notum. The red-brown color is mostly confined to the upper portions of the animal and slowly grades to a translucent white toward the foot. The lighter lateral aspects of the animal are further enhanced by the smaller blotches of lemon-yellow. Figure 2 Dissection of the anterior portion of the digestive system of Okenia ascidicola Morse, spec. nov. BP — buccal pump E — Esophagus LG -labial glands MO - mouth opening RS -radular sac Vol. 15; No. 2 THE VELIGER Page 99 Figure 3 Dissection of the reproductive complex of Okenia ascidicola Morse, spec. nov. A — ampulla HG —- hermaphroditic gland MG-AG —- mucus gland - albumen gland complex PR — prostatic region of the vas deferens VD -— vas deferens @ - female genital opening dg — male genital opening The internal morphology of Okenia ascidicola is similar to that described for other members of the genus (Mar- cus, 1957; Marcus & Marcus, 1967). The radula from the paratype has 24 rows of teeth of the generic radular formula 1:1:0-:1-1. The inner (lateral) tooth measures 0.16mm (Figure 4C) and bears 14 - 16 prominent dent- icles on the cusp. The outer (marginal) tooth measures 0.09mm (Figure 4B) and lacks denticles. The cusp of the marginal tooth is strongly recurved. The labial armature of Okenia ascidicola (Figure 5) is composed of 3 paired elements which do not form a complete ring around the mouth. The largest element is (A | { J | Figure 4 Okenia ascidicola Morse, spec. nov. A — veliger shell B — outer (marginal) tooth of radula C — inner (lateral) tooth of radula Scale = 0.05mm triangular in overall shape and consists of numerous stout teeth. The tips are bidentate medial of the paired ele- ments and become monodentate toward the lateral apices of the triangles. The elements are closely packed together and are pigmented with a brown-yellow coloration. The second paired elements are composed of elongate dent- icles which are narrow at their attachment and broader toward the apex. There is a tendency for the most distal denticles to be curved and to have an uneven margin. The denticles are all directed at right angles to those of the triangular elements. This second pair of elements is closely associated with the previous paired elements and is located parallel to the longer side of the triangle of the large pair. The third pair of elements consists of 2 patches of very irregular denticles which are haphazardly arranged in a pattern radiating from a center point. They are few in number and represent the lightest in coloration of the paired elements. Figure 5 Labial armature of Okenia ascidicola Morse, spec. nov. The oral tube, surrounded by the fleshy oral veil, leads into the muscular buccal mass. Glandular areas (Figure 2, LG) surround the oral tube. The dorsal portion of the buccal mass is expanded into a muscular buccal pump (Figure 2, BP) which is similar to that of Acanthodoris pilosa (Abildgaard, 1776) (vide Morse, 1968). The labi- al armature as described previously, appears to be capable of protraction to the area of feeding through the oral tube. Paired follicular salivary glands enter on the postero-lat- eral sides of the buccal mass and the esophagus exits from the posterior surface and enters the stomach. The diges- tive gland surrounds the ventral stomach and the intestine terminates at the anus in the center of the branchial plume. The hermaphroditic gland is located on the dorsal surface of the digestive gland (Figure 3). The male system Page 100 consists of the vas deferens enlarging into the ampulla and quickly narrows to connect up with a prostatic portion of the duct and eventually opens on the anterior right side of the nudibranch. Abundant scale-like spines occur on the penis. BIONOMICS Okenia ascidicola is so named because of the feeding be- havior and subsequent activity of the animal. The first animal was found associated with a clump of Molgula manhattensis and the second mature specimen was located inside of an empty ascidian tunic. Preference experiments were set up utilizing Ciona in- testinalis, and Molgula manhattensis. The nudibranchs would only feed on the latter. The animal approaches the base of the tunicate and rasps a circular hole in the tunic. It then proceeds to plow head first toward the interior, sucking in the soft contents and disappearing within the tunic until only the circle of branchiae is visible. This procedure requires about 4 hours. The nudibranchs are barely visible in this position. After several days, the tunic collapses, the nudibranch withdraws and moves away. When observing the collapsed tunic under higher magnifi- cation, the entrance hole was clearly visible and was surrounded by mucus. REPRODUCTIVE BEHAVIOR Two nudibranchs were placed in an aquarium on June 18. The animals were observed copulating on several occa- sions. This occurred on the bottom of the aquarium with a random approach of one animal to the other and with no adhesion to the bottom. On June 21, one nudibranch was found on its side (left) with the egg string being ex- truded from the enlarged female opening. Two other long strings measuring 6cm were found in the tank. The egg strings were only slightly coiled. The veliger shell (Figure 4A) measured 1 mm in width. The free swimming veligers died very soon after hatching. DISCUSSION Two species belonging to the genus Okenia have been reported from New England waters. In 1875, VERRILL de- scribed Idalia modesta and in 1882 listed its distribution from Block Island Sound, New Yor!: and Vineyard Sound, Massachusetts in 17 to 40 fathoms of water. In 1879, he THE VELIGER Vol. 15; No. 2 reported specimens of I. pulchella Alder « Hancock, 1854 which were collected by Mr. Emerton at Salem, Massa- chuscits. Verrill noted that the drawings and the specimen given to him by Emerton agreed with the description of Sars (1878), especially in regard to external characteristics and dentition, but not so well with those of ALDER « HAn- cock (1854, 1845-55). In 1882, Verritt listed those two species in the genus Jdaliella based on the lack of mid- dorsal appendages in accordance with Bercu’s 1881 monograph on the genus Idalia. The short, incomplete description of Idalia modesta by VerriLt (1875) makes it difficult to compare it with Okemia ascidicola. In the latter, the presence of a dorsal appendage, the differences in coloration, and the length of the tentacular extensions of the mantle (compared to conical papillae in Verrill’s description) are distinctive. The primary distinguishing characteristic of Okenia ascidicola from Idaliella pulchella is the labial armature. The variety of elements in O. ascidicola is not described for I. pulchella. In addition, the elements figured for I. pulchella by ALDER & Hancock (1845-55) are not similar to those found in O. ascidicola. The descriptions of I. pul- chella are of animals of a similar size to the two specimens of O. ascidicola and thus the lack of any mid-dorsal ap- pendages in the former is not due to an age difference. Al- though Marcus & Marcus (1967) noted the difficulty in seeing the poorly developed mid-dorsal appendages in O. sapelona, the appendages none the less are obviously present in O. ascidicola in both the living animals and in the type specimen after fixation in formalin and storage in 70% ethyl alcohol. Four other species of Okenia have been described from the western Atlantic waters. Marcus (1957) and Mar- cus & Marcus (1967) reported O. evelinae Marcus, 1957, O. impexa Marcus, 1957, and O. sapelona Marcus & Marcus, 1967 as being present along Miami, North Car- olina and Georgia coasts respectively. Recently, VocEL & ScHuLtz (1970) reported an additional species Okenta (Cargoa) cupella (Vogel « Schultz, 1970), nov. comb. from Chesapeake Bay, Maryland. Okenia ascidicola is similar to O. impexa in that both have a single papilla on the back but differs in the rhino- phores, dentition and labial armature. Okenia ascidicola is separated from O. cvelinae and O. sapelona by the single papilla, differences in the number of lateral ap- pendages, shapes of the radular teeth and labial armature. Okenia cupella, which in text seems very similar to O. impexa, differs from O. ascidicola by the rhinophores and dentition. It is unfortunate that no indication of labial armature is given for O. cupella. Vol. 15; No. 2 THE VELIGER Page 101 Bercu (1881) characterized the genus Jdalia as possess- ing mid-dorsal appendages, and having a complete ring forming the labial armature and the genus Idaliella by the absence of mid-dorsal appendages and an incomplete labial armature of hamate lateral plates. (Idalia is not available since it is preoccupied. ) THIELE (1931) listed Okenia with the two subgenera Okenia (Idaliella) and Okenia (Okenia). As pointed out by Lemcue (1971), the generic name Cargoa established by VocEL & ScHuLTz (1970) is a junior objective syno- nym of the genus Okenia and the latter name should be retained. Marcus (1957) discussed the genus Okenia in some detail and listed the valid species, indicating the subgenus to which each belonged. New additions were listed in 1967 by Marcus & Marcus. Okenia ascidicola has a dorsal cirrus on the back and an incomplete labial armature which invalidate the subgeneric designations. Thus, in conclusion, the genus Okenia is a valid genus within which species are found with and without mid- dorsal appendages between the rhinophores and branchiae and with and without a complete labial armature. Literature Cited ALDER, JoSHUA 1854. IX. Notice of some new species of British Nudibranchiata. Ann. Mag. Nat. Hist. 14: 102 - 105 ALDER, JoSHUA & ALBANY Hancock 1845-1855. A monograph of the British nudibranchiate Mollusca, with figures of all species. London, Ray Soc.,prts. 1 - 7; 438 pp.; 84 plts. Bercu, Lupwic SopHus RupboLF 1881. Uber die Gattung Jdalia Leuckart. 140-181; plts. 6-8 : LEMCHE, HENNING 1971. Okenia Menke, 1830, and Idaliella Bergh, 1881 (Mollusca, O- pisthobranchia) : Proposed addition to the official list. Z. N. (S.) 1931. Bull. Zool. Nomencl. 27 (5/6): 265 - 266 Marcus, ERNST 1957. On Opisthobranchia from Brasil II. don 43 (292): 390 - 486; figs. 1 - 246 Marcus, EveLINeE pu Bois REyMonp & ErRNst Marcus 1967. Some opisthobranchs from Sapelo Island, Georgia, U. S. A. Malacologia 6(1-2): 199 - 222; figs. 1-19 (31 December 1967) Morse, M. Patricia 1968. Functional morphology of the digestive system of the nudibranch mollusc Acanthodoris pilosa. Biol. Bull. 134 (2): 305 - 319 Sars, G. O. 1878. Bidrag til Kundskaben om Norges Arktiske fauna: I Mollusca Regionis Arcticae Norvegiae pp. I- XIII+1- 466; 34 + XVIII plts. Christiania VERRILL, ADDISON EMERY 1875. Results of recent dredging expeditions off the coast of New England. Amer. Journ. Sci. 10: 36 - 43 1879. Notice of recent additions to the marine Invertebrata of the northeastern coast of America, with descriptions of new genera and spe- cies and critical remarks on others. Part 1 - Annelida, Gephyraea, Nemertina, Nematoda, Polyzoa, Tunicata, Mollusca, Anthozoa, Echino- dermata, Porifera. Proc. U. S. Nat. Mus. 2: 165 - 206 1882. Catalogue of marine Mollusca added to the fauna of New Eng- land during the past ten years. Trans. Conn. Acad. Arts Sci. 5 (2): Arch. Naturgesch. 47 (1) : Journ. Linn. Soc. Lon- 447 - 587 VocEL, Rosatige M. & LEonarD P. ScHULTZ 1970. Cargoa cupella, new genus and new species of nudibranch from Chesapeake Bay, and the generic status of Okenia Menke, Idalia Leuck- art, and Idalla @rsted. The Veliger 12 (4): 388-393; 5 text figs. (1 April 1970) Page 102 THE VELIGER Vol. 15; No. 2 Note on Secondary Homonymy BY EMILY H. VOKES Department of Geology, Tulane University, New Orleans, Louisiana 70118 THE NOMENCLATURAL PROBLEM of secondary homonymy is one that is a trial to all workers, one that causes innu- merable shifting back and forth of names and one that clearly is not always understood. This is made apparent in a recent paper by CernoHorsky (1971: 188), who states that he does not consider Murex aculeatus Lamarck, 1822, a secondary homonym of Aranea aculeata Perry, 1811, nor of Muricites aculeatus Schlotheim, 1820. According to the International Code of Zoolog- ical Nomenclature, Article 57: “The Law of Homo- nymy applies to species-group names originally published in (primary homonyms), or later brought together in (secondary homonyms) the same genus or collective group, except as noted in Article 59c.” The latter states that: ‘““A name rejected after 1960 as a secondary homonym is to be restored as the valid name whenever a zoologist believes that the two species-group taxa in question are not congeneric, unless it is invalid for other reasons.” Secondary homonyms are created by bringing together two species formerly not in the same nominal genus. Such is the case presented by the genus Aranea Perry, 1810. Perry chose to employ the name “Murex” for species of the Fasciolariidae, and to create 1 new name, Aranea, for those spinous species today included in Murex s. s. This was a perfectly legal restriction of the multigeneric Murex of Linnaeus, which did include the Fasciolariidae as well as the Muricidae. However, as a result, the species named in the genus Aranea Perry are all valid, incontestable members of Murex, as recognized today. Even though they were named in a nominally different genus, they have been “secondarily brought together” in Murex, and I do not think there is any zoologist who will say that most are not congeneric with the type species of Murex. There are a few species that might be transferred to a genus Bolinus, in which case Aranea conspicua (== Murex cornutus, subgenus Bolinus) would no longer preoccupy Murex conspicuus Braun, 1863. But Aranea aculeata and Aranea pallida are both congeneric with Murex, and as such preoccupy Murex aculeatus Lamarck, 1822, and Murex pallidus Broderip, 1833, regardless of the fact that the junior species are a Chicoreus and a Trophon, respec- tively. Once a species is named in a genus, the subsequent generic placement is irrelevant. Murex aculeatus Lamarck can never escape its Murex birthright, a “Murex” it will always be. The only exception to this is in the case of two species named in different biologic genera, which have homonymous names (Code, Art. 57-c). An example would be two species with the same name described in Centronotus Schneider, 1801 (a fish), and Centronotus Swainson, 1833 (a Hexaplex). According to the Code (Art. 52) “homonymy is the identity in spelling of available names,” and “the differ- ence of a single letter is sufficient to prevent homonymy”’ (Art. 56-a and 57-d). However, there are several excep- tions to this noted in the Code. At the species-group level there are 12 exceptions cited (Art. 58) whereby differ- ences in spelling do not prevent homonymy, nor do differ- ences in termination due to gender have any effect (Art. 57-b-i). At the generic level there is a single exception, as noted in Art. 56-b, and this applies solely to names originally proposed for fossils. Article 20 states: “If an existing genus-group name has been modified by substi- tuting -ites, -ytes, or -ithes for the original termination, the modified name if applied only to fossils is not avail- able, except for the purposes of the Law of Homonymy” (7. e., it would preoccupy a subsequently proposed genus of the same name). Names including Muricites Schlot- heim, along with others of its kind, such as Pectinites and Tellinites, were used to denote fossil representatives of the Recent genera Murex, Pecten, and Tellina, respec- tively. Thus, Muricites and Murex, Pectinites and Pecten, Tellinites and Tellina, are considered to be identical names, and the species nomed in either member of the pair are affected by the Law of Homonymy (Art. 57). Whether they are primary homonyms, by act of legislation, or secondary homonyms by default, is a somewhat neb- ulous matter; perhaps it would be best to consider the -ites termination an unjustified emendation of the generic name, which does not affect species-group homonymy (Art. 57-b). In any case, the rules of homonymy apply and Muricites aculeatus Schlotheim, 1820, preoccupies Murex aculeatus Lamarck, 1822; Muricites cognatus Schlotheim, 1820, preoccupies Murex cognatus Bellardi, 1872; and Muricites funiculatus Schlotheim, 1820, pre- occupies Murex funiculatus Reeve, 1845. Literature Cited CrernoHorsky, WALTER OLIVER 1971. Contribution to the taxonomy of the Muricidae (Gastropoda: Prosobranchia). The Veliger 14 (2): 187-191; 1 plt. (1 Oct. ’71) Vol. 15; No. 2 THE VELIGER Page 103 Two Additions to the Opisthobranch Fauna of the Southern Gulf of California HANS BERTSCH ' (1 Plate; 3 Text figures) DuRING THE SUMMER OF 1969 I used the facilities of the Las Cruces Biological Station to study the opisthobranch fauna in the La Paz area of Baja California del Sur, Mexico. From this research in the southwestern Gulf of California, one new species has already been named (Bertscu, 1970b). In the paper, I describe a new species of Cephalaspidean and discuss the occurrence of a mem- ber of the nudibranch genus Limenandra in the Panamic province. CEPHALASPIDEA AGLAJIDAE Aglaja regiscorona Bertsch, spec. nov. (Figures 1, 2 to 5) Type Material: Holotype: mounted shell, California Academy of Sciences, Invertebrate Zoology Type Collec- tion, no 556. Paratypes: Three specimens, CASIZ Type Collection, nos. 553, 554, 555. Three specimens, Los An- geles County Museum of Natural History, no. 1617. Two color transparencies of the living animal have also been deposited with the holotype material, CASIZ color slide series, nos. 2723 and 2724. Type Locality: Bahia Las Cruces, Baja California del Sur, Mexico (24°13’N; 110°05’W); the type specimens were found crawling on the alga Spyridia filamentosa, inter- tidally, July 19 to 22, 1969; collector, Hans Bertsch. Description: Length in life: 3 to 5mm; width 1.25 to 1.75mm,; body color cream white, dorsum center darker " Associate, Department of Invertebrate Zoology, California Aca- demy of Sciences, San Francisco, California 94118. Permanent address: Franciscan School of Theology, 1712 Euclid Avenue, Berkeley, California 94709 dirty white (verging on light greenish-brown); edges of posterior lobes transparent white; cephalic hood frontal margin, and edges and sides of parapodia with numerous small black flecks; posterior lobes with some black spots; dorsum and cephalic shield covered with numerous papil- lae, some tipped with black (see Figure 1). Head shield triangular, projecting posteriorly and up- wards to a small, three-pointed crown. Parapodia small, held tight against sides of body, not extending over the Figure 1 Dorsal view of Aglaja regiscorona Bertsch, spec. nov. Drawing of living animal by author Page 104 dorsal surface. Two lobes project from rear, neither with a flagellum. Shell (Figure 2) calcified, 0.55mm long; nuclear whorl 0.18mm wide. Nucleus of shell with one complete whorl; small flange projects laterally at right angle to plane of whorl (Figures 3 and 4). Small ridges, separated by a slight notch, circles the lateral edge of the whorl (Figure 4). Wing bends sharply vertically to plane of nuclear whorl, and folds again nearly parallel to the plane of the whorl. Distal end rectangular (Figure 5). Discussion: Numerous factors distinguish Aglaja regisco- rona from the other American species of Aglaja. The specific name (from the Latin: King’s crown) was chosen in reference to its highly distinctive cephalic shield which resembles a royal crown. None of the other Aglaja species in the eastern Pacific, nor in the western Atlantic, have this unique configuration to their head shields. The coloration of Aglaja regiscorona resembles that of A. nana Steinberg and Jones, 1960. However, A. nana lacks the dorsal papil- lae, the three-point cephalic shield, and has less prominent posterior lobes. The body colors of A. purpurea (Bergh, 1893), A. diomedea (Bergh, 1893), A. adellae (Dall, 1894), A. pusa Marcus and Marcus, 1967, A. felis Marcus and Marcus, 1970, and A. hummelincki Marcus and Marcus, 1970, are all dark, in contrast to the light coloration of A. regiscorona. THE VELIGER Vol. 15; No. 2 The left posterior lobe of Aglaja ocelligera (Bergh, 1893) has a flagellum, while A. regiscorona does not. Aglaja gemmata (Morch, 1863) and A. punctilucens (Bergh, 1893) can be distinguished from A. regiscorona by their longitudinal dark striping. The shell of Aglaja regiscorona has a distinct whorl, curved apical border (rather than a flattened edge), and a broad, flat, not in-curled wing. This serves to distinguish it from the other species in the genus. NUDIBRANCHIA AEOLIDIDAE Limenandra nodosa Haefelfinger and Stamm, 1958 (Figures 6, 7) Occurrence, Morphology and Zoogeographical Com- ments: The original description of Limenandra nodosa Haefelfinger and Stamm, 1958, was based on approxi- mately 50 specimens from the French Riviera. HAEFEL- FINGER & STAMM (1958) established a new genus (Limen- andra) for the species, and included a second species: Baeolidia fusiformis Baba, 1949. Until recently, L. nodosa had been known only from the Mediterranean and L. Table 1 Comparison of morphology of Limenandra fusiformis from Japan (column I), L. nodosa from the Mediterra- nean (column II), and L. nodosa from the Gulf of Cali- fornia (column IIT) I II Ill Limenandra Limenandra Limenandra fusiformis nodosa nodosa (Gulf) Radula 11 x 0-1-0 8-10 x 0-1-0 9x 0-1-0 60 denticles 30 - 50 denticles 30 denticles Cerata rounded flattened flattened 12 - 15 rows 12 - 14 rows 12 rows 10-11 cerata in largest rows 1 - 9 cerata per row 1 - 8 cerata per row smooth papillated central cerata papillated on rows 4, 6, 8, 10, 11 Color ashy brown dull olive green pale green yellowish spots white-yellow-red-white circlets yellow and pink circlets small white spots over green-brown speckled over entire body entire body Jaws smooth masticatory edge long masticatory border long, smooth masticatory very finely striated, but border without denticulation Length 10 - 20mm 15 - 25mm 12mm studded on posterior margin with papilliform granules Rhinophores papillae over entire surface papillae start about 4 way up length of rhinophores; very few on front, concen- trated on posterior portion Tue VELIcER, Vol. 15, No. 2 [BERTscH] Figures 2 to 5 Figure 2 Vol. 15; No. 2 THE VELIGER Page 105 fustformis only from Japan. Marcus « Marcus (1970) reported a specimen of L. nodosa from Bonaire Island, Lesser Antilles, in the Caribbean, about 50 miles off the northern coast of Venezuela. On July 11, 1969, I found one 12mm long specimen of Limenandra nodosa at Bahia Las Cruces, Baja California del Sur, Mexico. It was under a rock, in about four feet of water. This is the first specimen of Limenandra from the Pacific coast of America (BERTSCH, 1971). Table 1 compares the morphology of the two known species of Limenandra with the specimen from the Gulf of California. A definite overlapping of characteristics is evi- dent, which further complicates the taxonomy of this genus. The radula, jaws, external coloration, and size are similar among the Mediterranean L. nodosa, L. fusiformis, and my specimen from the Gulf of California. The radula and jaws of L. nodosa from the Gulf of California are illustrated in Figures 6 and 7. The cerata of the Gulf ani- mal are flattened and papillate (as in the Mediterranean L. nodosa), in contrast to the rounded, smooth cerata de- scribed for L. fuszformis. The yellow-pink color circlets of the Gulf specimen appear intermediate between the white- yellow-red-white circlets of L. nodosa, and the yellowish spots on the back of L. fuszformis. However, the shape of the rhinophores of the Gulf animal more closely resemble that of L. fusiformis. Only the further collection and comparison of a great number of these animals, with concomitant attempts at interbreeding, can determine whether these variations are all characteristic of one, two, or three species. It is of interest that recent papers (e.g., Marcus, 1961; COLLIER & FARMER, 1964; Marcus & Marcus, 1967, 1970; Bertscu, 1970a; and Spoon, 1971) have reported an in- creasing number of circum-tropical or circum-subtropical Figure 6 Limenandra nodosa Haefelfinger « Stamm, 1958: jaws of the spe- cimen from the Gulf of California; height 0.5mm opisthobranch species from the Gulf of California, indi- cating certain faunistic relationships for opisthobranchs on the species level between the Panamic province and other tropical or subtropical regions. Natural History: The specimen of Limenandra nodosa collected from Bahia Las Cruces had the cream white egg sacs of a small copepod between the 7th and 8th rows of cerata. The nudibranch was kept alive in an aquarium for a few days to study its locomotion patterns. As do many nudi- branchs, it would periodically float upside down at the water surface. The crawling behavior was by the exten- sion-contraction method, with simultaneous forward and backward pumping of the cerata. All the cerata were jerked uniformly backward, pivoting at the base where the cerata are attached to the body. ‘Then they were jerked upward, and the animal’s body was extended forward longitudinally. The backward stroke was repeated, the animal contracted; then the forward jerk, extension, and animal's progression. ‘The forward movement of the ani- mal was in a regular rhythm with the ceratal pumping. It is not known whether the ceratal movement assisted or caused the animal’s forward progression, or was just a side effect of the extension-contraction locomotory method. This specimen from the Gulf of California has been de- posited as a hypotype in the California Academy of Sci- ences, Department of Invertebrate Zoology Type series, number 557. ACKNOWLEDGMENTS Many persons assisted me in the research and writing ol this article. Mr. Hugh Bertsch supplied the financial aid necessary to make the trip to the Gulf of California. The Figure 7 Limenandra nodosa: radular row of animal from the Gulf of California Explanation of Figures 2 to 5 Aglaja regiscorona Bertsch, spec. nov. Figure 2: Scanning electron micrograph of entire shell Figure 3: SEM close-up of nuclear end of shell, showing the bending of the wing vertically to the plane of the nucleus Figure 4: Nuclear whorl of shell, SEM close-up, showing lateral flange and small, encircling ridge Figure 5: Distal end of wing of shell, SEM enlargement Page 106 THE VELIGER Vol. 15; No. 2 staff and research workers at the Las Cruces Biological Station (particularly Dr. Rita Schafer and Rev. Alberic A. Smith) were quite friendly and helpful to me, even inter- rupting their own research to assist me. Gale G. Sphon, Allyn G. Smith, and James T. Carlton read the manu- script, offering criticism and encouragement; Richard A. Roller performed the dissections of the material and did the original drawings of the jaws and radula of Limen- andra nodosa. Dr. Thomas Hayes, Donner Laboratory of the Lawrence Radiation Laboratory, University of Cali- fornia, Berkeley, made the scanning electron micrographs of the Aglaja regiscorona shell. To all these, friends and colleagues, I offer my sincerest thanks. Financial aid to publish this paper was provided by the Janss Foundation. Literature Cited BasBa, KikuTARO 1949. Opisthobranchia of Sagami Bay, collected by his Majesty the Emperor of Japan. Iwanami Shoten, Tokyo, 104 pp.; 50 plts.; 7 text figs. BercHu, Lupwic SopHus RupDOLF 1893, Die Gruppe der Doridiiden. Mittheil. zool. Stat. Neapel 11 (1-2): 107-135; plt. 8 (25 September 1893) BertscH, Hans 1970a. Dolabrifera dolabrifera (Rang, 1828): Range extension to the Eastern Pacific. The Veliger 13 (1): 110-111; 1 text fig. (1 July 1970) 1970b. Opisthobranchs from Isla San Francisco, Gulf of California, with the description of a new species. Santa Barbara Mus. Nat. Hist. Contrib. Sci. 2: 16 pp.; 13 text figs. (1 December 1970) 1971. Natural history and occurrence of opisthobranchs of Las Cruces, Baja California, Mexico, and vicinity. The Echo 3: 16 (7 March 1971) Co.uier, CLinton L. & WesLeEY MERRILL FARMER 1964. Additions to the nudibranch fauna of the east Pacific and the Gulf of California. Trans. San Diego Soc. Nat. Hist. 13 (19): 377 - 396; plts. 1-6; 3 text figs. (30 December 1964) Dati, WititiamM HEALEY 1894. Description of a new species of Doridium from Puget Sound. The Nautilus 8 (7): 73-74 (1 November 1894) HAEFELFINGER, HAaNs-RuDOLF & RoceR A. STAMM 1958. Limenandra nodosa gen. et spec. nov. (Nudibranch, Aeolidiidae propr.), un opisthobranche nouveau de la méditerranée. Vie et Milieu 9 (4): 418-423; 1 text fig. Marcus, ERNST 1961. Opisthobranch mollusks from California. The Veliger 3 (SupplImt. I): 1-85; plts. 1-10 (1 February 1961) Marcus, Ernst & EvELINE Du Bois REYMoND Marcus 1970. Opisthobranchs from Curacao and faunistically related regions. Stud. Faun. Cur. Caribb. Isl. 33 (122): 1-129; 160 text figs. Marcus, EvELINE Du Bois REYMOoND & ERNST Marcus 1967. American opisthobranch mollusks. Studies in tropical oceano- graphy (Univ. Miami Inst. Marine Sci., Miami, Florida), no. 6: viii+ 256 pp.; figs. 1- 155 + 1-95 (December 1967) Morcu, Otto ANpREAS Lowson 1863. Contributions 4 la faune malacologique des Antilles danoises. Journ. Conchyl. 3¢ ser., 3 (11) :21 - 43 (1 January 1863) Spuon, GALE G. 1971. | New opisthobranch records for the eastern Pacific. liger 13 (4): 368 - 369 STEINBERG, Joan Emity « MEREDITH L. JONES 1960. A new opisthobranch of the genus Aglaja in San Francisco Bay. The Veliger 2 (4): 73-75; plt. 16 P (1 April 1960) The Ve- (1 April 1971) Vol. 15; No. 2 THE VELIGER Page 107 Review of the Bathyal Gastropod Genus Phanerolepida (Homalopomatinae) and Description of a New Species from the Oregon Oligocene CAROLE S. HICKMAN Department of Biology, Swarthmore College, Swarthmore, Pennsylvania 19081 (1 Plate; 1 Text figure) INTRODUCTION Two SPECIMENS of a new species of Phanerolepida Dall, 1907, from separate localities in the middle member of the lower Oligocene Keasey Formation in Oregon, consti- tute the first record of this deep-water genus outside of Japan and Okinawa. The new species also represents the earliest record of the genus, extending its stratigraphic range back into the Paleogene. It is the purpose of this report to describe the new species, to review the known occurrences of the genus, and to present some hypotheses regarding the evolution, ecological biogeography, and dis- junct distribution of the genus. It is remarkable that a poorly known genus from the Late Tertiary and Recent Japanese deep-water fauna should appear in an early Oligocene deep-water fauna on this side of the Pacific, widely separated in both time and space. Phanerolepida transenna (Watson, 1879), the sole living species, is restricted geographically to the area between 33° and 35°N latitude and bathymetrically to muddy substrates in the bathyal (archibenthal) zone, where it is most common between 600 and 800m (Oxv- TANI, 1968). Latitudinal and bathymetric restrictions on the species are further qualified by a unique vertical temperature structure at these latitudes along the Pacific coast of Honshu resulting from the meeting and mixing of the warm surface waters of an offshoot of the Kuroshio current and a submerged offshoot of the cold Oyashio cur- rent of Subarctic origin. Thus the temperature between 600 and 800m in the,vicinity of Sagami Bay, where P transenna occurs, is about 6° to 8° C, compared with tem- peratures in the overlying Kuroshio water averaging 15° C and temperatures in the underlying Western Pacific Bot- tom Water of 2° to 4° C (OxutTant, op. cit.). Upa (1937) designates this system between 600 and 800m as the Inter- mediate Water, and OxuTani (1967, 1968) discusses the characteristics and origin of the bathyal fauna, noting a high proportion of endemic molluscan species with the same restrictions imposed by geography, bathymetry, and water system as P transenna. It is against Okutani’s de- tailed background information on the Recent bathyal fauna of Japan that the significance of the Oregon Phaner- olepida material can be evaluated. Tue TYPE SPECIES in JAPAN Phanerolepida is characterized by a sturdy turbinate shell of considerably larger size than the small to minute shells of Homalopoma Carpenter, 1864. It is further distin- guished by a thin, concavo-convex operculum on which the spirals are not externally visible, in contrast to the thick paucispiral external whorl characterizing the oper- culum of Homalopoma. The callus is extensively devel- oped, and in the type species it is divided into a thick portion proximal to the aperture and a thin distal portion through which the underlying ornamentation of the body whorl is visible. The most diagnostic feature of Phanero- lepida is the net-like, finely-incised rhombohedral pattern of surface sculpture which appears to be unique among the Gastropoda. Both Watson (1879) and Dat (1907) described this surface pattern as having the appearance of shagreen. It is unusual in that the oblique rows of rhombs are not collabral, but inclined in the opposite di- rection from the aperture and growth lines. The pattern becomes increasingly fine on successive whorls and is some- times irregularly developed or interrupted by areas of smooth shell deposit. Page 108 THE VELIGER Vol? 5s Now2 If Phanerolepida were a Recent monotypic genus, one might place less importance on the uniqueness of the net- like surface texture of the shell. However, the pattern now appears to be characteristic not of a single species, but of a lineage that has existed for at least 40 million years. At the same time, the potential for producing a similar but not identical surface pattern apparently exists within the closely related genus Homalopoma, as evidenced by its expression in another endemic Japanese species, Homalo- poma granulifera Nomura & Hatai, 1940. The species occurs in shallow water (less than 100m) along the Japa- nese coast north of 35°N latitude. Its small size (less than 10mm high), features of the operculum, and the predominance of spiral sculpture are typical of Homalo- poma. However, a more faintly developed axial sculpture gives the shell a granular appearance. Under magnifica- tion the granules exhibit more or less square outlines and either vertical or irregular arrangement (Figure /6), in contrast to the oblique rows in Phanerolepida. Watson based his original description of Phanerolepida transenna on a single live specimen dredged by the Chai- lenger from a depth of over 1000m in the Sea of Enshu- Nada (Station 235). He placed his species in the genus Turbo Linnaeus, 1758. The original description (Wat- son, 1879), which was not illustrated, was repeated by Watson (1885-1886) in the Challenger Reports, and the holotype was figured. A second specimen, obtained from deep water in Tokyo Bay by the Albatross in 1906 prompted Dati (1907: 168) to propose Phanerolepida as a subgenus of Leptothyra Pease, 1869. The name is introduced in a discussion at the end of Dall’s description of Basilissa babelica because the specimen occurred in the same haul with the new species. There are no records indicating that P transenna was collected during the 50 years that followed. Hase (1964: 20) states that the species is “rarely collected from 200 to 500 meters in Sagami Bay.” OxutTani (1964) presents the most complete record of Phanerolepida transenna in a report based on collections by the R. V. Soyo-Maru between 1955 and 1963. He records 10 empty shells and 16 living specimens of P transenna from stations between 550 and 800m in Sagami Bay. Dr. Okutani has graciously provided 7 of these spe- cimens, from 700m in Sagami Bay, for comparison with the new species from the Oregon Oligocene. Two of these specimens have been donated to the U. S. National Mu- seum and are figured in this report (Figures /, 2, 5, 6, 9, and 10). FOSSIL OCCURRENCES There are 3 accounts of Phanerolepida as a fossil from localities in the Western Pacific. All 3 occurrences are in strata near or above the Miocene-Pliocene boundary, in contrast to the new Oregon species, which comes from strata near the Eocene-Oligocene boundary. Kuropa (1931) described P expansilabrum from the Pliocene of the Nagano prefecture (36°19’N, 138°07’E). Harar & NistyAMA (1952: 230) consider the age of the strata to be Miocene. I have not seen the holotype, but the spire appears to be higher than in the type species and demar- cated by a slightly impressed suture. Kuroda’s figure is not good enough to show details of surface pattern. Ortuxa (1968) documents the occurrence of P transenna from the Pliocene Tomiya sandstone of the Chiba prefec- ture (35°12’N, 139°51’E). Oxurani (1968) discusses the paleoecology of the Tomiya fossil assemblage and cites evidence that it formed under a similar set of environ- mental restrictions as those found in the vicinity of Sagami Bay. The Recent and fossil occurrences of Phanerolepida in Japan are summarized in Figure 17. One western Pacific occurrence of Phanerolepida has been recorded outside of Japan proper. MacNer (1960: Plate Explanation Phanerolepida transenna Watson Figures 1, 5, and 9: USNM 707162. Hypotype. Apertural, top, and side views. Recent, Japan. xX 1.5 Figures 2,6, and 10: USNM 707163. Hypotype. Apertural, top, and side views. Recent, Japan. x 1.5 Figure 14: USNM 707163. Hypotype. a-— Detail of surface texture from penultimate whorl. b — Detail of surface texture from body whorl. xX 10 Phanerolepida rehderi MacNeil Figures 3, 7, and 11: USNM 562794. Holotype. Apertural, top, and side views. Miocene or Pliocene, Okinawa. x 15 Figure 13: USNM 562795. Topotype. Top view. Miocene or Plio- cene, Okinawa. x 1.5 Phanerolepida oregonensis Hickman, spec. nov. Figures 4, 8, and 12: USNM 646902. Holotype. Apertural, top, and side views. Oligocene, Oregon. x 1.5 Figure 15: USNM 646902. Holotype. Detail of surface texture from body whorl. X< 10 Homalopoma granulifera Nomura « Hatai Figure 16: ANSP 242880. Hypotype. Detail of surface texture from body whorl. Recent, Japan. X 10 Tue VELicER, Vol. 15, No. 2 [Hickman] Figures 7 to 16 Figure 10 i Figure 12 Figure 14b Figure 15 Vol. 15; No. 2 THE VELIGER Sea of St? rN o Boshnada oc Page 109 gp MN es 35° Zi eo HHA Present distribution @ Fossil occurrence Figure 17 Recent and fossil occurrences of Phanerolepida in Japan 30) described P rehderi from beds near the Miocene-Plio- cene boundary on Okinawa, at the southern end of the Ryukyu Islands south of Japan. The species is represented by 5 specimens from 2 localities in the Shinzato tuff mem- ber of the Shimajiri Formation between 26°05’ and 26°20’N latitude on Okinawa. MacNeil’s species has sculpture which is intermediate in coarseness between P transenna and the new species from the Keasey Forma- tion. The shell has a distinctive outline resulting from an abrupt steepening of the apical whorls. Interruption of the reticulate sculpture pattern seems to be more common in PR rehderi than in the Recent P. transenna. Sharply demarcated areas of unornamented shell are present on the holotype, and on the topotype most of the body whorl lacks reticulate sculpture (Figures 3, 7, 11, 13). The Shinzato tuff fauna is a deep-water assemblage which resembles the Keasey fauna in the presence of Bathybembix and a diverse component of turrid gastro- pods. MacNeit (1960: 17) examined depth ranges of living relatives of species in the Shinzato tuff and repor- ted that most occur between 560 and 720m. SYSTEMATIC PALEONTOLOGY TURBINIDAE Homalopomatinae Phanerolepida Dall, 1907 Type, by monotypy, Turbo transenna Watson, 1879. Living, Japan. Page 110 Phanerolepida oregonensis Hickman, spec. nov. (Figures 4, 8, 12) Description: Shell large for subfamily, robust, heavy, with 3 whorls on type specimen; apex abraded; aperture circu- lar and nacredus within, prosocline at an angle of about 60° from the axis of coiling; inner lip covered by a broad crescent-shaped callus; suture slightly canaliculate; sur- face cross-hatched by impressed irregularly spaced spiral and oblique axial lines which divide the surface into small rhombs and give the shell a scaly or net-like appearance. The oblique rows of rhombs are not collabral but inclined in the opposite direction from the aperture and lines of growth. The surface pattern may be interrupted by small areas of shell with faint spiral sculpture, and on early whorls there is faint spiral sculpture superimposed on the rhombohedral sculpture. Dimensions of Holotype: height 19mm; maximum dia- meter 23.2mm. Hypotype: height 10.5mm; maximum diameter 15mm. Remarks: Phanerolepida oregonensis differs from both P. transenna and P. rehderi in having a much more strongly prosocline aperture, a more compressed form, and coarser surface sculpture. Phylogenetic Implications: In the known species of Pha- nerolepida, the rhombohedral surface sculpture has be- come progressively finer since the beginning of the Oligo- cene. The hypothesis that coarse sculpture is primitive in the genus is supported by the preservation of coarse sculp- ture on the early whorls of all species, since it is in accord with the principle that mutations which affect early onto- geny are less often viable than alterations in later stages of development (Figures / to /5). Origin of Phanerolepida from a Homalopoma-like an- cestor is suggested by the faintly spiral ridges on the early whorls of the Miocene or Pliocene species (Figures 7, 13) and the superposition of faint spiral sculpture on the rhombohedral sculpture of early whorls in the Oligocene species (Figure /2). Faint spiral sculpture occurs on the early whorls of some specimens of the Recent species, but it is not discernible on most. There are areas on both the Paleogene and Neogene species where the character- istic reticulate texture is replaced by an apparent relapse of smooth shell deposit marked by faint spiral ridges. One such area occurs on the body whorl of the holotype of P oregonensis (Figure 4). The term “relapse” seems par- ticularly appropriate with respect to the topotype of PR rehderi, on which the reticulate sculpture moves from THE VELIGER Vol. 15; No. 2 coarse to fine and back to coarse again before it finally disappears on the body whorl (Figure /3). Holotype: U. S. National Museum 646902. Hypotype: USNM 646903. Occurrences: The holotype was collected by the author in the blue-gray massively bedded siltstone exposed in the abandoned Smithwick-Haydite Quarry on the Spokane, Portland,and Seattle Railroad; NW! Sec. 8, T3N, R4W; Vernonia Quadrangle (USGS locality 25031). The type locality falls in the upper part of what has informally been designated as the middle member of the Keasey Formation (WARREN & NorsisraTH, 1946). Lower Oli- gocene. A smaller, poorly-preserved specimen was discovered in a collection made by Harold Vokes in conjunction with the geologic mapping of northwestern Oregon (WARREN et al., 1945). The specimen comes from USGS locality 15267, the second large cut from the south end of the high trestle crossing Oregon Highway 47, 1.4miles due west of Hoffman Hill Lookout, Vernonia Quadrangle. This locality is separated from the type locality by about 5km. USGS loc. 15267 appears to be slightly lower in the middle member of the formation, although the precise vertical separation cannot be determined because the two localities are on opposite sides of a heavily forested valley and attitudes are too variable in the region for accurate extrapolation. DISCUSSION The discovery of Phanerolepida in the early Oligocene of western North America raises some interesting questions of historical biogeography and lends new perspective to the question of the pronounced endemism in the Japanese bathyal fauna. Discussions of endemism in living species have focussed on the distinctions between relict (paleoendemic) and newly evolved (neoendemic) taxa (STEBBINS & Major, 1965: 3). Phanerolepida is now a relict or paleoendemic genus. It is not clear, however, whether the sole Oligo- cene occurrence represents a neoendemic phase, nor is it possible to determine whether the genus made its first appearance in the Eastern or Western Pacific. There are two major possible patterns of distribution for the genus during the Tertiary. It might have been a geographically widespread and broadly adapted member of the bathyal fauna that has declined to a small, highly specialized relict population; or it may have evolved as a specialist and migrated as a small narrowly adapted Vol. 15; No. 2 population as its peculiar environment shifted through time and space. Although there is no fossil evidence to support the first hypothesis, fossil deep-water molluscan assemblages are so rare and poorly known that we have no basis for rejecting the possibility that the genus was more abundant earlier in its evolutionary history. Most documented cases of endemism in taxa with long geo- logic histories show that the living species are relicts of broader patterns of distribution (see STEBBINS & Major, 1965). The alternative hypothesis that the genus might have evolved in the Eastern Pacific and migrated to its present location in the Western Pacific invites closer examination of the conditions under which Phanerolepida currently lives. Although the bathyal zone is usually a stable re- gion, the bathyal zone between 600 and 800 meters in Sagami Bay has many of the same characteristics as the unstable transition zone in the surface waters between the Kuroshio and Oyashio fronts. OKUTANI (1968: 79) sug- gests that the supply of water from the Oyashio Under- current may not be constant and that populations of warm- and cold-water species may undergo some of the same alternate fluctuations of establishment and extinc- tion as those that have been observed in the transition zone in surface waters to the north. In addition to the unique mixture of northern and southern faunal ele- ments, the Intermediate Water fauna is characterized by 85% endemic species (OKUTANI, 1967: 140). It is likely that this endemism not only reflects adaptations to unique stratification of water masses of very different properties, but also adaptations to fluctuations in the bathyal envi- ronment. There is no firm basis for postulating similar instability in the bathyal zone in which the Keasey Formation was deposited. It may be worth noting, however, that the late Eocene-early Oligocene was a time of climatic transition from widespread tropical conditions to the differentiation of cold water masses at northern latitudes. Current pat- terns off northwestern Oregon might have involved a similar interplay of warm and cold water masses. Another unusual feature which links all the occurrences of Phanerolepida is the presence of a deep water environ- ment very near shore. The similarity of inferred depo- sitional environments of the Keasey Formation and the Shinzato tuff member of the Shimajiri Formation illus- trate this parallelism particularly well. Both were depos- ited in tectonically mobile belts on the western slopes of deep trenches where the bathyal zone was developed very close to shore. Both contain a high proportion of tuffaceous material with occasional ash beds and indica- tions of active volcanism on the adjacent landmasses (MacNeEIL, 1960; Warren & NorpisraTH, 1946). THE VELIGER Page 111 There are additional links between the living Japanese bathyal fauna and the fauna of the Keasey Formation. Bathybembix aeola (Watson, 1878) and Acanthotrophon echinus (Dall, 1918), both elements of the restricted In- termediate Water fauna occurring from the lower shelf to 800m between 33° and 35°N latitude, have morphological analogs in the Keasey Formation. The author intends to explore this parallelism further in a forthcoming system- atic treatment of the Keasey gastropod fauna. Previous recognition that the Keasey Formation was deposited in deep water rests on a variety of general and specific observations. Moore & Vokes (1953) point out a number of general features indicating deep water: the lack of bedding, the diversity of turrid genera and species, the absence of typical shallow water genera, and the depth ranges of some analogous species, particularly bivalves from Recent faunas on the Pacific Coast. ZuLto et al. (1964), examining a specific faunal assemblage within the Keasey Formation, were able to postulate, on the basis of the abundance of an echinoid and coral species with modern counterparts, that the depth of the specific hab- itat represented was approximately 365m. The close affinities of the Keasey gastropod fauna with the modem bathyal fauna off Central Japan provide im- portant new insight into the nature of the Keasey paleo- environment and the evolution and historical biogeo- graphy of a number of molluscan lineages. ACKNOWLEDGMENTS I am grateful to Takashi Okutani of the Tokai Regional Fisheries Research Laboratory in Tokyo for the loan of material and for permission to retain reference specimens, which have been deposited in the U. S. National Museum. Robert Robertson of the Academy of Natural Sciences of Philadelphia provided helpful suggestions and assistance in the photography of shell textures. I thank Druid Wilson for arranging the loan of type specimens from the U. S. National Museum. A. Myra Keen, Warren O. Addicott, and James C. Hickman kindly read and criticized the manuscript. Literature Cited Dati, WituiAmM HEALey 1907. Descriptions of new species of shells, chiefly Buccinidae, from the dredgings of the U.S.S. “Albatross” during 1906, in the northwestern Pacific, Bering, Okhotsk, and Japanese Seas. Smithson. Misc. Coll. 50 (1727): 139-173 (9 July 1907) Hase, TADASHIGE 1964. Shells of the western Pacific in color, vol. II. Hoikusha, pp. 1 - 233; plts. 1 - 66; 1 map; 2 pp. text figs. Osaka, Japan, Page 112 THE VELIGER Vol. 15; No. 2 Hata, Kotora « Syozo NistyAMA 1952. Check list of Japanese Tertiary marine Mollusca. Tohoku Imp. Univ. Sci. Reprts., 2nd. ser. (Geology), spec. vol. 3: 464 pp. Kuropa, ToKuBEI 1931. Fossil Mollusca. In: FE Homma: Shinano Chubu Chishitsu- Shi [Geology of central Shinano]; part 4: 1-90; plts. 1-13 MacNeEIL, Francis STEARNS 1960. Tertiary and Quaternary Gastropoda of Okinawa. Survey Prof. Paper 339: 148 pp.; 31 plts.; 17 text figs. Moore, Raymonp CeEci_ & Harotp ERNEST VOKES 1953. Lower Tertiary crinoids from northwestern Oregon. U.S. Geol. Survey Prof. Paper 233-E: 113 - 148; 13 figs.; plts. 14 - 24 OxKuTANI, TAKASHI 1964. Report on the archibenthal and abyssal gastropod Mollusca col- lected mainly from Sagami Bay and adjacent waters by the R. V. Soyo-Maru during the years 1955-1963. Journ. Fac. Sci., Univ. Tokyo, Sect. II, 15 (3): 371 - 447; plts. 1-7 1967. Characteristics and origin of archibenthal molluscan fauna on the Pacific coast of Honshu, Japan. Venus, Japan. Journ. Malacol. 25 (3, 4): 136 - 146; 6 text figs. 1968. Systematics, ecological distribution, and paleoecological implica- tion of archibenthal and abyssal Mollusca from Sagami Bay and ad- jacent areas. Journ. Fac. Sci., Univ. Tokyo, Sec. II, 17 (1): 1-91; U. S. Geol. 1 plt.; 43 text figs. OruKa, YANOSUKE 1949. Fossil Mollusca and rocks of the Kiyosumi Group exposed at Japan. Journ. Minatomachi, Chiba Prefecture and its environs. Geol. Geogr. 21: 295 - 315; plt. 13; text figs. 1-3 STEBBINS, GEorGE LEDYARD & Jack Major 1965. Endemism and speciation in the California flora. Ecol. Monogr. 35: 1 - 35 Ups, MIcHITAKA 1937. Results of hydrographical investigation in Sagami Bay in con- nection with “buri” (Sertola quinqueradiata T. & S.) fishing. Journ. Imp. Fish. Exp. Sta. 8: 1 - 50 Warren, W. C., Hans NorpisraTH & R. M. GriveETTI 1945. Geology of northwestern Oregon west of Willamette River and north of latitude 45°15’. U.S. Geol. Surv. Oil and Gas Investig. Pre- lim. map 42; geol. map and text Warren, W. C. « Hans NorsBisRATH 1946. Stratigraphy of upper Nehalem River Basin, northwestern Ore- gon. Amer. Assoc. Petr. Geol. Bull. 30: 213-237; 2 text figs; 1 table Watson, Rosert Booc 1879. Mollusca of H.M.S. ‘Challenger’ Expedition. IV. Trochidae continued, viz. the genera Basilissa and Trochus, and the Turbinidae, viz. the genus Turbo. Journ. Linn. Soc. London 14: 692 - 716 1885-1886. Report on the Scaphopoda and Gastropoda collected by H. M. S. Challenger during the years 1873-1876. Reprt. Scient. Res. Voyage H.M.S. Challenger, Zoology 15: 1-722; plts. 1-50 Zuo, Victor, R. FE Karr, JouNn Wyatt DurHam & Epwin C. ALLISON 1964. The echinoid genus Salenia in the eastern Pacific. Palaeont. 7 (2): 331 - 349; plt. 56; text figs. 1-6 Vol. 15; No. 2 THE VELIGER Page 113 A Report on Cephalopods Collected by Stanford Oceanographic Expedition 20 to the Eastern Tropical Pacific Ocean September to November, 1968 W. GORDON FIELDS anp VERONICA A. GAULEY Department of Biology, University of Victoria, Victoria, British Columbia, Canada (1 Text figure) INTRODUCTION THE CEPHALOPODS collected by the Stanford Oceano- graphic Expedition 20 are described and their location of capture noted in order to increase recorded knowledge of cephalopod fauna of the eastern tropical Pacific Ocean. The expedition, aboard the RV “Te Vega”, left Guayaquil, Ecuador on 17 September, 1968 and arrived in San Diego, California on 29 November, 1968. The cruise track and stations where cephalopods were collected are shown in Figure 1. Reports on the cephalopod fauna of the eastern tropical Pacific are few. Horie (1904), Rosson (1948), CLARKE (1966), McGowan & Oxutani (1968), OKUTANI & McGowan (1969), Roper (1969) and Youne (1971) have described various cephalopod species from this gen- eral area. METHODS The collection consists of 17 specimens held by the Uni- versity of Victoria (UV) in the “Te Vega’ collection (TVG). The 6 different species identified have been de- scribed in detail by previous authors; therefore, these de- scriptions will not be repeated here except for an outline of the distinguishing features. Five of the specimens are unidentifiable to species due to loss of parts, digested state and larval stage. Specimens were collected by Tucker trawl, bongo net and hand line. Three specimens of Symp- lectoteuthis were found among material regurgitated by a Colombian booby, Sula leucogaster etesiaca Thayer & Bangs, 1905. The measurements and morphometric indices given in the systematic section and in Tables 1 and 2 are defined by Voss (1956). The eight morphological characteristics measured include: total length (TL); dorsal mantle length (ML) ; mantle width (MW); head width (HW); head length (HL) ; fin length (FL) ; fin width (FW) ; and arm length (AI-IV). Seven indices were calculated from these measurements: head width index (HWI); mantle width index (MWI); fin length index (FLI) ; fin width index (FWI); mantle arm index (MAI); arm length index (ALI); and head length index (HLI). In addition, length of the fin as measured along the plane of attachment (FL’) (Berry, 1912) and the index for this measurement (FLI’) were used. SYSTEMATIC SECTION OcTOPODIDAE Octopus sp. Specimens: Two larvae, UV-TVG 4 and 5, ML 7.0 and 4.0mm; station F-52, 4°53’N, 84°07’W, 2330 hrs., 20 October 1968; Tucker trawl, 100m to surface. Because of the small size of the specimens and lack of literature on larval octopods of this region, definite identi- fication was not attempted. Both specimens are complete Page 114 THE VELIGER Vol. 15; No. 2 Be 53 (o) 20 20° 10° fee Pacific Ocean Galapagos Be i Islands _ 110 100° go° 80° Figure 1 Cruise track and stations where cephalopods were collected on Stanford Oceanographic Expedition 20 Vol. 15; No. 2 THE VELIGER Page 115 Table 1 Measurements Collection Measurements in millimeters Species No. TL ML MW HL HW FL FL’ FW AI AII AIII AIV Ocho pusisps mrs ates oie karte a ce pela rast ae, 4 16 fl 43) AIST / / ays) 45) 6 a5) / Octo pusespiytencrt scene encores i 9 7 4 3 if Japetella sp........ 14 32 13) RS fh / / / 8:5 10 12 9 9 4 2 Abraliopsis affinis ..... 5 OS as 26 «12 Abraliopsis affinis ..... 2» of 26 13 5 Abraliopsis affinis 15 73 40 1@ Al ADT Alto psishalfinis: presen mcm eerie eerie 16 - 2913s ie i 20K 18 32 - - - - Bathyteuthis abyssicola .. ee Sa SO aa ia Viva One Mak re = 8 8 9 9 Bathyteuthis\bactdtfera .ccarenecceaere. I 22 12 6. & 7 3 2 4 Bho) 4 fe Ges) Bathyteuthis baci fer cccssmessmesinsnisnimiesisueureniee 2 35 16 10 Gi Nh Gay 11 7 10 10 11 Symplectoteuthis oualaniensis . 8 24 15 5 4 4 4 3 7 4 5 5 3 Symplectoteuthis oualaniensis 10 COZ Oli lS ©) TB AAO zh - 9 a2 2c) aaa Os Symplectoteuthis OUalantensis eeecoscsecsnsnessnemenne 11 = Gare WG a alg} - = - er NO ee eee 2? Symplectoteuthis sp. ecco 12 64* - - = = = - = = a = ie PSymplectoteuthis Sp. rrewersnsenmee 9 - 8 eS hos 2 2 4 - - - - DoOstdicusmeigasene ea mene 7 508 cys) Soe Ge GH G3 4h) 9 Aes) sey) toy PANO) SIS) Helicocranchia pfe ffert .ceccccscmn 3 23 16 - 2 6 2 1 3 4 6 8 3 / = measurement not applicable * = measurement approximate — = measurement not taken Table 2 Morphometrics Collection Species No. HWI HLI MWI FLI FLY FWI MAI ALI Octopus SP. eee Ah 64.3 / 64.2 / / Hf 116.7 37.5 Octopus sp. .... So 75.0 / 75.0 / / / 1332S e429 Na Bctell asp tect eee eters ne ere tte 14 72.2 / - / / / 150.0 37.5 30.7* 34.6 46.2 76.9 65.4 127.0 69.2 32.7 30.8 30.8 38.5 65.4 D3: Onl 2oal 76.9 38.5 36.7 40.0 33.3 73.3 63:3) 10333 106.7 43.8 = - 44.8* 69.0 2rd ONS - ~ Abraliopsis affinis Abraliopsis affinis Abraliopsis affinis Abraliopsis affinis Bathyteuthis abyssicola .. s - - - - = - - 25.7 Bathyteuthis bactdifer a .ccrcvrescsniesnneennrnnainsenenee 58.3 41.7 50.0 25.0 16.7 33 Sie OIEO 20.5 Bathyteuthis Dacidi fer esnsciecrsnccinsssnreneininnsinenenies 81.3 50.0 62.5 40.6 25.0 68.8 68.8 Sie: Symplectoteuthis oualaniensis ... 8 26.7 26.7 33.3 26.7 20.0 46.7 33.3 20.8 Symplectoteuthis oualaniensis .... Symplectoteuthis oualaniensis .. ?Symplectoteuthis sp. ecncccum ?Symplectoteuthis sp. Dosidicus Gi gas... 2 Helicocranchial prefer nt ee 3 37.5 12.5 - 12.5 6.3 18.8 50.0 34.8 / = index not applicable * — index approximate — = index not calculated Page 116 iE VELIGER Vol. 15; No. 2 and in good condition. They have 6 large reddish-brown chromatophores on the dorsal side of the head, a double row of very small chromatophores on the aboral side of each arm, and many small chromatophores of a faint reddish-brown on the dorsal posterior mantle and ventral mantle. Hoye (1904) has described 10 species of Octo- pus from the eastern tropical Pacific. BOLITAENIDAE Japetella sp. Specimens: One female, UV-TVG 14, ML 18mn;; sta- tion H-16, 13°25’N, 98°14’W, 2000 hrs., 8 November 1968; bongo net, 1500m. Japetella is a soft-bodied octopod with a wide mantle opening, uniserial suckers, and large eyes directed laterad. This specimen is a small, immature female and is in fair condition with a “wrinkled” mantle and damaged web. It has large, prominent gills which are 10mm long and have 11 lamellae in the outer demibranch. The funnel extends to the anterior edge of the eyes. It is broad and thin-walled. The funnel organ is not discernible. The longest arm is 37% of the total length of the animal. Due to the condition and immaturity of this specimen identi- fication to species was not made. Hoye (1904) has de- scribed two species of Japetella from this area. ENOPLOTEUTHIDAE Abraliopsis affinis (Pfeffer, 1912) Specimens: One female, UV-TVG 6, ML 26mm; one male, UV-TVG 7, ML 13mm; station F-52, 4°53’N, 84°07’W, 2330 hrs., 20 October 1968; Tucker trawl, 100 m to surface. One male, UV-TVG 15, ML 30mm; station Z-171, 19°04’N, 104°40’W, 2100 hrs., 18 November 1968; Tucker trawl, 300m to surface. One male, UV-TVG 16, ML 29mm; mantle only, no data. This species is noted for the arrangement of the photo- phores on the ventral side of the short, semi-fusiforra mantle. They are situated in longitudinal rows with a wide, median bare area terminating in a bare, circular patch on the distal third of the mantle. There are 2 large and 3 small photophores on the eye ball. The club has 3 large and 4 small hooks in a double row and a semilunar membrane on the outer side. In the male, the right vent- ral arm is hectocotylized with 3 offset semilunar crests; the left ventral arm has a large swimming web 3 times the width of the arm. The mature female, UV-TVG 6, has both tentacles and the right eye missing. Ripe eggs fill the posterior mantle cavity. Approximately 16 discharged spermatophores are embedded in the internal side of the dorsal mantle just to the right and behind the nuchal cartilage. The male, UV-TVG 7, is a juvenile with reproductive organs in a developmental stage. The ventral mantle pho- tophores are in the typical longitudinal arrangement but are not as numerous as in the adult. UV-TVG 15 is a mature male in fair condition with the left tentacle and the tips of the first right and third left arm missing. The semilunar crests of the hectocotylus have been destroyed but the swimming web of the left ventral arm is well developed and in good condition. There are many mature spermatophores 6.5mm long in the penis and spermatophoric sac. Although the fourth specimen, a mature male, UV- TVG 16, is missing the head, arms and data, it is included here because the mantle and internal organs are in very good condition and have the same morphology as UV- TVG 15. Spermatophores are present in the penis and the spermatophoric sac. Although they are much less numerous than in UV-TVG 15, they have the same length of 6.5mm. McGowan & OxutTani (1968) have compared Abrali- opsis affinis with 3 other North Pacific species and have indicated its distribution in the eastern tropical Pacific. Hoyte (1904), Prerrer (1912) and CrarKeE (1966) also note its distribution in this area. Bathyteuthidae Bathyteuthis abyssicola Hoyle, 1885 Specimens: One ?, UV-TVG 13, ML --; station G-36, 7°29/N, 87°58’W, 2055 hrs., 27 October 1968; Tucker trawl, 2500m to surface. Bathyteuthis is noted for its deep red colour, separate terminal fins and 6 oval light organs, one each at the base of the first 3 dorsal pairs of arms. Bathyteuthis abyssicola is distinguished from B. bacidifera Roper, 1968, by its thick, fleshy, protective arm membranes unsupported by trabcculac, smallcr gills and smaller tentacular clubs with fewer suckers; it differs from B. berry: Roper, 1968 by having smaller gills and fewer suckers on shorter, blunt arms (Roper, 1968: 171; table 1). The morphology and distribution of these species are discussed in detail in Roper (1969). This specimen of B. abyssicola is in poor condition. The mantle is everted and most of the internal organs are missing. Hoye (1904), Rosson (1948), Ciarke (1966), and Roper (1969) note the presence of this species in the eastern tropical Pacific. Vol. 15; No. 2 THE VELIGER Page 117 Bathyteuthis bacidifera Roper, 1968 Specimens: One juvenile, UV-TVG 1, ML 12mm; sta- tion D-56, 1°19’N, 84°07’W, 1415 hrs., 6 October 1968; Tucker trawl, 2500m to surface. One female, UV-TVG 2, ML 16mm; station F-40, 4°29'N, 84°10’W, 2245 hrs., 19 October 1968; Tucker trawl, 200 - 350m to surface. Bathyteuthis bacidifera possesses all those features pre- viously mentioned for Bathyteuthis. Its most distinctive characteristic is the long free trabeculae which replace the protective membranes on the proximal half of the arms. Roper (1968, 1969) has made detailed descrip- tions of this species and notes its distribution as being bathypelagic in the “ ... Eastern Pacific Equatorial Wa- ter Mass and possibly in the Indian Ocean Equatorial Water Mass (based on Chun’s [1910] single specimen) .” (Roper, 1969: 49). The juvenile is missing the right tentacular club but it is in better condition than the female which is missing both tentacles and the right second arm. Both specimens possess the typical long, free trabeculae on the arms. OMMASTREPHIDAE Symplectoteuthis oualaniensis (Lesson, 1830) Specimens: One juvenile, UV-TVG 8, ML 15mm; sta- tion F-52, 4°53’N, 84°07’W, 2330 hrs., 20 October 1968; Tucker trawl, 100m to surface. One male, UV-TVG 10, ML 61mm; one?, UV-TVG 11, ML 55mm approx., station Z-78, 5°34’N, 86°58’W, 1930 hrs., 22 October 1968; from stomach of Colombian booby, Sula leucogaster etesiaca Thayer & Bangs, 1905. The distinctive feature of juveniles and adults of this species is the fusion of the mantle with the funnel at the junction of the two perpendicular grooves of the funnel cartilage. CLARKE (1965, 1966) describes a form of this species which has a large light organ on the dorsal mantle surface. This was not observed in any of the “Te Vega” specimens of Symplectoteuthis. Symplectoteuthis oualaniensis has been reported from the eastern tropical Pacific by Hoye (1904), Voss (1963), and Crarke (1966). It has also been recorded from the western Pacific Ocean and the Indian Ocean (Sasaxt, 1929; Voss, 1963; CLARKE, 1966). The juvenile specimen, UV-TVG 8, is in good condi- tion. Specimens UV-TVG 10 and 11 have been partially destroyed by digestion with the arms being the most affected. The dorsal and ventral sides of the stomach and caecum of specimen UV-TVG 10 are parasitized by ap- proximately 140 immature specimens of the family Di- dymozoidae. 2Symplectoteuthis sp. Specimens: One mantle with part of funnel, UV-TVG 9, ML 8mn;; station F-52, 4°53’N, 84°07’W, 2330 hrs., 20 October 1968; Tucker trawl, 100m to surface. One mantle, UV-TVG 12, ML 64mm; station Z-78, 5°34/N, 86°58’W, 1930 hrs., 22 October 1968; from stom- ach of a Colombian booby, Sula leucogaster etesiaca. Specimen UV-TVG 9 was tentatively identified as Sym- plectoteuthis sp. on the basis of the structure of the funnel cartilage and its fusion to the mantle. The taxonomic position of UV-TVG 12 is even less certain as only the mantle remains. However, since it has the same form, colour and approximately the same size as specimens UV- TVG 10 and 11 and was collected from the same source at the same time, it has been placed under ?Symplecto- teuthis sp. Dosidicus gigas (d’Orbigny, 1835) Specimens: One male, UV-TVG 17, ML 325mm; sta- tion Z-10, 2°51’N, 83°16’W, 2030 hrs., 19 September 1968; hand line. Dosidicus gigas is characterized by its robust arms which become very attenuate at the extremities where they bear numerous, very small suckers. Adults attain a very large size, between 4 and 12 feet [1.20m and 3.60m] (PuHiLuips, 1961; CrarKeE, 1966). The “Ye Vega ” specimen is a small male in good condition. This species has been fre- quently recorded from the eastern tropical Pacific; a few of these authors are: D’ORBIGNY (in DE FERUSSAC & D- Orsicny, 1835), STEENSTRUP (1880), BERRY (1912), PFEFFER (1912), Puimuips (1933, 1961), and CLarKe (1966). It has also been recorded from Australia and the Solomon Islands (Brazier, 1892 in CLARKE, 1966). CRANCHIIDAE Helicocranchia pfefferi Massy, 1907 Specimens: One juvenile, UV-TVG 3, ML 16mm; sta- tion F-40, 4°29’N, 84° 10’W, 2245 hrs., 19 October 1968; Tucker trawl, 200 - 350m to surface. This species is noted for its pedunculate fins, the regular arrangement of chromatophores in rows on the sides cf the mantle, the extremely large funnel wich extends two thirds the length of the ventral arms and the large, stalked, conical eyes which bear a luminous organ. The arm for- mula is 3>2>1>4 or 3>2>4> 1. Helicocranchia pfeffert has been reported from the Pacific only by Oxv- TANI & McGowan (1969). These specimens and the “Te Vega” specimen have a small swelling on the dorsal sur- face of the head. There is a semilunar chromatophore against the swelling and a pair of circular chromatophores Page 118 on both sides between the cephalic pillar and eye stalks. The “Te Vega” specimen is in good condition except that the tentacles and eyes have been damaged and some of the arm suckers are missing. ACKNOWLEDGMENTS We would like to thank Dr. Jack Littlepage of the Univer- sity of Victoria for providing us with the cephalopod specimens from Stanford Oceanographic Expedition 20 operating under NSF Grants GB 6870 and GB 6871. The authors are grateful to Dr. L. Margolis of the Fisheries Research Board of Canada, Nanaimo, for identifying parasites and to Dr. William G. Pearcy of Oregon State University for the loan of Japetella heathi (Berry, 1911) specimens. We would also like to thank Mr. Steve Brocco of the University of Washington for his suggestions con- cerning the paper. Study of these specimens at the Uni- versity of Victoria was supported by National Research Council of Canada Grant A 1968 and by a grant from the University of Victoria Faculty Research Fund. Literature Cited Berry, SAMUEL STILLMAN 1912. A review of the cephalopods of western North America. Bull. U. S. Bur. Fish. 1 (XXX), Doc. 761: 267 - 336; plts. 32-56; 18 text figs. (24 July 1912) CriarKE, MALcoiM R. 1965. Large light organs on the dorsal surfaces of the squids Omma- strephes pteropus, Symplectoteuthis oualaniensis and Dosidicus gigas. Proc. Malacol. Soc. London 36: 319 - 321 1966. A review of the systematics and ecology of oceanic squids. Ady. Mar. Biol. 4: 91 - 300; 59 figs. THE VELIGER Vol. 15; No. 2 Férussac, ANDRE DE & ALCIDE D’ORBIGNY 1835-1848. Histoire naturelle générale et particuliére des cephalopodes acetabuliféres vivants et fossiles. pp. 1-361; 144 pits. Hoye, WILLIAM Evans 1904. Reports on the scientific results of the expedition to the eastern tropical Pacific ... Albatross. V. Reports on the Cephalopoda. Bull. Mus. Comp. Zool. Harvard 43 (1): 1-71; 10 plts. McGowan, JoHN ARTHUR & TAKASHI OKUTANI 1968. A new species of enoploteuthid squid, Abraliopsis (Watasenia) felis, from the California current. The Veliger 11 (1): 72 - 79; plts. 9, 10; 1 map (1 July 1968) OxuTANI, TAKASHI & JOHN ARTHUR McGowan 1969. Systematics, distribution, and abundance of the epiplanktonic squid (Cephalopoda, Decapoda) larvae of the California current April, 1954 - March, 1957. Bull. Scripps Inst. Oceanogr. 14: 1 - 90; 36 figs. PFEFFER, Georc J. 1912. Die Cephalopoden der Plankton-Expedition. Zugleich eine mono- graphische Ubersicht der oegopsiden Cephalopoden. Ergeb. Plankt.- Exped. Humboldt Stift. 2: i- xxi+1-815; Atlas 48 plts. Puituips, Juuius B. 1933. Description of a giant squid taken at Monterey with notes on other squid off the California coast. Calif. Fish & Game 19 (2): 128 - 136 1961. Two unusual cephalopods taken near Monterey. Calif: Fish & Game 47 (4): 416-417 Rosson, Guy Cosurn 1948. The Cephalopoda Decapoda of the Arcturus Oceanographic Ex- pedition, 1925. Zoologica 33 (3): 115-132 Roper, Ciype EF E. 1968. Preliminary descriptions of two new species of the bathypelagic squid Bathyteuthis (Cephalopoda: Oegopsida). Proc. Biol. Soc. Wash. 81: 161 - 172; 7 plts. 1969. Systematics and zoogeography of the worldwide bathypelagic squid Bathyteuthis (Cephalopoda: Oegopsida). Bull. U.S. Nat. Mus. 291: 1-210; 74 figs. Sasaki, MADOKA 1929. A monograph of the dibranchiate cephalopods of the Japanese and adjacent waters. Journ. Coll. Agr. Hokkaido Imp. Univ. 20: 1-357; 158 figs.; 30 plts. STEENSTRUP, JAPETUS 1880. In: “The cephalopod papers of Japetus Steenstrup”, transl. by A. VousgE, J. KNupsen & W. Rees (1962). Dan. Sci. Press, Copenhagen; pp. 1 - 330; illust. Voss, GivBerT L. 1956. A review of the cephalopods of the Gulf of Mexico. Bull. Mar. Sci. Gulf and Carib. 6 (2): 85-178; 18 figs. 1963. | Cephalopods of the Philippine Islands. Mus. 234: 1 - 180; 4 plts.; 36 text figs. Younc, Ricuarp E. 1972. The systematics and areal distribution of pelagic cephalopods from the seas off southern California. Smithson. Contrib. Zool. [in press] Bull. U. S. Nat. Vol. 15; No. 2 THE VELIGER Page 119 Selective Predation and Prey Location in the Sea Slug Navanax inermis GREG M. BLAIR anp ROGER R. SEAPY Department of Population and Environmental Biology, University of California, Irvine, Irvine, California 92664 (2 Text figures; 1 Map) INTRODUCTION THE SEA SLUG Navanax inermis (Cooper, 1862) occurs on low littoral and shallow sublittoral bottoms and is known to be a voracious predator on opisthobranch mol- lusks (RickETTs « Cavin, 1968). The prey preferences of N. inermis from a sandy bottom bay and an exposed rocky coastline were studied by Patne (1965) at San Diego, California. In both environments the most abun- dant species of opisthobranchs (Bulla gouldiana Pilsbry, 1893 in the bay and 3 species of nudibranchs on the rocky coastline) represented the dominant components of N. inermis’ diet. However, prosobranchs were conspicuously absent from its diet, and Paine (1963) observed that N. inermis would not ingest the prosobranchs Conus califor- nicus Hinds, 1844, Nassarius tegula (Reeve, 1853), or Olwella biplicata (Sowerby, 1825). On the mud-sand bottom surrounding Balboa Island at Newport Beach, California, Navanax inermis is a common and conspicuous macroinvertebrate. In this environment, available gastropod prey include the opisthobranchs Ha- minoea virescens (Sowerby, 1833) and Phyllaplysia tay- lori Dall, 1900, and the prosobranch Nassarius tegula. If N. inermis selects opisthobranch prey in proportion to their abundance in the environment, N. inermis occurring at Balboa Island should preferentially feed on H. virescens and P. taylori. Chemoreception is known to exist (KoHN, 1961) ina variety of gastropods. Distance chemoreception has been demonstrated in several nudibranchs (StEHOUWER, 1952; BraaMs & GEELEN, 1953) and in the neogastropod Conus (Koun, 1959). However, Navanax inermis actively tracks and captures its prey by contact chemoreception. Unlike the nudibranch Dirona albolineata MacFarland, 1912, which appears to locate prey by direct chemoreceptive con- tact (Ropituiarp, 1971), N. inermis locates its prey by first recognizing the presence of an acceptable prey mucus trail, and then following that mucus trail to its producer. Marcus (1961) showed that N. inermis has two chemo- receptive areas located on either side of its head and that it characteristically follows the mucus trails of its prey by placing one or both of these areas directly on the mucus trail. It then simply follows the trail, overtakes, and then ingests the prey. This predatory behavior pattern permits the experimental manipulation of predator and prey. For example, Paine (1963) guided Bulla gouldiana (a known prey type of N. inermis) in a figure nine pattern, but stopped the animal just before completing the circular portion of the number. When following the trail from the base of the figure nine pattern, N. inermis would pass B. gouldiana by only 2cm, but would not deviate from the trail. Instead it followed the figure nine to where the B. gouldiana stopped. In the present study, variations on this experimental approach were executed by manipulating various prey types along the prescribed mucus pathways or along pathways comprised of the mucus trails of dif ferent prey types. Navanax inermis was then placed in the vicinity of each trail and its movements observed and recorded. MATERIALS anp METHODS During April to June of 1971 Navanax inermis was ob- served and collected on the eastern shore of Balboa Island, Newport Beach, California (Figure 1) either above or near the low water mark. Specimens were observed on mud bottoms in the proximity of Zostera marina Linnaeus, 1753, or occasionally within the eelgrass itself. Individuals used in the food preference study were collected as they were encountered in the field and retained in 1-gallon ca- pacity buckets for an average of 48 hours and allowed to Page 120 THE VELIGER ~ VoliGenyon ails ic a meen Mens WUC GI, 1B) ie. Balboa Island Pacific Ocean Newport Bay - Balboa Reafiaculla Figure 1 Location of study area on Balboa Island, Newport Beach, California at 33°36’20” N latitude, 117°53’10” W longitude defecate any hard parts. This period of time was quite adequate since in the study by Pane (1965) only 20 to 30 hours were normally required for N. inermis to clear its gut. The buckets were kept in a shaded outdoor closet at temperatures that ranged from 18.0 to 20.7°C. The sea water in each bucket was replenished daily. Two areas of beach were selected to estimate the local abundance of the possible prey types of Navanax inermis Vol. 15; No. 2 THE VELIGER Page 121 Table 1 Gut Content Analyses of Navanax inermis rows BS. os a Prey length sz Time of day Prey defecated (mm) 10.5 Afternoon None 10.8 Afternoon None 11.5 Afternoon Haminoea virescens 5 11.8 Afternoon Teinostoma supravallatum 2 12.0 Morning Haminoea virescens 7,8 12.3 Morning None 19.7 Afternoon None 2a Afternoon None 26.5 Morning None 29.3 Afternoon None 32.3 Afternoon None 33.2 Afternoon None 39.8 Afternoon None 82.3 Afternoon Haminoea virescens 13, 14, 16 Crucibulum spinosum we Hermissenda crassicornis 42 90.7 Afternoon Hermissenda crassicornis 32 unidentified crustacean 8 119.1 Afternoon Haminoea virescens 11, 12, 13, 14 14, 14, 15, 16, 17 125.0 Afternoon None 130.2 Afternoon Haminoea virescens 12, 12, 13 Crucibulum spinosum 9 ' defecated in the living state 2 length of radula and their distribution relative to each other. One area contained dense beds of eelgrass (7m wide) and the other contained relatively sparse patches of eelgrass (12m wide). The length of each area extended from the high tide level down to a depth at which visibility in the water was minimal — usually about 2m. Sampling was carried out during one high tide, one intermediate tide, and 3 low tides. In the study on location of prey, a wading pool 1m in diameter was placed on the beach at the edge of the tide beneath the shadow of a pier. Sufficient sand was placed inside the pool to cover the bottom and the pool was filled to capacity with sea water. Temperature of the pool water was never more than 3°C warmer than the nearshore surface water temperature that ranged from 19 to 20°C. Various prey types were placed on the sand and guided by means of forceps to fit each distinct experimental de- sign. The nudibranch Hermissenda crassicornis (Esch- scholtz, 1831) and the tectibranch Bulla gouldiana were used in the majority of experiments because they were the most motile and easily guided species of prey. A specimen of Navanax inermis was next placed on the sand (taking care to place the animal well away from the trail so that it would encounter the trail “by chance” during its move- ments within the pool) and its movements observed and recorded. For each experimental arrangement, an average of 7 replications were recorded. RESULTS Very few Navanax inermis were collected within eelgrass beds. The great majority were found on undisturbed sandy-mud bottoms. The hard parts defecated by N. in- ermis (Table 1) revealed a predominance of Haminoea virescens in the diet. Haminoea virescens represented 75% Page 122 of the total number of prey passed through the guts of those specimens studied; Hermissenda crassicornis repre- sented 8%; and Teinostoma supravallatum (Carpenter, 1864), Crucibulum spinosum (Sowerby, 1824), N. inermis and an unidentified crustacean comprised 17%. Particu- larly noteworthy is the record of no prey hard parts from N. inermis between the sizes of 12 and 82g. The length of ingested H. virescens ranged from 5 to 17mm. Prey H. Tidal Area | Area 2 Height (m) Figure 2 Occurrence of gastropods in sampling areas 1 and 2 at Balboa Island, Newport Bay. For each date the tidal height at the time of observation is indicated by the horizontal dashed line. Observed gastropods in the two areas include Nassarius tegula ({_]), Phyll- aplysia taylori (CQ) and Haminoea virescens (@) THE VELIGER Vol. 15; No. 2 virescens of less than 8mm were selectively eaten by 11 to 12g N. inermis, while H. virescens of greater than 11 mm length were eaten only by N. inermis of greater than 82¢ weight. When all the data on the occurrence of prey in the 2 sampling areas (Figure 2) were added together, Hami- noea virescens comprised 62%, Phyllaplysia taylori 20%, and Nassarius tegula 18% of the gastropods collected. The summation of data from Figure 2 was justified on the basis that Navanax inermis occurred randomly on sandy-mud bottoms throughout the study area and that the numbers of available N. inermis limited to any specific area were too few for the adequate analysis of gut contents. Because sample sizes were small it was not possible to quantitatively assess population densities or describe the types of dispersion exhibited by each prey species. How- ever, it appeared (Figure 2) that Nassarius tegula was strongly aggregated; Phyllaplysia taylori was weakly ag- gregated; and Haminoea virescens was uniformly dis- persed. Both N. tegula and P. taylort were conspicuously absent from the 12m area of sparse eelgrass. During the present study a “searching” posture (with the body fully extended and the head occasionally making small sweeps) was observed consistently for each Navanax inermis, whether it had previously contacted a trail or not. When N. inermis detected the presence of a trail, the sweeping motion became much reduced, and the ani- mal then followed the trail. The angle at which N. in- ermis made first contact with the mucus trail varied, and did not appear to affect its ability to initiate movement upon the trail. After N. inermis made initial contact with the prey, it moved its head from one side of the prey shell or body to the other side and then ingested it directly. Following ingestion of the prey, the N.inermis immediately resumed its “‘searching”’ posture. The results of the specific experiments conducted on prey location are summarized in Table 2. Hermissenda crassicornis was used (Experiment 1) to describe a circu- lar pathway. Navanax inermis made contact with the circular trail and followed it to the site of initial contact, whereupon it veered away. An alpha-shaped trail (Ex- periment 2) was made with H. crassicornis; N. inermis entered the trail at its origin and followed the trail to its end. The remaining experiments involved use of straight trails. In the first of these experiments (Experiments 3 and 4), the trail of a known prey type was interrupted and replaced by the trail of a different known prey type. In both experiments N. inermis did not veer away at the intersection of the 2 trails. If one known prey type was replaced at the end of its mucus trail by a different known prey type (Experiments 5 and 6), N. imermis followed the path and ingested the prey directly. However, when Vol. 15; No. 2 THE VELIGER Page 123 Table 2 Response of Navanax inermis to Gastropod Mucus Trails =| o Gs a ae Experimental Design 1 A circular mucus trail (30 to 40cm diameter) made by Hermissenda crassicornis 2 A mucus trail in an alpha (qe) configuration (circular part 35 to 45cm diameter) made by Hermissenda crassicornis 3 A straight trail (50 to 60cm), one-half consist- ing of mucus from Bulla gouldiana, and the other half from Haminoea virescens 4 A straight trail (55 to 65cm), one-half consist- ing of mucus from Bulla gouldiana, and the other half from Hermissenda crassicornis 5 A straight trail of Bulla gouldiana (25 to 40cm) with Haminoea virescens placed at the end of the trail immediately before contact by Navan- ax inermis 6 A straight trail of Hermissenda crassicornis (35 to 40cm) with Haminoea virescens placed at the end of the trail immediately before contact by Navanax inermis 7 A straight trail (50 to 60cm), one-half consist- ing of mucus from Hermissenda crassicornis, and the other half from Nassarius tegula 8 A straight trail of Hermissenda crassicornis (30 to 40cm) with Nassarius tegula substituted im- mediately before contact by Navanax inermis 9 A straight trail of Bulla gouldiana (30 to 40 cm) with Nassarius tegula substituted immedi- ately before contact by Navanax inermis Results Number of >| Replicates Navanax inermis entered, followed the trail and exited at the point at which it first made contact with the trail Navanax inermis entered one arm of the alpha con- 6 figuration, and followed the trail through to the end, with no hesitancy or deviation at the intersec- tion of the loop Navanax inermis followed the entire trail without 6 hesitancy at the point where the Haminoea virescens trail began Navanax inermis followed the entire trail without 7 hesitancy at the point where the Hermissenda cras- sicormis trail began Navanax inermis followed the trail and, upon com- 7 pleting the trail, immediately ingested the substi- tuted Haminoea virescens Navanax inermis followed the trail and, upon com- 6 pleting the trail, immediately ingested the substi- tuted Haminoea virescens Navanax inermis followed the Hermissenda crassi- 7 cornis trail and veered away immediately after con- tacting the trail of Nassarius tegula Navanax inermis followed the Hermissenda crassi- 7 cornis trail and did not ingest the Nassarius tegula at the end of the trail Navanax inermis followed the Bulla gouldiana trail 7 and did not ingest Nassarius tegula at the end of the trail the latter half of this mucus path was replaced with the mucus from the neogastropod Nassarius tegula (Experi- ment 7), Navanax inermis lost the trail at the point where it contacted the mucus of Nassarius tegula. Further- more, Navanax inermis could not be induced into eating Nassarius tegula (Experiments 8 and 9) by placing Nas- sarius tegula at the end of a trail of a known prey type. DISCUSSION Haminoea virescens represented 62% of the total gastro- pod species present in the environment and 74% of the diet of Navanax inermis. Although Phyllaplysia taylori and Nassarius tegula were relatively abundant in the field (20% and 18%, respectively, of the gastropods present), both of these species were absent from the diet of N. in- ermis. The absence of Nassarius tegula from the diet is predictive in light of the present experimental evidence on rejection by N. inermis. Additionally, the distinctive behavioral characteristics of P taylori and Nassarius tegu- la would reduce the probability of their encounter in the field by N. inermis. Phyllaplysia taylori normally occurs (MacGinitie « MacGinitie, 1968) in beds of eelgrass. In the present study only small N. imermis were infre- quently encountered in eelgrass. Species of Nassarius re- main burrowed in bay bottoms until stimulated by distant chemoreceptive detection of decaying flesh when they will Page 124 THE VELIGER Vol. 15; No. 2 rise to the surface and aggregate around the dead animal (Koun, 1961). In the present study, Nassarius tegula was periodically observed in small groups of 4 or 5 individuals, either moving across the bay bottom or feeding on decay- ing fish. Thus, the aggregated distribution of Nassarius tegula decreases the probability of encounter in the field by N. inermis, whose movements during prey location appear to be random. In contrast to the aggregated dis- tribution of P taylori and Nassarws tegula, H. virescens appeared to be uniformly spaced (Figure 2) along the bottom. This spacing greatly enhances the probability of N. inermis meeting the mucus trail of an individual H. virescens. Thus, in addition to its abundance in the field, an important factor in favoring predation on H. virescens could be its optimal accessibility. In the experiments on prey location, Navanax inermis responded positively to a combination of mucus trails from different known prey types. It did not follow the mucus trails of Olivella biplicata, Conus californicus (Patne, 1963), or Nassarius tegula (as demonstrated in the present study). Indeed, Navanax inermis could not be induced to accept Nassarius tegula even if the mucus trail of it was preceded by that of an acceptable prey type or when Nassarius tegula was placed halfway within the mucus sheath at the end of a mucus trail made by Hami- noea virescens. When Nassarius tegula was replaced by H. virescens, the latter was quickly ingested. Thus, not only was Nassarius tegula observed to be inaccessible to Nava- nax inermis in the field, it was not an acceptable prey. Whether this reaction represented chemoreceptive rejec- tion or was simply a lack of response by Navanax toward the presence of Nassarius tegula is an area for future ex- perimentation. Navanax inermis did not exhibit any hesitancy in move- ment when following trails comprised of 2 different known prey types. Apparently, N. inermis will follow the mucus trail of opisthobranch prey without regard to the particu- lar species involved in the interaction. If encountering overlapping trails from 2 known prey types in the field, this characteristic would confer the adaptive advantage on N. inermis of continuing to follow one mucus path rather than hesitating and possibly losing track of both trails. The ability to utilize contact chemoreception in prey location makes Navanax inermis a highly efficient pred- ator. The evolution of this chemoreceptive mechanism has resulted in the reduction of energy required for prey cap- ture. The ability to differentiate acceptable opisthobranch prey from unacceptable prosobranch prey further reduces energy losses during prey location. CONCLUSIONS The carnivorous sea slug Navanax inermis exhibits distinc- tive prey selectivity and a unique mechanism for prey location. The diet of N. inermis occurring on sandy-mud bottoms is different from that previously reported from a sand-bottom bay and exposed rocky coastline. On sandy- mud bottoms Haminoea virescens is the most accessible prey type occurring in the environment as well as the most abundant prey type in the diet of N. inermis. Two poten- tial species of prey (Nassarius tegula and Phyllaplysia taylori) were abundant in the field but were not access- ible to N. inermis and were absent from its diet. Navanax inermis utilizes contact chemoreception to locate and follow the mucus trails of its opisthobranch prey. In the field, mucus trails were made over sand by carefully guiding various gastropod prey through prede- termined pathways. In every case when a prey type was used that was known to be a preferred prey species, N. inermis would follow the mucus trail, overtake, and ingest the prey. By replacing one prey type with another halfway through the trail, various combinations of mucus trails were obtained. Navanax inermis continued to follow a trail comprised of 2 different known prey types, but would not follow the last half of a trail if it was made by a gastropod other than a known prey type. The utilization of contact chemoreception in the location of acceptable prey is an important mechanism of energy conservation. Literature Cited Braams, W.G. « Hanniz EF M. GeELen 1953. The preference of some nudibranchs for certain coelenterates. Arch. néerl. Zool. 10 (3): 241 - 262 Koun, ALAN JAcoBs 1959. The ecology of Conus in Hawaii. Ecol. Monogr. 29: 47 - 90 1961. Chemoreception in gastropod molluscs. Amer. Zool. 1: 291 to 308 MacGinit1e, Georce Esper & Nettie MacGIniTIE 1949. Natural history of marine animals. McGraw-Hill Book Co., New York, N. Y. xii+473 pp.; 286 text figs. Marcus, Ernst 1961. Opisthobranch mollusks from California. (Supplmt. I): 1-85; plts. 1-10 Paine, Ropert TREAT 1963. Food recognition and predation on opisthobranchs by Navanax inermis (Gastropoda: Opisthobranchia). The Veliger 6 (1): 1-9; 1 plt.; 1 text fig. (1 July 1963) 1965. Natural history, limiting factors, and energetics of the opistho- branch Navanax inermis. Ecology 46 (5): 603-619; 9 text figs. Ricketts, Epwarp FE & Jack CALVIN 1968. Between Pacific tides. v-xilit+3 - 502; 46 pits. RosILLIARD, GorDON A. 1971. Predation by the nudibranch Dirona albolineata on three species of prosobranchs. Pacif. Sci. 25 (3): 429 - 435 SrrEHOUWER, H. 1952. The preference of the slug Aeolidia papillosa (L.) for the sea anemone Metridium senile (L.) Arch. néerl. Zool. 10: 161 - 170 The Veliger 3 (1 February 1961) Stanford Univ. Press, Stanford, Calif. Vol. 15; No. 2 THE VELIGER Page 125 Notes on Two Endemic South African Cypraea R. N. KILBURN anp D. W. AIKEN Natal Museum, Pietermaritzburg, and P.O. Box 13035, Knights, South Africa (1 Text figure) THE INFREQUENCY with which endemic South African Cypraea (subgenera Cypracovula, Luponia and Bernaya) are collected alive has resulted in our knowledge of their dentition and anatomy being sadly deficient. The radulae of C’. fultoni Sowerby, 1903 and C. capensis Gray, 1828 are here described, together with notes on relationships and distribution, and observations on the anatomy of the second species. Cypraea (Bernaya) fultoni Sowerby, 1903 (Text figure 1 A) A portion of the radula of this species was found by the second author amongst the completely decomposed con- tents of a shell taken from the stomach of a fish caught in Natal, and kindly made available by Mrs. E. Visagé of Johannesburg. The radula pattern is that of the group R1 of Kay (1960: 280), although far from typical. The rachidian, which is higher than wide, has a dumbbell-shaped internal bract, but neither a subtending bract nor basal denticles; the base is flat, with rounded corners. The laterals are similarly higher than wide, and are interesting in that they possess a pair of denticles on either side of the meso- cone, instead of the normal single denticle; further ex- amples are required to show whether this feature is usual for the species. The only similar type of dentition that can be traced occurs in the Western Australian Cypraea rosselli (Cotton, 1948) (cf Witson & McComp, 1967: plt. 334 E), which is presumably consubgeneric. Unfortunately nothing is kriown of mantle texture or the structure of the female genitalia in C. fulton. Distribution: While most specimens of C’ypraea fultoni in collections are merely labelled “off Natal,” the locality “off Durban” is not infrequently seen. It should be real- ised, however, that this port merely serves as the base of operations for most commercial fishing vessels in Natal, and hence as the point of sale for these and other readily marketable shells. The only reliable data available to the authors indicate the chief habitat of C. fultoni to be in the region of Aliwal Shoal, just south of Umkomaas (ca. 30°15’S). The map given by Burcess (1970: 57) is highly misleading. Cypraea (Cypraeovula) capensis Gray, 1828 (Text figure 1 B) Recently two living examples of this species were collected by Mrs. P. W. Faulkner at Gonubie, near East London (28°01’E), and kindly forwarded in a preserved state to the first author, together with relevant field notes. Al- though the bodies could only be extracted piecemeal, the more important taxonomic characters were traceable. Cypraea capensis is the type species of the subgenus Cyp- raeovula Gray, 1824. Both specimens were sexually mature females with bright orange ovaries containing ripe ova. A simple thin- walled bursa copulatrix and an apparently glandular receptaculum seminis were present. The mantle (in pre- servative) was thin, smooth and narrow, the siphonal margin apparently smooth. In life (pers. comm. Mrs. Faulkner) the mantle was not observed to be ever ex- panded over the shell; in colour it was brownish, with dark dots and faint white lines; the foot and tentacles were bright orange-yellow. The radula of this species was figured by SCHILDER (1932: fig. 12), the present material agreeing in all fea- tures save for details of the shape of the cusps; the denti- tion type is that of Kay’s category R1. Unfortunately the radula cannot be interpreted taxo- nomically in view of the lack of information on the dentition of related species. Not unexpectedly there is a certain resemblance to BarNarp’s figure (1963: 5c) of Page 126 THE VELIGER Vol. 15; No. 2 Figure 1 Radulae of (A) Cypraea fultoni Sowerby and (B) Cypraea capensis Gray Line represents 0.5mm the radula of the species recorded by him as a globose form of Cypraea fuscorubra Shaw, 1909 (although inter- nal bracts were not indicated by him). Whatever the true identity of his material, it does seem to represent the sub- genus Luponia Gray, 1832, which must be regarded as a synonym of Cypraeovula, Cypraea (Cypraeovula) amphi- thales Melvill, 1888 being completely intermediate in shell characters between the two groups. Cypraea capensis clearly does not fit into either of Kay’s anatomical categories (op. cit.: 285), combining an R1-type dentition with female genitalia of the tigris- type. It is interesting to note that Witson & McComs (1967: 466) found a similar combination to occur in the subgenus Zoila Jousseaume, 1884. While C'ypraeovula was referred, as a full genus, to the subfamily Cypraeovulinae by ScuiLper (1936: 84), Zozla was allocated first to the Cypraeinae, then (ScuiLpEr, 1965: 176) to the Cyprae- orbinae. For future statistical purposes we give the following quantitative data derived from the shells of the two female Cypraea capensis recorded above. Specimen A: Dimensions 29.7 < 17.6mm; columellar teeth 41, lab- ral* teeth 25 Specimen B: Dimensions 29.3 & 18.3mm; columellar teeth 44, lab- ral teeth 26 These specimens were collected from under rocks in low tide pools and must be regarded as strays from the infratidal region. The distribution data given by Burcess (1970: 322) are almost completely erroneous. Cypraea capensis reaches its western limit at Jeffreys Bay (24°55’E), where even beach-worn shells are very rare. It is moderately common in the Port Alfred (26°54’ E), to Kei River mouth (28°23’ E) area, but becomes scarcer in Transkei waters, and appears to attain its eastern limit at Port St. Johns (29° 3201) Literature Cited BarNnarpD, Keppret Harcourt 1963. Contributions to the knowledge of South African marine Mollus- ca. Part III. Gastropoda. Prosobranchiata. Taenioglossa. Ann. So. African Mus. 47 (1): 1-199; 37 text figs. Burcess, C. M. 1970. The living cowries. pp. 1 - 389; plts. 1 - 44 Cox, Lesyiz REGINALD 1960. General characteristics of Gastropoda. Jn R. C. Moore (ed.) Treatise on invertebrate palaeontology, prt. I, 1: 84 - 169; figs. 51 - 88E Kay, ELizaBeTH ALISON 1960. Generic revision of the Cypraeinae. London 33 (6): 278 - 287; 8 text figs.; 1 table Ontons, C. T. (ed.) 1967. The shorter Oxford English dictionary. Third Edition; Claren- don Press, Oxford ScHILDER, FRANZ ALFRED 1932. ° Beitrage zur Kenntnis der Cypraeacea. No. 16. Die Radula eini- ger bisher nur als Schalen bekannter Arten. Zool. Anz. 100 (7-8) : 166 - 170 1936. Anatomical characters of the Cypraeacea which confirm the conchological classification. Proc. Malacol. Soc. London 22 (2): 75-112; 2 plts. 1965. The geographical distribution of cowries. 171 - 183; figs. 1-3 Witson, Barry R. & JENNIFER A. McComs 1968. The genus Cypraea (subgenus Zoila Jousseaume). Indo- Pacific Mollusca 1 (8): 457 - 484 A. S. Barnes & Co., Cranbury, N. J. Proc. Malacol. Soc. The Veliger 7 (3): (1 January 1965) ' The adjective “labial,” conventionally used to indicate the outer lip in cypraeid literature, is derived from the noun labium, which in reality refers to the inner lip (cf. Cox, 1960: 131; Onions, 1967: 1095), 7. ¢. in the present context “labial” would be syn- onymous with “columellar”’! Vol. 15; No. 2 THE VELIGER Page 127 Comments on the Authorship of Some Subfamilial Names in the Turridae (Mollusca : Gastropoda ) WALTER OLIVER CERNOHORSKY Auckland Institute and Museum, Private Bag, Auckland, C. 1, New Zealand THE MOST RECENT SUBFAMILIAL arrangement of the toxo- glossan family Turridae is the one proposed by PoweELt (1966). His arrangement has been extended and modi- fied by McLean (1971). Both workers, however, over- looked chronological priorities for family-group names, and the existence of prior names and authorships requires changes. Casey’s (1904) proposal of new taxa of the rank of tribe must be given due consideration in a subfamilial classification since the categories of families and tribes are co-ordinate under the rules of article 36 of the Code of ICZN. Cochlespirinae Powell, 1942 The subfamilial taxon Turriculinae Powell, 1942, cannot be maintained in turrid nomenclature for the group con- taining the genera Turricula Schumacher, 1817, and Cochlespira Conrad, 1865. Although not in use in Mitri- dae because of primary homonymy of the type genus, Turriculidae Carpenter, 1861, and Turriculinae A. Adams, 1864, based on the mitrid genus Turricula Fabricius, 1823, nevertheless preoccupy Turriculinae Powell, 1942. The subfamilial taxon Pseudotominae Bellardi, 1875 (and of Hoernes & Auinger, 1891, and Casey, 1904) cannot be utilized as a substitute because of primary homonymy of the type genus Pseudotoma Bellardi, 1875 (non Gray, 1825). Turrinae Swainson, 1840 McLean (op. cit.) correctly credited the authorship of the taxon to Swainson and not to Powell. Synonyms are Pleurotominae Swainson, 1840, Taraninae Casey, 1904 (ex Taranini) and Lophiotominae Morrison, 1966. Clavinae Casey, 1904 In the two recent arrangements of the family, the sub- familial taxon Clavinae has been credited to Powell, 1942, but Casey, 1904 (ex Clavini) must be acknowledged as the author. Synonyms are Brachytominae Thiele, 1929, with its type genus Brachytoma Swainson, 1840, virtually a nomen inquirendum, Drillimae Morrison, 1966 and Crassispirinae Morrison, 1966. The latter subfamily has been separated from the Clavinae by McLEAn (op. cit.). Conorbiinae Pilgrim in Vredenburg, 1925 Usually cited as of Powell, 1942, the family-group name already appears as Conorbidae in VREDENBURG’s (1925) paper on the post-Eocene molluscs of India on page viii. In the preface to this work, G. E. Pilgrim is credited with the groupings of families in the table of contents after the untimely death of E. Vredenburg. Cryptoconinae Wenz, 1938, used by Norpsteck (1968), is a synonym of Conorbiinae. Daphnellinae Casey, 1904 The authorship of Daphnellinae has been credited to Hedley, 1922, by PoweLt (op. cit.) and McLean (op. cit.), but the taxon has been established previously by Casey, 1904 (ex Daphnellini). The prior Raphitominae Bellardi, 1875, must be considered in case that Raphi- toma Bellardi, 1848, is assigned to the same group as Daphnella Hinds, 1844. Curiously enough, Raphitominae has been proposed as a new subfamily by Norpsteck (op. cit.), despite a prior usage by previous authors (e. g. Hoer- nes & Auinger, 1891; Powell, 1966). Pleurotomellinae Nordsieck, 1968, is a synonym of Daphnellinae Casey, 1904. Clavatulinae H. « A. Adams, 1853 The erection of the subfamilial name Clavatulinae dates from 1853 and not from 1858 as generally quoted. Pusio- nellinae H. « A. Adams, 1853, and Clionellidae Stimpson, 1865, are synonyms. Page 128 THE VELIGER Vol. 15; No. 2 Mitromorphinae Casey, 1904 Three subfamily names are available for the group of turrids centering around the Mitromorpha-Mitrolumna complex of species. Diptychomitrinae Bellardi, 1888, based on the type genus Diptychomitra Bellardi, 1888, a syno- nym of Mitrolumna Bucquoy, Dautzenberg « Dollfus, 1883, is the oldest available name, despite the synonymy of the type genus. The next available name is Mitro- morphinae Casey, 1904 (ex Mitromorphini), published 19 May 1904, which has chronological priority over Mitrolumnidae Sacco, 1904, dating from August of that year. The group under discussion has been previously re- ferred to as the “group of mitromorphid genera” and assigned to the Borsoniinae by Powe Lt (1966), or as the “mitromorphine group of Turridae’ (CERNOHORSKY, 1970). McLean (op. cit.) acknowledged the group as a distinct subfamily, but accepted the later Mitrolumninae Sacco, 1904. The recent emendation of article 23(b) of the Code of ICZN by the International Commission on Zoological Nomenclature (1970) poses a minor taxonomic problem as far as the usage of at least 2 of the names is concerned. Synonymy of the type genus Diptychomitra does not inva- lidate the family-group name Diptychomitrinae, notwith- standing the fact that Diptychomitra Bellardi has not been used as a genus-group. Not one of the three sub- family names qualifies as having been in “general use” in the last 50 years, and a petition to the Commission for the acceptance of Mitromorphinae Casey, 1904, in prece- dence over Diptychomitrinae Bellardi, 1888, may be neces- sary for the stability of nomenclature. Clathurellinae H. « A. Adams, 1858 McLean (1971) proposed the new subfamily name Clathurellinae, in which case he has been anticipated by H. « A. Apams, 1858, who proposed the taxon as a sub- stitute name for Defranciinae H. « A. Adams, 1853. The latter subfamily is an invalid family-group name based on the homonymous type genus Defrancia Millet, 1826 (non Bronn, 1825). Powe. (op. cit.) retained Clathurella Carpenter, 1857, and associated genera in the Mangeliinae. Mangeliinae Fischer, 1883 Authors cite the subfamily name Mangeliinae as from Fischer, 1887, but the taxon was established by FiscHER in fasc. 6 (p. 587) of his “Manuel de Conchyliologie,” which dates from 20 December 1883. Mangeliinae has also been used by Tryon in 1884. Belinae Hoernes & Au- inger, 1891 (credited to Bellardi) and Cytharinae Thiele, 1929, are synonyms. C’ythara Schumacher, 1817, the type genus of Cytharinae, remains a dubious taxon. Literature Cited Apvams, Henry & ARTHUR ADAMS 1858. The genera of Recent Mollusca; arranged according to their organization. J. van Voorst, London, 2: 654 (November 1858) BELvarpI, Luici 1888. I molluschi dei terreni terziarii del Piemonte e della Liguria. Mem. Real. Accad. Sci. Torino 39: 152 (20 September 1888) Casey, THomas L. : 1904. Notes on the Pleurotomidae with descriptions of some new gen- era and species. Trans. Acad. Sci. St. Louis 14 (5): 123-170 (19 May 1904) CERNOHORSKY, WALTER OLIVER 1970. Systematics of the families Mitridae and Volutomitridae (Mol- lusca: Gastropoda). Bull. Auckl. Inst. & Mus. No. 8: 1 - 190; plts. 1-18; 222 text figs. (1 October 1970) FiscHER, PAUL 1883. Manuel de conchyliologie et de paléontologie conchyliologique ou histoire naturelle des mollusques vivants et fossiles. E Savy, Paris, fasc. 6: 513 - 608 (20 December 1883) Hoernes, Rupoir « M. AUINGER 1891. Die Gasteropoden der Meeres-Ablagerungen der ersten und zwei- ten Miocanen Mediterran-Stufe in der ésterreichisch-ungarischen Mon- archie. Abhandl. k. k. geol. Reichsanst. 12 (7): 283 - 330; plts. 37 - 42 INTERNATIONAL ComMIssION ON ZooLocicAL NOMENCLATURE 1970. Declaration 43. Repeal of article 23(b). Bull. zool. Nomen- clature 27 (3/4): 135 - 163 (December 1970) McLean, James HamiILToNn 1971. A revised classification of the family Turridae, with the proposal of new subfamilies, genera, and subgenera from the Eastern Pacific. The Veliger 14 (1): 114-130; 4 plts. (1 July 1971) Morrison, JosEpH PauL ELDRED 1966. On the families of Turridae. Union for 1965: 1 - 2 Norpsiccx, Fritz 1968. Die europaischen Meeres-Gehauseschnecken (Prosobranchia) vom Eismeer bis Kapverden und Mittelmeer. Gustav Fischer Ver- lag, Stuttgart, pp. i- xiii + 1-273; plts. 1-31 Powe xi, ARTHUR WILLIAM BADEN 1942. The New Zealand Recent and fossil Mollusca of the family Turridae with general notes on turrid nomenclature and systematics. Bull. Auckl. Inst. & Mus. No. 2: 1 - 188; plts. 1 - 14 (15 July 1942) 1966. The molluscan families Speightiidae and Turridae. An evaluation of the valid taxa, both Recent and fossil, with lists of characteristic Ann. Reprts. Amer. Malac. species. Bull. Auckl. Inst. & Mus. No. 5: 1 - 184; plts. 1 - 23; text figs. (1 November 1966) Sacco, FREDERICO 1904. I molluschi dei terreni terziarii del Piemonte e della Liguria. Carlo Clausen, Torino, prt. 30: 1-203 + i-xxxvi; plts. 1-31 (August 1904) Tryon, GeorcE WASHINGTON, Jr. 1884. Manual of conchology; structural and systematic. Pleurotomidae. Philadelphia, 6: 151-413; plts. 14-34 VREDENBURG, E. 1925. Descriptions of Mollusca from the post-Eocene Tertiary forma- tion of North-Western India: Cephalopoda, Opisthobranchiata, Siphon- ostomata. Mem. Geol. Surv. India 50 (1): i-xii + 1-350; Index pp. i- xvi; plts. 1-13 (13 July 1925) Vol. 15; No. 2 THE VELIGER Page 129 The Role of Wave Impact and Desiccation on the Distribution of Littorina sitkana Philippi, 1845 BY SYLVIA BEHRENS Department of Zoology, University of British Columbia, Vancouver 8, British Columbia, Canada ' (1 Text figure) INTRODUCTION Two SPECIES OF PERIWINKLES, Littorina scutulata Gould, 1849, and L. sitkana Philippi, 1845, coexist on most beaches near the city of Vancouver, in the Gulf Islands and on the west coast of Vancouver Island, British Colum- bia. Littorina sitkana, unlike L. scutulata, is absent from dry beaches and from wave exposed sites lacking shelter, but thrives in wave-sheltered and damp habitats such as mud flats, tide pools and crevices (BEHRENS, 1971). Littorina scutulata has a planktonic dispersal stage, whereas L. sitkana develops directly from benthic egg masses (BEHRENS, op. cit.). Thus, the maintenance of L. scutulata populations in any one place is dependent upon constant planktonic recruitment whereas the persistence of L. sitkana populations is dependent upon the survival of all developmental stages in the life cycle. Results from this study indicate that the physical factors such as desic- cation acting on juveniles and wave impact affecting adults can select against L. sitkana and exclude this spe- cies from some beaches. THE ROLE or WAVE IMPACT on THE DISTRIBUTION of Littorina sitkana Extremely small Littorina scutulata are found on wave- swept and crevice-less beaches such as Chesterman’s Is- land on the west coast of Vancouver Island. To investigate the action of intense surf as a possible factor acting selec- tively against L. sitkana as well as against large animals ' Present address: Department of Biology, University of Oregon, Eugene, Oregon 97403 of both species, series of laboratory and field tests were performed. METHODS An equal number of animals of both species, or of a single species, but of two size classes, were painted with cellulose- base paint. When species comparisons were made, Littori- na scutulata and L. sitkana were matched for size. The animals were then dipped in sea water and allowed to attach to the rock or barnacle substratum of the beach and were then subjected to wave action of the incoming tide. After a trial period ranging from 6 hours to 2 days, the test site and adjacent areas were carefully searched. All missing animals were assumed to have been dislodged by waves. Laboratory experiments using concrete slabs as substrata and a running sea water jet to simulate wave force were performed to check field results. RESULTS anp DISCUSSION Both field and laboratory data indicate that Littorina scu- tulata are less likely to be dislodged by waves than are L. sitkana (Table 1). Littorina sitkana, with its round shape and many grooves, may offer more resistance to wave action than the more streamlined L. scutulata. Large Littorina sitkana were more easily dislodged by wave impact than smaller ones (Table 1). Large L. scutu- lata appeared as resistant to wave force as smaller ones (Table 1). Thus, young (or small) L. sttkana could pre- sumably live on exposed beaches; however, wave action would select against them as they attained reproductive size (ca. 5mm). Page 130 THE VELIGER Vol. 15; No. 2 Chesterman’s Island Seattle >. Vancouver miles British Columbia - Lilly f L,. Washington y San Juan 4 . Island to} 5 10 [WJ t______! miles Figure 1 Map of Puget Sound and Vicinity showing locations of study areas Vol. 15; No. 2 Table 1 Ability of Littorina sitkana and Littorina scutulata to resist wave exposure in the field and in the laboratory Difference Proportions between of animals remaining on comparisons Source of data substrate after test interval Chi squared L. sitkana L. scutulata Field pooled data from 8 runs 254/487 366/487 55.657 wey Laboratory pooled data from 3 runs 3/54 19/54 122842) (Ys) ae small large L. scutulata LL. scutulata Field 35/50 34/50 N.S. small large L. sitkana L. sitkana Field 34/50 19/50 91032 5s Laboratory pooled data from 6 runs 37/121 15/126 12.947 bY (Y) —- Yates correction for small cell frequencies was used numbers of * indicate level of significance when the null hypo- thesis of no difference between values has been rejected. ive OOS — an OL Ay =e 0!001-inass indicates no significant difference DESICCATION or JUVENILE STAGES AS A POSSIBLE FACTOR RESTRICTING tHe DISTRIBUTION oF Littorina sitkana Survival of juvenile Littorina sitkana in a location in- habited naturally by L. scutulata only was investigated at Lilly Point (Figure 1). The rocky foreshore in this area is characterised by barnacle-covered cobble and rocks, not larger than 15cm in diameter, resting on a sandy bottom. The low intertidal area is mostly sand interspersed with 4 barnacle covered concrete blocks (50 x 50 x 50cm). I worked on the site of an abandoned fish cannery where an artificial substratum, consisting of compressed tin can scraps and cobble, is completely covered with barnacles and extends from the mid to the high intertidal region. Numerous barnacle-covered pilings (the remains of the cannery’s pier) run in rows from the mid to high intertidal area. Absence of shade, as well as good drainage, tend to make the Lilly Point site a dry beach at low tides in sunny weather. Animals cannot find shelter under the cobble and rocks, for these are embedded in coarse sand. THE VELIGER Page 131 To determine the critical factor in the life history which could prevent Littorina sitkana from living at Lilly Point, adults, egg masses and newly hatched snails were trans- planted to the area. MATERIALS anp METHODS To determine whether adult Littorina sitkana could live at Lilly Point, 500 young L. sitkana (not more than 5mm in length) were released on the “compressed tin can rock” and on one piling stump in May of 1969. Eight “cages” were prepared by pulling a square of fine plankton netting over the concave half of little neck clam shells. Four of the cages contained 10 newly hatched snails each and 4 cages contained 5 older snails (1mm or longer). One of each type of cage was set up in the fol- lowing locations: on pilings at the 13 foot tidal level, in artificial tide pools (32 ounce orange juice jars) at the 13 foot tidal level, on pilings at the 9 foot level, and in arti- ficial tide pools at the 9 foot tidal level. The “tide pools” and cages were attached to the piling stumps using rubber bands cut from an inner tube. The number of surviving animals, salinity, and temperature of the tide pools and air were recorded the next day (Table 2). Egg masses collected from False Bay, San Juan Island (Figure 1) were divided into two parts. Each half was Table 2 Survival of two size classes of juvenile Littorina sitkana caged at the 9 foot and 13 foot tidal levels at Lilly Point from May 17 to May 18, 1969 o g 2 S Fh Laika aioe tee rd 5 Recovery of Littorina sitkana ms wo sal medium 30% 27°C 7 small (newly hatched) snails tidal level water all with their foot moving. (9 ft) pool Cage with larger (1.0mm or longer) snails was lost medium 20° GC 9 small snails, all alive, 5 large tidal level air snails, all but one opened o- (9 ft) dry perculum when moistened high tidal 25%, 27°C 8 small snails, all alive; 5 large level (13 ft) water snails, all alive pool high tidal 20°C 9 small snails, all dead; 4 large level (13 ft) air snails, 3 alive, 1 with broken dry shell Page 132 placed into a plastic petri dish lid and fine plankton net- ting was wrapped around the dishes. These “cages” were attached to the pilings at the high tide levels and to con- crete blocks at the low tide levels, so that half of each egg mass was represented at each tidal level. The number of hours of exposure to direct mid-day sunshine at the 5 and 12 foot tide level was estimated from weather data (for Ladner, British Columbia, compiled by Mrs. M. A. Behr- ens) and a tide table. The condition of the egg masses and the number of hatched snails were recorded subsequently (Table 3). Table 3 Hatching success of Littorina sitkana egg masses at Lilly Point Five egg masses of Littorina sitkana were divided in two. One half of each egg mass was attached to pilings at the high tide level and the other half to concrete blocks at the low tide level at Lilly Point wn =) 4 xe) g ou) : Number of hatched es) ie) a sg 2 g Littorina sitkana 53e Fc &§ September | September 7 ink 5 ft not sampled 50 alive * us (in ft red egg mass 0 alive light Ope not sampled 7 alive * pink (3 ft yellow and dry 0 alive dark 6 ft 25 hatched 32 alive pink Ge ft red and dry 0 alive light 6 ft red egg mass 47 alive pink (13 ft 2 hatched 0 alive light g) ik lost pink (a ft covered with covered with sediment silt * indicates puncture in cage RESULTS After one year, 6 of the 500 Littorina sitkana were re- covered on the tin can rock. All the animals had grown to roughly 10mm in length. The rest of the animals had either died or dispersed from the investigated area. One yellow egg mass located on the wave- and sun-sheltered side of a piling stump was found in May 1970. The egg mass, however, dried up before the embryos could hatch. All the young Littorina sitkana caged for 26 hours at the mid-tidal level survived and those retained inside the high tide pools survived (Table 2). However, all the small snails (less than 1.0mm) caged to the high piling stump THE VELIGER Vol. 15; No. 2 were dead. The cages and pool at the high tide level (13 foot) were calculated to be exposed to approximately 11 hours of direct sunshine, those at the mid-tide level (9 foot) for about 6 hours during the duration of the experi- ment. It would seem that desiccation and not the high temperatures per se killed the small snails at the high tide level, since the temperature in the high pool was 7°C higher than the air temperature at the time of measure- ment (Table 2). From weather and tide data during the period August 23 to September 1, the 5 foot tide level was estimated to be exposed to a total of 6 hours of direct mid-day sun and the 12 foot level to at least 30 hours. A total of 161 young Littorina sitkana hatched at the 5 foot level as opposed to only 2 at the 11 foot level. All the egg masses at the high level had dried out by September 7 (Table 3). This correlation suggests that desiccation was responsible for egg mass mortality at the high tide level but not at the lower. CONCLUSIONS The fact that the transplanted Littorina sitkana survived at Lilly Point for a year, grew and even reproduced, indi- cates that no major selective factor was operating during this period of time to prevent adult L. sitkana from living at Lilly Point. Desiccation, acting on egg masses and newly hatched individuals may be a critical factor preventing Littorina sitkana from living at Lilly Point and other dry beaches. It is conceivable that a permanent population of L. sit- kana could be established at Lilly Point if tide pools or damp crevices were added. Egg masses hatched at low tide levels, but the abrasive action of shifting sand and silt, especially during storms, seems to prevent any grazers from living there permanently. ACKNOWLEDGMENTS This study forms part of a Master’s thesis done at the University of British Columbia. I would like to thank my advisor Dr. Robin Harger, and Dr. John Stimpson for their encouragement and criticism. This research was financed by the National Research Council of Canada Grant No. 67660 to Dr. J.R. E. Harger. Literature Cited BEHRENS, SYLVIA 1971. The distribution and abundance of the intertidal prosobranchs Littorina scutulata and Littorina sitkana. MSc. thesis. Zool. Dept., Univ. British Columbia Vol. 15; No. 2 THE VELIGER Page 133 Seasonal Migration and Population Regulation in the Limpet Acmaea (Collisella) digitalis PAUL A. BREEN Department of Zoology, University of British Columbia, Vancouver 8, British Columbia, Canada ' (7 Text figures) INTRODUCTION THE LIMPET SPECIES Acmaea digitalis Rathke, 1833 occu- pies a broad band within the intertidal zone, from near mid-tide almost to high tide level in the study area de- scribed below. Within this band are many different types of microhabitat, and superimposed are seasonal changes in physical and biotic conditions in the intertidal zone. The stresses placed on a species living in such a mosaic result in many adaptations that can be studied relatively easily. FRANK (1965), in an extensive study of a population of Acmaea digitalis in Oregon, found that behavioural adaptations are responsible for determining the vertical range and the size distribution at a given place within the range. He found that small limpets settle at the lower end of the shore and migrate upward in successive years, so that larger individuals tend to be found on the higher parts of the range. This has also been observed in a species of Patella in Britain (Lewis, 1954). FRANK also found that local density of limpets appeared to be regulated by dis- persing behaviour. The object of this study, carried out in British Columbia in 1969 and 1970, was to examine further the relation between behaviour and population regulation. Two behav- iour patterns were studied: homing and seasonal migra- tion. Homing behaviour has been discussed in a previous paper (BREEN, 1971); this paper deals with seasonal migration. Many of the experiments and results described below confirm experiments carried out by FRANK (1965). This paper is perhaps justified, however, in consideration of Frank’s statement “‘what does a limited though extensive set of observations and measurements, gathered over a rel- atively short time span and in a small portion of the ' Present address: Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada. species’ range, signify regarding the performance of this and similar sorts of animals over their total area of distri- bution? These limitations ... clearly imply that inde- pendent confirmation of significant conclusions is partic- ularly important.” ECOLOGY or Acmaea digitalis PuysiIcaL Factors This study was carried out on a rocky shore near Port Renfrew, British Columbia, known locally as Botanical Beach in reference to the Seaside Station maintained there by the University of Minnesota from 1900 to 1910. Botan- ical Beach consists of a broad sandstone shelf, intruded by hard metamorphic rock, which is up to 100m wide at low tide. The shelf has been eroded into a complex array of pools, benches, and prominences. (HALL, 1906, gives a more complete geological description. ) Although the beach borders the Strait of Juan de Fuca, it is directly exposed to Pacific storms and wave action coming from the west and northwest, and is an exposed shore. Tides are mixed semi-diurnal, with a range of from 6.1 to 12.6 feet (1.8 to 3.8m). Tides, sea conditions and weather combine to produce a drastic contrast in shore conditions between winter and summer. In summer, lower low tide occurs between dawn and noon during most of the lunar cycle, and lower high tide in the afternoon. Summer weather usually includes long periods of hot, dry weather, so the shore is exposed to drying conditions during most of the day. The sea remains relatively calm. In winter, lower low tide occurs between dusk and midnight, while higher high tide occurs during the day, so the shore is covered during most of the daylight hours. Winter weather is cool and wet, with al- most constant rainfall and fogs. Sea conditions are much Page 134 THE VELIGER Vol. 15; No. 2 Figure 2 Size frequency distribution of limpets at different tidal heights along a transect. Tidal height of each sample is given in parentheses 50 Tidal Height (ft) (m) (9.0) (adjacent column —) 25 (2.7) rougher than in summer, and so the rocks are washed far above the actual tide height. The result of these factors is that the shore is never dry between mid-October and late spring, while during the summer it is generally dry during most of the day. Freezing conditions, such as those observed by FRANK (1965) in Oregon, were not present during the winter ae (8.5) (26) encompassed by this study. The effects of very cold weath- er and ice on limpet populations could therefore not be 95 evaluated. Seeot atTo 0 DISTRIBUTION OF Acmaea digitalis The distribution of Acmaea digitalis was determined quantitatively in May, 1969, by means of a transect on a 2 gently sloping part of the shore which was partly protected S Ba from direct wave action. A line was laid down the shore —_g and marked at 1m intervals. Limpets were counted and % removed from within 10cm of the line, and were later 3 25 (7.8) (2.4) measured. Tidal heights of points along this transect were is 5 0 a jaw 50 is 25 Ges)" (QB) : © 7 8 9 10 Tidal Height (ft) Figure 1 Size Class (mm) Density of Acmaea digitalis vs. tidal height along a transect Vol. 15; No. 2 THE VELIGER Racenls5 determined later, in conjunction with a mapping survey, by means of a surveyor’s level. Acmaea digitalis were found at this site from 6.0 to 10.0 tidal feet (1.8 to 3.1m). Density of limpets along the transect is shown in Figure 1. Density reaches a peak at 7.2 feet (2.2m) and then declines with increasing tidal height, except that around 8.5 feet (2.6m) was found an abundance of small, shallow pools in which A. digitalis does not occur. Figure 2 shows the distribution of size frequencies at different heights. The modal size class in- creases with increasing tidal height. These observations agree with those of FRANK (1965), and support his sug- gestion that limpets settle at the lower end of the vertical range and migrate upward in successive years. Very small limpets (2-5mm) began to appear in April and May, 1970, from 6.0 to 8.0 feet along the transect. It should be noted that in a steeper area more directly exposed to surf, the species occurred between 9.0 and 14.0 feet (2.7 to 4.3m). Tidal height is thus only a relative measurement, subject to modification by local factors. Although this was essentially a one-species study, the distributions of other species of limpets were noted casual- ly on the transect site. Acmaea pelta Rathke, 1833 and A. paradigitalis Fritchman, 1960, occurred partially within the same vertical range as A. digitalis, but appeared to be mostly in pools and on very flat surfaces, whereas A. digita- lis was found on sloping surfaces and almost never in pools. Very few limpets of other species were ever seen in A. digitalis aggregations. Haven (1971) found a division of habitat between A. digitalis and A. scabra (Gould, 1846) in California. Acmaea scutum Rathke, 1833, occurred only below 7.5 feet (2.3m), and a slight overlap with the lower population of A. digitalis occurred. DISTRIBUTION AND ABUNDANCE OF Foop In summer, few macrophytes occurred within the range of Acmaea digitalis, except for a few tufts of Gelidium sp. and Fucus sp., which the limpets did not appear to graze. A thin film of microscopic plants covered the substrate; when grazers were excluded the film thickened and proved to be composed of colonial diatoms. In October, 1969, the thin film became a dense mat, composed of strands up to 3mm long, covering most of the middle and upper intertidal zone. CaSTENHOLZ (1961) observed a similar thickening of the mat in Oregon, and attributed it to a decrease in littorine density. At Port Renfrew the dense mat appeared in October even in areas where littorines had never occurred; so its appearance was not caused by a decrease in littorine abundance. An alternate explanation might be the change in physical conditions which occurred in October. The diatom mat quickly disappeared in areas adjacent to dense aggregations of limpets and declined slowly in the other areas of the shore. After 4 months it had reached summer levels again, except in one place where there were no grazers at all; here it remained until March. Grazing, thus, is a likely cause of the mat’s decline. Individual Porphyra sp. settled on the upper intertidal zone in November, but quickly disappeared below 12.0 feet (3.7m). Grazing by limpets and littorines might have been responsible for this disappearance. This alga re- mained above 12 feet until late spring. From these observations it was inferred that the main diet of Acmaea digitalis consists of diatoms, and that food is most abundant during the period from October through March. OCCURRENCE or SEASONAL MIGRATIONS Two samples of individually marked limpets were used to determine whether or not seasonal migration occurs in the population at Port Renfrew. Both samples were Figure 3 Directions of limpet migration during the period September 1, 1969 to February 16, 1970. Each dot represents one limpet; those in the centre circle represent non-migrants, those in the upper sector upward migrants, and so on Page 136 marked in early summer, 1969 (see BREEN, 1971, for discussion of marking technique). The positions of limpets were recorded in September, 1969, and February, 1970, with reference either to a fixed point on the rock (first sample) or to a grid (second sample). From these data the net fall and winter movement of each limpet could be determined. A limpet that remained within 1m of its September position was considered not to have migrated. Figures 3 and 4 show the directions in which migration occurred during this period. Although many limpets did not show net movement, an upward tendency was clearly demonstrated by migrants. Figure 4 Directions of limpet migration during the same period as Figure 3 in a second sample The positions of limpets in the first sample were again determined in June, 1970, and net movements between February and June were calculated. Although fewer lim- pets migrated during this period, a slight downward net movement was shown (Figure 5). It was concluded from this that seasonal migration does occur at Port Renfrew, with an upward migration in fall and winter and a lesser, downward migration in spring. THE VELIGER Vol. 15; No. 2 Figure 5 Directions of limpet migration during the period February 16 to June 5, 1970 RELATION or UPWARD MIGRATION witH DENSITY In June, 1969, an experiment was designed to test whether density affects the proportion of limpets which migrate from an area. A concretion was found on the shore which was 1.5m across, 0.5 high, roughly circular and surround- ed by a flat sandstone shelf. At the base of this, which was slightly concave, many limpets sheltered during low tide, and a few more were found on the top of the concretion. Two wedge-shaped areas were formed by placing 3 fences, of plastic mesh sealed to the rock with cement, from the top of the concretion out 1m onto the sandstone shelf. Limpets within these two areas were then marked indi- vidually. The fences prevented lateral movements but allowed migration downward to the sandstone shelf and upward to the open top of the rock. One area was designated a control group. Density of limpets in the other area was increased at intervals during the summer by the addition of unmarked limpets removed Vol. 15; No. 2 THE VELIGER Page 137 from elsewhere, until in August it was 3 times the original density. The position of each marked limpet was recorded at monthly intervals; and shell lengths were recorded on July 5 and November 22, 1969. Number of Limpets > =) no oO Figure 6 Number of limpets remaining in an experimentally crowded area (A) and in a control area (B) from June to December, 1969. (see text for explanation) Figure 6 shows the number of limpets which remained in each area from June through December, 1969. Despite the large increase in density in the experimental area, most marked animals in each group remained until Octo- ber. At that time the experimental group declined sharply, while the control remained relatively constant. The change in the experimental group could have been caused by emigration, mortality, or both. A search was made for emigrant limpets in December, 1969, within a radius of 5m from the concretion. One marked limpet from the control and 5 from the experimental group were found. It is known from other observations that limpets are capable of moving more than 5m in a month, so these may not have been the only emigrants. Mortality may have been partly responsible for the decline of limpets in the crowded group, since more than 30 limpets disappeared and only 5 could be found. It could be concluded, however, that emigration from the crowded group was greater than that from the control group, and that emigration did not occur until fall. Growth rates of limpets in the two groups were com- pared by means of regressions of attained length on initial length (Table 1). Limpets in the control group grew sig- nificantly faster than the crowded limpets during the peri- od July 5 to November 22. Table 1 A comparison of the growth rates of experimentally crowded limpets with those of a control group. The re- gression lines compared are those of attained length on initial length (Ford-Walford plot) Group crowded control Regression equation Y = 0.28+0.85X Y = 0.42+0.80X Sample size 31 42 F from comparing slopes F from comparing adjacent means (x = 1.74) 3 significant at a = 0.01 SUMMER MORTALITY In May, 1969, when this study was begun, there were many attachment scars of limpets found in the high inter- tidal zone. This indicated that individuals recently pres- ent had either died or migrated away. The radical change in physical conditions on the upper intertidal area, be- tween winter and summer, coupled with the observation that limpets migrate into the upper intertidal area from lower areas during winter, suggests that mortality should Table 2 Tidal heights and original number of limpets in 6 areas used to determine survival rate from May 1 to July 26, 1970 (Figure 7). Limpets in the lowest area were counted in 2 groups: those assumed to be newly-settled (2 - 5 mm), and older ones. These are given as groups 6a and 6b, respectively Group Tidal Height Number of (feet) (m) Limpets May 1 1 14.7 4.5 35 2 14.6 4.4 279 3 12.0 Se 410 4 10.9 3.3 327 5 10.4 3.2 252 6a 9.4 2.9 287 6b 9.4 28) 163 Page 138 THE VELIGER Vol. 15; No. 2 be high during summer as a result of warm dry conditions there. This was tested by measuring survival in groups of limpets at different heights on the shore. Six permanent counting areas were marked on the rock in May, 1970, and all limpets in each area were counted periodically through- out the summer. As a check on migration from counting areas, some limpets in each of the upper 4 squares were marked with quick-drying paint, and searches were made for these outside the counting areas when counts were made. Emigration from counting areas was found to be negligible. The tidal heights of each area (determined with a sur- veyor’s level), original number of limpets in each and the percent survival are shown in Table 2 and Figure 7. ‘The lowermost area contained both newly-settled limpets and older ones; these were counted separately and survival rates are presented for each. Survival was high in the lower 3 areas (either immigration to the areas occurred, or the initial counts were too low), but decreased with in- creasing tidal height. An exception to this pattern was seen in survival of newly-settled limpets in the lowermost area, which was the lowest of any group. It was not possible to assign any one cause to the mor- tality observed in this group of observations. Direct effects of desiccation were tested in the following way: Limpets normally cling to the substrate sufficiently well that they are not dislodged by a tap on the side of the shell. Limpets weakened or dead, however, can be tapped loose from the rock. In July, 1969, after a period of dry weather and calm seas, limpets in the upper intertidal area were tested by using this ‘tapping’ method. Of several hundred tested, 75 were dislodged. These were placed immediately into cold seawater and examined half an hour later. Only 3 failed to revive in seawater. In 1970 the weather was cooler, and when the same test was carried out in July only very few limpets were dislodged. All revived when placed in seawater. This crude test suggests that death resulting directly from desiccation is rare. Partly empty shells were some- times found in small groups on the shore at low tide, which suggested that predation was responsible. Possible preda- tors observed included mink, mice, crows, gulls, and shore birds. During prolonged observations of crows and shore birds no limpet was ever seen being eaten. Mink and mice, however, could not be observed closely enough to deter- mine what was being eaten. Predation might account for high mortality in the upper intertidal area if limpets are made more vulnerable to predation as a result of desiccation. FRANK (1965) ob- served a mouse removing limpets which were weakened by dry, hot weather, and suggests that mice probably cannot Percent Survival Figure 7 Survival of limpets from May 1 to July 26, 1970 in counting areas at different tidal heights. Tidal heights and the number of limpets originally present in each area are given in Table 2 Vol. 15; No. 2 remove a healthy limpet. Thus high mortality in summer might be considered an indirect effect of desiccation. RELATION or UPWARD MIGRATION witH GROWTH Growth of limpets that had migrated from an area in fall and winter was compared with growth in the limpets which remained in the area. Length data were obtained from the two groups of marked limpets used to determine whether upward migration occurred at Port Renfrew and discussed above. Limpets in each group were measured in July, 1969, and again in February, 1970, so within each group the growth of limpets migrating in fall could be compared with growth in those that did not migrate (Table 3). (Within each group the initial lengths of migrants and non-migrants were compared and found to be statis- tically equal, thus a t-test was used to compare the growth increments.) In both groups the migrant limpets grew more than the non-migrants during fall and winter. Table 3 A comparison between the mean growth increments of migratory and non-migratory limpets in 2 samples of marked individuals, from July 1, 1969, to February 16, 1970 Group 1 migratory non-migratory mean increment (cm) 0.064 0.119 variance of increment 0.0037 0.0022 F ratio of variances 1.65 n. s. value of ‘t’ 2.714 Group 2 migratory non-migratory mean increment (cm) 0.089 0.025 variance of increment 0.0056 0.0047 F ratio of variances 1.21n.s. value of ‘t” 4.96 4 4 significant at a = 0.05 Better growth of migrants can be explained in two ways. First, density is lower at higher shore levels, and since migrants in fall and winter tend to move upward they possibly encounter less intraspecific competition for food. Second, the size distribution changes with increasing tidal THE VELIGER Page 139 height; larger size classes becoming more predominant. CasTENHOoLz (1961) found that large Acmaea digitalis are slightly less efficient at removing algae than smaller individuals. Strmson (1970) found that the territorial species Lottia gigantea (Gray, 1834) does not graze down to bare rock, but leaves a thin film of algae. Smaller species, such as A. digitalis, outside Lottia territories graze down to bare rock, and Stimson suggests that Lottia would be outcompeted if it did not defend its territory. An alternate explanation for greater growth in fall mi- grants at Port Renfrew might be that small A. digitalis graze more efficiently than larger individuals; and thus the different size composition found at higher shore levels is responsible for better growth there. An experiment was designed in February, 1970, to de- termine the better of these explanations. Three adjoined plots, each 65cm square, were constructed with plastic mesh fences. The natural biomass of limpets within each plot was determined by removing all limpets and measur- ing their shell length. Shell length was then converted to body dry weight by means of a regression developed from 107 limpets for this purpose. This regression was loge dry weight (g) = — 6.638+2.05 length (cm) The natural average biomass was found to be 6.87¢ per plot. Limpets 2.0 to 2.5cm were collected from elsewhere, marked individually and measured. These were then add- ed to the empty plots to form 3 treatments: (1) a control, consisting of enough marked limpets to equal the natural plot biomass, (2) a high density treatment, with double the natural plot biomass, and (3) a mixed high density Table 4 Comparisons among mean growth increment of 3 groups of limpets (see text for explanation). The control mean is compared with the high density mean, and the high density mean with the mixed high density mean Mixed High Treatment Control High Density Density number 25 - 30 26 mean growth increment (cm) 0.0048 —0.0417 —0.0677 variance of increment 0.00443 0.00208 0.00259 F ratio of variances 2al Sines: 1.24n.s. value of ‘t? 3.06 5 1.99 n.s. 5 significant at a = 0.01 (one-tailed), d. f. = 53 Page 140 THE VELIGER Vol. 15; No. 2 ee SEE eee treatment, consisting of a biomass of marked limpets equal to the natural biomass, plus an equal weight of smaller (1.25 to 1.75cm) limpets. These biomasses were calcu- lated using the regression above. Treatments were maintained in each plot from Febru- ary 19 to July 24, 1970, when all marked limpets were removed and again measured. Growth in both high densi- ty plots was significantly lower than in the control (Table 4), but there was only a slight, non-significant difference between the 2 high-density treatments. This indicates that growth is inhibited by high densities, as already shown above, but that the size composition of competing Acmaea digitalis makes little difference in growth. DISCUSSION Of the two behaviours examined in this study, seasonal migration appears to be the more important with respect to regulation of local densities. Although the component parts of this regulating mechanism have been examined in the preceding sections, it has not been studied as a whole, so its operation as described below must be treated as an hypothesis. Fall migration appears to be density-dependent in that the proportion of limpets which migrate from an area depends on the density in the area. This might partially regulate density at all levels of the shore in the following way: If heavy settlement were to occur at the lower part of the range of Acmaea digitalis, migration of older lim- pets from that area in fall would reduce density there. The older limpets that migrated would, in turn, produce an increased density in the area to which they migrated, and migration of the limpets originally there would be expect- ed. Thus the heavy settlement of young might produce a wave of fall migration up the shore. Lesser settlement of young could be expected to have a lesser effect. Density at a given level of the shore might not be controlled within rigid limits in this way, but at least partial regulation could occur. Conditions which produce high mortality are not pres- ent on the upper shore levels during fall, so these areas can be invaded by fall migrants. Migration is dependent on density, so the number of limpets which move to the highest levels depends on the density at lower levels. Mor- tality during the next summer among migrants on high parts of the shore can therefore be thought of as density- dependent in the population as a whole, even though it is independent of density in the area in which it occurs. For instance, if density on the shore is fairly low, few limpets will migrate onto the higher levels, and the proportion of deaths due to summer mortality will be low. If density is high, however, a higher proportion will migrate to the higher levels, and the proportion of deaths in the next summer will be greater. The fact that high mortality occurs in summer at high shore levels, while lesser mortality occurs at lower levels, suggests at first that upward migration in fall is being selected against. Such selection might be outweighed, how- ever, by the fact that fall migrants show better growth than non-migrants, probably because of reduced intra-spe- cific competition for food. If fecundity is also increased for the same reason, a selective advantage of upward migra- tion can be postulated. It might be possible for a limpet that migrates onto the high intertidal area to leave more offspring, as a result of increased fecundity, than a limpet that does not migrate, even if the migrant dies during the next summer and the non-migrant survives. Newly-settled Acmaea digitalis observed in April and May indicate that breeding occurs in late winter or early spring, after the time at which food is most abundant. This is between the times of upward migration and summer mortality, so the selective advantage just postulated seems possible. Frank (1965) found high winter mortality at the lower part of the shore and high summer mortality at the higher part. He suggests that seasonal movements, upward in fall and downward in spring, are an adaptive response to such mortality patterns. Migration may have evolved in res- ponse to other factors as well. It was noted earlier that settlement of Acmaea digitalis from the plankton occurred only below the 8 foot tidal level at Port Renfrew. A prob- able explanation for this is that small limpets cannot with- stand desiccation as well as larger ones (Davies, 1969). A critical tide level (Doty, 1946) might occur for newly- setted limpets, which ceases to be critical after they have grown larger and can withstand longer exposure to drying. Thus upward migration might be an adaptation allow- ing limpets, as they grow, to exploit habitats which were previously unsuitable. It would be advantageous for a limpet to migrate upward whenever possible because of the lower density at higher levels, and hence the better opportunities for growth there. Downward migration obviously cannot be explained in these terms, and FranxK’s (1965) suggestion may be cor- rect. It is important to note, however, that downward mi- gration docs not completely solve the problem of summer mortality, because net movements after migration are up- ward. This would suggest that, if both types of migration are advantageous in some respect, upward migration is more advantageous. If one considers only those factors dealt with here, this seems reasonable because migration upward confers the advantage of better opportunities for Vol. 15; No. 2 THE VELIGER Page 141 growth at virtually all shore levels. Migration downward is advantageous only at the upper levels of the shore where summer mortality is a serious factor. Results from the crowding experiment show that lim- pets tend to be conservative in movement during summer, and migrate from crowded areas only when conditions change in the fall: Dangers from desiccation are presum- ably serious enough in summer that, even in very crowded conditions, limpets prefer to remain in familiar territory where shelter is assured rather than seek out less crowded areas. For this reason, seasonal migration is probably more important in population regulation than homing behaviour. Homing is possibly an adaptation to reduce the risk of desiccation, such as aggregation behaviour is (MILLARD, 1968). Haven (1971) suggests that this is the case in Ac- maea scabra in California. This could be tested by meas- uring the degree of homing in A. digitalis at different levels and at different times. The expectation would be that homing increases at higher shore levels and is greatest during the warm, dry months, even in those limpets that do not migrate seasonally. A great deal of emphasis has been placed above on des- iccation as an important factor of the environment of Acmaea digitalis. This approach provided the basis for a possibly acceptable conceptual model of how populations adapt to variation in space and time. It must be empha- sized, however, that other factors might be equally or more important in producing adaptations within this species. ACKNOWLEDGMENTS ‘This study formed part of a Master’s degree programme at the University of British Columbia. My supervisor, Robin Harger, was helpful throughout the project, par- ticularly when the time came to write it up. Dr. John Stimson gave freely of his time and advice, and was in- directly responsible for my having chosen limpets to work on. Dr. N. J. Wilimovsky very graciously allowed me to work at the Marine Biological Station at Port Renfrew, and Steve Heizer permitted me to work within his own area there. Steve, Khoo Hong Woo and John Himmelman added greatly to the sheer joy of working at Botanical Beach. These people, Sylvia Behrens and Ora Johannsson helped with some aspects of fieldwork described in this study. This study was supported by a grant from the National Research Council of Canada to Dr. Robin Harger. Literature Cited Breen, Paur A. 1971. Homing behavior and population regulation in the limpet Ac- maea (Collisella) digitalis. The Veliger 14 (2): 177 - 183; 10 tables (1 October 1971) CasTENHOLZ, RicHARD WILLIAM 1961. The effect of grazing on marine littoral diatom populations. Ecology 42: 783 - 794; 6 figs.; 3 tables Davies, PETER SPENCER 1969. Physiological ecology of Patella. III. Desiccation effects. Journ. Marine Biol. Assoc. U. K. 49: 291 - 304; 5 figs.; 3 tables Doty, MaxweLt STANFORD 1946. Critical tide factors that are correlated with vertical distribution of marine algae and other organisms along the Pacific coast. Eco- logy 27: 315 - 328 FRANK, PETER WOLFGANG 1965. The biodemography of an intertidal snail population. Eco- logy 46: (6): 831 - 844; 8 figs.; 6 tables FritcHMaNn, Harry Kier, II 1960. Acmaea paradigitalis sp. nov. (Acmaeidae, Gastropoda). The Veliger 2 (3): 53 - 57; plts. 9-12 (1 January 1960) Hatt, C. W. 1906. Some geological features of the Minnesota Seaside Station. Postelsia (1906): 305 - 347 Haven, STONER BLACKMAN 1971. Niche differences in the intertidal limpets Acmaea scabra and Acmaea digitalis (Gastropoda) in Central California. The Veliger 13 (3): 231-248; 10 text figs. (1 January 1971) Lewis, J. R. 1954. Observations on a high-level population of limpets. Journ. Animal Ecol. 23: 85 - 100 MILLARD, CAROL SPENCER 1968. The clustering behavior of Acmaea digitalis. 11 (Suppl.): 45-51; 4 text figs.; 1 table Stimson, JoHN SECOMBE 1970. Territorial behavior of the owl limpet, Lottia gigantea. Eco- logy 51 (1): 113-118 The Veliger (15 July 1968) Page 142 THE VELIGER Vol. 15; No. 2 Observations on Growth, Feeding, Reproduction, and Development in the Opisthobranch, Fiona pinnata (Eschscholtz) JOHN J. HOLLEMAN Department of Biological Sciences, Merritt College, Oakland, California 94619 (5 Text figures) INTRODUCTION OBSERVATIONS ON GROWTH in nudibranchs have been reported by THompson (1964), while THompson (1967) discussed development in Cadlina laevis (Linnaeus, 1767) and development in opisthobranchs in general. Potts (1970) discussed growth, feeding and reproduction of Onchidoris fusca (Miller, 1776). In the summer of 1967, washed on to the shore at the Bodega Marine Laboratory and the beach at Salmon Creek, Sonoma County, California, following several storms were pieces of driftwood on which were observed the nudibranch Fiona pinnata (Eschscholtz, 1831) and the barnacle Lepas anatifera (Linnaeus, 1758). Observa- tions have provided information on the growth, predation, reproductive activity and larval development of Fiona pinnata. METHODS anp MATERIALS The nudibranchs were removed from the driftwood and placed individually in finger bowls where they were main- tained for 24 days. Water was changed daily; at that time food was added. Length and weight determinations were made on alternate days. The length measurements were made using an ocular micrometer, and wet weight deter- minations were obtained by using a Mettler semi-micro- analytical balance. The finger bowls were placed in a tray of running sea water to maintain a constant temper- ature. On the 17‘ day of observations, pairs of the separately maintained nudibranchs were placed in finger bowls for a period of 8 to 10 hours, after which time the pairs were separated and returned to their individual bowls. OBSERVATIONS Growth: The 12 smallest individuals of Fiona pinnata collected from the driftwood were selected and used in the observations on growth. During these observations the stalked barnacle, Lepas anatifera, was supplied as food in excess as determined by the presence of live barnacles at the end of each 24-hour period. The average length of the nudibranchs was 3.37 mm when initially placed in the finger bowls and 29.97mm at the conclusion of the ob- servations (Figure 1). This represents approximately a 900% increase in length in a 24-day period or an average increase of 1.11mm per day. The greatest increase in length by an individual was from 2.79 to 33.32mm for an average increase of 1.27mm per day. The average wet weight gain for the observation peri- od was from 1.3mg to 448.8mg. This represents an aver- age increase of 18.64mg per day during the period of observation (Figure 2). Feeding: Ten Lepas anatifera were added each day to the finger bowls that contained individual Fiona pinnata. Fiona attacks Lepas by first positioning itself at the poste- rior junction of the peduncle with the base of the body proper; then, with the jaws holding the soft tissue just below the plates, the radula rasps away the tissue. Those barnacles actively feeding at the time of a nudibranch attack continued feeding during the initial phases of the attack. Several barnacles were able to dislodge the nudi- Vol. 15; No. 2 length in mm Figure 1 Increase in length in mm. The average length (dot) and the size range are indicated branch by shaking back and forth and sideways. If the nudibranch was small, the action of the barnacles was successful and the nudibranch either moved away in search of another barnacle or returned to the attack. Af ter a successful attack at the base of the body, the barn- acles appear to be stunned or relaxed as the plates gape and no cirral activity was observed. The nudibranch moves to the front of the barnacle, enters in-between the open scutal and tergal plates and begins to feed. During feeding the action of the radula could be observed as well as the movement of the food in the cerata. The nudi- THE VELIGER Page 143 on iS oS as Je ep o 3 o ‘ | | . Treas 7 We Nona eee TQWA sO 18,20. 23 25 days Figure 2 Increase in wet weight in mg. The average weight (dot) and the range of weights are indicated branchs fed only on living barnacles and ignored all dead individuals that were placed in the finger bowls. When Fiona pinnata, which had been starved for 2 days, was offered other sources of food, it became active, moving to the food. ‘The hydroid Obelia longissima (Pal- las, 1776) was offered to a nudibranch and it immediately moved onto the colony, but did not feed. The nudibranch appeared to be stung by nematocysts and moved off the hydroid in a very jerky fashion. Cardiac activity was ob- served to cease; however, after a 2-hour period, the nudi- branch had returned to normal activity. Two other sources of food were offered: the stalked barnacle Polycipes poly- merus (Sowerby, 1833) and the acorn barnacle, Balanus glandula (Darwin, 1854). In normal circumstances, F pinnata was unable to attack either of these barnacles suc- cessfully. However, if either barnacle had a damaged Page 144 730° + 400 F 300 average wet weight in mg 5 10 15 20 25 30 average length in mm Figure 3 Relationship of the average length to the average wet weight scutum, tergum, or basis, or, in the case of the stalked barnacles, a damaged peduncle, F pinnata would com- mence feeding at the injured site. Observations were made on the relationship of the size of Fiona pinnata and the size of the food successfully eaten (Figure 4). The smaller nudibranchs, 2 to 3.3mm, when offered a range of barnacle sizes would attack the smaller barnacles, ignoring the larger ones. Several feed- ing attacks were made on the larger barnacles, but the barnacles were able to successfully shake off the nudi- branch. When individual nudibranchs 5mm or larger were offered a range of barnacle sizes, the larger barnacles were selected. Reproduction: On the 17" day of observations, 2 indi- vidual Fiona pinnata were placed in the same finger bowl. Immediately the rhinophores became elevated and active. The cerata, which had been lying flat, were erected. Moving about each other, the nudibranchs positioned themselves head to head and then advanced so that their right sides were in contact. Reciprocal copulation oc- THE VELIGER Vol. 15; No. 2 width of Lepas anatifera in mm eras alg ne ales = lea ena ] ] ie yiaeag 5 10 length of Fiona pinnata in mm Figure 4 Relationship of the length of Fiona pinnata to the size of Lepas anatifera eaten. @ represents Lepas anatifera eaten, © represents individuals alive at the conclusion of 24 hours curred immediately. This pair copulated for 5 minutes, then separated and moved apart for a period of 10 min- utes, and then copulated a second time for another 5 minute period. Copulation lasted 10 to 15 minutes in 5 other pairs observed and after separation no further copu- lations were observed. The pairs were separated after an 8 to 10 hour period and returned to their individuals bowls. | Two individuals produced egg masses 123 hours after copulation. Within 2 days, 10 of the 12 nudibranchs had laid egg masses, with 9 having laid 2 or more masses. The white egg masses laid in a spiral have a length of 5.2mm and a height of 3.1mm. The average size of an egg was 495 p. Five days after the first egg mass was laid, free swim- ming veligers were observed (Figure 5). The veligers swam actively for 7 days, but then began to die. Twelve days after the first egg mass was laid, the first adults died. All the adults had died by the 14"" day following the initial laying of egg masses. DISCUSSION described. The adaptive advantage of the growth rate The previous observations on growth (THomeson, 1964; Potts, 1970) in nudibranchs were made on intertidal Vol. 15; No. 2 Figure 5 Veliger, three days after hatching and subtidal benthic species which have growth periods measured in months. Fiona pinnata, a pelagic species, has a much faster growth rate than any of those previously described. The adaptive advantage of the growth rate may be related to the transitory nature of the substrate on which these nudibranchs live; that is, drifting material may be deposited on a beach at any time. This is in contrast to intertidal or subtidal species where once the veliger has settled on a fixed substrate, growth may pro- ceed at a slower rate since there is less likelihood of the destruction of the substrate. MacFartanp (1966) reports that Fiona pinnata is found in most instances upon driftwood and seaweed THE VELIGER Page 145 “subsisting upon hydroids, Velella and Janthina.” He also reported that specimens from Monterey, California, were collected from a drifting kelp stipe covered with Lepas hilli (Leach, 1818). Marcus (1961) reports finding FE pinnata on a board with lepadids at Dillon Beach, Cali- fornia. To the list of food sources is added the goose bar- nacle, Lepas anatifera. The fused plates of the acorn barnacles, Balanus glandula, and the tough skin of the peduncle of the leaf barnacle, Polycipes polymerus, pre- vent E pinnata from feeding successfully. The observations made do not provide any indication of the length of the veliger stage or what mechanism in- itiates settlement. The rapid development to the veliger stages places Fiona pinnata with those nudibranchs that are of the planktotrophic type that THompson (1967) describes as having not only a short embryonic period but also small ova. However, the large size of the ova (495) of EF. pinnata makes it markedly different from the plankto- trophic type where ova size ranges from 40 to 170m in diameter. The egg masses are of the type designated as type A by Hurst (1967) wherein eggs occur throughout the ribbon. The hatching of the veliger in 5 days com- pares favorably with other planktotrophic larvae where embryonic periods are reported to vary from 2 to 28 days and with opisthobranchs that have egg masses of type A. Rapid embryonic development to a free swimming veliger is probably advantageous in a pelagic animal where the possibility exists that the substrate for the attached egg masses could be stranded on a shore. CONCLUSION 1. Growth in Fiona pinnata is rapid with an average in- crease in length of 1.11mm and in wet weight of 18.64mg per day. 2. Fiona pinnata preys on Lepas anatifera, selecting a prey size that can be attacked successfully. 3. Embryonic development to a free swimming veliger is rapid, taking only 5 days. ACKNOWLEDGMENT I wish to thank Dr. Cadet Hand, Director of the Bodega Marine Laboratory, for providing space and facilities at the laboratory where these observations were made. Literature Cited Hurst, ANNE 1967. The egg masses and veligers of thirty northeast Pacific opistho- The Veliger 9 (3): 255 - 288; plts. 26-38; 31 text figs. (1 January 1967) branchs. Page 146 THE VELIGER MacFar.tanp, FRANK MACE 1966. Studies of opisthobranchiate mollusks of the Pacific coast of North America. Mem. Calif. Acad. Sci. 6: xvi+546 pp.; 72 plt. (8 April 1966) Marcus, Ernst 1961. Opisthobranch mollusks from California. The Veliger 3 (Supplmt. I): 1-85; plts. 1-10 (1 February 1961) Potts, G. W. 1970. The ecology of Onchidoris fusca (Nudibranchia). Journ. Marine Biol. Assoc. U. K. 50: 269 - 292 TuHompson, THomAs EVERETT 1964. Grazing and the life cycles of British nudibranchs. In: D. J. Crisp (ed.) Grazing in terrestrial and marine environments, pp. 275 - 295. Blackwell, Oxford, England 1967. Direct development in a nudibranch, Cadlina laevis, with a dis- cussion of developmental processes in Opisthobranchia. Journ. Marine Biol. Assoc. U. K. 47: 1 - 22 Vol. 15; No. 2 Vol. 15; No. 2 THE VELIGER Page 147 A Preliminary List of Known Opisthobranchs from the Galapagos Islands Collected by the Ameripagos Expedition GALE G. SPHON' AND DAVID K. MULLINER’ (1 Map) INTRODUCTION In Marcu 1971, seven professional and amateur mala- cologists, calling themselves the Ameripagos Expedition, visited the Galapagos Islands, Ecuador. With the per- mission of the Charles Darwin Research Station, numer- ous species of mollusks were collected. Approximately 25 opisthobranch species were obtained from 38 stations. These stations ranged from intertidal to 38m in depth. Eleven of the opisthobranch species are included in this report. The opisthobranch fauna (other than shelled cephal- aspideans) of the Galapagos has been neglected by pre- vious workers. Pirspry & VANATTA (1902: 556) report Doris peruviana Orbigny, 1837 and Eates (1966: 364) cites Aplysia juliana Quoy & Gaimard, 1834. KEEN (1971: 812) also reports Tylodina fungina Gabb, 1865. These are the only 3 species we have been able to find recorded in the literature. Only Tjlodina was collected by the ex- pedition. The names of the islands used in this paper are the mixture of the Spanish and English names in common usage among the inhabitants of the archipelago. Unless otherwise noted, at least one voucher specimen of each species discussed in this paper is deposited at the Los Angeles County Museum of Natural History. The specimens from Nayarit, Mexico, that are mentioned, have been deposited there also either as preserved speci- mens or radula slides. ' Curatorial Assistant, Invertebrate Zoology, Los Angeles County Museum of Natural History, Los Angeles, California 90007 2 Research Associate, San Diego Natural History Museum, San Diego, California 92112 STATION OBSERVATIONS With the exception of the collections made at the Charles Darwin Research Station at Academy Bay, Santa Cruz Island, and Sullivan and Bartolomé Bays on Bartolomé Island, only a few hours were spent collecting at the other stations. This limited the amount and variety of opisthobranchs that could be taken. Most intertidal collections were made from lava rocks well cemented to the substrate. At the southwest corner of Baltra Island (station 18) there were few mollusks even though the area appears as though it should abound with them. A lava ledge extends out some distance, and it was one of the few areas where there were many small tide pools and turnable rocks. However, there was a yellowish clay-like sediment present that may have been an inhibiting factor for the intertidal mollusks. Only at this station did we find this peculiar sediment. In contrast, another site we observed close-up on Baltra was the boat docking area (station 1). Even though we made no at- tempt to collect opisthobranchs from station 1, the shore- line was made up of the characteristic Galapagos lava and did not have the peculiar yellowish clay-like sedi- ment. Flamingo Cove, near Post Office Bay on Floreana Island (station 10) has several large shallow pools with many small and medium sized rocks and was the only place where we found the green alga, Caulerpa racemosa Forskal « J. Agardh var. occidentalis C. Agardh « Borge- sen. Caulerpa is well known for being host to a variety of sacoglossans. Although this is the only station where we actually encountered the alga, we were told by several people who live on the islands that it is not uncommon in the archipelago. Page 148 THE VELIGER Vol. 15; No. 2 9° 1° if gg9° ite Pinta (\ Marchena Cs 0° 0° 25 6-7 Bartholomé eT Noah eh Fernandina é 99.93 orth Seymour a Jeni -/ Daphne=® fhe Baltra 30-31 15 Duncan 223 34 Can Gree 13 a Barrington an Cristobal We AS | 6 N 10, 12 Floreana Go W E 92° oe eae <> Hood noe S 10 Flamingo Cove, near Post Office Bay, Floreana Island; 1°14’ Ameripagos Expedition Collecting Stations for the Galapagos Islands, Ecuador Station Number 1 2 3 Boat dock, Baltra Island; 0°25’30”S, 90°15’17” W; inter- tidal Charles Darwin Research Station, Academy Bay, Santa Cruz Island; 0°45’05” S, 90°15’38” W; intertidal Charles Darwin Research Station, Academy Bay, Santa Cruz Island; 0°45’05”’S, 90° 15’38” W;; in 1 to 3 meters Sullivan Bay, Bartolomé Island; 0°17’20’S, 90°33’30” W; intertidal Sullivan Bay, Bartolomé Island; 0°17’20’S, 90°33’30” W; in 1 to 3 meters Bartolomé Bay, Bartolomé Island; 0°17’S, 90°33’30” W; in- tertidal Bartolomé Bay, Bartolomé Island; 0°17’S, 90°33’30” W;; in 1 to 3 meters S, 90°27’30” W; intertidal Corona del Diablo, near Post Office Bay, Floreana Island; 1°14’S, 90°27’30” W;; in 2 to 4 meters Academy Bay, Santa Cruz Island; 0°25’S, 90°15’38” W; 15 to 30 meters South side of North Plaza Island; 0°34’36”S, 90°09’40” W; intertidal Southwest corner of Baltra Island; 0°29’20” S, 90°17’40” W; intertidal Sombrero Chino Island; 0°22’20”S, 90°17’40” W; inter- tidal Sombrero Chino Island; 0°22’20’S, 90°34’30’ W; in 1 to 23 meters Jervis Island; 0°25’S, 90°42’ W;; in 3 to 23 meters Punta Alfaro, Isabela Island; 0°25’20”S, 90°57’10” W; in- tertidal Duncan Island; 0°35’50” S, 90°39’15” W;; intertidal Duncan Island; 0°35’50” S, 90°39/15”W;; in 1 to 3 meters Barrington Island; 0°51’30”S, 91°02’30” W;; intertidal Vol. 15; No. 2 THE VELIGER Page 149 Punta Alfaro, Isabela Island (station 28), was like most of the other areas where intertidal collecting was done, except for having a rocky rubble bar that is un- covered at low tide. There were also a few dead coral heads that had lodged on the bar, indicating that coral was present in the area. Duncan Island (station 30) was, considering the short time we had there, the most productive of all our stations for opisthobranchs. We collected at a small cove or inlet protected by a large mass of rock that was almost big enough to be called an islet. Within the cove, the shoreline is the typical lava boulder type found throughout the archipelago. However, the bottom of the cove is made up of sand with large areas of living coral that can be easily reached by wading knee-deep at low tide. The diversification of habitats probably accounted for the variety of dorids, aeolids, sacoglossans, and pleurobranchs we found there. SPECIES OBSERVATIONS Bulla punctulata A. Adams, in Sowerby, 1850 Keen (1971) reported this species from Magdalena Bay, Baja California, Mexico, to Peru. It is the only species of shelled cephalaspidean that was found by this expedition. This species was not taken alive intertidally; however, beach specimens were collected at Flamingo Cove (sta- tion 10), the south side of North Plaza Island (station 15) and the southwest corner of Baltra Island (station 18). Living specimens were taken from 1-3m at the Darwin Research Station (station 3), from 2-4m at Flamingo Cove (station 12), from 1 - 23m at Sombrero Chino Island (station 23), and at Duncan Island stations 31 (1-3m), and 34 (10- 25m). Dolabrifera dolabrifera (Rang, 1828) This is a circumtropical and circumsubtropical species that has recently been reported from the eastern Pacific. BertscuH (1970) based his record on one specimen col- lected at Las Cruces Bay, Baja California, Mexico (20 miles east of La Paz). It has also been taken at Cholla Bay, Sonora, Mexico, by Wesley Farmer and from Mazat- lan, Sinaloa, Mexico by Antonio Ferreira (personal com- munications). We extend the range from the Gulf of California to the Galapagos Islands. We collected this species at 6 localities: intertidally at Sullivan Bay, Bartolomé Island (station 6); Flamingo Cove, Floreana Island (station 10) ; Duncan Island (sta- tion 30) ; Sombrero Chino Island (station 22) ; on the bar at Punta Alfaro, Isabela Island (station 28); and inter- tidally and to 2m at the Darwin Research Station, Santa Cruz Island (station 2). Tylodina fungina Gabb, 1865 This is a moderately common species and the recorded northern limit is Cayucos, San Luis Obispo County, Cali- fornia (SPHON & LANcE, 1968). From there its range extends to Todos Santos, Baja California, Mexico. Du- SHANE (1966) reports it from Punta Colorado in the Guaymas area of Sonora, Mexico. McBretH « BowLus (1969) report it from Espiriti Santo Island in the Gulf of California, and Kren (1971) reports it from Costa Rica as well as from the Galapagos Islands. We collected 2 specimens intertidally at Bartolomé Bay (station 8) and 2 additional specimens were collected from 2-4m at Corona del Diablo, Floreana Island (station 12). All 4 animals were living on a bright yellow sponge which is the typical habitat for the species in southern California. Umbraculum ovale (Carpenter, 1856) Keen (1971) reports this species as occurring from Cape San Lucas, Baja California, Mexico, to Panama. One specimen was taken in 1 - 3m of water in Sullivan Bay, Bartolomé Island (station 7). This record extends the range of the species south from Panama to the Gala- pagos Islands. The single specimen collected by the expedition is in the private collection of Mrs. Jackey Grundman, Downey, California. Berthelinia chloris (Dall, 1918) Berthelinia chloris is one of the sacoglossans that live and feed exclusively on the green alga Caulerpa racemosa. It resembles its host plant in color and can generally only be seen in the field when the light strikes the shiny shell in the duller algae. Nineteen specimens were collected intertidally at Flamingo Cove, Floreana Island (station 10). This was the only station where we saw Caulerpa. The specimens were all attached by a mucous thread fastened near the base of the plant. No specimens were found on the younger portions of the alga. This may be due to the fact that they were collected at low tide when the Caulerpa was either out of water or in warm shallow peols no more than 45cm deep. When the animals are disturbed, they are able to withdraw completely into the shell and close it tightly. Keen (1971) reports this species from Punta Abreojos, on the Pacific side of Baja California, Mexico, to the southern end of the Gulf of California and, possibly, at Page 150 Guaymas, Sonora, Mexico. We are able to extend the range of the species to the Galapagos Islands. Lobiger souverbier Fischer, 1856 While it was known for some years that this species occurs in the eastern Pacific, it has only been reported from Santa Cruz, Nayarit, Mexico, living on Caulerpa (SPHON, 1971a). This is a circumtropical species that is also found in Hawaii and the Caribbean. Four specimens of this species were found on Caulerpa racemosa var. occidentalis from the intertidal region of Flamingo Cove, Floreana Island (station 10). It is prob- able that both this species and Berthelinia would be found where Caulerpa occurs. Both seem to live and feed ex- clusively on this green alga. Berthellina engeli Gardiner, 1936 As Bertscu (1970) pointed out when he rejected the subspecific taxon Berthellina engeli ilisima Marcus & Mar- cus, 1967, a decision on the validity of the species will have to await the examination of the holotype. Even though KEeen (1971) elevated B. e. ilisima to specific rank as a valid taxon, we consider that there is not enough difference between the Caribbean and Panamic speci- mens for even subspecific differentiation. We agree with Bertsch’s conclusion that these animals should be consid- ered as one species — Berthellina engeli Gardiner, 1936. The distribution is not an unusual one for opisthobranchs, as there are many species that occur world-wide in trop- ical or subtropical seas. The northernmost locality record is one specimen re- ported by Ler « BropHy (1969) from 72m off Santa Cruz Island, Santa Barbara County, California. It has also been taken several times in the Palos Verdes Pen- insula area of Los Angeles County, California by Donald Cadien (personal communication). BertscH (1970) cites many localities throughout the Gulf of California, Mexico, that have been mentioned in the literature. We collected this species at 4 stations in the Galapagos Islands, and it is probably the most common externally shell-less opisthobranch occurring in the archipelago. Many more specimens were noted than were collected. The stations from which we have intertidal collections are: the Darwin Research Station at Academy Bay (sta- tions 2 and 3) ; Flamingo Cove (station 10) ; and Duncan Island (station 30). In addition, 2 specimens were taken in 30m at a reef in Academy Bay (station 13). Most of the specimens seen were the brilliant orange color that gives this species the common name of “orange blob.” The one exception to this coloration was a speci- men collected intertidally at Duncan Island (station 30) that was a bright lemon yellow. The radula, jaw plates, THE VELIGER Vol. 15; No. 2 and shell are the same as those of the orange Berthellina engell. Pleurobranchus (Pleurobranchus) areolatus (Morch, 1863) Marcus & Marcus (1967) report this species from Florida to the Canal zone, Panama, in the western Atlantic and from Punta Penasco to Guaymas, Sonora, Mexico, in the eastern Pacific. BErtscH (1971) reports it from the Las Cruces Bay area in Baja California, Mexico. The senior author also took this species intertidally at Sayulita, Nayarit, Mexico, in January 1970, and KEEN (1971) extends the range to western Panama. Our collec- tion records enable us to extend the range to the Galapa- gos Islands. We took one specimen from the intertidal area in Sullivan Bay (station 6) and one specimen from the intertidal area at Flamingo Cove (station 10). Two ad- ditional specimens were collected from 10m at Jervis Island (station 27). Chromodoris baumanni Bertsch, 1970 In his original description of the species, BERTSCH (1970) cites locality records in the La Paz region of Baja California, Mexico, and from 20m in the Guaymas area of Sonora, Mexico. In January of 1970, the senior author also collected this species from the Santa Cruz and Sayu- lita areas in Nayarit, Mexico, where it was fairly abundant intertidally. This species was photographed by Mr. Allyn G. Smith of the California Academy of Sciences, San Francisco, California, on his visit to Academy Bay in 1964 (personal communication). We also collected one specimen inter- tidally at the Darwin Research Station (station 2). Chromodoris sedna (Marcus & Marcus, 1967) Even though this species has only recently been named, it has long been known to be one of the most common nudibranchs from the Gulf of California to Nayarit, Jalis- co, and Colima, in Mexico The single specimen collected by us was taken intertidally at the Darwin Research Sta- tion on Academy Bay (station 2). Hypselodoris agassiz (Bergh, 1894) This species was synonymized with Hypselodoris cali- forniensis (Bergh, 1879) by Pruvot-Fot (1959) and only recently reinstated as a valid species (SPHON, 1971b). Hypsclodoris agassizi ranges south along the Sonora coast of the Gulf of California in Mexico to its type locality in Panama. One specimen was collected inter- tidally at the Darwin Research Station on Academy Bay (station 2), and extends the range southward to the Gala- pagos Islands. Possibly it may range south to Peru or even to northern Chile. Vol. 15; No. 2 THE VELIGER Page 151 Table 1 Species Collected Collecting Stations 2 SO SO TOWL2F 13) Loy 1822) 23727928) 30) 3h 34 Bulla punctulata A. Adams, 1850 Dolabrifera dolabrifera (Rang, 1828) x Tylodina fungina Gabb, 1865 Umbraculum ovale (Carpenter, 1856) Berthelinia chloris (Dall, 1918) Lobiger souverbiei Fischer, 1856 Berthellina engeli Gardner, 1936 x Pleurobranchus areolatus (Mérch, 1863) Chromodoris baumanni Bertsch, 1970 Chromodoris sedna (Marcus & Marcus, 1967) Hypselodoris agassizi (Bergh, 1894) x XK xX xX Xx x xX x xX X x x x xX x x x x x x x x x x ACKNOWLEDGMENTS We wish to extend our thanks to Twila Bratcher, Jackey Grundman, William E. Old, Jr., and Carolyn Stover for their help in the field. We also wish to thank Hans Bertsch, William K. Emerson, Richard Roller, Allyn G. Smith, and Edward Wilson for having critically read the manu- script. Most particularly, we wish to thank Mrs. Eveline Marcus for critically reading the manuscript and for her encouragement. Literature Cited ADAMS, ARTHUR 1850. Monograph of the family Bullidae. In: G. B. Sowerby, The- saurus conchyliorum. London 2: 553 - 608; pits. 119 - 125 AGaARDH, J. G. 1872. Till algernes systematik, nya bidrag Forsta afd. Arsskr. 9 (8): 1-71 Bercu, Lupwic SopHus RupoLF 1879. On the nudibranchiate gastropod Mollusca of the North Pacific Ocean, with special reference to those of Alaska. _ Proc. Acad. Nat. Sci. Philadelphia, prt. 1: 71 - 132; plts. 1-8 (13 May 1879) 1894. Reports on the dredging operations off the west coast of Central America to the Galapagos, to the west coast of Mexico, and in the Gulf of California, in charge of Alexander Agassiz, carried on by the U. S. Fish Commission steamer ‘Albatross,’ during 1891, Lieut. Com- mander Z. L. Tanner, U. S. N., commanding. XIII. Die Opistho- branchien. Bull. Mus. Comp. Zool. Harvard Univ. 25 (10): 125 to 233; plts. 1-12 (October 1894) Bertscu, Hans 1970a. Dolabrifera dolabrifera (Rang, 1838): Range extension to the eastern Pacific. The Veliger 13 (1): 110-111 (1 July 1970) 1970b. Opisthobranchs from Isla San Francisco, Gulf of California, with the description of a new spccics. Contrib. Sci., Santa Barbara Mus. Nat. Hist. 1 (2): 1-16 (1 December 1970) 1971. Natural history and occurrence of opisthobranchs at Las Cruces, Baja California, Mexico, and vicinity. The Echo 3: 16 (7 March 1971) Lunds Univ. BorcEseENn, F 1907. An ecological and systematic account of the Caulerpas of the Danish West Indies. Kongl. Danske Vidensk. Selsk. Skrift., vii, Naturvid. og Math. Afd. 4 (5): 337-392 CarPENTER, PHILIP PEARSALL 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, prt. 24 (for 1856): 159-166 (11 November 1856) CockERELL, THEODORE Dru ALISON & CHARLES ELIOT 1905. Notes on a collection of California nudibranchs. Journ. Malacol. 12 (3): 31 - 53 Coruier, Cuinton L, & WesLtey MERRILL FARMER 1964. Additions to the nudibranch fauna of the east Pacific and Gulf of California. Trans. San Diego Soc. Nat. Hist. 13 (19): 377 - 396; illust. (30 December 1964) Dati, WittiAm HEALEY 1918. Description of new species of shells chiefly from Magdalena Bay, Lower California. Proc. Biol. Soc. Wash. 31:5-8 (27 Feb.) DuSuHane, HELEN 1966. Range extension for Tylodina fungina Gabb, 1865 (Gastropoda). The Veliger 9 (1): 86 (1 July 1966) Eares, NEvuE B. 1960. Revision of the world species of Aplysia (Gastropoda, Opistho- branchia). Bull. Brit. Mus. (Nat. Hist.), Zool. 5 (10): 269 - 404 (January 1960) Fiscuer, M. 1856. Descriptions d’espéces nouvelles. (Gs 2s Oy Gass, Witt1am More 1865. Descriptions of new species of marine shells from the coast of California. Proc. Calif. Acad. Sci. 3: 182 - 190 Garpiner, A. P. 1936. Engel’s paper on “The English species of the family Pleuro- Journ. Conchyl., ser. 2, branchidae.” Journ. Conchol. 20 (7): 195 - 198 Keen, A. Myra 1971. Sea shells of tropical West America: marine mollusks from Baja California to Peru. Stanford Univ. Press, Stanford, Calif. i- xiv+ 1066 pp.; ca. 4000 figs.; 22 color plts. (1 September 1971) Lee, Ricuarp S. « Patrick Bropuy 1969. Additional bathymetric and locality data for some opisthobranchs and an octopus from Santa Barbara County, California. The Veliger 12 (2): 220-221 (1 October 1969) McBeru, JAMes WarreN & R. D. Bowtus 1969. Range extension of Tjlodina fungina in the Gulf of California. The Veliger 12 (2): 229 (1 October 1969) MacFarvanp, FRANK MAcE 1905. A preliminary account of the Dorididae of Monterey Bay, Cali- fornia. Proc. Biol. Soc. Wash. 18: 35 - 54 (2 February 1905) Marcus, EveLINe Du Bots ReyMonp & ErRNstT Marcus 1967. American opisthobranch mollusks. Stud. Trop. Oceanogr. Miami, 6: viiit 256 pp.; figs. 1- 155+1-95 Mo6rcu, Otro ANDREAS Lowson 1863. Contributions 4 la faune malacologique des Antilles danoises. Journ. Conchyl. (3) 3 (11): 21-43 (December 1967) Page 152 THE VELIGER Orsicny, ALCIDE DESSALINES D’ 1837. Voyage dans l’Amérique Meéridionale. Mollusques. Paris, 5 (3): 188 Pitspry, Henry Aucustus & Epwarp GuIREY VANATTA 1902. Papers from the Hopkins Stanford Galapagos Expedition, 1898- 1899. XIII. Marine Mollusca. Proc. Wash. Acad. Sci. 4: 549 - 560; pit. 35 (30 September 1902) Pruvot-For, ALICE 1951. Révision du genre Glossodoris Ehrenberg. Journ. Conchyl. 91(3-4): 76-164 (1 July 1951) Rano, Paut Kase, SANDER LEONARD 1828. Histoire naturelle des aplysiens. Paris, Impr. Firmin Didot, 7+83 pp.; 25 plts. SpHon, GALE G. 1971a. New opisthobranch records for the eastern Pacific. The Veliger 13 (4): 368 - 369 (1 April 1971) 1971b. The reinstatement of Hypselodoris agassizi (Bergh, 1894) (Mol- lusca : Opisthobranchia). The Veliger 14 (2): 214 (1 Oct. ’71) Spuon, Gate G. & James Ropert LANCE 1968. An annotated list of nudibranchs and their allies from Santa Barbara County, California. Proc. Calif. Acad. Sci. (4) 36 (3): 73 - 84; 1 text fig. (25 September 1968) Vol. 15; No. 2 Vol. 15; No. 2 THE VELIGER Page 153 Some Opisthobranchs (Mollusca: Gastropoda) from Oregon BY GALE G. SPHON Los Angeles County Museum of Natural History, Los Angeles, California 90007 (1 Text figure) INTRODUCTION THE RUGGED ROcKy intertidal areas of coastal Oregon have been little explored for opisthobranchs, and litera- ture pertaining to opisthobranchs from that geographical area is almost non-existent. Many of the collecting sites are in state parks, and collecting in them is either by per- mit from the Oregon State Fish Commission or is totally prohibited. During the period from August 4 to 9, 1971, specimens of 19 species of opisthobranchs were collected intertidally at 5 localities in Oregon (Figure 1) ; these specimens are deposited in the Los Angeles County Museum of Natural History. All of the specimens collected, except those of Coryphella fusca O’Donoghue, 1921, were within the re- ported ranges of the respective species. Only Acantho- doris nanaimoensis O’Donoghue, 1921, has been reported from an Oregon locality (Coos Bay) (STEINBERG, 1963). REVIEW oF THE LITERATURE Goutp (1842: 311) stated: “Several nudibranchiate gastropods were observed in the Oregon region, but none of them were figured or described in sufficient detail to furnish specific characters.” This is the first literature record that I am able to find of any opisthobranchs from Oregon. The first species cited was in 1857 when Carpen- ter recorded Melibe leonina (Gould, 1852). However, he gave no specific locality. O’DoNoGHuUE (1926: 236) stated that there was one locality from Oregon in his list of 101 species of opisthobranchs from the Pacific coast, but that locality is not to be found mentioned in his paper. Marcus (1961) recorded 3 species: Onchidella borealis Dall, 1871, from Sunset Bay; Aglaja diomedea (Bergh, 1893), from Charleston; and Armina columbiana O’Don- oghue, 1924 [=A. californica (Cooper, 1863a)] from Oregon. STEINBERG (1963) cited Acanthodoris nanaimo- ensis and BeEMaNn (1963) recorded Phyllaplysia taylort Dall, 1900. Both species were from Coos Bay. Osis & Gipson (1970) figured Hermissenda crassicornis (Esch- scholtz, 1831) and Archidoris montereyensis (Cooper, 1863a) but gave no specific locality for the specimens. The most recent record is by THompson (1971) of two oc- currences of Tritonia exsulans Bergh, 1894, from “‘off the Oregon coast” in depths of 1000 and 1200m. COLLECTING LOCALITIES 1) Depoe Bay State Park, Lincoln County, Oregon A small area of shelf rock, located directly across High- way 101 from the main shopping area, including several large tide pools, runnels, and surge channels. 2) Seal Rocks State Park, Lincoln County, Oregon A large area with numerous undercut rock reefs and small islands; there are also many runnels and tide pools exposed at low tide. The majority of the specimens col- lected here were in tide pools, many of them clinging to the surface film of the water, others on the sides of the pools or on the algae in the pools. 3) Strawberry Hill, Neptune State Park, Lane County, Oregon The area just south of Strawberry Hill consists of a gravel beach next to the bluffs, a series of rounded wave- washed boulders, and a large shelf area with large run- nels and tide pools, uncovered at low tide. 4) North Cove, Cape Arago State Park, Coos County, Oregon On a very low tide it is possible to make one’s way out to Shell Island over the shelf rock. Much of the shelf is covered with boulders, tide pools and rock reefs which afford many varieties of habitats. Page 154 THE VELIGER Vol. 15; No. 2 124° , Seaside e Cannon Beach O e Tillamook R e Pacific City E e Lincoln City G le Newport le Waldport O N 440 i e Florence North Cove @) South Cove 43° e Port Orford fe Gold Beach e Brookings 124° 5) South Cove, Cape Arago State Park, Coos County, Oregon The west side of this cove is generally made up of medium sized boulders and small tide pools. Most of the opisthobranchs from this locality were either in tide pools, on the sides of ledges or rocks, or gliding suspended from the surface film of the water. Table 1 ee > 2 2 ae FQ e) ® iS) ie) 0 2 ee $ 3 5 oe A n n (4 n Acanthodoris hudsoni 1 Acanthodoris nanaimoensis 4 14 Antiopella barbarensis 15? 4 7! Archidoris montereyensis 10? 8 1 Catriona alpha 8 Coryphella fusca 1 Coryphella trilineata 3 Dendronotus frondosus 2 6 Diaulula sandiegensis 1 3 7 3 9 Dirona albolineata 10 Us Wits Eubranchus sp. 1 Hermissenda crassicornis 3 1! 4x Laila cockerelli 1 ? Pleurobranchus sp. 1 Rostanga pulchra 2 11 14 1 8 Trinchesia abronia 1 2 Trinchesia albocrusta 1 Triopha carpenteri 7 20: 10" 6 Tritonia festiva 1 3 1 many more specimens seen LIST or SPECIES The species are arranged alphabetically, the names used being the currently accepted ones. The overall geographic distribution is given, as are a few remarks on the habitat. My major sources for the distributional data are: Gos- LINER & WiLuiAMs, 1970; Hurst, 1967; Lance, 1961; Marcus, 1961; O’DonocHuE, 1926; Rotter, 1970; Rot- LER & Lone, 1969; SpHon & Lance, 1968; and STEIN- BERG, 1963. At the end of the list will be found names of additional species, culled from the literature, that have been reported as occurring in Oregon. Acanthodoris hudsoni MacFarland, 1905 Vancouver Island, British Columbia, Canada, south- ward to Shell Beach, San Luis Obispo County, California. Only one specimen was collected; it was found suspend- ed from the surface film of a tide pool at Strawberry Hill. Acanthodoris nanaimoensis O'Donoghue, 1921 Vancouver Island, British Columbia, Canada, south- ward to Shell Beach, San Luis Obispo County, California. Vol. 15; No. 2 This species was found at Seal Rocks and Strawberry Hill. In every instance the specimens were on the sides of ledges or rocks in tide pools. Antiopella barbarensis (Cooper, 1836b) Vancouver Island, British Columbia, Canada, south- ward to San Quintin, Baja California, Mexico. While this species was not found at Depoe Bay or South Cove, it remains the most common species (in number) collected or observed. The usual habitat was the surface film of the water in quiet tide pools. In one large pool at Strawberry Hill I counted over 125 specimens, both in the pool and clinging to the surface film of the water. Archidoris montereyensis (Cooper, 1863) Alaska southward to San Diego, San Diego County, California. This species was not found at Seal Rocks or South Cove. Apparently it prefers the rough pounding of the open sea. At Depoe Bay it was found in deep surge channels in fair numbers and because of the inaccessibility of the habitat only a few could be collected; many more were observed. At Strawberry Hill specimens were collected from un- der a seaweed-covered ledge that was exposed for only a short time at dead low tide. At North Cove, 1 specimen was found under a seaweed- covered ledge at extreme low tide. Catriona alpha (Baba « Hamatani, 1963) San Juan Islands, Puget Sound, Washington, south- ward to San Diego, San Diego County, California; also found in Japan. All specimens of this small aeolid were found under rocks in tide pools at South Cove. In a few instances egg masses were present at the time the specimens were col- lected. Coryphella fusca O'Donoghue, 1921 Departure Bay, Vancouver Island, British Columbia, Canada, southward to Seal Rocks State Park, Lincoln County, Oregon (the former southern record was the San Juan Islands, Puget Sound, Washington). One large specimen was found on an algal stipe in a tide pool at Seal Rocks. Coryphella trilineata O'Donoghue, 1921 Vancouver Island, British Columbia, Canada, south- ward to Coronados Islands, Baja California, Mexico. Only 3 specimens of this beautiful small acolid were found; all were taken at South Cove under rocks in tide pools. THE VELIGER Page 155 Dendronotus frondosus (Ascanius, 1774) Cosmopolitan in the northern hemisphere. This species was found at both Strawberry Hill and Seal Rocks. All specimens were crawling on the stipes of kelp in tide pools or large, quiet open areas. Diaulula sandiegensis (Cooper, 1863a) Alaska to Cabo San Lucas, Baja California, Mexico; also reported from Japan. Diaulula sandiegensis was found at all 5 localities, but not in as great numbers as Antiopella barbarensis or Her- missenda crassicornis. Most of the specimens were located on the sides of ledges or rocks covered by the overhanging seaweed and were from 1 to 3 inches (25 to 75mm) in length. There was variation in both the basic color and oval markings. The color ranged from dark brown to almost white. The number of the “rings” varied from 4 to 18. Dirona albolineata Cockerell & Eliot, 1905 Puget Sound, Washington, southward to San Diego, San Diego County, California; also reported from the U. S.S. R. This is one of the most strikingly beautiful opistho- branchs collected. It was very abundant at 3 localities: Seal Rocks, Strawberry Hill, and North Cove. The size ranged from approximately 1 to 4 inches (25 to 100mm) in length. The habitat was either on the sides of tide pools or on the kelp in the pools. In a few cases, specimens had been stranded in exposed kelp as the tide receded. Eubranchus sp. One specimen was found in seaweed in a tide pool at Strawberry Hill. Hermissenda crassicornis (Eschscholtz, 1831) Sitka, Alaska, southward to Punta Eugenia, Baja Cali- fornia, Mexico. While this species was not quite as abundant as Antio- pella barbarensis, it was found at all 5 localities and in very much the same type of habitat. Laila cockerelli MacFarland, 1905 Vancouver Island, British Columbia, Canada, south- ward to Cape San Lucas, Baja California, Mexico. Only 1 specimen was found and it was taken at South Cove. The specimen was the typically colored “northern” form of the species with the row of white “buttons” down the center of the dorsum. ? Pleurobranchus sp. One specimen was found on the side of a tide pool at Strawberry Hill. Page 156 THE VELIGER Vol. 15; No. 2 Rostanga pulchra MacFarland, 1905 Vancouver Island, British Columbia, Canada, south- ward to Chile. This species was found at all 5 localities. Most often it was in the open at the bottom of tide pools, but occasional- ly along the sides of rocks. Trinchesia abronia (MacFarland, 1966) Mukkaw Bay, Washington, southward to Pismo Beach, San Luis Obispo County, California. Specimens were found at both North and South Coves at Cape Arago. Those at North Cove were on algal stipes, while those at South Cove were under rocks. Trinchesia albocrusta (MacFarland, 1966) Friday Harbor, Washington, southward to Pismo Beach, San Luis Obispo County, California. One specimen was collected from seaweed at Seal Rocks. Triopha carpenteri (Stearns, 1873) Vancouver Island, British Columbia, Canada, south- ward to San Diego, San Diego County, California; also found in Japan. The only locality where Triopha carpenteri was not found was Depoe Bay. It was moderately common to abundant at the other 4 sites. Ordinarily, Tiiopha was found in tide pools, either on the sides or bottom or crawling on the algae. Occasionally, as Dirona, it would be trapped in exposed seaweed when the tide receded. Specimens ranged from less than 1 inch (25mm) to over 4 inches (100mm) in length. Tritonia festiva (Stearns, 1873) Vancouver Island, British Columbia, Canada, south- ward to Los Coronados Islands, Baja California, Mexico. Specimens were found on the undersides of rocks in tide pools at both North and South Cove. ADDITIONAL SPECIES REPORTED From OREGON Aglaja diomedea (Bergh, 1894) Alaska southward to Morro Bay, San Luis Obispo County, California. Armina californica (Cooper, 1863a) Vancouver Island, British Columbia, Canada, south- ward to Panama. Melibe leonina (Gould, 1852) Alaska southward to Punta Hipolito, Baja California, Mexico. Onchidella borealis Dall, 1871 Alaska southward to Duxbury Reef, Marin County, California. Phyllaplysia taylori Dall, 1900 San Juan Islands, Puget Sound, Washington, southward to San Diego, San Diego County, California. Tritonia exsulans Bergh, 1894 Alaska to Punta Santo Domingo, Baja California, Mexico; also reported from Japan; Manatee Bay, Flori- da; and Panama Bay on the Atlantic coast of Panama. ACKNOWLEDGMENTS I wish to express my thanks to the Fish Commission of Oregon for its help and the permit to collect in restricted areas (Permit no. 233-71). I also wish to thank Mr. Richard Roller for helping with the identifications of the aeolids and for critically reading the manuscript. Literature Cited ASCANIUS, PEDER 1774. Beskrivelse over en Norsk Sneppe Oget Soedyr (Molluscum Amphitrite frondosa). Det. Kong. Norsk. vidensk. selsk. skrift. 5: 135 - 158 [not seen] Basa, KixutTaré & Iwao HAMATANI 1963. A cuthonid, Cuthona alpha n. sp. with a radula of Catriona type (Nudibranchia-Eolidoidea). Publ. Seto Mar. Biol. Lab. 11 (2): 339 - 343; plt. 11 Beeman, Rospert Davip 1963. Variation and synonymy of Phyllaplyia in the northeastern Pacific (Mollusca : Opisthobranchia). The Veliger 6 (1): 43 - 47; 5 text figs. (1 July 1963) Bercu, Lupwic SopHus RUDOLF 1894. Reports on the dredging operations off the west coast of Central America to the Galapagos, to the west coast of Mexico, and in the Gulf of California, in charge of Alexander Agassiz, carried on by the U. S. Fish Commission steamer “Albatross,” during 1891, Lieut. Com- mander Z. L. Tanner, U. S. N., commanding. XIII. Die Opistho- branchien. Bull. Mus. C »mp. Zool. Harvard Univ. 25 (10): 125 to 233; plts. 1-12 (October 1894) CARPENTER, PHILIP PEARSALL 1864. Supplementary report on the present state of our knowledge with regard to the mollusca of the west coast of North America. Reprt. Brit. Assoc. Adv. Sci. for 1863: 517 - 686 (August 1864) CockErELL, THomas Dru ALison & CuHartes N. E. Exior 1905. Notes on a collection of California nudibranchs. Journ. Malacol. 12 (3): 31-53; plts. 7, 8 Cooper, JAMES GRAHAM 1862a. On some new genera and species of California Mollusca. Proc. Calif. Acad. Sci. (1) 1 (2) :202 - 207 (January 1863) 1862b. On new or rare Mollusca inhabiting the coast of California. Proc. Calif. Acad. Sci. (1) 3: 56 - 60 (September 1863) Dari, Witiiam HEALEY 1871. Descriptions of sixty new forms of mollusks from the west coast of North America and the North Pacific Ocean, with notes on others already described. Amer. Journ. Conchol. 7 (2): 93 - 160; plts. 13 - 16 (2 November 1871) EscHSCHOLTZ, JOHANN FRIEDRICH 1831. Zoologischer Atlas enthaltend Abbildungen und Beschreibungen neuer Thierarten, wahrend des Flottencapitains von Kotzebue zweiter Reise um die Welt, auf der russisch-kaiserlichen Kriegsschlupp Pred- priaetié in den Jahren 1823-1826. prt. 4: 1-19; plts. 16-20 (Berlin, G. Reimer) [not scen] Vol. 15; No. 2 iERVERIGER Page 157 Gos Liner, TERRENCE M. & Gary C. WILLIAMS 1970. The opisthobranch mollusks of Marin County, California. The Veliger 13 (2): 175-180; 1 map (1 October 1970) Gou.p, Aucustus AppISON 1852. United States exploring expedition during the years 1838, 1839. 1840, 1841, 1842 under the command of Charles Wilkes, U.S.N. 12: Mollusca shells, pp. 1 - 510 Hurst, ANNE 1967. The egg masses and veligers of thirty northeast Pacific opistho- branchs. The Veliger 9 (3): 255 - 288; plts. 26-38; 31 text figs. (1 January 1967) Lance, JAMES RosBert 1961. A distributional list of southern California opisthobranchs. The Veliger 4 (2): 64-69 (1 October 1961) MacDonatp, Gary R. 1970. Range extensions for Acanthodoris hudsoni MacFarland, 1905, and Onchidoris bilamellata (Linnaeus, 1767). The Veliger 12 (3): 375 (1 January 1970) MacFar.anp, Frank Mace 1905. A preliminary account of the Dorididae of Monterey Bay, Cali- fornia. Proc. Biol. Soc. Wash. 18: 35 - 54 1966. Studies of opisthobranchiate mollusks of the Pacific coast of North America. Mem. Calif. Acad. Sci. 6: xvi+546 pp.; 72 plt. (8 April 1966) Marcus, ERNST 1961. Opisthobranch mollusks from California. (Supplmt. I): 1-85; plts. 1-10 O’DonocHuE, CHartes HENRY 1921. Nudibranchiate Mollusca from the Vancouver Island region. Trans. Roy. Canad. Inst. 13 (1): 147-209; plts. 7-11 (21 Feb. 21) The Veliger 3 (1 February 1961) 1926. A list of the Nudibranchiate Mollusca recorded from the Pacific coast of North America with notes on their distribution. Trans. Roy. Canad. Inst. 15 (2): 199 - 247 Osis, Latimons & Gary Gipson 1970. A guide to Oregon’s rocky intertidal areas. 5 (Fish Comm. Oreg.): 1 - 34 Rosiiiiarp, Gorpon A. 1971. Range extensions of some northeast Pacific nudibranchs (Mol- lusca : Gastropoda : Opisthobranchia) to Washington and British Co- lumbia, with notes on their biology. The Veliger 14 (2): 162 - 165 (1 October 1971) Educat. Bull. no. (July 1970) Rotier, RicHarp A. 1970. A supplement to the annotated list of opisthobranchs from San Luis Obispo County, California. The Veliger 12 (4): 482 - 483 (1 April 1970) Rovier, Ricuarp A. & STEVEN J. Lone 1969. An annotated list of opisthobranchs from San Luis Obispo County, California. The Veliger 11 (4): 424-430; 1 map (1 April 1969) SpxHon, Gate G. & James Rospert LANCE 1968. An annotated list of nudibranchs and their allies from Santa Barbara County, California. Proc. Calif. Acad. Sci. 36 (3): 73 - 84; 1 text fig. (25 September 1968) STEINBERG, JOAN EmILy 1963. Notes on the opisthobranchs of the west coast of North America. — IV. A distributional list of opisthobranchs from Point Conception to Vancouver Island. The Veliger 6 (2): 68 - 73 (1 October 1963) TuHompson, THOMAS EVERETT 1971. Tritoniidae from the North American Pacific coast (Mollusca: Opisthobranchia). The Veliger 13 (4): 333-338; 3 text figs. (1 April 1971) Page 158 NOTES & NEWS First Recorded Occurrence of Littorina tessellata Philippi, 1847, from the Shores of North America BY FRASIER O. BINGHAM Rosenstiel School of Marine and Atmospheric Science University of Miami, Miami, Florida 33149 ° (1 Text figure) On Jury 13, 1971, a single living specimen of Littorina tessellata Philippi, 1847, was collected by the writer from a concrete bulkhead located on the Biscayne Bay side of Key Biscayne, Florida (25°40’N, 80°10’W). The speci- men, a female, has a shell length of 143mm. Figure 1 Littorina tessellata Philippi, 1847 14.5 mm ' Contribution No. 1504 from the University of Miami, Rosenstiel School of Marine and Atmospheric Science, 10 Rickenbacker Causeway, Miami, Florida 33149 THE VELIGER Vol. 15; No. 2 BEQuaerT (1943), who refers to the snail as Littorina nebulosa tessellata, lists its range at “Bahamas, Antilles and the Caribbean coast of South America.” WARMKE & AszotTtT (1961) also place the snail as a subspecies of L. nebulosa and note that it has been reported from Puerto Rico. The museum of the Rosenstiel School of Marine and Atmospheric Science, University of Miami, contains 2 lots of this species that may have been collected in the Florida Keys in the early 1920’s. The data for these specimens, however, cannot be relied upon as the particular collection in which they appear had been badly neglected before being donated to the museum. My thanks go to Dr. Joseph Rosewater of the United States National Museum who verified the identification of the species. The specimen, shown in Figure 1, is now in the U. S. National Museum collection. Literature Cited BEQUAERT, JOSEPH CHARLES 1943. The genus Littorina in the western Atlantic. 1-28; plts. 1-7 WarmMkeE, GERMAINE L. & RosertT TucKER ABBOTT 1961. Caribbean seashells; a guide to the marine mollusks of Puerto Rico and other West Indian islands, Bermuda and the lower Florida Keys. Livingston Publ. Co., Narberth, Pa. x+345 pp.; 44 plts.; 34 text figs. Johnsonia 7: Tue CALirorNiA MALACOZOOLOGICAL Society, Inc. announces Backnumbers of THE VELIGER and other publications Volumes 1 through 8: out of print Volume 9: $22.- Volume 10: out of print Volume 11: $24.- Volume 12: $28.- Volume 13: $24.- Volume 14: $28.- Supplement to Volume 3: $6.-* plus $-.75 handling charge [Part 1: Opisthobranch Mollusks of California by Prof. Ernst Marcus; Part 2: The Anaspidea of California by Prof. R. Beeman, and The Thecosomata and Gymnosomata of the Cali- fornia Current by Prof. John A. McGowan] [The two parts are available separately at $3.- each plus a handling charge of $-.75 or as indicated above. If purchased separately, each part is subject to the Califor- nia State sales tax if mailed to California addresses. ] Vol. 15; No. 2 Supplement to Volume 7: $2.-* plus $-.60 handling charge [Glossary of A Thousand-and-One Terms used in Conchology, compiled by Winirrep H. ARNoLp] Supplement to Volume 11: $5.-* plus $-.75 handling charge. [The Biology of Acmaea by Prof. D. P. Azzort ef al., ed.] Supplement to Vol. 14: $5.-* plus $-.75 handling charge [The Northwest American Tellinidae by Dr. E. V. Coan] Items marked with * are subject to sales tax in the State of California; residents of that State please add the appropriate amount to their remittances. Prices subject to change without notice. Send orders with remittance to: Mrs. Jean M. Cate, Manager, Post Office Drawer R, Sanibel, Florida 33957. Please make checks payable to C. M. S., Inc. Shipments of material ordered are generally made within two weeks after receipt of remittance. Subscription to Volume 15: $18.- domestic, $19.50 in Canada, Mexico, Central and South America; $20.- in all other foreign countries. {We are pleased to announce that we have completed arrangements with Kraus Reprint Co. to reprint those of our publications that are out of print. Inquiries regarding the availability and price(s) of desired items should be addressed to: Kraus Reprint Co. 16 East 46" Street, New York, N. Y. 10017 Backnumbers of the current volume will be mailed to new subscribers, as well as to those who renew late, on the first working day of the month following receipt of the remittance. The same policy applies to new members. Affiliate Membership for the fiscal year July 1, 1972 to June 30, 1973 has been set at $8.-. Postage for members in Canada, Mexico, Central and South America $1.50, for members in any other foreign country $2.- additional. Effective January 1, 1967 there will be an initiation fee of $2.- for persons joining the Society. Membership open to individuals only - no institutional or society memberships. Please send for membership ap- plication forms to the Manager or the Editor. Membership renewals are due on or before April 15 each year. If renewal payments are made after April 15 but before March 15 of the following year, there will be a re-instatement fee of $1.-. Members whose dues pay- THE VELIGER Page 159 ments (including the re-instatement fee) have not been received by the latter date, will be dropped from the rolls of the Society. They may rejoin by paying a new initiation fee. The volume(s) published during the time a member was in arrears may be purchased, if still available, at the regular full volume price plus applicable handling charges. Regarding UNESCO Coupons We are unable to accept UNESCO coupons in payment, except at a charge of $2.50 (to reimburse us for the ex- penses involved in redeeming them) and at $0.95 per $1.00 face value of the coupons (the amount that we will receive in exchange for the coupons). We regret that these char- ges must be passed on to our correspondents; however, our subscription rates and other charges are so low that we are absolutely unable to absorb additional expenses. Supplements Many of our members desire to receive all supplements published by the Society. Since heretofore we have sent supplements only on separate order, some members have missed the chance of obtaining their copies through over- sight or because of absence from home. It has been sug- gested to us that we should accept “standing orders” from individuals to include all supplements published in the future. After careful consideration we have agreed to the proposal. We will accept written requests from individuals to place their names on our list to receive all future sup- plements upon publication; we will enclose our invoice at the same time. The members’ only obligation will be to pay promptly upon receipt of the invoice. Requests to be placed on this special mailing list should be sent to the Manager, Mrs. Jean M. Cate, Post Office Drawer R, Sanibel, Florida 33957. Moving? If your address is changed it will be important to notify us of the new address at least six weeks before the effective date, and not less than six weeks before our regular mailing dates. Because of a number of drastic changes in the regulations affecting second class mailing, there is now a sizeable charge to us on the returned copies as well as for our remailing to the new address. Page 160 We are forced to ask our members and subscribers for reimbursement of these charges; further, because of increased costs in connection with the new mailing plate, we also must ask for reimbursement of that expense. Effective January 8, 1968 the following charges must be made: change of address - $1.- change of address and re-mailing of a returned issue - $2.-. We must emphasize that these charges cover only our actual expenses and do not include compensation for the extra work involved in re-packing and re-mailing returned copies. General Notices REGARDING POSTAL SERVICE While increases in postal charges were anticipated, the actual amount involved could not be ascertained until 4 days before the effective date. Thus, we have been un- able to adjust our membership dues and subscription rates to cover these increases. Effective immediately, we must also raise our handling charges for backissues and other materials. Further, we will not acknowledge the receipt of manuscripts, unless an addressed envelope with the necessary postage is enclosed. We must call the attention of our Members and Sub- scribers to the fact that we mail our journal on the date stated on the cover of a particular issue. After we have delivered the journal to the Post Office, our control ends. Delays in delivery seem to become more and more com- mon. Needless to say that we regret this very much; we had hoped that when the salaries of the Postal Workers were increased, the service would improve. However, this seems not to be the case. In view of the ever increasing difficulties in the postal service, it is essential that members and subscribers not only give us prompt and early notice of address changes, but that proper arrangement for forwarding of our jour- nal be made with the local post office (at the old address). We are not able to replace lost copies free of charge but must charge single copy rates. There will, of course, be only the usual charge of $1.00 for re-forwarding a copy IF it has been returned by the post office to us. We also must urge our members and subscribers to place written THE VELIGER Vol. 15; No. 2 complaints with the U. S. Post Office Department in case of loss, as every copy of our journal carries our guarantee for return postage. Thus, destruction of a copy of our journal by postal employees constitutes gross neg- ligence and the person concerned deserves an official reprimand, at least. Publication Date of THE VELIGER THE PUBLICATION DATE of The Veliger is the date printed on the index page; this applies even if the date falls on a legal holiday or on a Saturday or Sunday, days when the U. S. Post Office does not expedite second class mail matter. That the printed date is the actual date of pub- lication under the rules of the International Commission on Zoological Nomenclature is based on the following facts: 1) The journal is delivered to the Post Office on the first day of each quarter, ready for dispatch; 2) at least three copies are mailed either as first class items or by air mail; 3) about 20 copies are delivered in person to the mail boxes or to the offices of members in the Berkeley area; 4) two copies are delivered to the re- ceiving department of the General Library of the Univer- sity of California in Berkeley. Thus our publication is available in the meaning of the Code of the ICZN. The printed publication date, therefore, may be relied upon for purposes of establishing priority of new taxa. CALIFORNIA MaALAcozoo.LocicaL Society, Inc. is a non-profit educational corporation (Articles of In- corporation No. 463389 were filed January 6, 1964 in the office of the Secretary of State). The Society publishes a scientific quarterly, the VELIGER. Donations to the Society are used to pay a part of the production costs and thus to keep the subscription rate at a minimum. Donors may designate the Fund to which their contribution is to be credited: Operating Fund (available for current production) ; Savings Fund (available only for specified purposes, such as publication of especially long and signi- ficant papers); Endowment Fund (the income from which is available. ‘The principal is irrevocably dedicated to scientific and educational purposes). Unassigned dona- tions will be used according to greatest need. Contributions to the C.M.S., Inc. are deductible by donors as provided in section 170 of the Internal Revenue Vol. 15; No. 2 Code (for Federal income tax purposes). Bequests, lega- cies, gifts, devices are deductible for Federal estate and gift tax purposes under section 2055, 2106, and 2522 of the Code. The Treasurer of the C. M. S., Inc. will issue suitable receipts which may be used by Donors to substan- tiate their respective tax deductions. Endowment Fund In the face of continuous rises in the costs of printing and labor, the income from the Endowment Fund would materially aid in avoiding the need for repeated upward adjustments of the membership dues of the Society. It is the stated aim of the Society to disseminate new infor- mation in the field of malacology and conchology as widely as possible at the lowest cost possible. At a Regular Membership meeting of the Society in No- vember 1968 a policy was adopted which, it is hoped, will assist in building up the Endowment Fund of the Society. An issue of the journal will be designated as a Memorial Issue in honor of a person from whose estate the sum of $5000.- or more has been paid to the Veliger Endowment Fund. If the bequest is $25 000.- or more, an entire volume will be dedicated to the memory of the decedent. Western Sede AM Tue SixtH ANNUAL MeetING of the Western Society of Malacologists will be held at the Asilomar Conference Grounds in Pacific Grove, California July 11 to 14, 1973 and will feature contributed papers, symposia, displays and study workshops on molluscan subjects. Inquiries may be sent to the Secretary, Mrs. Edith Abbott, 1264 W. Cienega Avenue, San Dimas, CA 91773. Applications for membership in the Society should be sent to the Treas- urer, Mr. Glenn Burghardt, 14453 Nassau Road, San Le- andro, CA 94577. Dues are $2.50 for regular members and $1.00 for students. Executive Board Members for the year are: President: Mrs. Twila Bratcher; First Vice-President: Dr. James H. McLean; Second Vice-President: Dr. James Ny- bakken; Secretary: Mrs. Edith Abbott; Treasurer: Mr. Glenn Burghardt; Members-at-Large: Dr. George Rad- THE VELIGER Page 161 win and Dr. George Davis; the three most recent Past Presidents: Dr. A. Myra Keen; Dr. Eugene V. Coan, and Mrs. Beatrice L. Burch. BOOKS, PERIODICALS, PAMPHLETS On some Patinopecten from North America by Kéicum6 Masupa. Palaeontological Society of Japan Transactions, N. S. no. 83; pp. 166-178; plts. 19 - 21. September 20, 1971. This useful report treats all species referred to the Mio- cene to Recent genus Patinopecten. The taxonomic focus, however, is on two zoogeographically significant Pliocene genera that have heretofore been incorrectly assigned to this eastern North Pacific genus. Leopecten, a new genus from the Gulf of California, provides early evidence of a land barrier between the Atlantic and Pacific Oceans. Mizhuopecten from coastal Washington is one of four western Pacific genera that migrated eastward during the Pliocene providing important ties across the North Pacific. W. O. Addicott. Seashells by S. PETER Dance. Hamlyn Publishing Group Limited, London. 159 pp.; 332 figs. in color; 40 pence. 1971. This new paperback starts out like other introductory books on mollusks with the necessary survey of classes, habitats, and geographical distribution and the usual sys- tematic review. Where it differs from others is by its frank- ly limiting the coverage to the mollusks with economic value, those that have been used by man in various ways or that have become objects much coveted by collectors. Illustrations are by James Nicholls, original paintings of exceptional fidelity, almost photographic in texture. All are fresh and new, not copied from previous figures. The style of the book is easy, relaxed, and readable, with enough humor to maintain interest. The anectodes about the various species are carefully culled from the literature and have the ring of authenticity even though space is lacking for documentation. The author is in a position to provide trustworthy data, and he does; the work is scien- tific in format, even to complete adoption of the metric system (the reader must learn to cope not only with milli- Page 162 meters and centimeters for length but also with kilograms for weight). In a first reading of the book only a few minor points were noted that one suspects the author will correct in later editions, such as the inverted orientation of Peni- cillus (cited under the non-binomial name Brechites) and an unduly long range for the Californian Serpulorbis squamigerus (cited as “Aletes’). There are short chapters on collecting and buying, on books to read, and on shell clubs of the world. The latter list is admittedly incomplete but should prove useful to the neophyte. One wonders, however, what the basis was for selection of the 21 clubs mentioned, especially the 3 for the United States, for these cited would seem to be a very uneven sampling from the standpoint of size, activity, accessibility, and location. This book can be recommended as one of the best of its kind on the current market, and it should appeal to a wide spectrum of readers. VLL Malacological Review P.O. Box 801, Whitmore Lake, Michigan 48189, U.S. A. vol. 5: 94 pp.; illust. 1972 In addition to 3 brief communications, this issue con- tains the abstracts and proceedings of the ‘Mollusk Semt- nar, Ann Arbor, 1971.’ A new additicn to the list of departments is a section of obituaries. An announcement of a forthcoming supplement to the current volume, but not included in the subcription rate, should be of interest to serious students of malacology. The topic will be“ The freshwater mollusks of Taiwan (Formosa). RS Index to the Revista de la Sociedad Malacologica ‘Carlos de la Torre’ Volumes 1-9, 1943-1954 (all volumes issued) compiled by Morris K. Jacosson. Sterkiana 44: pp. 1-44, December 1971. Copies available at US$1.00 from the compiler whose address is: 455 Beach 139” Street, Rock- away, N. Y. 11694. While this work is not very exciting reading - such as a mystery story by one of the more skillful writers - it is, however, of far greater value. A few random samples convince us that the work is accurate and apparently ex- haustingly complete. ‘To the fortunate owners of the set of the ‘Revista’ or, for that matter, even a part of it, this will prove to be one dollar well spent. RS THE VELIGER Vol. 15; No. 2 Proceedings of the First International Conference on Meiofauna Nett C. Huuines, ed. Smithsonian Contributions to Zoo- logy No. 76; Washington, D. C.; 1971. 205 pp.; illust. Available at $2.25 (paper cover) from Superintendent of Documents, U.S. Govmt. Printing Office, Washington, D. C. 20402 This work contains 27 papers of 30 presented at the first International Conference on Meiofauna, held in Tunis, Tunisia, July 1 to 11, 1969. The various papers are arranged under 3 subheadings; 1. Systematics and ecology of meiofauna taxa; 2. Eco- logy of meiofauna; 3. Sampling for meiofauna. Of special interest to malacologists is the paper by Berti. SwepMarK: A review of Gastropoda, Brachio- poda, and Echinodermata in marine meiobenthos (pp. 41 to 45. RS British Prosobranchs by ALasTair GraHas. Synopses of the British fauna (new series) no. 2. pp. 1 - 112; 119 text figures. Academic Press, London and New York. US$ 4.00. December 31, 1971. The full title on the flyleaf reads: British prosobranch and other operculate gastropod molluscs, keys and notes for the identification of the species. The material is well organized and the illustrations, line drawings, are of excellent quality. While, no doubt, this work will be of primary importance to our British and European readers, it will also be helpful to students of the groups treated, no matter where they may be working. In view of present-day book prices, the cost of this book seems modest. RS Australian Seashores in Colour by Kerrn GILLeTT and JoHN Yatpwin. C. E. Tuttle Company, Rutland, Vermont. 112 pp.; 64 color photo- graphs, 49 black-and-white photographs. September 30, 1970. U.S. $5.00. Aimed at the amateur, this book contains superb color photographs beautifully reproduced, of the more spec- tacular marine animals encountered along the Australian shores. It may be considered a companion volume to the next book. RS Vol. 15; No. 2 The Australian Great Barrier Reef in Colour by Kerr Giitett. C. E. Tuttle Company, Rutland, Ver- mont. 111 pp.; 50 color plates; 16 white-and black plates. August 9, 1971. No indication of price. This book is also distinguished by its excellent color photographs. Ten of the color plates are devoted to some of the mollusks at home in the area of the Great Barrier Reef. We were especially pleased with the 5 plates por- traying living animals. Other animal groups are also rep- resented by pictures of living examples. RS Australian Crustaceans in Colour by AntHoNy Hearty and Jonn Yatpwin. C. E. Tuttle Company, Rutland, Vermont. 112 pp.; 52 color plates. 1972. US$6.75. Like the others in this series, this book appeals to the eye with its outstanding reproductions of excellent color photographs, Of interest to the malacologist will be the figures showing hermit crabs with the molluscan shell occupied and the commensal shrimp (not visible in the illustration) in the black-lip pearl oyster. RS { These three books are 18.5 cm (72 inches) wide and 17.5 cm (6$ inches) high.} The Sea Shells of Sagami Bay, collected by His Majesty the Emperor of Japan. Described by TokusBer Kuropa, TaDASHIGE Hae, and Katura Oyama. Edited by the Biological Laboratory, Imperial Household. Published by Maruzen Co., Tokyo. 1971. Pp. 1 - 741 in Japanese; 121 plates (105 in color) ; + pp. 1-489 in English; Index, pp. 1-51 in English and Japanese; | foldout map. 13 000 Yen ($58.-). By any criterion, this is an impressive book — by the numbers of species that could be collected in a single Japanese bay; by the number and quality of the color plates; or by sheer size (it weighs a little over 8 pounds). The color illustrations are done at natural size; smaller forms that need greater magnification are included on the black and white plates. New taxa are described by various combinations of the authors, and thus the citations may prove cumbersome; for example, in Muricidae, the genus Reishia Kuroda and Habe should also be cited as “in Kuroda, Habe, and Oyama.” A new subfamily, Ergalataxinae, is proposed in THE VELIGER Page 163 Muricidae, to include some species hitherto classified in Trophoninae and Thaididae, subfamily Drupinae. Un- fortunately, here as with a number of other of the new taxa, reasons for proposal and comparisons with the most closely related units are either omitted or are over-brief. Synonymies are given for all of the 1121 species and subspecies, with a statement of type locality and exact localities of collection. Notes on general distribution and ecology of each one also are included. Of the taxa de- scribed as new there are 30 genera and subgenera and 104 species and subspecies. Because of the wide distribu- tion of many of the species in the Indo-Pacific, the book will have usefulness far beyond the limits of southern Japan, and it is one that any collector could be proud to own. MK Latin and Greek for Biologists by T. H. Savory. Pp. 1 - 34. Merrow Publishing Co., Ltd. Watford, England, 1971. US$ 4.00. The author was spurred on to prepare this small (54 by 84 inches) booklet by the observation that the teaching of Latin and Greek has been more and more de-empha- sized and finally completely abandoned in most schools. Consequently, modern biologists are ill equipped to under- stand the meanings of names of organisms nor are they able to savor the gentle — and, sometimes the not so gentle — humor of earlier authors. In the opinion of this reviewer, the lack of the so-called classical education ac- counts, no doubt, for the prevalence of patronymics used to name new taxa in relatively recent times. This small booklet, within its limited scope, attempts to guide modem authors over some of the pitfalls caused by the lack of this knowledge. It could be wished that considerably more material had been presented without increasing the relatively high price, although the make-up of the booklet si worthy of a far more ambitious work. RS Molluscan Digest The International Publication for Malacological Research volume 2, number 8, August 1, 1972; pp. 85 - 96. Ob- tainable on subscription ( rates: inquire of either editor). Edited by Steven J. Long, 110 Cuyama Avenue, Pismo Beach, California 93449 and Jack Brookshire, 2962 Bal- boa Avenue, Oxnard, California 93030. This publication, by being limited essentially to the citation of malacological articles and books, has an envi- Page 164 THE VELIGER able record of keeping abreast of the current literature. The editors also seem to enjoy active cooperation from many sources, no doubt because the publication fills a very important need. Mr. Long will, upon request, send sample copies. The subscription rate, in view of the im- portant service rendered, is modest. RS A Catalog of Dealers’ Prices for Marine Shells by Tom Rice. Third edition. 70 pp., 84 by 11 inches. $3.-. Of Sea and Shore Publ. Port Gamble, Washington 98364. May 1, 1972. As in the previous editions of this list, the prices quoted for shells seem more realistic than in some other similar publications. They can well be the basis for exchanges among collectors. RS Simpésio Brasileiro de Paleontologia Anais da Academia Brasileira de Ciéncias, supplement to volume 40: 661 pp.; numerous illustrations. Rio de Jan- eiro GB, December 30, 1971. The Brazilian Symposium on Paleontology was held in Rio de Janeiro September 20 to 25, 1971. 'This volume includes 47 of the papers presented; among them one by W. P. Woodring, entitled: Zoogeographic affinities of the Tertiary marine molluscan Faunas of Northeastern Brazil (pp. 119 - 124; 3 text figures). This seems the only paper that dealt with mollusks exclusively. Most papers are in Portuguese, 8 in English and 1 in French. As is to be expected, the topics run the gamut of about all branches of Paleontology and several papers are concerned with Foraminifera and several have a bearing on Gondwana. Unfortunately we are unable to state how this valuable volume may be procured except by suggesting that those interested inquire of Dr. Herman Lent, President of the Editorial Commission, Caixa Postal 229 — ZC-00 — Rio de Janeiro, GB — Brazil. RS Vol. 15; No. 2 We are pleased to be able to include herewith the half- tone plates which, due to circumstances beyond our con- trol, had to be omitted from our July issue. The plates should be inserted to face the pages listed as follows: Renders Eioumest toes (hi ae ees esa 10 Reno ety Eagaines) Ltn Gir Viterbi Weer ee a: 12 TNOKOa EMOUMES COZ 8 Ue en ute uae aan, 16 INOKOD SEIGMTES GEO LOW Mea cnc tasecieteienrocteie TS) paisa oe IREtIC bake aces hee SEIN oh Ror SN cat es ee 52 ber LNGSON STA) Sst Sr ee eo Ree er Oe eve em emia Be erent 56 % JD S) S/S Gi ogy, sot cate into SER Ne ee er 58 b i haste y Ny by i ; i a! THE VELIGER is open to original papers pertaining to any problem concerned with mollusks. This is meant to make facilities available for publication of original articles from a wide field of endeavor. Papers dealing with anatomical, cytological, distri- butional, ecological, histological, morphological, physiological, taxonomic, etc., aspects of marine, freshwater or terrestrial mollusks from any region, will be considered. Even topics only indirectly concerned with mollusks may be acceptable. It is the editorial policy to preserve the individualistic writing style of the author; therefore any editorial changes in a manuscript will be submitted to the author for his approval, before going to press. Short articles containing descriptions of new species or other taxa will be given preferential treatment in the speed of publication provided that arrangements have been made by the author for depositing the holotype with a recognized public Museum. Museum numbers of the type specimens must be included in the manuscript. Type localities must be defined as accurately as possible, with geo- graphical longitudes and latitudes added. Short original papers, not exceeding 500 words, may be published in the column “NOTES and NEWS”; in this column will also appear notices of meetings of regional, national and international malacological organizations, such as A.M. U., U.M. E., W.S. M., etc., as well as news items which are deemed of interest to our Members and subscribers in general. Articles on “METHODS and TECH- NIQUES” will be considered for publication in another column, provided that the information is complete and techniques and methods are capable of duplication by anyone carefully following the description given. Such articles should be mainly original and deal with collecting, preparing, maintaining, studying, photographing, etc., of mollusks or other invertebrates. A third column, entitled “INFORMA- TION DESK,” will contain articles dealing with any problem pertaining to collecting, identifying, etc., in short, problems encountered by our readers. In contrast to other contributions, articles in this column do not necessarily contain new and original materials. Questions to the editor, which can be answered in this column, are invited. The column “BOOKS, PERIODICALS, and PAMPHLETS” will attempt to bring reviews of new publications to the attention of our readers. Also, new timely articles may be listed by title only, if this is deemed expedient. Manuscripts should be typed in final form on a high grade white paper, not exceeding 81,” by 11”, at least double spaced and accompanied by a clear carbon or photo copy. A pamphlet with detailed suggestions for preparing manuscripts intended for publication in THE VELIGER is available to authors upon request. A self-addressed envelope, sufficiently large to accommodate the pamphlet (which measures 51/4,” by 814”), with double first class postage, should be sent with the request to the Editor. EDITORIAL BOARD Dr. Donatp P. Assott, Professor of Biology Hopkins Marine Station of Stanford University Dr. Jerry DonouveE, Professor of Chemistry University of Pennsylvania, Philadelphia, and Research Associate in the Allan Hancock Foundation University of Southern California, Los Angeles Dr. J. Wyatr DurHam, Professor of Paleontology University of California, Berkeley, California Dr. E. W. Facer, Professor of Biology Scripps Institution of Oceanography, La Jolla University of California at San Diego Dr. Caper Hanp, Professor of Zoology and Director, Bodega Marine Laboratory University of California, Berkeley, California Dr. Joet W. Hepcretu, Resident Director Marine Science Laboratory, Oregon State University Newport, Oregon Dr. A. Myra KEEN, Professor of Paleontology and Curator of Malacology, Emeritus Stanford University, Stanford, California Dr. Victor LoosanorrF, Professor of Marine Biology Pacific Marine Station of the University of the Pacific Dr. Joun McGowan, Associate Professor of Oceanography Scripps Institution of Oceanography, La Jolla University of California at San Diego Dr. Frank A. PitEexA, Professor of Zoology University of California, Berkeley, California Dr. Ropert Rosertson, Chairman and Pilsbry Chair of Malacology, Department of Malacology Academy of Natural Sciences of Philadelphia Dr. Peter U. Roppa, Chairman and Curator, Department of Geology California Academy of Sciences, San Francisco Mr. Attyn G. SmituH, Research Associate Department of Geology California Academy of Sciences, San Francisco Dr. Ratpu I. Smiru, Professor of Zoology University of California, Berkeley, California Dr. Cuares R. STASEK, Associate Professor of Zoology Florida State University, Tallahassee, Florida EDITOR-IN-CHIEF Dr. Rupo.tr SToHLER, Research Zoologist, Emeritus University of California, Berkeley, California ASSOCIATE EDITOR Mrs. JEAN M. Cate Sanibel, Florida A Quarterly published by CALIFORNIA MALACOZOOLOGICAL SOCIETY, INC. Berkeley, California VOLUME 15 January 1, 1973 NUMBER 3 CoNTENTS Convergence in Pulmonate Radulae (4 Plates) ALAN SOLEM . . . . 165 External Description of a Tivine erie bifidus (Odhner, 1936) Gate a Dendronotacea) . (2 Text fae C. H. Cartson &« P J. Horr .. . » 172 Food-Preference of the Nudibranch Acolidia pa fillies a ie Effect an fr Toeenes of the Prey on Predation. (5 Text oe Vircinia L. WaTERS. . . . . : 5 Gio. (o). CURA DEM: Hoe | Embryonic Development of the Onnenntl Snail, ieheieg ye ppoonensis. (1 Plate) Arex S. Tompa & JaMeEs N. CaTHER. . . 193 Observations of the Feeding Habits of Tochuina lmuats Pallas) (eatopeaa: Tritoniidae) . Mary K. WicksTEN & JoHN D. DE Martini. . . sheet WePEKQE Some Records on West American Cenozoic Gastropods of oe Gene Hehe (1 Plate; 2 Text figures) MAHDOKHT JAVIDPOUR. . . er ere eT GO The Intertidal Behavior of the Be Clam, £ Donax oss Dall, 1921 (2 Plates; 3 Text figures) Tuomas H. Irwin . . . . 206 Preliminary Note on Hepaeun item: a Eanonie Stages | in 1 Diplodon neenhe (2 Plates) CeLtia GLUZMAN DE PascaR . . . 5 PYG Thermal and Salinity Effects on Ciliary Abate of Excised ‘Gil Tissue (ee Bivalves of North and South Carolina. (4 Text figures) APANG TE SHOEMAKERGH arin get emen Deiat). sae is ee ele ee ws QED [Continued on Inside Front Cover] Note: The various taxa above species are indicated by the use of different type styles as shown by the following examples, and by increasing indentation. ORDER, Suborder, DIVISION, Subdivision, SECTION, SUPERFAMILY, Famity, Subfamily, Genus, (Subgenus) New Taxa Second Class Postage Paid at Berkeley, California ConTENTs — Continued A Field Study on the Clustering and Movement Behavior of the Limpet Acmaea digitalis. (1 Plate; 3 Text ee James W. WitLoucHBy . . . ee Co Ce ROMO roo Be BER Description of a New Species of the Stent Hae Swainson, 1840 from the South Mozambique Channel, Indian Ocean (Gastropoda : Coralliophilidae) . (1 Text figure) Masao AzuMa . . 4 a 2a8 Additional Notes on seas Pacific Gast Monee - Garand Boslogealt and Chronological Ropert R. TALMADGE . . . SOS BLP Polydora and Related Genera (each Sone as ages in Mollusk Shells and Other Calcareous Substrates. (4 Text figures) James A. BuAKE:& JOHN W)EVANS * 0 227 27. cy Wate noy eres ae enn oma Range Extensions of Several Littorinids (Mollusca : Coe in Florida. FrasieER O. BINGHAM. . . 250 The Occurrence of Polycera zosterae 20 Deacons 1924 in ye Bodega Bay ‘Résios, California, with Notes on Its Natural History (Gastropoda : Nudibranchia). (1 Map; 1 Text figure) TERRENCE M. Gostiner.& Gary C. Witrtmams. . . . . 2. 5 « « « « «© « 252 METHODS & TECHNIQUES .. . .; Meee tn SO LCmO yo! wo) OIL: Preserving Terrestrial Slugs by PaceDy ke H. H. CrowE.i A Device for Collecting Free-Swimming Bivalve Larvae from Laboratory Aquaria. (1 Text figure) Kevin J. ECKELBARGER NOTES & NEWS ackithare ht . 257 Spawning and Development of ae oo in aes Dae of Ilex voindleti (Mollusca : Cephalopoda) . S. v. Boterzxy, L. Rowe « L. AROLES New Name for Pyramidella (Triptychus) olssoni Bartsch, 1926 James X. Corcan BOOKS; PERTODIC@ALS!& PAMPEICEMS 0 sey) enna Distributed free to Members of the California Malacozoological Society, Inc. Subscriptions (by Volume only) payable in advance to Calif. Malacozool. Soc., Inc. Volume 15: $18.- Domestic; $19.50 in the Americas; $20.- in all other Foreign Countries Single copies this issue $12.-. Postage additional. Send subscription orders to Mrs. Jean M. Carte, Post Office Drawer R, Sanibel, Florida 33957. Address all other correspondence to Dr. R. StoHEr, Editor, Department of Zoology, University of California, Berkeley, California 94720 California Malacozoological Society, Inc. % DEPARTMENT OF ZOOLOGY ~- UNIVERSITY OF CALIFORNIA . BERKELEY, CALIFORNIA An Explanation The regrettable increase in dues and subscription rates announced on page 259 of this issue is in part the result of an alarming and ever-increasing loss of individual copies of our journal in the mails. From a modest loss of one copy in our first year of publication, losses have now increased to an astonishing 6 percent of the total mailing. Since we endeavor to replace lost issues without additional cost to the individual recipient, the total labor and expense of producing ''The Veliger'’ are increased, and in the last analysis this results in spreading the cost of the losses over the entire subscribership. Although we lodge reports of losses and our complaints with the Berkeley Post Office, it is evident that the losses must be ascribed to distributing centers and local Post Offices at the points of destination, including a growing number of foreign countries. Improvement of postal services can only be expected if all postal patrons who have suffered losses register their complaints with their own post offices at the same time they request from us the replacement of lost issues. We earnestly and urgently request that every member or sub- scriber who fails to receive his or her copy lodge a complaint with the local postmaster, with a carbon copy to The Consumer Advocate Office of the Postmaster General Washington, D. C. 20260. If losses or mishandlings are repeated, copies of such written complaints might also be sent to one's elected representatives in Congress. Regrettably, we are unable to advise foreign members and subscribers how best to deal with their local postal authorities, but we believe that they too must find some way to appeal to their local Post Offices for more careful handling of posted material. sig. H} Cadet H. Hand, President, C.M.S., Inc. Vol. 15; No. 3 THE VELIGER Page 165 Convergence in Pulmonate Radulae ALAN SOLEM Department of Zoology, Field Museum of Natural History Roosevelt Road and Lake Shore Drive, Chicago, Illinois 60605, (4 Plates) OPTICAL OBSERVATIONS of pulmonate radulae have re- vealed numerous similarities in cusp outlines, but the depth of field limitations inherent to optical study have limited the amount of data obtainable. Pirspry (1893- 1895: xili-xiv) summarized the basic patterns of variation in cusp structure, focusing on departures from a primitive tricuspid pattern either to the broad, gouge-like cusps found in arboreal snails or a reduction to bicuspid or un1- cuspid structures. Despite numerous drawings of radular cusps published subsequently, our knowledge concerning the trends and patterns of radular evolution remains es- sentially at the level of Pilsbry’s summary. The scanning electron microscope is a tool that will revolutionize our knowledge of radular structure. Sum- maries of the initial uses of this instrument in malacology and a report on radular preparation and viewing tech- niques recently have been published (SoLEMm, 1970, 1972). The latter paper reported the existence of an interlock system between the rows of teeth during feeding. Sym- patric species of Australian Camaenidae were figured to show varying patterns of interlock. This paper traces the evolution of very similar support mechanisms in the endodontoid family Charopidae, sur- veys stages in the evolution of algae-scraping cusps in the Enidae, and demonstrates the functionally identical, but structurally different, pattern of cusp structure in the Partulidae. ACKNOWLEDGMENTS Illustrations for this paper were made at the Electron Optics Laboratory of the American Dental Association during cooperative research on the feeding mechanisms of mollusks. I am indebted to Dr. Harvey Lyon, Mr. John Lenke, and Mr. George Najarian of the ADA for invalu- able technical assistance in SEM operation, and to Miss Barbara Walden, Mrs. Nancy Kozlowski, and Mrs. Doro- thy Karall for assistance with specimen and manuscript preparation. The quality of the SEM photographs in SoLEM (1970, 1972) and this paper owe much to the skill and dedication of Mr. Fred Huysmans, photographer at Field Museum of Natural History. Work on the Charo- pidae was done under sponsorship of National Science Foundation Grant GB-6779. Their support is gratefully acknowledged. MATERIALS anp METHODS Specimens from the alcohol collections at Field Museum of Natural History were prepared for SEM observation according to the techniques outlined in SOLEM (1972). After initial orientation and viewing of the radula at 100, to 500x magnification, detailed observations were made from a variety of angles at 1 000« to 6000x. The illustra- tions published here are selected from more extensive sets of photographs and were chosen to demonstrate the par- ticular points under discussion rather than to show the overall tooth patterns and intergroup changes in cusp structure. SYSTEMS or SUPPORT Snails feed by a complex set of movements involving pro- trusion of the radula and its supporting cartilages, moving the cartilages in relation to the substrate, and pulling the rows of teeth forward, up and around the tip of the car- tilages, and then back into the mouth. The teeth are ar- ranged in horizontal rows with the cutting edges (cusps) pointing towards the posterior of the radula. Complex folds and rotational movements mean that at times the cusps point towards the anterior end of the animal, at the moment of rounding the odontophoral tip they point towards the top of the animal, and after rounding the tip Page 166 THE VELIGER Vol. 15; No. 3 they point towards the posterior. Tooth orientation in terms of the body axis shifts with the stage in the feeding stroke. Asa result the use of ‘‘anterior-posterior’’ terminol- ogy is best limited to ends of the radula and should not refer to body axis orientation. When teeth in one row are brought into contact with a food source and cut or slice into the object, resistance pres- sure on the cusp is transmitted to the anterior portion of the basal plate (since the cusp points backward). In genera such as Papuina (SOLEM, 1972: figs. 12-16) there is a long anterior extension of the basal plate. Resistance encoun- tered by the cusp is buttressed by this extension pressing against the underlying odontophoral cartilage. The Australian Camaenidae were shown (SotEM, 1972: figs. 21-29) to have very different patterns of support, with the anterior end of the tooth encountering resistance being forced down into contact with the posterior portion of the basal plate belonging to the tooth in the next anterior row. The three rather closely related Australian genera showed quite different systems of interlocking for the lateral teeth, although the pattern of interlocking for the marginals was virtually identical. Many other families show similar adaptations. Evolution of Interrow Support Systems in the Charopidae The Charopidae are the largest endodontoid family, with an extensive and complex radiation in Australia, New Zealand, New Caledonia, Lord Howe Island, Melanesia, Micronesia and part of Polynesia. Some species are known from South Africa and South America. This is the group variously referred to or fragmented into the Flammulin- idae, Phenacohelicidae, Charopidae, and Pseudocharo- pidae by most workers. Data concerning its differentiation from the Punctidae and Endodontidae is presented else- where (SOLEM, in preparation). Here it is sufficient to note that the basic radular pattern is for tricuspid central and lateral teeth, with the marginals variously altered. The commonest form of the teeth is found in such diverse areas as St. Helena, South Africa, Australia, New Zealand, Tonga, and South America. A good example of this type is Pseudocharopa pinicola (Pfeiffer, 1854) from Lord Howe Island (Figures 7, 2). The central tooth (mid- dle row in Figure /) is tricuspid and slightly but distinctly smaller than the adjacent laterals. Ectoconal and endo- Explanation of Figures / to 6 Pseudocharopa pinicola (Pfeiffer, 1854) Figures / -2: Station 2, Max Nichol’s Memorial, north end, Lord Howe Island. Field Museum of Natural History number 127872. Figure 7: central and first lateral teeth from posterior end of radula X 2320 Figure 2: early marginal teeth X 2330 Maoriconcha oconnori (Powell, 1941) Figures 3-4: Bock Peak, near Mt. Stevens, Wakamarama Range, Collingwood, West Nelson, South Island, New Zealand (ca. 172°27’ E, 40°48’S). Auckland Institute and Museum. Figure 3: early lateral teeth Figure 4: mid-marginal teeth x 1545 x 1570 Suteria ide (Gray, 1850) Figure 5: Waiwera-Pohoi Road, north of Auckland, North Island, New Zealand. Field Museum of Natural History number 135430. Two lateral teeth with right tooth pulled partly loose from the basal plate X 2935 Mystivagor mastersi (Brazier, 1876) Figure 6: Station 17, near Goathouse, northeast slope of Mt. Lidg- bird at 1200 feet elevation, south end of Lord Howe Island. Field Museum of Natural History number 127963. Early to mid-lateral teeth showing flared anterior basal plate with teeth in both elevated and resting position x 1315 Explanation of Figures 7 to 12 Draparnaudia michaudi (Montrouzier, 1859) Figures 7-8: Station NC-13, Heinghene, northeast coast of New Caledonia. Field Museum of Natural History number 159299. Figure 7: central and early lateral teeth x 1480 Figure 8: mid-marginal teeth from right side of radula at poste- rior end x 1470 Amimopina macleayi (Brazier, 1876) Figures 9-10: Little Stuart River, Silver Plains, Cape York Pen- insula, Queensland, Australia. Australian Museum, Sydney, number C63785 Figure 9: central and lateral teeth viewed from a moderately high x 745 X 728 angle looking diagonally anteriorly Figure /0: mid-marginal teeth Rhachistia histrio (Pfeiffer, 1854) Figures // - 12: La Roche, Mare, Loyalty Islands, New Caledonia. Field Museum of Natural History number 109435. Figure //: central (lower left) and early lateral teeth viewed from almost directly above x 1575 Figure /2: central and lateral teeth viewed from about a 55° angle looking diagonally forward X 835 [Sotem] Figures 1 to 6 Tue VELIcGER, Vol. 15, No. 3 Tue VELIGER, Vol. 15, No. 3 [SoLem] Figures 7 to 12 Vol. 15; No. 3 , THE VELIGER Page 167 conal cusps of the laterals are equal in size and far smaller than the mesocone. Careful inspection shows that there is no clear overlap of the basal plates between rows going from middle to right of the photograph, and only slight overlap in going from right to left. Viewing the marginal teeth (Figure 2) shows that the endocone (cusp on upper side in photograph) has become larger than the ectocone, the teeth sit on very small basal plates that are distinctly separated from each other, and the teeth lie at a sharp angle to the plane of the basal membrane. In this type of tooth there is no major interlock system between rows although probably under stress there could be slight over- lap. Referring again to the central and lateral teeth (Figure 7), note that the anterior margin of the tooth shows only a very slight indentation in the central and virtually no indentation in the laterals. Maoriconcha oconnori (Powell, 1941), a New Zealand charopid with reduced shell, has slightly modified teeth (Figures 3, 4). Compared with Pseudocharopa, the lateral teeth (Figure 3) have the anterior margin of the tooth noticeably ‘notched’. The supporting ridge under the mesocone of the tooth in the next anterior row (left in photograph) fits into the notch when the tooth is elevated and under stress. The teeth barely visible in the lower right portion of the photograph are elevated. It is clear that the anterior edge of the teeth is resting against the basal plate with the mesoconal ridge firmly wedged within the notch of the tooth in the immediately posterior (left) row. The marginal teeth, however, show very little differ- ence in the basal plate structure or in the cusp form (Figure 4). While the teeth are slightly more slender and distinctly more elongated than in the Pseudocharopa, the development of an interlock system for the central and lateral teeth required only alterations in the anterior part of the tooth. Exactly the same modification is seen in Suteria ide (Gray, 1850) (Figure 5). Utilizing a fold in the radula to extract information, the overlap of the teeth rows is evi- dent. The anterior part of the radular basal plate is not attached, but angles upwards to extend above the posterior section of the basal plate in the next anterior row. The tooth on the lower side of this photograph has been torn loose from the basal membrane and is twisted upwards. The lower protruding ridge on the left margin is part of the attachment area. It obviously ends well short of the an- terior margin of the cusp structure. Having this section free of the basal membrane and elevated permits its over- lap, see the tooth in the upper portion of the photograph. While this is the basic pattern in the Charopidae, with differences in the shape of the basal notch (compare Figures 37 and 5) providing the main alterations, some species show a flared posterior ridge development exactly equivalent in function to that found in the Camaenidae. Mystivagor masters: (Brazier, 1872) is a rare charopid found on Lord Howe Island. Mainly characterized by a succineiform shell (see HEDLEY, 1891: plt. 21, fig. 9), dis- section shows that it is a modified charopid only generically differentiated from Pseudocharopa (SOLEM, unpublished). The radula (Figure 6) retains the basic tricuspid teeth, but in the lateral teeth the anterior is flared outwards and upwards into a broad ridge that rests against the posterior basal plate section when the cutting edge is elevated. The relatively low magnification of this photograph permits seeing teeth in a number of stages between elevated and horizontal. The Charopidae show a basic pattern of only slightly overlapping basal plates, as exemplified by Pseudochar- opa, major overlap and interlocking during feeding stress, see Maoriconcha and Suteria, with some experiments into anterior ridge support as seen in Mystivagor. This is a far less dramatic pattern of change in radular support struc- ture than was shown in just the three sympatric genera of Australian Camaenidae (SoLeM, 1972: figs. 21-29). The Charopidae are much smaller in size and presumably have a narrower range of both size and type of food materials than do the Camaenids. The Charopidae have not been investigated in terms of diet, but the extremely uniform cusp structure suggests that there may be comparatively little food resource use radiation. The Pacific Island Endodontidae are equivalent to the Charopidae in habitat and patterns of radiation. Their pattern of cusp structure is markedly distinctive, but the basic support system is virtually identical. Lateral teeth from an undescribed genus related to Thaumatodon are shown in Figure 17. This photograph is of a place where the radula was folded and creased, hence the teeth are in an abnormal position relative to each other. The cusps on the tooth in the center of the picture are pointing straight down and the underside of the anterior basal plate section is visible. This has not been torn free of the basal mem- brane, but 1s normally unattached. It angles upwards from the attached posterior basal plate section that is shown slanting towards the lower left corner of the picture next to the ectoconal cusp. If the tooth was rotated 135° up- wards and to the left. this tree section of the basal plate would come in contact with the basal plate of the tooth at upper left of the picture and its cusps would be in ele- vated, stressed position. The fact that the notching of the tooth is minimal does not alter the basic identity of the support pattern. Algal Scraping Cusp Evolution in the Enidae Development of broadened and gouge-like cusps in ar- boreal snails that feed on algae has occurred in many families. The pattern seen in Papuina was illustrated in Page 168 SoteM (1972: figs. 12-16). Here the early lateral teeth were huge, almost vertically erected spade-like ridges with the later lateral teeth tending to develop minor side cusps. This is a logical evolutionary pattern in the Camaenidae where unicuspid central and early lateral teeth are very common, as for example in Australian desert camaenids used to show basal plate support systems (SOLEM, 1972: figs. 21-29). The situation is quite different in the Enidae where bicuspid radular central and laterals are far more common than tricuspid teeth (see HeEssr, 1933). Radulae from a New Caledonian endemic species, Draparnaudia michaudi (Montrouzier, 1859), an Australian endemic genus, Amz- mopina, and an African species introduced into New Caledonia and the New Hebrides, Rhachistia histrio (Pfeiffer, 1854), provide evidence of another pattern of evolving functional scraping cusps. Specimens of Draparnaudia (Figures 7, 8), although arboreal in habitat, have only weakly modified teeth. The mesocone of both central and lateral teeth (Figure 7) is broadly rounded with only a slight blunting to the tip. While the central tooth retains only the slightest trace of side cusps, the laterals have a very prominent pointed ectocone. The angle of view in this picture is about 45° from the horizontal and looking slightly backwards from above the right side of the radula. Hence the ectocones on the functionally right side of the central tooth (lower part of photograph) appear to be aligned with the mesocone. However, when looking at the laterals from the left side of the radula (upper part of photograph), it is obvious that the ectocones are more sharply elevated and have their highest point of elevation well behind that of the ectocone on the same tooth. When functioning, the mesocone would come in contact with the food source first, the ectocone slightly later in the feeding motion. ‘The ectocone is ele- vated almost to the same height as is the mesocone. As in the Camaenidae and Charopidae, there is a sophis- ticated pattern of tooth interlock. The central tooth (mid- THE VELIGER Vols 15;3Nome dle row of Figure 7) rests between two elevated ridges on the corner of the next anterior basal plate, while the laterals (upper and lower tooth rows) sit on a knob and ridge pattern. The knob would provide more vertical support, while the ridge would provide resistance to any lateral shift of the tooth upon encountering pressure. In contrast, the marginal teeth (Figure 8) apparently have only an emergency overlap system with vague remnants of the basal plate ridge system (see tooth at upper left). The small, unicuspid teeth at the upper right are not central teeth, but part of a deformed row of lateral-mar- ginal transition teeth. In the marginal teeth the ectocone shows a strong tendency to split into several cusps, is not elevated to the same extent as the mesocone, and is not situated in a clearly anterior position. The Australian Amimopina macleayi (Brazier, 1876) (Figures 9, 10) is more typical of arboreal taxa in cusp structure. In looking at the centrals and laterals (Figure 9) the angle of viewing is slightly higher than in Figure 7, and the direction of view is reversed, that is, it is from the posterior end looking forward. Here the unicuspid central tooth has a spatulate, serrated edge, while the basal plate shows only a weak anterior extension that seems to barely overlap onto the edge of the next basal plate (lower right of photograph). Lateral teeth in the lower left section of the photograph show the cusp outlines quite clearly. The mesocone is greatly broadened and with blunt, serrated edge. Although the first lateral shows no trace of an endo- cone, progressive development of the same is seen going from the center to left corner of the photograph. The ectocone is seen as a basically unicuspid structure sitting well behind the mesocone with a tendency to split. When the view is shifted to the upper right section, the ectocone is seen to be a claw-like, almost vertical projection that is equal in height to the broad mesocone, but sitting almost at the anterior end of the basal plate. Marginal teeth (Figure 10) have the endocone quite prominent in size, retain the broadened mesocone with traces of cusp edge Explanation of Figures 13 to 17 Samoana canalis (Mousson, 1865) Figures 13, 15, 16: Station 28, Vai’a’ata, near Vaiola, 900 feet ele- vation, Savaii, Western Samoa. Field Museum of Natural History number 152570. Figure /3: vertical view of central and lateral teeth from posterior end of radula x 1000 Figure 15: low angle view of central and lateral teeth from poste- rior end of radula x 840 Figure /6: view of lateral teeth from same area of radula from a steeper angle. The bits of porous material are contaminants of styrofoam dust from a storage box and not food particles or snail tissue < 770 Partula auraniana (Hartman, 1888) Figure /4: Mosina Bay, Vanua Lava, Banks Group, New Hebrides. Field Museum of Natural History number 109346. of single lateral tooth from right side of radula with a portion of the x 1865 Angled view central tocth visible at upper left New genus of Endodontidae Figure 17: Station F-7, west coast of Tuvutha, northeast Lau Archi- pelago, Fiji. Field Museum of Natural History number 168136. Lateral teeth bent by a sharp fold in the basal membrane showing free anterior portion of basal plate X 5130 Tue VE.IcER, Vol. 15, No. 3 [SoLem] Figures 13 to 17 oy | | . oe Re 4 Vol. 15; No. 3 serrations, while the ectocone is split into two cusps and lies markedly to the anterior of the mesocone. They differ from the laterals in that the ectoconal cusps are not pos- teriorly elevated, but lie in the plane of the slanted meso- conal protrusion. The African Rhachistia histrio (Pfeiffer, 1854) (Figures 11, 12) shows a slightly different pattern. Seen from above (Figure 11) the mesocone has a very broad, blunt tip, while the ectocone is irregularly bicuspid. In the lower left portion of Figure // the anterior part of the central tooth can be seen. When viewed from above at a 55° angle look- ing diagonally forward (Figure 1/2), the bicuspid ectocone is seen to extend vertically upwards in exactly the same fashion as the unicuspid ectocone of Amimopina (Figure 9). Even rudimentary examination of Figures 9 and // shows that the details of mesoconal cusp broadening, pat- tern of anterior cusp elevation, and type of anterior basal plate termination are quite different. The functional aspects of the lateral teeth in the two radulae are identical. First a spatulate mesocone scrapes against the food source surface, then the elevated ectocone catches and pulls any loose pieces. The details of how this dual action mechan- ism is constructed in the two taxa are very different. Since the anatomical structures of Rhachistia and Amimopina are not similar, their evolution from different sections of the family is certain. The similarities in cusp position and structure are convergent. Both types were probably de- rived from a basic pattern similar to that found in Drap- arnaudia (Figures 7, 8), which is standard in nearly all enids (see Hesse, 1933). As shown below, the functional pattern of a posterior scraping cusp followed by an equally elevated catching cusp also is found in the Partulidae (Figures 13-16, 18-21). Tooth Structure in the Partulidae Following Konno (1968), the three genera of the family Partulidae are Eua, Samoana, and Partula. He hypothe- sized that Eua was the most primitive, Samoana evolved from Eua, and Partula was derived from Samoana. The data presented here give no information concerning inter- generic relationships, but concentrate on the functioning similarities to the enid radulae and demonstrate that in addition to interlock systems between rows, there can be functional interlock systems between tecth in the same row. When viewed from directly above (Figure 13), the central tooth of Samoana canalis (Mousson, 1865) is seen to have remnant side cusps, while the anterior end of the basal plate rests firmly upon the posterior section of the basal plate in the next row. The lateral teeth have a spatu- THE VELIGER Page 169 late mesoconal cusp with serrated edge, while the ectocone lies well anterior (towards bottom of the photograph) of the mesocone and also has a broadened, serrated cusp edge. The uppermost teeth in Figure 3 indicate the great extent of basal plate overlap in the laterals. When viewed from above at perhaps a 40° angle looking diagonally anteriorly (Figures 75 and 16), the cusp relationships and pattern of basal interlock become clear. As in the enids, the ectoconal cusp is elevated to the same height as the mesocone (upper portions of Figures 15 and 16) and con- sists of a single curved blade. This would be easily de- rived from the structures seen in Draparnaudia (Figure 7) and is much less complicated than the ectoconal eleva- tions seen in both Amimopina and Rhachistia (Figures 9 and 12). Basal plate overlap is particularly obvious in Figure /6. The anterior portion of each tooth normally lies directly above the posterior portion of the next an- terior basal plate. It fits between two ridges on the basal plate and apparently (see upper left of Figure 16) normally is only slightly raised above the recipient basal plate even when in a non-functioning position. This is even more clearly shown in Eua globosa (Pilsbry & Cooke, 1934) from Tonga (Figures 20, 21). These photographs were taken at a lower angle and looking more directly anteriorly than in Figures 75 and 16. Asa result, the extent of basal plate overlap (Figure 20) can be seen quite clearly, while a high magnification shot (Figure 27) demonstrates the contact point between the basal plate and anterior termination. Figure 18 shows the overlap in the central tooth (upper complete row), with details of the central tooth overlap- ping seen in the upper left of Figure 20. Comparisons between Eua globosa (Figure 18 and 20) and Samoana canalis (Figures 15 and 16) in regard to central tooth structure show changes in basal plate configuration and anterior tooth margin. Similarly, inspection of Figures 15 (Samoana) and 18 (Eua) shows that the lateral teeth of Eua have a much stronger basal ridge that is more transversely oriented (Figure 20) than in Samoana. The anterior mar- gin of the lateral teeth (Figures 16 and 18) also show slight differences in shape. In Partula auraniana Hartman, 1888 from the New Hebrides (Figure /4) the lateral teeth are essentially as in Samoana in regard to basal plate ridging, while the central tooth (partly shown in upper left of figure) has a more prominent ectoconal cusp than does the central tooth of either Samoana (Figure 13) or Eua (Figures 18, 20). Marginal teeth of all three genera retain a spatulate mesocone, but have the ectocone reduced to a slender point (see upper left of Figure 19). There is no basal plate overlap between rows of teeth, but instead the marginals have a support system whereby the blade of the tooth is supported by the basal plate of the next inner tooth in the Page 170 THE VELIGER Vol. 15; No. 3 same row (Figure 19). This photograph is of marginal teeth from the left side of the radula and the view is from a very low angle looking towards the outer margin of the radula. The teeth are mid-marginals in position. At the bottom of the photograph, note how the right anterior margin of the tooth is curved upwards and how the cusp extends significantly towards the viewer in relation to its basal plate. Then observe how the same structure on the second tooth from the bottom in this photograph rests against an elevated ridge on the left margin of the first tooth’s basal plate. The stress on the marginal teeth dur- ing feeding apparently involves lateral strain rather than the front axis stress on the lateral and central teeth. Hence the shift in support function from between row interlock in the central and laterals to between teeth of one row in the marginals. Compared with the enids (Figures 7-12), the partulids are identical in basic lateral tooth functioning, leading with a serrated mesocone and following with an equally elevated ectocone to catch loosened pieces. ‘The pattern of interrow support and the details of tooth form are quite distinctive. Marginal teeth in the two families are very different from each other in form and structure, although the basic cusp patterns have many things in common. Both groups have taxa specialized for algal scraping and the functional aspects of the cusps are the same, yet the struc- ture underlying this function differs radically. The simi- larity in cusp form was observed many years ago with optical equipment, but the differences in understructure could not be seen without use of the scanning electron microscope. DISCUSSION Examples from the Charopidae, Endodontidae, Enidae and Partulidae demonstrate some of the variety found in interrow supporting mechanisms in the pulmonate mol- lusks. This extends the observations on the Camaenidae that were reported previously (SOLEM, 1972). These inter- lock mechanisms differ widely within and between groups, but are functionally useful during the stress of actual feeding. The observations made here have involved the use of excised radulae artificially mounted to simulate feeding position. While satisfactory to show the existence of the interlock mechanisms and to suggest hypotheses concern- ing their exact functioning, observations on radulae that are still in position on the odontophoral cartilages will be needed to interpret differences. RuNHAM (1969) used freeze-drying techniques to observe partly dissected buc- cal masses with the odontophoral tip exposed and washed for observation. Critical point drying offers an equally useful technique for studying essentially im sitw radular tips. Full understanding of the functional differences that led to the differentiation into lateral and marginal teeth will require im situ study, examination of the extracted radula, and feeding track observations. In all of these the scanning electron microscope will be an invaluable aid. Currently we are in the same stage in exploiting the use of this instrument that Robert Hooke and the Dutch microscopists were during the mid-1600’s in their experi- ments using the optical microscope. The cusp structure of arboreal snails in the Camaenidae (SoLEM, 1972: figs. 12-16), Enidae (Figures 7-12), and Partulidae (Figures 13-16, 18-21) is seen to involve broadly spatulate mesoconal cusps that in unworn condi- tion have serrated tips. In the camaenid genus Papuina this is the sole mechanism, but in the Enidae and Partuli- dae the broad mesocone is followed (in a functional sense) by an equally elevated, pointed ectocone. In all three groups the details of understructure and patterns of stress supports are very different, indicating independent ori- gins for these structures. The functional convergence in cusp patterns, however, strongly suggests that this scrap- ing mesocone followed by a pointed or curved ectocone is an extremely efficient arrangement. Observations on radulae of sympatric arboreal species are planned to see whether these species show differences in cusp form that could be related to diet differences and hence indicate niche separation. Also studies of arboreal taxa in other families are being pushed to find out if the basic pattern of mesocone-ectocone sequence is followed in other taxa such as the Bulimulidae. In two groups, the Charopidae and Enidae, species are illustrated that suggest stages in the evolution of row Explanation of Figures 18 to 2/ Eua globosa (Pilsbry « Cooke, 1934) Figures 18-2]: Station T-19, above forestry camp at 600 feet elevation, Eua, Tonga. Field Museum of Natural History number 152388. Figure 78: central and early lateral teeth viewed at moderate angle from left side of radula > 1050 Figure /9: marginal teeth on left side of radula viewed at very low x 1570 Figure 20: central and early lateral tecth viewed at low angle X 1320 Figure 27: contact point between anterior elevated cusp section X 4335 angle looking towards edge of radula looking almost directly anteriorly with posterior part of next basal plate Tue VEeE.icErR, Vol. 15, No. 3 [SoLEM] Figures 18 to 21 - t — — =a Vol. 15; No. 3 THE VELIGER Page 171 EEE interlock (Charopidae) or algal scraping cusp structure (Enidae). These are not intended to represent linear evo- lutionary stages in any sense, but are simply chosen to demonstrate the basic structure and types of modifications needed to arrive at the advanced character state. SUMMARY Patterns of interlock between radular teeth in adjacent rows are present in many families of pulmonates. Possible basic patterns in structure and the types of progressive modifications are shown in the Enidae and Charopidae. Convergence in cusp form for the probable purpose of algal scraping is demonstrated in the Partulidae and En- idae, together with hypotheses concerning their function- ing during feeding. These preliminary observations were possible only because of the scanning electron microscope. When combined with more advanced techniques in speci- men preparation, far more data on the patterns of mol- luscan feeding can be obtained than was possible in the past. Literature Cited HEDLEY, CHARLES 1891. The land and fresh-water shells of Lord Howe Island. Rec. Austral. Mus. 1 (7): 134-144; plts. 21-22 (30 June 1891) Hesse, Pau 1933. Zur Anatomie und Systematik der Familie Enidae. Arch. Naturgesch., N. F 2 (2): 145-224; 43 text figs. Konpo, YosHIo 1968. Partulidae: preview of anatomical revision. 81 (3): 73-77; 1 table Pirspry, HENry AuGUSTUS 1893 - 1895. Manual of conchology. Second series: Pulmonata. 9: xlviiit+ 366 pp.; 71 plts. (16 November 1893 to 2 February 1895) RunHAM, NorMAN 1969. The use of the Scanning Electron Microscope in the study of gastropod radula: The radulae of Agriolimax reticulatus and Nucella lapillus. Proc. 3rd Europ. Malac. Congr., Malacologia 9 (1): 179 to 185; 7 text figs. SoL—EM, ALAN 1970. Malacological applications of scanning electron microscopy. I. Introduction and shell surface features. The Veliger 12 (4): 394 to 400; plts. 58-60; 1 table (1 April 1970) 1972. Malacological applications of scanning electron microscopy. II. Radular structure and functioning. The Veliger 14 (4): 327 - 336; 6 plts.; 1 text fig. (1 April 1972) The Nautilus (18 April 1968) Page 172 THE VELIGER Vol. 15; No. 3 External Description of a Living Aranucus bifidus (Odhner, 1936) (Opisthobranchia : Dendronotacea) C. H. CARLSON anp P. J. HOFF University of Guam (2 Text figures) THE DENDRONOTACEAN FAMILY Aranucidae was estab- lished by ODHNER (1936) to accommodate a single species collected in the Gilbert Islands by S. Bock in 1917. Ara- nucus bifidus does not appear to have been collected since the original specimen was reported and consequently there has been no description of the external parts of the living animal. Aranucus bifidus is a commonly occurring species found throughout the year on both the windward and leeward reef flats of Guam. Specimens have also been found at Anatahan and Pagan Islands in the northern Marianas. Figure 1 Aranucus bifidus (Odhner, 1936) Dorsal View Description of External Aspects: Length 7 to 12 mm. The body is long, higher than it is wide, with the back margins clearly marked off from the smooth sides (Fig- ure 1). The dorsum is smooth from head back to tapering tail and normally has 4, rarely 5, pairs of smooth bifid projections along the margin. The first 3 pairs are of nearly equal size with the first pair being occasionally smaller and the fourth pair always smaller. One branch of each pro- jection curves in toward the middorsum and on large ani- mals overlaps the opposite projection; the other branch curves outward. On some animals there is a projection suggesting the beginning of a fifth pair and sometimes a single complete bifid projection. The rhinophores are retractile into a high, wide sheath that has a fairly large pointed lobe projecting laterally and slightly anteriorly (Figure 2). The peduncle of the Figure 2 Aranucus bifidus (Odhner, 1936) Rhinophore rhinophores is fairly heavy at the base, then narrows until it reaches the rhinophore club which is brush-like. The club is composed of a single long central papilla surround- ed by 12 or 13 shorter, thin, digitiform papillae. Vol. 15; No. 3 THE VELIGER Page 173 The head has 2 pairs of tentacular processes, one pair long and tapering, directed forward; the other pair short, directed antero-laterally. The foot, which projects very slightly past the body, is thin, widened and rounded anteriorly and is furrowed a- long its entire length. When not in contact with the sub- strate it is frequently folded at the midline. The genital pore is directly below the first set of mar- ginal projections on the right and the anus is lateral be- tween the first and second set. Eye spots are barely visible through the dorsum at the posterior base of the rhino- phores. Color: The color of the dorsum varies from a light pink to a dark magenta, darker at the base of the marginal projections. The sides are lighter with a very light streak just below the margin. There is an internal dark spot visible middorsally between the first pair of projections and the orange color of the ovaries shows through the dorsum beginning at the second set of marginal projec- tions, sometimes extending back to the fourth set. The marginal projections are white, as is the tail. The rhinophore sheath has a dark red-violet base, light- er on the outside. The projecting lobe is white. The ped- uncle of the rhinophore is transparent, the brush-like pa- pillae are orange with the long central one having a white tip. The basal third of the longer tentacles is red-violet with the remainder white. The shorter tentacles are trans- parent on smaller animals, and pink and translucent white on larger animals. The foot is transparent with tiny specks of translucent white. Literature Cited Opuner, Nits HyjaLMar 1936 Nudibranchia Dendronotacea. A revision of the system. Mélanges Paul Pelseneer. Mém. Mus. Roy. d’Hist. Nat. Belg., Ser. II, Fasc. 3: 1057-1128; 1 plt.; text figs. 1 - 47 Page 174 THE VELIGER Vol. 15; No. 3 Food-Preference of the Nudibranch Aeolidia papillosa, and the Effect of the Defenses of the Prey on Predation BY VIRGINIA L. WATERS Pacific Marine Station, Dillon Beach, California 94929 (5 Text figures) INTRODUCTION IT HAS LONG BEEN KNOWN that at least European Aeoli- dia papillosa (Linnaeus, 1761) preys on anemones (Bou- TAN, 1898; Extor, 1910), and more recent observations have confirmed this (MILLER, 1961; SweENNEN, 1961). However, there is little agreement as to which species are eaten or preferred (Table 1). It appears that Aeolidia may show a distinct preference within a particular locali- ty, but that the species preferred may vary from place to place. Of several factors which may cause the nudibranchs to feed on different species in different localities, I was par- ticularly interested in the defense of the prey. There has been little work published on the effect of defenses on predation. Ropson (1961) noticed that Aeolidia fed only on the base and column of Stomphia coccinea. The nudi- branchs withdrew whenever they touched the tentacles. Not only were the tentacles effective in limiting predation, but the anemones swam away when Aeolidia contacted them, usually leaving the nudibranchs behind. BouTan (1898) briefly discussed the difficulties nematocysts caused Aeolidia. He noticed that the nudibranchs secreted large amounts of mucus upon contact with the anemones and that the nematocysts became entangled in this and so did not injure the nudibranchs. RussELL (1942) stated that acontia of Metridium marginatum became caught in the large quantity of mucus secreted by the nudibranchs but that they were eaten along with the whole anemone. Wo tter (1967) described the extrusion of acontia and contraction of Metridium senile as Aeolidia began to feed on the anemones, with no mention of the effect of such behavior on the nudibranchs. Rosin (1969) found that when Anthopleura nigrescens was attacked by the eolid ' Present address: P O. Box 103, Arcata, California 95521 Herviella spec. nov. the anemones regularly detached from the substrate within a few minutes. The nudibranchs would hold on to an anemone for a while, but eventually the animals would separate and the anemone would fall. The nudibranchs would then resume feeding on a new anemone. The relationship between Metridium senile and Aeoli- dia is particularly interesting. Nearly all of the European workers and Russet (1942) in New England (Table 1) indicated that Acolzdia eats this species or even prefers it to others. No one has said that Aeolidia does not eat Metridium. However, observing animals from Puget Sound, Washington, I discovered that when I placed a nudibranch on such an anemone, the anemone immedi- ately contracted and extruded acontia. The nudibranch for its part withdrew violently and became covered with thick mucus when touched to the anemone. When placed at the base of an Epzactis prolifera, it immediately began feeding. Yet, the acontia of European and New England Metridium did not seem to prevent the nudibranchs from attacking the anemones. In addition to nematocysts, escape responses, and de- tachment, the occurrence of anemones in dense concen- trations of individuals could minimize the effects of pre- dation by reducing the chances that a given individual would be entirely consumed. The adaptive significance of the occurrence of the local Anthopleura elegantissima in dense groups could thus be related to predation by nudi- branchs. The effectiveness of grouping would depend on the predatory methods of Aeolidia, however. In addition to grouping, the column of this anemone is covered with sand so that very little of the body surface is exposed. When the anemones are expanded, the tentacles and oral disk are the most accessible parts. The primary objectives of this study were (1) to obtain preliminary information on the food of Aeolidia papillosa Vol. 15; No. 3 THE VELIGER Page 175 Table 1 Species eaten or preferred by Aeolidia (from literature) ” Worker McMuitan, 1942 not stated Species preferred Other species offered or mentioned Tealia crassicornis RussELL, 1942 not stated Metridium marginatum STEHOUWER, 1952 Metridium senile BraaMs & GEELEN, 1953 Actinia equina Actinothoe anguicoma Diadumene cincta Tealia felina Metridium senile 6 species of hydroids, including Tubularia indivisa Miter, 1961 Actinia equina Anemonia sulcata Sagartia troglodytes Tealia felina Tubularia indivisa Rosson, 1961 SWENNEN, 1961 Wo tter, 1967 Stomphia coccinea Metridium (senile?) Sagartia (troglodytes?) Tealia (felina?) Actinia equina Metridium senile Metridium senile Tealia felina Actinothoe anguicoma Diadumene cincta Sagartia troglodytes Actinia equina Sagartia troglodytes Tealia felina 2 The observations were made in different localities in Europe, ex- cept those of RussELt, 1942, which were made on the Atlantic coast of the United States in yet a different part of its range, and (2) to begin to answer the question “What governs local food prefer- ence?” by investigating the defensive responses of the prey. The effects of the following potential defenses on preda- tion were studied: (a) nematocysts, particularly those of the acontia of Metridium senile and of Diadumene luciae, and (b) detachment or other escape responses. In addi- tion, the effect of tentacles, sand on the column, dense groups, and the occurrence of detachment (if present) in Anthopleura elegantissima were studied. As a necessary adjunct to a study of defenses, the behavior of Aeolidia in detecting and locating prey and in feeding was observed. MATERIALS anp METHODS The study was conducted during the summer of 1969 at the Pacific Marine Station, Dillon Beach, California. Individuals of all species of anemones found in the inter- tidal zone of various local beaches were collected to be used in the experiments and observations. They were: Anthopleura artemisia (Pickering, 1848) ; Anthopleura elegantissima (Brandt, 1835) ; Anthopleura xanthogrammica (Brandt, 1835) ; Corynactis californica Carlgren, 1936; Diadumene luciae (Verrill, 1898) (called Haliplanella lu- ciae by Hanp, 1955) ; Epiactis prolifera Verrill, 1869; Metridium senile Linnacus, 1767; Tealia coriacea (Cuvicr, 1798) ; and Tealia crassicornis (Miiller, 1776). Anthopleura artcmisia lives buried in sand and attached at the base to rocks in protected areas, such as between large boulders, in zones 3 and 4 of RickEeTTs & CALVIN, 1968. Page 176 THE VELIGER Vol. iS Nows Anthopleura elegantissima occurs on rocks of the protected outer Coast or in quict waters of bays, in zone 3. The anemones occur in large dense masses of individuals which appear to originate from a single individual by longitudi- nal fission (Forp, 1964; Hann, 1955). Sand, gravel, and bits of shell adhere tightly to the exposed parts of the columns of these anemones. Anthopleura xanthogrammica, the largest species of the 3, lives in more or less protected areas of the open coast as well as on the protected outer coast in the same localities as A. elegantissima, but below that species. The anemones are solitary or occur in small groups which are not as tightly packed as those of A. elegantissima. Corynactis is a very small anemone occurring in pro- tected areas on rocks in the protected outer coast, in zone 3 and below, in dense aggregations. The anemones have capitate tentacles with very large nematocysts. Diadumene, an introduction from Japan (RICKETTS & Carvin, 1968), occurs on oyster shells and rocks of bays and estuaries, in zone 2. Acontia are present. Epiactis occurs in protected areas on rocks and algae in the protected outer coast, and on a variety of solid objects including plants in bays and estuaries, in zones 3 and 4. Metridium is a large anemone occurring in rocks, wharf pilings, and floats in quiet water, in zone 4 and below. Acontia are present. Tealia coriacea occurs in rocks in protected areas with shell, sand, and gravel attached to the column and often ea se Sea A.x. buried in sand and gravel. This species was difficult to obtain and was not used extensively in the study. Tealia crassicornis, a large anemone, occurs on rocks of the open coast with Anthopleura xanthogrammica, in zone 4 and below. When size or degree of aggregation of anemones is not mentioned, the anemones are not noteworthy in those re- spects. Most of the nudibranchs studied were collected from rocks covered with Anthopleura elegantissima on the san- dy beach below the marine station. A few were collected from rocks of the north jetty at the entrance to Bodega Bay, on which A. elegantissima, A. xanthogrammica, Cor- ynactis, and Epiactis were the most abundant anemones. Some nudibranchs were also collected from rocks in To- males Bay (Nick’s Cove) which had A. elegantisstma living on them. In all, about 20 nudibranchs were collected. Those from each locality were not studied separately, be- cause I was unable to obtain enough individuals from the jetty or Nick’s Cove. EXPERIMENTS PERFORMED The experiments to determine food preference were of 2 main types: A. In the first, several nudibranchs were introduced into a plastic cage (30 « 19 x 12cm) containing (with some exceptions) one individual of each species of anemone ie ; = A.a. M. & 5 5 25 r 30 4 p p35 RW 40 D 5 10 15 A 20 i ee Lote + 3C. +1 Dz -1Ap. +2D.414.4. +1Ter. 41D. -1A.p. +1A.a. —2A.p. —1A.p. Figure 1 Experiment A, number 1: Number of days Acolidia spent eating the different anemones and order in which they were eaten. Arrows show number of anemones (abbreviated as in Table 3) or nudibranchs (Ap) added (+) or removed (—) on that day. Open end of bars indicates anemones were not consumed entirely Vol. 15; No. 3 Days Se A A HO. WAL, SPD, ap Nal —wPArp: THE VELIGER Page 177 kA 20 h 30 -14.p.AX_1A.p. +1D. + +1 A.a. -1A-p. nm wm > Figure 2 Experiment A, number 2: Number of days spent eating the differ- ent anemones and order in which they were eaten. Symbols as in Figure 1; * indicates nudibranch died which had been allowed to attach. The cages were covered with cheese cloth to prevent escape of the nudibranchs. Two experiments of this type were run simultaneously for most of the research period (6 weeks). Since the cages also served as holding tanks for nudibranchs not being used in other experiments and as sources of nudibranchs for other experiments, the number in the cages shifted from time to time, as did the individuals involved. The duration of each experiment and the changes made in the numbers of nudibranchs present are shown in Figures 1 and 2. The criteria used to determine preference were: (1) which species were eaten; (2) the order in which the anemones were eaten; (3) the length of time taken to consume each anemone, and (4) the proportion of nudi- branchs feeding during each observation relative to the proportion doing something else (being inactive or wan- dering). Observations were generally made twice a day. B. The second type of food-preference experiment in- volved offering a group of 2-5 nudibranchs a choice be- tween 2 species of anemones which had been put in un- covered glass dishes (11 cm in diameter) and allowed ts attach. A few combinations were not used because of lack of time and nudibranchs, and because they were not cru- cial in determining preference. For the same reasons repli- cations of some combinations were not made. Nevertheless, a given species of anemone was offered to groups of nudibranchs at least 6 times in combination with different species. Judgment of food-preference was based on the same Criteria used for experiment A. Again, observations were made twice a day. The experiments were terminated when one or both anemones were completely eaten or when the nudibranchs persistently wandered or escaped rather than eating. Three further types of experiments were performed to provide information on various aspects of the feeding be- havior of Acolidia and defenses of the anemones, and to provide supplementary information on food-preference. C. To determine whether Aeolidia were attracted to food from a distance, a preferred species of anemone was placed upstream from the nudibranchs. In the first 2 ex- periments, nudibranchs were offered a choice between anemones and water alone to serve as a control for their response to currents. In the third experiment, the responses to 2 species offered at the same time were compared. In all cases water flowed gently into 2 plastic cages (30 « 19 x 12cm) containing respectively either the anemones and water or the 2 species of anemones. A rubber tube (4 inch diameter) connected each of these cages with one at a slightly lower level containing the nudibranchs. The upper ones rested on the bottom halves of several plastic petri dishes 8mm deep. The ends of the tubes extended to the bottom of all 3 cages. Water flowed out of the nudibranch cage through holes bored near the top. The aneraones had been put in the bottom half of a petri dish and allowed to attach before being introduced to the cage. The experi- ments were run for 24 hours, after which the number of nudibranchs in the 3 cages was noted. Only 3 experi- ments were performed because of insufficient time, space, and nudibranchs. Page 178 THE VELIGER Vol. 15; No. 3 D. To provide information on the defensive adaptations of anemones and their effect on the nudibranchs, as well as on searching and food-locating behavior of the nudi- branchs, nudibranchs were introduced to bowls in which anemones had attached, and the behavior of predator and prey was observed. E. The last type of experiment dealt with the feeding behavior and activity pattern of nudibranchs offered groups of Anthopleura elegantissima and the defenses of this species. Two experiments were performed. In the first, 2 nudibranchs were put into an uncovered enamel pan (17x 29%5cm) into which 20 anemones had been placed several weeks earlier and which had attached and spaced themselves out. The anemones were not tightly packed together as in nature but had spaces of several centimeters between most of them, nor did they have sand adhering to their columns. They had been collected from different localities at different times and thus were from different clones. Observations of the behavior of the nudi- branchs and anemones were made usually twice a day for 10 days. For the second experiment about 20 anemones were collected from a single area on a rock below the ma- rine station, put in an uncovered round glass dish (14 cm in diameter and 4 cm deep) with adhering sand and loose sand taken from the base of their rock, and allowed to at- tach. Three nudibranchs were then introduced. This ex- periment lasted 8 days and observations were made usually twice a day. RESULTS EXPERIMENT A, Number 1 At the beginning of the experiment 5 nudibranchs were put with the following anemones: diameter of species base (cm) 1 Anthopleura elegantissima A) 1 Anthopleura xanthogrammica 5.0 2 Epiactis prolifera 1.0 and 2.5 2 Metridium senile both 3.5 1 Tealia coriacea 5.0 1 Tealia crassicornis 5.0 Later Anthopleura artemisia, Corynactis californica, Dia- dumene luciae, and another Tealia crassicornis were ad- ded. The number of individuals of each species added and the timing of the additions are indicated in Figure 1. The size of these anemones was not measured. Figure 1 shows that the anemones were eaten in a definite order. The first ones eaten were Epiactis and An- thopleura elegantissima. The smaller Epiactis was com- pletely eaten within two hours following introduction of the nudibranchs, while the larger one and A. elegantis- sima were started. The second ones eaten were Tealia coriacea and A. xanthogrammica. Tealia was attacked within 6 hours and Anthopleura within 24 hours after the first anemones were eaten. Tealia crassicornis was the last of the original anemones to be eaten. Although this ane- mone was first attacked on the day A. xanthogrammica was completely eaten, very little was eaten then. The nudi- branchs did not really begin eating it until the second day after T: coriacea had been consumed. Diadumene (introduced the day before) was attacked the same day as the second attack was made upon Tealia crassicornis. This same anemone was never completely eaten, although it was reduced to ? of the edge of the pedal disk by the 4 day. A period of 5 days elapsed following this day without the nudibranchs having eaten any parts of the remaining anemones: the original Met- ridium and the 3 Corynactis added on the 10" day of the experiment. However, the presence of extruded acontia and mucus in the water seen on 3 observations during this time indicated that Metridium had been attacked. At the end of this 5-day period, 2 more Diadumene and one A. artemisia were added. All 3 were soon attacked, and all but the pedal disk of one Diadumene were completely eaten within 2 days. The new A. artemisia and T. crassi- cornis added soon afterwards were not attacked during the remaining 8 days of the experiment. Likewise, Corynactis and Metridium were not attacked during this time. DISCUSSION Although the nudibranchs showed a distinct preference for certain species, their relative preference for others re- mained unclear. It appeared that Epiactis and Antho- pleura elegantissima were preferred to others offered, but the preference (if any) between these 2 species was not clear. The fact that the smaller Epiactis was eaten before the other 2 (both the same size) indicated that size of prey may play a role in determining food-preference when other things are equal. Although A. xanthogram- mica and Tealia coriacea were the same size and were attacked within a day of cach other, A. xanthogrammica seemed to be preferred, judging by the comparatively short time taken to consume that anemone and by the smaller proportion of time spent wandering (Figures 1 and 3). The relative preference for Diadumene and A. artemisia was unclear. The first time the anemones were in- Vol. 15; No. 3 ERVIELIGER Page 179 troduced one Diadumene was not completely eaten while Anthopleura was, whereas the second time they were ad- ded Diadumene was partially eaten while the other was 100 80 60 40 20 Figure 3 Experiment A, 1 and 2: Percent nudibranchs wandering during the observations made while they were eating each species. Names of anemones abbreviated as in Table 3. The data were obtained by counting the number of nudibranchs wandering during each obser- vation, obtaining the total for the period in which each species was being eaten, and calculating the percent of the total nudibranch- observations. A few anemones were not included because of incon- sistent results (Anthopleura artemisia and Diadumene) or because nudibranchs were not feeding on them during the observations, although they had been eating them previously (Diadumene, the smaller Epiactis of the first experiment, and the Epzactis of the second experiment). The data for Corynactis and Metridium in the first experiment were obtained only from the period of 5 days in which no other anemones were available. The data for these ane- mones in the second experiment were obtained during the period beginning after the original Tealia had been removed until the end of the experiment, although some anemones were available and were slightly eaten during this time. For both experiments, only the nudi- branchs wandering during the time the first Tealia crassicornis was being eaten were included in the data for Téalia not eaten at all. How the preference for Diadumene and Anthopleura fit into the order of preference for the orig- inal anemones could not be determined, since the original anemones were eaten by the time these last 2 were added. Likewise, the relative preference for Diadumene and Te- alia crassicornis was unclear. The fact that both were at- tacked at the same time indicated equal preference, but the fact that Diadumene was not completely eaten indi- cated a stronger preference for Tealia. However, toward the end of the experiment the fact that the new Tealia was not eaten at all while 2 of the 3 Diadumene were at least partially eaten indicated a preference for Diadu- mene. In summary, the anemones can be arranged in the fol- lowing order from most to least preferred: Epzactis and Anthopleura elegantissima; A. xanthogrammica; Tealia coriacea; T. crassicornis; Corynactis and Metridium. In addition, Diadumene and A. artemisia were preferred to Corynactis and Metridium. EXPERIMENT A, Number 2 At the beginning of the experiment 5 nudibranchs were put with one each of the following species: diameter of species base (cm) Anthopleura elegantissima 35) Anthopleura xanthogrammica 3.5 Corynactis californica 0.5 Epiactis prolifera 2.0 Metridium senile 3y) Tealia crassicornis 7.0 Later Anthopleura artemisia, Diadumene luciae, and a new Tealia crassicornis were added. The number of indi- viduals involved and the timing of the additions are in- dicated in Figure 2. The size of the new anemones was not measured. Figure 2 shows that again the original anemones were eaten in a definite order. Epzactis, the first one eaten, was consumed between the 2"? and 3" day, and Anthopleura xanthogrammica was attacked on the 4" day. Tealia was attacked on the 9" day, but was never completely eaten. It began to decompose on the 22™ day and was removed 2 days later. The first Diadumene added was attacked on the day of its introduction. Neither the second Diadumene nor the Page 180 THE VELIGER Vol. 15; No. 3 Anthopleura artemisia added later was eaten by the end of the experiment, although 2 days after their introduction a nudibranch was seen feeding on Diadumene and one day later one was feeding on Anthopleura. The new Tealia added still later was never consumed entirely, although it was first attacked on the day after its introduction and was grazed on throughout the rest of the experiment. Neither Corynactis nor Metridium was eaten, although acontia and mucus were seen in the water during several observations from the 10" day to the end of the experi- ment. DISCUSSION The apparent food-preference was similar to that of the first experiment. Again, Epzactis and Anthopleura ele- gantissima were the first anemones eaten. That Epiactis was eaten first may have been related to its smaller size. The preference for A. elegantissima over A. xanthogram- mica was not as definite as in the first experiment. How- ever, the facts that A. elegantissima was attacked first, was eaten in a shorter time (both were the same size), and less time was spent wandering (Figure 3) indicated a pref erence for that species. Anthopleura xanthogrammica was definitely preferred to Tealia. Again, the relative prefer- ence for Tealia and Diadumene was unclear. In the first instance it appeared that Diadumene was preferred, since it was eaten completely while Tealia was only grazed on slightly over a long time; while in the second instance it seemed as though Tealia were preferred, since the nudi- branchs attacked Tealia before they had completely eaten the previously attacked Diadumene. There was only slight interest in A. artemisia and Metridium and none in Cor- ynactis. In summary, the order of preference seemed to be: Epvactis and Anthopleura elegantissima; A. xanthogram- mica; Tealia crassicornis; Corynactis and Metridium. In addition, Diadumene was preferred to A. artemisia, Cor- ynactis and Metridium. These two experiments also revealed something of the predation methods of Aeolidia. (1) Generally, one or at most 2 anemones were attacked and fed upon simul- taneously. (2) Once begun, the anemones were usually completely eaten (Diadumene being the primary excep- tion, of which a portion of the pedal disk was often left). (3) The nudibranchs when not actually feeding on pre- ferred anemones tended to remain inactive, usually near the anemone being eaten. However, when a less preferred species was being eaten or when an anemone was not being eaten at all more of the nudibranchs were wander- ing when observed (Figure 3). Thus, it seemed that in the latter cases nudibranchs spent more time wandering than when eating preferred anemones. The great difference between the two experiments in the percent wandering when the data for Corynactis and Metridium were taken (Figure 3) was probably due to the much greater state of starvation of the second group of nudibranchs, 3 of which had already died of starvation (Figure 2). Evidence that death was due to starvation was the overall decrease in size of the nudibranchs since the beginning of the experiment, as well as a disproportionate decrease in size of the branches of the digestive gland within their cerata. No nudibranchs died during the first experiment. Those of the first experiment had completely eaten 2 large anemones after they had completed Antho- pleura xanthogrammica: Tealia coriacea and T. crassi- cornis. In contrast, those of the second experiment had not even completed the one T: crassicornis. Further, the data for the second experiment were taken from a period be- ginning 2 days later from the onset of the study than for the first group. It is also noteworthy that the nudibranchs of thesecond experiment consistently spent more time wan- dering throughout the experiment (except the very end) than did those of the first one, thus spending more energy per unit time. EXPERIMENT B The combinations which were offered to Aeolidia and the number of times each was offered are indicated in Table 2. The number of experiments in which each species was eaten first, second, or at the same time as the other species, and the species offered with it for each category are shown in Table 3. The anemones fell into 3 groups which could be ranked from most to least preferred. The first group included Epr- actis, Anthopleura elegantissima, and A. xanthogrammica. These anemones were either eaten first or at the same time as the other species offered. They were eaten simul- taneously, however, only with other members of this group (except for 2 experiments in which Aeolidia ate A. ele- gantissima and Diadumene together). The proportion of nudibranchs wandering when offered anemones of the first group in combination with any other species was less than the proportion wandering when offered only anemones of the other 2 groups (Figures 4 and 5). The 3 species could not be ranked within the group. The second group included Diadumene and Metridium. In all cases in which Diadumene was eaten first, the ane- mones offered belonged to the least-preferred group. In 3 experiments it was not eaten at all. Diadumene was eaten in a much greater proportion of the experiments involving Voltan Now 3 THE VELIGER Page 18] Table 2 Combinations of anemones offered to Aeolidia in experi- ment type B. Letters denote each experiment of a particular combination which was performed Base Diameter (cm) Combination Epiactis and Anthopleura elegantissima Epiactis and Anthopleura xanthogrammica Epiactis and Corynactis Epiactis and Metridium Epiactis and Tealia crassicornis Anthopleura elegantissima and A. xanthogrammica Anthopleura elegantissima and A. artemisia Anthopleura elegantissima and Corynactis Anthopleura elegantissima and Diadumene Anthopleura elegantissima and Metridium Anthopleura elegantissima and Tealia Anthopleura xanthogrammica and Diadumenc Anthopleura xanthogrammica and Metridium Anthopleura xanthogrammica and Tealia Diadumene and Anthopleura artemisia Diadumene and Corynactis Diadumene and Metridium Diadumene and Tealia Metridium and Anthopleura artemisia Metridium and Corynactis Metndium and Tealia Corynactis and Anthopleura artemisia Corynactis and Tealia . 0.5 and 0.8, respectively . no data . both 2.0 pleS rand e2-5) 1.5 and 0.8 . 1.0 and 1.5 . 1.5 and 4.0 . both 3.5 . both 1.5 . 2.0 and 3.0 . 1.5 and 0.5 p lhovandO0!5 . 1.5 and 0.5 . both 2.0 . 4.0 and 3.0 . +.0 and 1.0 no data . 3.5 and 3.0 . 0.5 and 1.5 . 0.5 and 1.5 both 0.5 . both 0.5 . both 0.5 . 1.0, no datum . both 0.5 . 0.4 and 0.5 . 1.5 and 1.0 0.5 and 0.8 . 3.0 and 0.5 . 3.0 and 0.5 . 0.8 and 1.5 . 0.8 and 0.5 0.8 and 3.0 m Ot vand ales a. 3.0 and 0.5 P Pe perp oaoaaeParte® oP PP p Pp P TP P TP ps P Pp Pf P OTD it than Metridium (80% vs. 45%). Nevertheless, it was surprising that Metridium was eaten in such a large proportion of the experiments. In 2 instances (when of- ferred with Diadumene) it was even the first one eaten. In the other cases, it was eaten only after the preferred one had been consumed. In every case in which Metridi- um was eaten, however, feeding occurred only after I had repeatedly replaced the nudibranchs, which kept cs- caping to the water table. It is also noteworthy that the anemones were small (1.5-2.0cm). Evidence that the defenses of large Metridium may be more effective in pre- venting predation than those of smaller ones is presented in the section on behavior of Afetridium. It is further inter- esting that (except for the cases with Diadumene) the nudibranchs ate Mctridiwm only after eating other ane- mones. This fact indicated a greater tendency to attack Metridium after the nudibranchs had been feeding for a while than when they had not eaten at all. The third group included Anthopleura artemisia, Cor- ynactis, and Tealia crassicornis. These anemones were not Page 182 THE VELIGER Vol. 15; No. 3 Table 3 Experiment B: Order in which anemones were eaten Explanation in text first with together with second with not eaten with spe) nl 9 FP mM mM Gh Mm m % Is mM mM VG sp. n E A SOOM OAle pl uw Ole Aeen yt Se Om, = = 0 - - M. 1 Ales, il C. 1 Ts 1 Ase 6 io0k Davao nO) 790) 0 VB 3,13) CONNOR iu Om l me een M. 1 Aloe, Alii, 72 D 2 C. 1 Us 1 Als 45 OT EDL I 2 33) ES.) Sle OFM EO Fee men ets OR Oa M. 1 I, Ih 1: 2 D ED Ae Oe NBS Al SO alee IB OME 3 GC. 3 M. 2 If 2 Mis 2a TB DE 2 Oe iO). yer SENS; 21/2 Ee ee TONE 5 one) Neri Ale, Il AG Alin, i G: 1 lis 1 Aly, 0 - - 0 0 - = 0}, = = Onl OO pArer a2 D. 2 M. 1 G 1 G 0 0 - - 0 0) =) oS) On 0 = = ts} KOO) 1 VANCE D. 3 M. 1 Alin Il ie 1 ot he ae OO ae se ao PARCEL Are D. 2 M. 1 C. 1 E. — Epjiactis; A.e.— Anthopleura elegantissima; A.x.—Anthopleura xanthogrammica; D.—Diadumene; M.-Metridium; A.a.—Anthopleura artemisia; C.—Corynaciis; T. — Tealia crassicornis; n —number of experiments in each category: % — percent of the total number of experiments with given anemone eaten at all during the course of the experiments (2-0 days). The preferred anemones, in contrast, were usually attacked within a few hours after introduction of the nudi- branchs, and were completely eaten by the second or third day, the time taken related to the size of the anemones. When offered the least preferred anemones, the nudi- branchs spent a high proportion of time wandering in the bowls or they escaped to the water table where they were frequently eating anemones stored there (Figures 4 and 5.) It is noteworthy that nudibranchs were never seen to be eating the species of the second or third groups on the water table, but only those of the first group. Vol. 15; No. 3 100 80 60 40 20 E. + Ave. +A.x. Figure 4 Experiment B: Percent wandering when offered a combination in- cluding: (1) the 3 most preferred anemones; (2) the 2 of intermediate preference, and (3) the 3 anemones of least prefer- ence. Each bar represents the percent of the total nudibranch-ob- servations involving an anemone in each group in combination with one of the same or of a less preferred group. The observations in- cluding an anemone in combination with one of a more preferred group are omitted, since the more preferred species would govern the activity pattern DISCUSSION The results of this series of experiments showed an order of preference similar to that shown by experiment type A. Epiactis, Anthopleura elegantissima, A. xanthogrammica were preferred to all others, and Corynactis was not eaten at all. The primary differences included (1) the lack of distinction in type B between the preference for Epiactis and A. elegantissima on the one hand, and A. xanthogram- mica on the other; (2) the fact that some Metridium THE VELIGER 100 Page 183 80 60 40 20 Figure 5 Experiment B: Percent wandering when each anemone was the only one available (after the preferred one had been eaten). Each bar represents the percent of the total nudibranch-observation for the periods in which each anemone was the only one available. Data are unavailable for Epiactis (eaten too rapidly), as well as fer Corynactis and Diadumene (not offered alone) were eaten; and (3) the fact that A. artemisia and Tealia were not eaten at all. This type of experiment provided further information on predation methods of groups of Aeolidia. (1) The nudibranchs fed on the preferred anemones during the same period of time, alternating between the 2 present, rather than eating one totally before attacking the other. (2) ‘They completely consumed all anemones but Dia- dumene. (3) When offered a combination including a preferred species, the nudibranchs spent most of the time either eating or being inactive. They spent a relatively small amount of time wandering: 36% of the nudibranchs observed were eating, 38% were inactive, and only 26% Page 184 THE VELIGER Vol. 15; No. 3 were wandering. With the less preferred species, however, only 10% were eating, 30% were inactive, and 60% were wandering. EXPERIMENT CG In the first trial 5 nudibranchs were offered a choice be- tween a group of Epiactis and water alone. Within the first 2 hours 2 nudibranchs had arrived in the anemone cage and a third was on its way in the tube. Within 85 hours all nudibranchs had gone across and were feeding on the anemones. In the second trial 5 nudibranchs were offered a choice between a group of Anthopleura elegantissima and water alone. Two nudibranchs moved across within 9 hours, fol- lowed by 2 others within 24 hours from the start of the trial. All 4 nudibranchs were eating when observed. ‘The 5" animal had escaped to the water table. In the third trial 5 nudibranchs were given the choice between Epiactis and Anthopleura elegantissima, Within 24 hours one had gone across to each species. The other 3 were in the original cage wandering. Within 24 more hours they had escaped to the water table where they were eating an A. elegantissima. Why they did not go across to one of the 2 anemones is unclear. Perhaps they were equally attracted to both species and the resulting strong approach conflict resulted in indecision and ambiguous behavior. In conclusion, these preliminary experiments showed that Aeolidia could use distance chemoreception to detect and locate its prey. That the nudibranchs were attracted to substances released by anemones was further indicated by an observation during a trial run using Epiactis. A nudi- branch which was put at the end of the control tube (wa- ter only) showed no response other than to move away, while the same animal put at the end of the tube from the anemone cage immediately crawled in and arrived in that cage within 15 minutes. BEHAVIORAL INTERACTIONS or ANEMONES anp NUDIBRANCHS 1. Searching, Prey Locating, and Feeding Behavior of Nudibranchs When a nudibranch which had been without food for 2 or more days was put in a bowl with a favored species of anemone (Epiactis, Anthopleura elegantissima, or A. xanthogrammica), the nudibranch often extended its body and moved the anterior } - 3 back and forth in the water with the oral tentacles and rhinophores extended. If the nudibranch did not contact an anemone, it reattached to the substrate and moved forward, perhaps repeating the head-raising behavior several times, and correcting its course to go more directly toward the anemone. Frequently the nudibranch did not raise the anterior part of the body off the substrate, but simply moved forward swinging the head and especially the extended oral tentacles from side to side and frequently touching the oral tentacles to the substrate. The rhinophores meanwhile were also moved around in the water in various directions. During search- ing the buccal mass was often protruded. If while searching the nudibranch touched an anemone with the mouth or oral tentacles, it immediately retracted its head, pointed the anterior third of the cerata for- ward so that the anteriormost ones hid the head beneath them, and contracted the oral tentacles. This general con- traction was followed by re-extension of its head and oral tentacles toward the stimulus. When contact occurred again, there was slight retraction, but the nudibranch continued forward, applied its mouth to the anemone, and began to feed. The nudibranchs generally began eating the part of the anemone first contacted (unless it were the tentacles), usually the base of the column. If the tentacles had been contacted (usually causing the nudibranch to retract more strongly than when the column or oral disk were touched), the nudibranchs often began eating the margin of the column just aboral to the tentacles. If while the nudibranch was moving along cerata happened to touch an anemone, the touched cerata contracted sharply, adjacent ones were pointed toward the touched ones, and the whole animal usually contracted. This initial response was followed by extension of the head toward the stimulus, contact (and slight contraction), and feeding. When nudibranchs were feeding or otherwise inactive, their head, tail, rhinophores, and oral tentacles were re- tracted so that most of the body was hidden under the cerata. A feeding animal could be distinguished from a non-feeding one by the fact that the buccal mass of a feeding nudibranch was protruded and applied closely to the anemone. In this posture the nudibranchs strongly resembled anemones, especially Anthopleura elegantissi- ma. There was no striking difference in strength of response to contact with any of the anemones except Corynactis and Metridium, which elicited a stronger contraction. When these 2 anemones were touched the nudibranchs turned and moved away after their initial contraction. The clubbed tips of the tentacles of Corynactis adhered tightly to the part of the nudibranch touched, particularly to the cerata, and the nudibranch had to pull hard to free itself. The behavioral interactions of the nudibranch and Met- Vol. 15; No. 3 ridium are described below. The essential difference in response to Epzactis, Anthopleura elegantissima, and A. xanthogrammica on one hand, and to Corynactis, Dia- dumene, Metridium, Tealia, and A. artemisia on the other, was that the nudibranchs usually turned toward and began eating the first 3 species of anemones, but turned and moved away from the latter 5 species. In addition, the nu- dibranchs usually did not exhibit clear-cut searching be- havior when put with the latter anemones. 2. Behavior of Anemones All anemones contracted sharply upon contact with the nudibranchs, the contraction being more rapid and strong- er than when touched gently with a probe. Usually, Epi- actis, Anthopleura elegantissima, A. xanthogrammica, and Tealia bent the column toward the nudibranchs with their tentacles still extended. With repeated or prolonged con- tact the anemones retracted their tentacles, closed the sphincter muscle around the margin of the oral disk, and contracted the column farther, becoming more or less round. When the nudibranchs began feeding on Epzactis, A. elegantissima, and A. xanthogrammica, the anemones usually contracted their muscles even more, but without decreasing much in size and losing much water; thus the column became hard and round. The column often tended to be thin-walled or inflated, especially on the side toward the nudibranch. Epiactis invariably (8 observations) released its hold on the substrate within a few minutes after onset of feed- ing by a nudibranch. Detachment began in the area closest to the nudibranch and was initiated by contraction of the pedal disk margin, followed by lifting up of the margin and progressive detachment of the entire disk. Anthopleura elegantissima also often detached soon after feeding began (7 of 11 observations) ; A. xanthogrammica usually (5 observations) detached, at least partially, with- in a few minutes of being fed upon. None of the anemones detached when nudibranchs only touched them. Anthopleura xanthogrammica tended to remain de- tached for an indefinite period of time after the nudi- branchs had ceased feeding and released the anemones, while the other 2 species usually reattached. The reattach- ment subjectively had a greater tendency to occur in A. elegantissima than in Epiactis. The released anemones would lie on the substrate rounded up until they reat- tached. The Tealia and Metridium which were eaten in the pref erence experiments were usually detached but not partic- ularly inflated or turgid when the nudibranchs were eating them. The Anthopleura artemisia attacked during the THE VELIGER Page 185 preference experiments were detached and turgid though not particularly inflated while being eaten. Diadumene was the only species of anemone which did not detach while being eaten, although it became quite turgid. Coryn- actis never became inflated or detached. None of the anemones showed a swimming escape re- sponse. 3. Behavioral Interactions of the Nudibranchs and Metridium and Diadumene Metridium Metridium showed no response to the presence of a nudibranch unless actual contact was made. Upon instan- taneous contact with any part of the nudibranch an anemone immediately retracted its tentacles and contract- ed the column, although it usually did not extrude acontia. When small (less than 2 cm diameter) anemones were ob- served under a dissecting microscope, the acontia on the side touched could be seen to move upward and outward toward the nudibranch. Acontia were usually not extruded unless prolonged or repeated contact was made. When further contact was not made the anemone would soon re- extend itself and appear normal. When further contact was made, however, the anemone contracted again even more strongly, extruded acontia in the region of con- tact, and closed its sphincter over its tentacles and oral surface, remaining in that state for an indefinite period of time. Gentle contact of an expanded anemone with a probe caused only slight contraction, soon followed by re-extension. The length of time of prolonged contact by a nudi- branch necessary to cause extrusion varied somewhat. In a series of 8 observations, extrusion occurred after $ to 6 minutes with an average of 2.6, most occurring in 2 to 4 minutes. When the anemones were gently touched with a probe, in contrast, extrusion did not occur until after at least 8 minutes of repeated touching. It is noteworthy that extrusion often continued after the nudibranch had left, and that the extruded acontia which remained attached to the anemone were eventually re- tracted. When a nudibranch touched an acontium, it strongly contracted its whole body, especially the part touched, and turned sharply, moving away from the stimulus. All parts of the body were sensitive, including the foot. The nudibranch also secreted large amounts of viscous mucus. Usually the acontia became entangled in the mucus along with large numbers of discharged nematocysts. Whenever an acontium happened to contact the nudibranch itself, usually a ceras, it adhered tightly. When this happened, Page 186 the nudibranch quickly and strongly contracted and bent the ceras to which the acontium was attached (sometimes autotomizing the ceras), erected the others and generally pointed them toward the stimulus, and tried to move away. Although the nudibranchs used in the behavioral ob- servations managed to free themselves, on 3 successive days in experiment A - 1 nudibranchs were found wrapped in thick mucus with acontia caught in the mucus and wrapped around some cerata. The first nudibranch was removed and placed on the water table where the next day it appeared normal except for contracted cerata in one area, and was feeding. It appeared to be completely re- covered within 3 days. The other 2 nudibranchs were left in the cage where they recovered within one day. Toward the end of experiment A - 2 a nudibranch was found nearly dead with the body wall of its back broken and with some of the viscera protruding through the hole. It is probable that it had been injured by acontia, al- though none were extruded at the time of observation, because the nudibranchs had been attacking Metridium during the past few days. Although it is possible that another nudibranch had attacked it, that possibility is unlikely because I saw no other evidence of possible can- nibalism even after some nudibranchs had been without food for 3 weeks. Rather, it seems as though these 3 nudibranchs were weakened enough from starvation that their defenses were no longer effective. Boutan (1898) noticed the same weakness in an Aeo- lidia spent from spawning which was not able to escap2 from an anemone onto which he had dropped it, but was taken in and digested. Healthy ones he had dropped onto an anemone were able to escape. I also found that ane- mones (Anthopleura elegantissima and A. xanthogram- mica) would accept and digest dead or weakened nudi- branchs. The feeding response was not just due to lack of a defensive response of the nudibranchs, but due to their own lack of defensive response as well. That acontia were a very strong deterrent to predation was observed on many occasions. (1) Sometimes nudi- branchs after their initial withdrawal upon contact with Metridium re-approached it with the buccal mass pro- truded and explored it with their oral tentacles and oral surface. This invariably elicited extrusion of acontia, and upon contact with them the nudibranchs contracted sharply and moved away. (2) On many occasions in choice experiments involving Metridium, threads of mu- cus were seen crisscrossing the bowl, with acontia, dis- charged nematocysts, and sometimes autotomized cerata caught in them, while Metridium remained intact. Similarly, Yarnall (personal communication) frequently noticed in the field that Aeolidia in Monterey Bay, Cali- THE VELIGER Vol. 15; No. 3 fornia, would cease feeding when acontia became en- tangled in their cerata. The nudibranchs in the laboratory which became entangled and could not free themselves died within 24 hours. He also found several moribund nudibranchs with acontia entangled in their cerata in the field. Nevertheless, he commonly found acontia in the stomachs of Aeolidia. Harris (1971) found that the defenses of Metridium usually prevented the nudibranchs from feeding on large anemones in New England. Some preliminary experiments I did showed that perhaps the local nudibranchs would also eat small ones but not larger ones. The effectiveness of the defenses of Metridium of different sizes merits further investigation. Diadumene The mutual responses of the nudibranchs and Diadume- ne were much less definite than those of the nudibranchs and Metridium. Again, contact was necessary to elicit a response. Upon contact, an anemone retracted its tenta- cles, partially contracted its column, and moved acontia upward in the region of the stimulus. Upon repeated or prolonged contact, the tentacles were retracted complete- ly, the sphincter around the margin of the oral disk was contracted, hiding the tentacles, and the column was con- tracted strongly against the water inside. The acontia were moved farther upward or outward and were often extrud- ed. Acontia were extruded once when a nudibranch crawled over an anemone, and once when one bit and began feeding on an anemone. The latter nudibranch continued eating, ignoring the acontia. Acontia generally caused the nudibranchs to withdraw slightly, but the nudi- branchs did not respond significantly more strongly to acontia than to any other part of Diadumene. Their re- sponse to contact with any part of an anemone was like that to contact with a probe. Likewise, the anemone’s response was not significantly different from that to such contact. FEEDING BEHAVIOR AnD ACTIVITY PATTERN or NUDIBRANCHS OFFERED GROUPS or Anthopleura elegantissima, AND DEFENSIVE RESPONSES oF THE ANEMONES There were numerous difficulties in determining activity patterns. Individual nudibranchs and anemones were of- ten difficult to recognize, and this was complicated by the fact that new nudibranchs would appear in the dishes and the ones being studied would disappear. The latter diffi- Vol. 15; No. 3 THE VELIGER Page 187 culty especially occurred during the second experiment, which took place in a submerged dish which was down- stream from other anemones, including a partially eaten Anthopleura xanthogrammica to which the nudibranchs kept migrating. However, certain aspects of the activity pattern of the nudibranchs and of the behavior of the anemones became apparent. 1. The nudibranchs did not keep their hold on an ane- mone once they had attacked it initially, nor did they usually remain inactive nearby. Rather, they let go and wandered off when not feeding. 2. Periods of eating (lasting a few minutes to a few hours) alternated with periods of inactivity of longer duration (several hours to several days), and sometimes with periods of wandering as well. 3. In the absence of a definite current of water flowing over them (first experiment), the nudibranchs tended to eat individuals within a group only partially, rather than tending to consume one before moving to another. For example, at the end of the first experiment, after a nudibranch had been feeding within a group of 10 anemones for 4 days, there were pieces of 5 anemones (rims of pedal disks) and 4 slightly damaged anemones (epidermis missing in places) remaining. Only one ane- mone had disappeared. However, when a unidirection- al current flowed over the nudibranchs (second ex- periment), it seemed as though they tended to attack and consume one anemone before attacking another. For example, the nudibranchs kept moving upstream to feed on the Anthopleura xanthogrammica men- tioned above, rather than remaining with and feeding on the anemones in the group. Nevertheless, when not moving upstream the nudibranchs moved from ane- mone to anemone within the group without consuming any of them. 4. The anemones attacked during the second experiment (in which most of the anemones were in contact with each other) were those on the edge of small groups or which were solitary. The nudibranchs usually did not crawl over anemones to eat one in the midst of a group. 5. Relatively few anemones detached. Of 45 observed anemones 10 (22%) detached. About half of these re- attached when left alone. The others remained de- tached, lying rounded up on the bottom, even though they had little damage and were not attacked again. 6. The attached anemones tended to move away from the nudibranch as they were being eaten and to continue moving after thenudibranch had stopped eating, so that within 24 hours an anemone had often moved 5 cm or more away from its location when first attacked (one anemone moved 5 cm in 4 hours). Some continued moy- ing for several days (20 cm in 3 days, in one case). 7. The anemones in the second experiment dropped most of the sand adhering to them when collected when they were left undisturbed to attach before the nudibranchs were introduced, and they kept dropping the sand I repeatedly poured over them, making it impossible to determine the effect of sand on predation. GENERAL DISCUSSION AnD CONCLUSIONS Food Preference On the basis of experiments A and B, the anemones can be put into 3 groups which can be ranked from most to least preferred. Group I includes Epiactis prolifera, Anthopleura ele- gantissima and A. xanthogrammica. These anemones were eaten whenever they were offered, were eaten first when nudibranchs were offered a choice between them and ane- mones of the other 2 groups, and were consumed rapidly with little wandering. The relative preference for the ane- mones within this group was less definite. Experiment A, however, provided some evidence that Epiactis and A. elegantissima may be preferred to A. xanthogrammica (see discussions following experiments). Field observations in- dicated a preference for A. elegantissima. Most of the nu- dibranchs were found on rocks with that species rather than with Epiactis or A. xanthogrammica. Defenses seemed to play no role in determining which of the 3 anemones was preferred. Defenses involved nema- tocysts, inflation, detachment, and (indirectly) size (which appeared to be related to toughness). Only size seemed to govern the order and rapidity with which the anemones were eaten. Acolidia ate the anemones in spite of the dif ficulties caused by nematocysts, or possible difficulties in maintaining a hold or in biting and rasping the anemo- nes caused by inflation. Detachment caused no problem as long as the nudibranchs were eating, for they held the prey tightly. However, inflation coupled with detachment could be of value when the nudibranchs let go after feed- ing, by enabling the anemones to roll away. Detachment alone could be of value to large anemones, such as Antho- pleura xanthogrammica, which could be torn from a nudi- branch’s grasp by a sudden surge of water or by its own weight. An additional defensive response of A. elegantissi- ma was to move away as a nudibranch was eating it and to continue moving after the nudibranch had ceased feed- ing. This behavior would be safer than detaching, which is likely to result in an anemone falling onto an unsuitable substrate or being washed ashore. Page 188 Group II includes Diadumene luciae and Tealia crassi- cornis, both of which were sometimes eaten at least in part. They were not the first ones eaten, were often eaten only partially, and were eaten over a longer period of time, and more time was spent wandering than when anemones of group I were being eaten. In addition, nudibranchs were never seen near these species in the field. Defenses did not seem to be important deterrents in the laboratory. Defenses included the nematocysts of both, the acontia and inflation of Diadumene, and the detach- ment and large size of Tealia. However, the bending in Tealia and those of group I of the column with still ex- tended tentacles toward the nudibranch could be of ad- vantage by causing the nudibranch to recoil. In recoiling it could contact another anemone which may be in a better position for attack. During several observations nudibranchs did not attack the first anemone they touched, but resumed searching after recoiling eventually to at- tack another anemone which they encountered. Tealia was about the same size as the Anthopleura xan- thogrammica used in the study, had equally effective de- fenses, and was made equally available in the laboratory, yet the nudibranchs distinctly preferred Anthopleura. Examination of the feces of nudibranchs which had been eating each species alone for several days indicated greater physiological adaptation to eating Anthopleura than Tealia. The feces of nudibranchs which had been eating the red anemone Tealia were pink. When examined microscopically, the feces proved to be full of discharged nematocysts, pink cells including some living clumps with beating flagella, and many ciliate protozoans. Those which had been eating A. xanthogrammica had white feces con- taining undischarged nematocysts, ciliates (the observed differences in the ciliate fauna were not investigated), and zooxanthellae. No intact living cells from the anemone itself were present. Amorphous white granular material probably represented undigested remains of the anemone. Although the nudibranchs seemed to be less efficient in processing Tealia, Tealia was able to support them well enough for them to lay eggs (which were pink instead of white as when eating Anthopleura), grow, and store food in the digestive gland (which was pink instead of green as when eating Anthopleura). The relative weights of the 2 anemones which must be eaten to provide the same rate of growth and egg production would be interesting to inves- tigate. The observations of Tealia suggest that learning may play a role in food preference. The only time a T: crassi- cornis was eaten completely, rapidly, and with little wan- dering was in experiment A - 1. This anemone was the original one in the cage and was attacked soon after T: coriacea had been consumed. The second T) crassicornis, THE VELIGER Vol. 15; No. 3 added well after the first had been eaten, was not eaten at all. The T: cortacea was declining when attacked early in the experiment. The tendency of Aeolidia to attack wounded anemones is reported in the literature (e. g. STEHOUWER, 1952). Thus, it is possible that the nudi- branchs had a greater tendency to attack T: corzacea than they would have had if the anemone had been healthy. The fact that the original T: crassicornis was attacked soon after T. coriacea had been eaten while neither the new one nor those in other experiments were attacked, indicates that the nudibranchs may have become conditioned to eating this genus. The fact that the new Tealia added later was not attacked indicates that the conditioning must be frequently reinforced to persist. The possibility of condi- tioning is discussed further below. Group III includes Anthopleura artemisia, Corynactis californica, and Metridium senile. These anemones were eaten very rarely, if at all. Further, the nudibranchs were not found with them in the field, although at least Coryn- actis and Metridium were very common and occurred in dense groups. Anthopleura and Metridium were preferred to Corynactis, the only anemone which was never eaten at all. The defenses of Anthopleura investigated were similar to those of the anemones of groups I and II, yet the ane- mones were very rarely eaten. In contrast to all other species, the defenses of Coryn- actis and Metridium were an effective deterrent to preda- tion. That is not to imply that without their defenses the nudibranchs would eat them readily. In fact, Aeolidia would not attack Corynactis even when the tentacles were retracted within the closed oral disk area. Nevertheless, the nudibranchs exhibited a very strong negative response to the clubbed tips of the tentacles of Corynactis and te the acontia of Metridium. Both of these were potentially dangerous, as behavioral observations showed. ‘The pri- mary defenses of nudibranchs against acontia were their abilities to secrete copious amounts of viscous mucus which prevented discharged nematocysts from touching their epidermis, and to pull away from acontia which managed to adhere despite the mucus. Weakened animals became entangled in acontia; escape was accompanied by loss of entangled cerata. Healthy animals also tended to lose cera- ta to which acontia had attached. Their defense against Corynactis was simply to contract strongly and pull away. It was interesting that the acontia of Diadumene did not elicit a strong avoidance response or the secretion of mucus. Tealia, Diadumene, and Metridium are also mentioned in the literature as being eaten by Aeolidia (Table 1). Likewise, none of the workers indicated that Tealia was the preferred species. However, SwENNEN (1961) cited unpublished observations of Diadumene being preferred to Metridium. Metridium was indicated by two workers to Vol. 15; No. 3 THE VELIGER Page 189 be a preferred species and by 4 others as being eaten, in- cluding Swennen who raised young nudibranchs on it. In addition to these published observations on Metridi- um, 4 people (L. Harris, V. Human, T. Gosliner, and J. Yarnall) have told me that they have found large numbers of Aeolidia among the abundant Metridium on submerged pilings (particularly in Monterey Bay, California), and have either seen the nudibranchs feeding on Metridium or have seen evidence that they feed on this species. Harris (personal communication) found the same relationship on the Atlantic coast of the United States as well as in Monterey. Only Harris and Yarnall noticed any particular adverse effect of acontiaon the nudibranchs. However, they (like Russet, 1964) noted that the nudibranchs would eat the acontia. The fact that few if any other anemones were present in the habitats observed suggests that per- haps in the absence of less dangerous prey the nudibranchs may learn to cope with the defenses of Metridium and come to eat the anemones in spite of the defenses. Woop (1968) found that the prosobranch Urosalpinx cinerea (Say, 1822) had an increased tendency to feed on a species after eating it for a while, which he called “ingestive con- ditioning.” Similar ingestive conditioning may occur in Aeolidia as suggested by the present observations on Tealia and those just described on Metridium. This possibility is supported by the observations of Yarnall (personal com- munication) that the nudibranchs which had been eating Metridium preferred Metridium even when given a choice between it and Epzactis, while those which had been eat- ing Epiactis preferred that species to Metridium. How- ever, Gosliner and Harris (personal communication) ob- served that the nudibranchs which had been eating Met- ridium preferred Anthopleura elegantissima when given a choice between it and Metridium. Ingestive condition- ing was unlikely to have been governing the relative pref erence of the nudibranchs I studied for the 3 most pre- ferred species, because they did not prefer A. elegantissima to Epiactis or A. xanthogrammica, although most had been feeding on that species before being collected. How- ever, the lack of conditioning could explain why they would not eat Metridium. The various ramifications of ingestive conditioning would be interesting to investigate. In conclusion, the facts that (1) when anemones were made equally available in the laboratory the nudibranchs exhibited definite preferences, (2) the defenses of the anemones other than Corynactis and Metridium were equally effective, and (3) ingestive conditioning was unlikely to be important in the nudibranchs studied, indi- cate that preference for particular anemones was not proximately determined by these 3 possible factors alone. A fourth possible proximate factor is the relative nutri- tional value of the different anemones. Nutritional value would be related to the rapidity with which the anemones are eaten and digested and to the efficiency of processing by the nudibranchs, as well as to the original nutrient content. The efficiency with which nudibranchs can handle their prey and extract the nutrients would presumably be genetically based and be the result of evolutionary adap- tations to eat and digest particular species. Thus relative nutritional value would involve an interaction between the nutrient makeup of the anemones and the processing effi- ciency of the nudibranchs. The potential nutrient value of the prey, however, would presumably be important as an ultimate factor in the evolution of food-preference and the concomitant feeding adaptations. These two aspects of nutritional value were not investigated as such, but the observations of the feces of nudibranchs which had been feeding on Anthopleura xanthogrammica or Tealia indi- cate that the nudibranchs may have different abilities to process the various species. Relative palatability is a fifth possible proximate fac- tor. Similar to nutritional value, this factor would be ex- pected to involve an interaction between the original de- fensive adaptations (including the possession of distasteful or painful characteristics) of the prey and evolution of preference in the predator along with the co-occurring adaptations involved with handling the prey’s defenses. Thus, palatability is more likely to be dependent on the evolution of food-preference than on some intrinsic prop- erty of the prey. To the extent that the relative degree to which a particular species was eaten is a measure of rela- tive palatability, this possible factor was investigated. Since some of the main possible proximate factors behind food-preference were either unimportant or de- pended in part on the adaptations of the predator, it seems that preference may be genetically determined in the local populations of Aeolidia. The evolution of pref- erence may have been ultimately based on these factors, but they do not seem important any longer. Evidence is presented later that the evolution of preference for at least Anthopleura elegantissima and A. xanthogrammica may be related primarily to the tendency for these two species to occur in dense concentrations. The hypothesis that preference is genetically determined is supported by the prediction (among others) made by EMLEN (1966) on the basis of a mathematical model that other things being equal, animals would be more selective when satiated and more indiscriminate when starved. His model concerned the caloric value and con- sumption times of different foods as a prediction of which ones would be eaten. Since Aeolidia was selective even when starving, it would seem as though something were operating to govern food-preference (other than degree of starvation relative to caloric value and consumption Page 190 times of different foods), which is probably genetical predisposition for the reasons just presented. Searching and Feeding Behavior Experiment C, behavior observations, and the fact that escaped nudibranchs tended to congregate around and feed on the same anemone indicate that Aeolidia is attract- ed to its prey from a distance. In addition, contact of ane- mones especially with the oral tentacles was an important method of location and identification of prey. During searching the oral tentacles were greatly extended and swung from side to side as if feeling for something, and the behavior upon contact depended upon whether or not the touched anemone was a member of a preferred species. Feeding on preferred anemones continued without in- terruption for a few minutes to several hours and usually ceased before the anemone was completely consumed. The principal exceptions involved small Epiactis and Antho- pleura elegantissima which the nudibranchs ate rapidly with no observed cessation of feeding. Feeding rate seemed to depend on size of anemone (with size and state of star- vation of nudibranchs equal), but when size of anemone was constant, the rate seemed to depend on the degree of toughness of the anemones. Although absolute feeding rate was not investigated, the subjective impression was that Eptactis was eaten the most rapidly for its size, followed by A. elegantissima and A. xanthogrammica in that order. Based on the translucence of the column and the thickness of the body wall, it seemed that Epzactis was the most delicate anemone, followed by A. elegantissima and A. xanthogrammica. The other anemones were not eaten reg- ularly enough for an estimate to be made of the rapidity with which they were eaten. Nudibranchs began feeding on any part of the anemo- nes except the tentacles, although they rarely began with the oral disk. The principal damage to anemones which had been abandoned after the initial attack was to the epidermis and outermost layers of the underlying tissues. After a longer time and after several feeding periods the nudibranchs would often have eaten through the wall of the column to the gastrovascular cavity. Often the ane- mones were not abandoned until they had been reduced to doughnut-shaped pieces, apparently the rims of the pedal and oral disks. It is noteworthy that (judged sub- jectively) these parts were thicker and tougher than other parts of the column. When other preferred anemones were not available, the nudibranchs ate the entire anemone, including these rims, the tentacles, septal filaments, and even the acontia of Metridium and Diadumene. When an abundance of a preferred species (Antho- pleura elegantissima in experiment E) was available, the THE VELIGER Vol. 15; No. 3 nudibranchs tended to begin a new anemone once they had ceased feeding and had let go of the first one. This tendency was caused partially by the behavior of the anemone: detachment and falling to the bottom or mov- ing away on the pedal disk. It was also caused by the behavior of the nudibranchs, which let go after feeding. They sometimes began wandering upon cessation of feed- ing, but more frequently the nudibranchs remained qui- escent for several hours and began wandering later. The later wandering seemed to be governed by hunger, and the anemone attacked seemed to be the first one contacted in its wandering in the absence of a definite current of water flowing over the animals. The first anemone contact- ed usually was not the original anemone, which had escaped from the immediate area. In a definite current of water the nudibranchs seemed to be attracted to wounded anemones as STEHOUWER (1952) found, since they congregated around single ane- mones upstream even when intact anemones were closer. In experiment E - 2 the scent of the wounded Anthopleura xanthogrammica exerted a stronger attraction than even the wounded A. elegantissima nearby on which the nudi- branchs had been feeding. Yarnall (personal communica- tion) saw good evidence that Aéolidia is attracted to damaged anemones (Metridium) in the field. In areas of dense concentrations of Metridium he found that the nudi- branchs would be clustered around and feeding on a single anemonerather than being evenly scattered through- out the group of anemones and feeding alone. In the ab- sence of a definite current, however, I found that the nu- dibranchs usually ate alone. The nudibranchs presumably ate alone because (1) they did not detect the anemones which nearby nudibranchs were eating, (2) the strength of the scent from anemones being eaten by nearby nudi- branchs was not strong enough to attract them over the scent of or contact with nearer intact anemones, so that they consequently attacked the first anemone they found, or (3) the scent from nearby wounded anemones coniung from different directions confused the nudibranchs, caus- ing many changes in direction while wandering which might or might not result in the location of a wounded anemone. These possibilities may also explain why during experiments with a definite unidirectional current the nudibranchs tended to eat the anemones completely be- fore attacking another, while they tended to wander from anemone to anemone in experiments without a definite current. The facts that nudibranchs tended not to feed con- stantly until an anemone was completely consumed, that they let go when not feeding, that Anthopleura elegantis- sima escaped by either detaching or moving away on its pedal disk, that nudibranchs followed an inactive period Vol. 15; No. 3 THE VELIGER Page 191 by wandering and tended to attack the first anemone con- tacted (at least in still or turbulent water), and that nudibranchs tended to attack isolated anemones or those on the edge of groups, could have provided selective pres- sure in the evolution of grouping behavior in A. elegantis- sima. Grouping would minimize the chances that a given individual would be consumed. Grouping would also benefit the nudibranchs, as it would provide an abundant source of food concentrated in definite localities enabling the nudibranchs to spend a minimal amount of time and energy searching for food. Further, Anthopleura elegantissima is not subject to large fluctuations in population size with the seasons. It is pos- sible that Aeolidia is evolving specificity for A. elegantis- sima, since most nudibranchs in nature were with this spe- cies. Whether the local distribution of Acolidia is governed by settlement preferences of the veligers or by searching of the postlarval stages would be interesting to discover. Abundance, dense concentrations of individuals, and population stability are characteristics which would be necessary in a prey population for food specificity of a predator to evolve (MacArtuur, 1961; PIANKA & PIAN- KA, 1970). One would expect specificity to evolve when- ever possible, as it would enable the evolution of specific adaptations to handle the food efficiently. Further, it would be better for behavior to be controlled so that the nudibranchs would remain in an area of suitable food, rather than wandering here and there as they detect dif- ferent species, as it would minimize the time and energy spent in the search for food. Anthopleura elegantissima would be superior in at least some of the above attributes to the other anemones stud- ied, with the possible exception of A. xanthogrammica. The latter species also occurs in great abundance and is a much larger anemone. Thus, one individual would provide food for a longer time, and the total biomass per unit area may be greater than for A. elegantissima. Possible disad- vantages of specializing on A. xanthogrammica would in- clude the more scattered distribution of individuals, the greater difficulty (with less digestive efficiency?) of eating a larger anemone with presumably tougher and thicker layers of connective tissue, and the greater potential ef fectiveness of detachment of a larger and heavier ane- mone. SUMMARY Food-preference, the effect of the defenses of the prey on predation, and feeding and prey-locating behavior of the anemone-eating nudibranch Acolidia papillosa on the central California coast were investigated. Based on the experiments and observations, the follow- ing generalizations can be made: 1. The 8 principal species of anemones occurring inter- tidally can be put into 3 groups depending on the de- gree of preference shown for them, with the order within the groups remaining unclear. From most to least preferred, the groups are: I Anthopleura elegantissima, A. xanthogrammica, Epiactis prolifera; II Diadumene luciae, Tealia crassicornis; III Anthopleura artemisia, Corynactis californica, Metridium senile. The lack of preference for Metridium here differs from the distinct preference reported in the literature for European M. senile. The lack of preference seemed to be primarily due to the strong aversion of the nudi- branchs to acontia. The extrusion of acontia was a definite defense response which invariably occurred when Aeolidia repeatedly and prolongedly contacted Metridium. ‘The nudibranchs responded by secreting copious and viscous mucus, withdrawing sharply, and moving away. 2. Food preference seemed to be genetically determined, rather than being proximately due to: a) defenses of the prey (except for the acontia of Metridium and nematocysts of the tentacles of Coryn- actis). The defenses observed were: nematocysts (present in all anemones) ; inflation of the column (present in A. elegantissima, A. xanthogrammica, Epi- actis, Diadumene, Metridium); detachment from the substrate (A. artemisia, A. elegantissima, A. xan- thogrammica, Epiactis, Tealia, Metridium) ; and a- contia (Diadumene, Metridium) ; b) accessibility of prey in nature; c) learning (although evidence is presented which sug- gests that this may modify genetically determined preference) ; d) relative nutritional value of different species of ane- mones ; e) relative palatability of the different species. 3. Aeolidia could detect and was attracted to the anemo- nes of group I at a distance, and exhibited character- istic searching behavior. Prey location and identifica- tion were aided by contact of the anemone with the oral tentacles. Location by contact seemed to be the primary prey-detection mechanism in the absence of a definite current of water flowing over an anemone to the predator. In a definite current distance chemore- ception seemed to be more important, and wounded Page 192 THE VELIGER Vol. 15; No. 3 anemones exerted a stronger attraction than intact ones. 4. In regard to feeding activity pattern: a) Nudibranchs did not tend to feed continuously un- til an anemone was consumed; b) they released the anemone when not feeding; c) they tended to attack the first anemone of the pre- ferred species contacted in the absence of a definite current of water; d) feeding was followed by an inactive period which in turn was followed by a period in which the nudi- branchs wandered; e) only in the absence of other individuals of a pre- ferred species did the nudibranchs consume an ane- mone completely. 5. The characteristics of the feeding behavior just de- scribed plus the fact that A. elegantissima either de- tached when being fed upon and fell to the bottom when released, or moved away on its pedal disk after being released, could make the occurrence of this spe- cies in dense masses of individuals an adaptation which would minimize the chance that a particular individual would be eaten. 6. Nearly all nudibranchs used in the study were found with A. elegantissima, rather than with the other spe- cies of anemones. This species would be predicted on theoretical grounds to be ideal prey for a food special- ist (other things being equal). It is possible that speci- ficity for A. elegantissima may be evolving in the local populations of Aecolidia papillosa. ACKNOWLEDGMENTS This study was conducted at Pacific Marine Station, Dil- lon Beach, California. I wish to express my sincere grati- tude to Mr. David H. Montgomery, a visiting instructor, and to Dr. Edmund H. Smith, Director of Pacific Marine Station, for making my stay possible, and especially to Dr. Smith for his generous allocation of work space. I also wish to express my deep appreciation to Mr. Montgomery for all his enthusiasm and interest during the project, for his invaluable help in collecting the animals, and particu- larly for his careful reading of the manuscript. I wish to thank my husband, Dr. James F Waters, for all his en- couragement, advice, and patience during the preparation of the manuscript. Larry Harris, Vernon Human, Terrence Gosliner, and Jack Yarnall are in my debt for telling me of their observations of Aeolidia and Metridium, and mak- ing me realize that learning in Aeolidia may be more im- portant than I had thought. My thanks also go to Jack Yarnall for his helpful comments on the manuscript. The students of the invertebrate zoology class, especially Miss Linda Welch, assisted me greatly in collecting the nudi- branchs. Literature Cited Boutan, Louis 1898. Moeurs de !’Eolis papillosa Linné. Arch. Zool. exp. gén. ser. 3, no. 6, notes & rev. no. 10: XXXVII- XLII Braams, W.G. « Hannie FE. M. GEELEN 1953. The preference of some nudibranchs for certain coelenterates. Arch. néerl. Zool. 10 (3): 241 - 264 Extot, Cuar.es N. E. 1910. A monograph of the British nudibranchiate Mollusca. Suppl. Ray Soc. London, part IV: 198 pp. EmMueEN, J. M. 1966. The role of time and energy in food preference. Am. Nat. 100 (916): 611-617 Forp, C. E. 1964. Reproduction in the aggregating sea anemone, Anthopleura ele- gantissima. Pacif. Sci. 18 (2): 138-145 Hanp, Caper 1955. | The sea anemones of central California, Part II: The endomy- arian and mesomyarian anemones. Wasmann Journ. Biol. 13 (1): 37-99 1955. The sea anemones of central California, Part III: The aconti- arian anemones. Harris, LARRY 1971. Ecological observations on a New England nudibranch-anemone association. The Echo 4: 22 MacArtuur, Rosert H. 1961. Population effects of natural selection. 195 - 199 McMi tan, N. E 1942. Food of nudibranchs. Miter, MicHagEL CHARLES 1961. Distribution and food of the nudibranchiate mollusca of the South of the Isle of Man. Journ. Anim. Ecol. 30: 95 - 116 Pianka, E. R. & H. D. Pranxa 1970. The ecology of Moloch horridus (Lacertilia: Western Australia. Copeia 1970 (1): 90- 103 Ricketts, Epwarp FE & Jack CALvin 1968. . Between Pacific tides. v-xilit+3 - 502; 46 plts. Rosson, ELaIne A. 1961. The swimming response and its pacemaker system in the ane- mone Stomphia coccinea. Journ. exp. Biol. 38: 685 - 694 Rosin, RutH 1969. Escape response of the sea-anemone Anthopleura nigrescens (Verrill) to its predatory eolid nudibranch Herviella Baba, spec. nov. The Veliger 12 (1): 74-77 (1 July 1970) RussE__, Henry DrumMMOND 1942. Observations on the feeding of Aeolidia papillosa L., with notes on the hatching of the veligers of Cuthona amoena A. & H. The Nautilus 55 (3): 80 - 82 STeEHOUWER, H. 1952. The preference of the slug Aeolidia paptllosa (L.) for the sea anemone Metridium senile (L.) Arch. néerl. Zool. 10: 161 - 170 SWENNEN, CHARLES 1961. Data on distribution, reproduction and ecology of the nudi- branchiate Mollusca occurring in the Netherlands. Netherl. Journ. Sea Res. 1 (1-2): 191-240 Wo ter, HELMA 1967. Beitrage zur Biologie, Histologie und Sinnesphysiologie (insbe- sondere der Chemorezeption) einiger Nudibranchier (Mollusca, Opis- thobranchia) der Nordsee. Zeitschr. Morph. Okol. Tiere 60: 275 to 337 Woop, LANGLEY 1968. Physiological and ecological aspects of prey selection by the marine gastropod Urosalpinx cinerea (Prosobranchia: Muricidae). Malacologia 6 (3): 267 - 318 (30 June 1968) Wasmann Journ. Biol. 13 (2): 189-251 Amer. Nat. 95 (882): Journ. Conch. London 21: 327 Agamidae) in Stanford Univ. Press, Stanford, Calif. Vol. 15; No. 3 THE VELIGER Page 193 Embryonic Development of the Camaenid Snail, Varohadra yeppoonensis ALEX S. TOMPA ano JAMES N. CATHER Department of Zoology, University of Michigan, Ann Arbor, Michigan 48104 (1 Plate) Jourpatn (1884) UsED THE TERM podocyste to refer to the embryonic specialization of the foot of land snails which serves for respiration, excretion and albumenotrophy. SmmroTH (1912) noted that the podocyst is present in all stylommatophorans except in a species of the Succineidae, and in a camaenid, Bulimus citrinus Bruguiére, 1792 (= Amphidromis chloris (Reeve, 1848). He bases his report on the single observation of SEmpER (1862) who briefly considered the development of Amphidromis in compari- son to the more extensively studied Ampullarza. In our previous work (CaTHER & Tompa, 1972) we have examined the physiological role of the podocyst espe- cially with respect to albumenotrophy, and have con- firmed the absence of the podocyst in a number of other succineid species. We have recently studied the develop- ment of the camaenid Varohadra yeppoonensis (Beddome, 1897) (see IREDALE, 1940) and have found it to be typi- cally sigmurethran with respect to the structure and func- tion of the podocyst. We suspect that Semper either worked with fixed material, and removed the podocyst by mistaking it for an extraembryonic membrane, or he lacked specimens which were at the stage of development required to confirm the presence of this embryonic organ. Varohadra \ays clutches of 70-100 eggs usually just beneath the surface of moist, loose soil or occasionally on the sides of the containers holding them. Eggs were re- moved after deposition, and kept at 22°C in a saturated atmosphere. Each egg has an outer jelly-like protective layer sur- rounding a flexible shell made of loosely bound calcareous crystals. Within this shell is the transparent chorion sur- rounding the albumen and embryo. The oval shaped eggs are 2 - 3mm long. The ovum is approximately 200 in diameter and is moderately yolky for a land snail egg. The first 2 cleavages are equal, whereas later ones result in the formation of unequal micromeres and macromeres typical of spiral cleavage. In later stages of development, in order to pre- serve embryos with the podocyst fully expanded, we nar- cotized them in 0.35% NaCl saturated with propylene phenoxetol (Goldschmidt Chemical Division of Wilson Pharmaceutical and Chemical Corporation, New York, NYS) The podocyst, similar to that of other sigmurethrans, is shown after 5 days of development (Figure 7) when it is a very large, fan shaped organ extending from the poste- rior end of the foot. During the next days of development the podocyst expands and is brought forward dorsally to envelop the entire embryo (Figure 2), while at the same time a portion of it lies in contact with the inside of the chorion. When the embryo is removed from the egg, the podocyst contracts and is pulled back from its position around the embryo, so that it trails behind the foot (Fig- ure 3). As the embryo grows, the podocyst is rapidly reduced in size, until just prior to hatching when it re- mains as a fringe-like membrane separated from the foot by a constriction (Figure 4). By the time of hatching, after 12 - 16 days of development, no vestige of the podo- cyst remains. Since we have found that the camaenid Varahadra yep- poonensis has a developmental pattern similar to other sigmurethrans, we must view the earlier, incomplete report of Semper, noting an absence of a podocyst, with skepticism. Thus we find that embryological evidence lends its weight to the concept that the Stylommatophora form a homogeneous group, excepting only the Heterure- thra, as shown by the consistent development of the podo- cyst, which we view as an embryological adaptation for terrestrial life. Page 194 THE VELIGER Vol. 15; No. 3 ACKNOWLEDGMENTS We wish to thank Dr. J. B. Burch for the parental animals used in this study. Literature Cited Catuer, J. N. « Avex S. Tompa 1972. |The podocyst in pulmonate evolution. Malacol. Rev. 5: 1-3 IREDALE, Tom 1940. A basic list of the land mollusca of Australia. Part II. Austral. Zool. 9: 1-39 Jourpain, S. 1884. Sur les organes segmentaires et le podocyste des embryons des Limaciens. C. R. Séances Soc. Biol. 98: 308 - 310 SEMPER, C. 1862. Entwicklungsgeschichte der Ampullaria polita Deshayes nebst Mittheilungen tiber die Entwicklungsgeschichte einiger anderer Gastro- poden aus den Tropen. Natuurk. Verhandl. Utrechtsch. Genootsch. Kunst. en Wetensch. 1: 1 - 20; 4 plts. StmrotH, HeEInricH RUDOLF 1912. Pulmonata. In: Die Klassen und Ordnungen des Tier-Reichs. (H. G. Bronn, ed.). vol. III: Mollusca, Abt. II. Gastropoda, Buch 2. Plate Explanation Figure 1: Embryo of Varohadra 5 days after spawning showing the podocyst (p) extending posteriorly from the foot (f). The shell (s) already covers the visceral hump X 32 Figure 2: Embryo at 9 days of development viewed frontally to show the paired lobes of the podocyst (p) encompassing the body x 36 Figure 3: The same embryo as in Figure 2 showing the podocyst retracted from the body of the embryo x 18 Figure 4: Embryo at 11 days when the podocyst (p) is reduced to a degenerating vestige of the posterior end of the foot (f) X 26 Tue Ve icer, Vol. 15, No. 3 [Tompa & CaTHeEr] Figures / to 4 Figure ] Figure 3 Figure 4 7 7 7 Sort atl Vol. 15; No. 3 THE VELIGER Page 195 Observations of the Feeding Habits of Tochuina tetraquetra (Pallas) (Gastropoda : Tritoniidae) MARY K. WICKSTEN anp JOHN D. DEMARTINI Department of Biology, Humboldt State College, Arcata, California 95521 BoTH THE LARGE nudibranch Tochuina tetraquetra (Pal- las, 1788) and the alcyonacean Gersemia rubiformis (Pal- las, 1788) are found subtidally to depths of at least 50 feet (15m) in Trinidad Bay, Humboldt County, Califor- nia (41°03’N, 124°08’ W). In the field, 7: tetraquetra was observed grazing solely on G. rubiformis, although other cnidarians were common in the area. Casual observations on specimens kept at the Marine Laboratory, Trinidad, California, suggested that the nudibranch would starve to death in the absence of G. rubiformis. In an effort to determine whether the nudibranch was restricted to Gersemia rubiformis as a food source, we obtained 2 healthy specimens of Tochuina tetraquetra at a depth of 50 feet (15 m) on Prisoner’s Rock, Trinidad Bay, California, during October, 1971. These animals were kept in a refrigerated aquarium at the Marine Laboratory, Trinidad. The specimens were offered a variety of cnidarians as food, but only Gersemia rubiformis was accepted. Tochu- ina tetraquetra retracted violently upon contact with the tentacles of both Corynactis californica Carlgren, 1936, and Anthopleura xanthogrammica (Brandt, 1835). They ignored the coral Paracyathus sp. Upon finding a colony of Gersemia rubiformis, Tochu- ina tetraquetra spread its oral veil over a portion of the colony. It then settled down for hours, slowly rasping a large groove into the colony. Colonies an average of 4 cm in diameter were eaten and totally digested within 14 days. When disturbed during feeding, the nudibranch might move for a while, but soon returned to its rasping. This feeding pattern is similar to that of Tritonia hom- bergi, as described by THompson, 1958 (in Hyman, 1967: 535)): Feces of Tochuina tetraquetra consisted almost entirely of spicules of Gersemia rubiformis. On occasion, the feces contained pieces of substrate to which the alcyonacean had been attached, indicating that the nudibranch had eaten the colony to the very base. Following feeding, Tochuina tetraquetra often assumed a resting position. It contracted itself tightly into a hump. The rhinophores were retracted. It would stay motionless in this position for up to a day at a time. This posture seemed to have no relationship to the availability of food. Such a resting position has previously been reported for Dendonotus iris Cooper, 1863, by WopBer (1970: 383), but that animal’s posture is different from that of T: tetra- quetra. We have found a few colonies of Gersemia rubiformis at a depth of 50 feet (15m) at Point Cabrillo, Mendo- cino County, Californa (39°21’N, 123°49’W). Although we did not find Tochuina tetraquetra there, it seems likely that the ranges of both animals follow the same patterns. Tochuina tetraquetra has been reported from northern Japan (THomeson, 1971: 335) to Santa Barbara (Rot- LER & Lone, 1969: 429), while RickeTTs et al. (1969: 202) described Gersemia rubiformis as “boreal-arctic, reported as far south as Trinidad Head in Humboldt County, California.” It seems likely that the scarcity of T. tetraquetra south of Trinidad Bay is directly related to the lack of abundant colonies of G. rubiformis. Literature Cited Hyman, Lisppie HENRIETTA 1967. The invertebrates, vol. 6: Mollusca I. York, N. Y. 792 pp.; 249 figs. Rotter, Ricuarp A. & STEVEN J. Lone 1969. An annotated list of opisthobranchs from San Luis Obispo County, California. The Veliger 11 (4): 424-430; 1 map (1 April 1969) McGraw-Hill, New TuHompson, THomAsS EVERETT ? 1971. Tritoniidae from the North American Pacific coast (Mollusca: Opisthobranchia). The Veliger 13 (4): 333-338; 3 text figs. (1 April 1971) WosseER, Don R. 1970. A report on the feeding of Dendronotus iris on the anthozoan The Veliger 12 (4): (1 April 1970) Cerianthus sp. from Monterey Bay, California. 383 - 387; plts. 55 - 57 Page 196 THE VELIGER Volo Noms Some Records on West American Cenozoic Gastropods of the Genus Afora MAHDOKHT JAVIDPOUR Isfahan University, Isfahan, Iran (1 Plate; 2 Text figures) INTRODUCTION SIX SPECIES OF THE TURRID gastropod Aforia from the west coast of North America define a phylogenetic line- age which is potentially useful in age determination and correlation of the marine Cenozoic of this area. The pur- pose of this report is to describe and illustrate these species, one of which is new, and to define the morphologic char- acteristics upon which these species are differentiated. Aforia appeared during the middle Oligocene on the Pacific margin. A foria campbelli Durham, 1944 is the oldest known fossil record of the genus. The only other Tertiary records are from the Pliocene of Japan (Powe Lt, 1966). The genus was especially abundant in and characteristic of moderately shallow water strata in middle ‘Tertiary basins of coastal Oregon and Washington (Figure 16). There are no known occurrences in the middle and the late Miocene, but the genus is represented in the Pliocene of the Gulf of Alaska by Aforia circinata (Dall) which ranges today from the Bering Sea to the northwest coast of Washington. The genus has not previously been monographed, al- though DurHam (1944) treated 3 middle Tertiary species from western Washington: A. campbelli Durham, A. clal- lamensis (Weaver), and A. wardi (Tegland). Powe.Li (1966) reviewed the modern distribution of A forza in the eastern Pacific, noting that its relatively shallow water occurrences near the equator are an excellent example of “biopolarity”. Two of the 4 Oligocene and Miocene spe- cies from Washington referred to Aforia by PoweELi (1966: 44), “A.” borgenae (Tegland) and “A.” marrow- stonensis (Durham), however, are here regarded as rep- resenting different turrid genera. Species of Aforia are particularly useful in correlation of Oligocene and Miocene strata in western Oregon and Washington where a well-defined phylogenetic sequence is developed (Figure 17). This lineage is defined upon a number of serial morpho- logic changes: 1) A secondary angulation, or carina, appears at the base of the body whorl in Oligocene and Miocene spe- cies, attains its strongest development on the late Oligo- cene and early Miocene species Aforia clallamensis and A, tricarinata, but is not developed on the Pliocene to Recent species A. circinata. 2) The primary angulation is located near the base of the whorls of the spire on the earliest species of Aforia but gradually moves toward a medial position in later species. 3) The subsutural slope is deeply concave in the oldest species but becomes gradually less so in newer species. 4) The position of the growth line sinus is located near the middle of the subsutural slope on the oldest species of Aforia but closer to the angulation on the latest species. 5) The angulation is sharp in the oldest species but be- comes less so in successively younger species. Aforia may be useful in determining paleobathymetry of Tertiary molluscan assemblages of the west coast of North America. Depth records of A. circinata from mod- ern collections in the U.S. National Museum indicate a range of from 34 to 121 fathoms, with almost all of the records deeper than 50 fathoms. Accordingly, fossil occur- rences of this genus may be representative of at least outer sublittoral (lower neritic) depths. The modern geo- graphic range of this species from the Bering Sea to the Straits of Juan de Fuca, Washington, indicates associa- tion with cool temperate and cold water molluscan faunas. Vol. 15; No. 3 THE VELIGER Alaska 50° British Columbia 40° 30° California \ © Recent OO Pliocene @ Miocene © Oligocene or Miocene ‘ X Oligocene 20° 130° 120° 110° Figure 16 Index Map of Northwestern Pacific Ocean showing Occurrence of Aforia Page 197 Page 198 THE VELIGER Seattle Series Area N. Olympic Peninsula Grays Harbor County Washington Washington : bi Blakeley Washington Clallam Astoria Formation Formation Formation Lincoln Creek Formation Twin li n : Oligocene River Formation Cowlitz : Lyre Formation i Formation Eocene Eocene Bede Puget Aldwell Group Formation C) Aforia campbelli (and “A.” packardi) @) Aforia addicotti, spec. nov. @ Aforia wardi Figure 17 Vol. 15; No. 3 Southwest Washington Astoria Formation Astoria LORD ORRORROR OOOH Formation Nye 6) SP MET : © ©) Yaquina Formation Lincoln @ Creek Formation Siltstone of Alsea Goble Volcanics Nestucca Formation (4) Aforia clallamensis 6) Aforna tricarinata Correlation of some Western Washington and Oregon Marine Tertiary Formations (from YouncguisT, 1961 and SNavELy et al, 1969) , showing occurrences of some species of Aforia Vol. 15; No. 3 THE VELIGER Page 199 ACKNOWLEDGMENTS GASTROPODA The study was supervised by Dr. W. O. Addicott of the U. S. Geological Survey and Stanford University, who suse NEOGASTROPODA gested the study and accorded me the excellent working facilities and placed at my disposal the species from Ceno- TURRIDAE zoic collection to which he has dedicated so much of his effort. He also made arrangements for receiving species from different collections, and allowing me access to his personal library. His help and guidance concerning spe- cific problems were invaluable. He patiently offered en- couragement and corrected the entire manuscript. I wish to express my sincere thanks to Dr. Addicott, under whose direction and advice the paper was prepared. His con- tinued support and enthusiasm are deeply appreciated. Particular thanks go to the following persons for lend- ing specimens: Dr. A. Myra Keen, Dr. J. T: Smith of the Stanford University; Dr. Leo G. Hertlein of the Califor- nia Academy of Sciences; Dr. J. W. Durham, Mr. J. H. Peck of the Museum of Paleontology, University of Cali- fornia, Berkeley; and Mr. J. Armentrout of the Burke Memorial Museum, University of Washington. Special thanks are due to Mr. Kenji Sakamoto of the U. S. Geological Survey for making the photographs used in this report. I am also indebted to Mr. John Miller of the U. S. Geological Survey for making rubber casts and for help during the course of this study. The writer wishes to express her great appreciation to the Geology Department of Stanford University for ex- tending an invitation to conduct post-doctoral studies during 1971 and for the use of all facilities. SYSTEMATIC DESCRIPTIONS Abbreviations for locality description and museum collec- tions used in this section are: CAS — California Academy of Sciences, San Fran- cisco, California SU — Stanford University, Stanford, California SUPTC -— Stanford University Paleontological Type Collection, Department of Geology, Stan- ford, California UCMP -— University of California Museum of Paleon- tology, University of California, Berkeley USGS -—- U.S. Geological Survey, Washington, D. C. locality register USGSM - U. S. Geological Survey, Menlo Park, Cali- fornia, cenozoic register USNM_ - U.S. National Museum, Washington, D. C. UW — University of Washington, Seattle, Washing- ton Aforia Dall, 1889 Type Species (OD) Pleurotoma circinata Dall, 1873. Pliocene to Recent. Recent Range: Bering Sea southeastward to the Straits of Juan de Fuca, Washington. Diagnosis: Shell large, high spired. Angulation distinct and located near the middle of the whorl. Lower part of whorl sculptured by numerous raised revolving lines, and more clearly, on the body whorl. A second prominent but less well developed angulation often occurs below the pri- mary carina on the body whorl. Growth lines make a deep “V”-shaped sinus about the middle of the subsutural slope. Anterior canal slightly flexed and recurved. Aforia campbelli Durham, 1944 (Figures J, 6, 10) 1942 Aforia clallamensis wardi (Tegland). WEAvER, Univ. Wash. Publ. Geol. 5: 516 (in part) ; plt. 97, fig. 10 1944 Aforia campbelli Durham. Univ. Calif. Publ. Geol. Sci., Bull. 27 (5): 183; plt. 14, fig. 4 Holotype: UCMP no. 14961 Type Locality: UCMP loc. A-1636. Type “‘Porter’’ Bluffs along northeast side of highway beginning at a point 270 yards southeast of first exposure southeast of Porter sta- tion and extending 180 yards. Grays Harbor County, Washington, Lincoln Creek Formation; Middle Oligocene. Description: Shell of moderate size, high spired. Whorls sharply angulated near base. Whorl profile above angula- tion deeply concave, ornamented by prominent growth lines. These lines constitute a deep, broadly “U’’-shaped sinus located somewhat more than half the distance from the suture to the angulation. Lower part of angulation concave, ornamented by several revolving lines that are usually much finer and closer set than on the body whorl. A second strong spiral cord occurs below the angulation on the body whorl. Numerous fine revolving lines occur below the angulation, crossed by very fine longitudinal growth lines. Inner lip with well developed narrow callus. Anterior canal long and slightly inclined to the left. Page 200 TE VEEIGER Vol. 15; No. 3 Measurements of Holotype: height 71mm; width 23mm Discussion: This species differs from Aforia wardi by a higher spire and the more concave area above the angula- tion. The angulation is less acute than on A. ward. Occurrence: UW locs. A-1603, A-395, A-3299, A-3282, 3314, Porter sec., Lincoln Creek Form. UCMP loc. A- 1636 Lincoln Creek Form., Middle Oligocene, Grays Har- bor County, Washington; locs. 9003, 9005, 9013, Lincoln Creek Form., Middle Oligocene, Grays Harbor County, Washington. USGS loc. 18950, Lincoln Creek Form., Thurston County, Washington. Aforia ward (Tegland, 1933) (Figures 11, 14) 1933 Leucosyrinx clallamensis wardi Tegland. Univ. Calif. Geol. Sci., Bull. 23 (3): 124; plt. 10, figs. 5-8 1942 Aforia clallamensis wardi. WEAVER, Univ. Wash. Publ. Geol. 5: 516; plt. 97, fig. 6 1944 Aforia wardi. DurHAM, Univ. Calif. Publ. Geol., Bull. 27 (5): 184 Holotype: CAS no. 5471 Paratypes: UCMP nos. 32204, 32206; SUPTC no. 792 Type Locality: CAS loc. 227, “Bluffs along the east side of the N. PG. N. and O. WR. R. tracks at Georgetown”, sec. 20, T. 24 N., R. 3 E., King County, Washington. Blake- ley Formation, Late Oligocene. Description: Shell medium sized, whorls strongly angu- lated. Sutures deeply impressed. Whorl profile between suture and shoulder gently concave, angulated area located near lower third of whorl. Area above angulation orna- mented by a series of growth lines, which make a deep sinus at the middle of shoulder. Area below angulation exceedingly concave, ornamented by weak revolving lines. A secondary angulation appears on body whorl, forming a basal keel. There are numerous fine revolving lines on the body whorl. Canal not preserved. Measurements of Holotype (canal incomplete): height 40 mm; width 23 mm. Discussion: This species is similar to Aforia campbell, but can be distinguished by the lower spire and the less concave area above the angulation. The angulation is more acute than on A. campbelli. Occurrence: UW locs. B-0356, B-0357, Middle fork Satsop River sec., Lincoln Creek Form.; UW loc. B-0273 Canyon River sec., Lincoln Creek Form. CAS loc. 227, Blakeley Form., Georgetown, Washington; UCMP locs. 681, 1804, A-8724, Blakeley Form., U. Oligocene, Kitsap County, Washington, loc. A-1806, Blakeley Form., U. Oli- gocene, Bainbridge Island, Kitsap County, Washington; Loc. F-17 (Rau, 1966), Lincoln Creek Form., Grays Har- bor County, Washington. USGS loc. M-2589, Lincoln Creek Form., Wahkiakum County, Washington; loc. M- 4043, Blakeley Form., Upper Oligocene, Kitsap County, Washington. Plate Explanation Figure 1: Aforia campbelli Durham. U.C.M.P. 10786; loc. 9003. Height (incomplete) 21mm, width 8mm. Lincoln Creek Formation, Middle Oligocene. Grays Harbor County, Washington. x 14 Figures 2, 7: Aforia clallamensis (Weaver). U.S.N.M. 646831. U. S.G.S. loc. M-4038. Height (incomplete) 39mm, width 16mm. Upper part of Twin River Formation, Oligocene or Miocene. Clal- lam County, Washington. Figure 3: Aforia circinata (Dall). U.S.N.M. 646838. U.S.G.S. loc. M-4392. Height (incomplete) 28mm, width 9mm. Tugidak Formation, Pliocene. Tugidak Island, Alaska. Figure 4: Pseudoperissolax merriami Clark. Paratype. U.C.M.P. 11286. U.C.M.P. loc. 3055. Height 37 mm, width 22mm. Kirker Tuff, Oligocene or Miocene. Contra Costa County, California. Figure 5: “Aforia” packardi (Weaver). Holotype. C.A.S. 473. C.A.S. loc. 256. Height 24mm, width 11 mm. Lincoln Creek For- mation, Oligocene. Lewis County, Washington. Figure 6: Aforia campbelli Durham. U.S.N.M. 64682. U.S.G.S. loc. 1895. Height 19mm, width 6mm. Lincoln Creek Formation, Middle Oligocene. Grays Harbor County, Washington. x 2 Figure 8: Aforia addicotti Javidpour, spec. nov. U.S.N. M. 646834. U.S.G.S. loc. M-3191. Height (incomplete) 50mm, width 25 mm. Siltstone of Alsea Formation, Upper Oligocene, Lincoln County, Oregon. Figure 9: Aforia circinata (Dall).S.U.P.T.C. 10057. Height 53 mm, width 26mm. Recent. Kodiak Island, Alaska. Figure 10: Aforia campbelli Durham. Holotype. U.C.M.P. 14961. U.C.M.P. loc. 1636. Height 60 mm, width 18mm. Lincoln Creek Formation, Middle Oligocene. Grays Harbor, Washington. Figure 11: Aforia wardi (Tegland). U.C.M.P. 10787. U.C.M.P. loc. 681. Height 39mm, width 18mm. Blakeley Formation, Upper Oligocene. Bainbridge Island, Kitsap County, Washington. Figure 12: Aforia addicotti Javidpour, spec. nov. Holotype. U. W. Burke Memorial Museum 60600 U.W. loc. B0058. Height (incom- plete) 62mm, width 30mm. Siltstone of Alsea, Upper Oligocene. Lincoln County, Oregon. Figure 13: Aforia clallamensis (Weaver). U.S.N.M. 646832. U.S. G. S. loc. 4090. Height 56 mm, width 22 mm. Twin River Formation, Oligocene or Miocene. Clallam County, Washington. Figure 14: Aforia wardi (Tegland). Holotype. C.A.S. 5471. C.A. S. loc. 227. Height 40 mm, width 23 mm. Blakeley Formation, Up- per Oligocene. Georgetown, Washington. Figure 15: Aforia tricarinata Addicott. U.S.N.M. 649126. U.S. G. S. loc. 15329. Height 68 mm, width 25mm. Yaquina Formation, Lower Miocene. Lincoln County, Oregon. Tue VELIcER, Vol. 15, No. 3 [Javippour] Figures 1 to 15 Vol. 15; No. 3 THE VELIGER Page 201 Aforia addicotti Javidpour, spec. nov. (Figures 8, 12) Holotype: U. W. Burke Memorial Museum no. 60600 Type Locality: UW loc. BO0058. Siltstone of Alsea, Upper Oligocene. Description: Shell large and heavy. Sutures deeply im- pressed. Spire high. Periphery of spire and body whorl sharply angulated. Angulation occurs below middle of whorls of spire. Surface above angulation straight to slightly concave, ornamented by numerous growth lines that make deep sinus located just below the middle of the subsutural slope. Area below angulation concave, orna- mented by about 12 revolving lines. A second strong spiral cord appears on the body whorl] below the primary angu- _lation. Body whorl ornamented by numerous revolving lines and much weaker longitudinal lines. Canal straight and very long. Inner lip smooth. Aperture calloused. Measurement of Holotype: height, incomplete, 62 mm, width 30 mm Discussion: In shape and appearance this species is sim- ilar to Aforia wardi. The angulation is near the middle of the whorl, relatively higher than on A. wardi. The area below the angulation is much less concave on the new species and the angulation is sharper on A. ward. Occurrence: U. W. Burke Memorial Mus. loc. B 0058. Siltstone of Alsea, Toledo Quarry, Yaquina Bay, Oregon. USGS locs. M-1979, M-3191, Siltstone of Alsea, Upper Oligocene. Aforwa clallamensis (Weaver, 1916) (Bigunese2 570 13)) 1916 Turris clallamensis Weaver. Univ. Wash. Publ. Geol. 1: 52; plt. 4, fig. 59 1918 Pseudoperissolax merriami Clark. Univ. Calif. Publ. Ge- ol. Bull. 11(2): 181; plt. 21, fig. 4 [not plt. 22, figs. 10, 15] 1933 Leucosyrinx clallamensis. TEGLAND, Univ. Calif: Publ. Geol. Bull. 23 (3): 123 - 124; plt. 10, figs. 3, 4 1942 Aforia clallamensis. WEAVER, Univ. Wash. Publ. Geol. 5: 516; plt. 97, fig. 1 1944 Afona clallamensis. DuRHAM, Univ. Calif. Publ. Geol. Bull. 27 (5) : 184 1963 Aforia clallamensis. Moore, U.S. Geol. Survey Prof. Pa- per 419: 47; plt. 10, figs. 16, 18 1966 Aforia clallamensis. AvpicotT, Journ. Paleont. 40 (3) : 641; plt. 76, figs. 10, 11 Holotype: CAS no. 555 Type Locality: UW loc. 258, sea cliff one-half mile west of Twin River, in sec. 22,T. 31 N. R. 10 W, Clallam Coun- ty, Washington. Upper part of Twin River Formation, Late Oligocene or Early Miocene. Description: Shell large, whorls of spire with distinct angulation located a little below the central portion of each whorl. Surface of whorls above angulation slightly concave, ornamented by numerous growth lines which make a deep sinus located somewhat above the middle of the subsutural slope. Faint longitudinal growth lines oc- cur below the angulation and, more clearly, on the body whorl. A second prominent but less well developed angu- lation occurs below the primary carina on the body whorl and on the penultimate whorl. Aperture narrow and cal- lused. Canal straight. Inner lip smooth. Measurement of Holotype: height 66 mm, width 28 mm Discussion: A foria clallamensis (Weaver) is similar to A. wardi (Tegland) but differs by having a less sharp angu- lation and also less concave surface above the angulation. The profile of the body whorl is straight on A. clallamensis but concave on A. wardz. Poorly preserved specimens that may represent A foria clallamensis occur in a collection from UCMP loc. A-1806, together with at least one specimen that is clearly A. war- di. The lower angulation on the penultimate whorl of these specimens is extremely weak. They are doubtfully identified as A foria cf. A. clallamensis. Occurrence: UW loc. 258, Twin River Form., Clallam County, Washington, loc. 489, Twin River Form., Wash- ington; loc. 271, Twin River Form., Washington. UCMP loc. A-3677, Twin River Form., Upper Oligocene, Clal- lam County, Washington, loc. A-6, Twin River Form., Oli- gocene, Clallam County, Washington, loc. 3055, Kirker Tuff, Contra Costa County, California. SU label no. 3024, Twin River Form., Oligocene, Clallam County, Washing- ton. USGS loc. M-2120, Nye mudstone, Lincoln County, Oregon, loc. M-4038, Twin River Form., Clallam County, Washington, loc. 4090, Twin River Form., Oligocene or Miocene, Clallam County, Washington. Aforia tricarinata Addicott, 1966 (Figure /5) 1966 Aforia clallamensis tricarinata Addicott. Journ. Paleont. 40 (3) : 641; plt. 76, figs. 9, 12, 13 Holotype: USNM no. 649125, a rubber cast Type Locality: USGS Cenozoic loc. M-1990 in NE $ sec. Page 202 4, T. 11, S. R 11 W, Yaquina quadrangle, Lincoln County, Oregon. Nye Mudstone, Early Miocene. Original Description: Large, fusiform, with seven whorls on incomplete type specimen. Whorls angulated near mid- point by coarse spiral cords, profile convex above and concave below. Upper half of later whorls with a central- ly located broad spiral band: lower half with similar band located immediately above suture. Alternating spiral threads of secondary and tertiary strength occur on later whorls below medial carina. Suture collared, impressed. Body whorl and spire incomplete. Very fine growth lines indicate a sinus located near posterior quarter line on later whorls. Measurements of Holotype: height (incomplete) 45 mm, width (incomplete) 20 mm Discussion: A foria tricarinata is closely related to A. clal- lamensis but differs in having a prominent spiral cord be- tween the suture and the primary angulation on all but the earliest whorls. Occurrence: USGS Cenozoic locs. 21806, M-1990, and M-3630, Nye Mudstone. USGS loc. 15329, upper part of Yaquina Form., and USGS locs. 2755 and 18907a, strati- graphic position doubtful, Lincoln County, Oregon. Aforia circinata (Dall, 1873) (Figures 3, 9) 1873 Pleurotoma circinata Dall. Calif. Acad. Sci. Proc. 5: 4; plt. 2, fig. 5 1902 Pleurotoma circinata. Dati, Proc. U. S. Nat. Mus. 24 (1264): 515; plt. 36, fig. 1 1921 Aforia circinata. Dati, U. S. Nat. Mus. Bull. 112: 68; pit. 11, fig. 6 1927 Aforia circinata. OLDRoyp, Stanford Univ. Publ. Geol. Sci. 2 (1): 63; plt. 4, fig. 1 1966 Aforia circinata. PowELL, Bull. Auckland Mus. no. 5: 43: plt. 5, fig. 12 Type Locality: Nateekin Bay, Captain’s Bay, Unalaska. Recent. Description: Shell thin, fusiform, with high spire and an- gulated whorls. Angulation located near the middle of the whorl. Growth lines make a deep “U-shaped sinus on the lower half of the subsutural slope. Whorl profile above angulation slightly concave. Lower part of whorl sculp- tured by numerous raised revolving lines. Body whorl slightly shorter than spire, ornamented by numerous re- volving lines which are crossed by alternately heavier and finer longitudinal lines. Aperture ovate, canal long and inclined to the left. THE VELIGER Vol. 15; No. 3 Discussion: This species differs from the Oligocene and Miocene species of Aforia in having a thin shell, a re- curved anterior canal, and in lacking a secondary angula- tion on the body whorl. On some of the Recent specimens from Alaska, however, a poorly developed anterior angu- lation appears on the final quarter turn of the body whorl. The angulation is located almost on the central part of each whorl. Pliocene specimens from Alaska have a deep sinus that is located closer to the angulation than in modern specimens. Occurrence: Recent: USNM locs. 225566, 225586, 211- 973, 222525, 222483, 222495, 209710, 130511, 222958, Pribiloff Islands, Bering Sea, 34 to 121 fathoms; locs. 211- 979, 211980, 206086, 209729, Unalaska, Aleutian Islands, 68 to 85 fathoms; loc. 222303, Numiak Island, Aleutian Islands, 85 fathoms; loc. 223933, off Unalaska, Aleutian Is- lands, 78 fathoms; loc. 211974, 223100, 211978, Unimak Island, Aleutian Islands, 60 to 81 fathoms; loc. 210158, Bering Sea, 62 fathoms; locs. 224079, 224246, 223879, 224218, 223174, 224429, 224633, off Pribiloff Islands, Bering Sea, 49 to 86 fathoms. Recent: SU loc. 51982, Bristol Bay, Alaska, 49 fathoms. Pliocene: USGS loc. M- 2522, Yakataga Form., Middleton Island, Alaska; loc. M- 4272, Gulf of Alaska; locs. M-4394, M-4392, M- 4402, Tugidak Island, Alaska. “Aforia” packard: (Weaver, 1916) 1916 Turris packard: Weaver. Univ. Wash. Geol. 1 (1): 55; plt. 5, fig. 64 1916 Turris packardi. WEavER, Wash. Geol. Surv. Bull. 13: 313 1942 Aforia packardi. WEAVER, Univ. Wash. Publ. Geol. 5: 516; pit. 97, fig. 3 1944 “Aforia”’ packardi. DuRHAM, Univ. Calif: Publ. Geol. Bull. 27 (5): 184 Holotype: CAS no. 473 Type Locality: UW loc. 256 in railway cuts on the O. W. R.R. and N. Co. One-fourth mile northwest of Galvin Station in sec. 27, T. 15 N., R. 3W, Lewis County, Wash- ington, Lincoln Creek Formation, Oligocene. Description: Shell small and pagodaform, whorls of spire strongly angulated near base. Two strong spiral cords located on the angulation of each whorl. Area above angu- lation somewhat concave, ornamented by 7 - 9 very faint revolving lines. Axial lines of growth prominent, forming a shallow sinus near base of whorls of the spire. Surface below angulation slightly concave, sculptured with about four faint revolving lines. Body whorl! sculptured by about 22 prominent revolving lines below the angulation, and numerous faint longitudinal lines. Inner lip smooth, outer Vol. 15; No. 3 THE VELIGER Page 203 lip with sharp angulation. Canal deep, medium in length, inclined slightly to the left. Measurements of Holotype: height 24 mm, width 11 mm Discussion: This small species is distinguished by its pa- godaform spire, and, especially, by having 2 spiral cords on the angulated area. But as DurHAM (1944: 184) mentioned, reference of this species to Aforia is question- able because the turrid notch is broad, not very deep, and its lower border crosses over the anglation. Occurrence: UW loc. 256, Lincoln Creek Form., Lewis County, Washington; locs. A-575, A-52, Porter sec., Lin- coln Creek Form. UCMP loc. T: 8, Lincoln Creek Form., Oligocene, Grays Harbor County, Washington. USGS Cenozoic loc. 18974, Lincoln Creek Form., Oligocene, Grays Harbor County, Washington; loc. M 1729, Lincoln Creek Form., Porter Bluffs, western Washington. LOCALITY DESCRIPTIONS C.A.S. California Academy of Sciences loc. 227 Upper Oligocene, Blakeley Formation. “Bluffs along the east side of the N. PG. N. and O. W.R.R. tracks at Georgetown.” Stanford University 3024 Oligocene or Miocene. Twin River Formation. Clallam Coun- ty, Washington. cat. no. 51982 Recent. Bristol Bay, Alaska, 49 fathoms, 55°20’ N, 164°00’ W. U.C.M.P. University of California, Museum of Paleontology loc. A-6 Oligocene or Miocene. Twin River Formation, Clallam Coun- ty, Washington. Shale cliffs in first large embayment east of East Twin River. loc T-8 Oligocene. Lincoln Creek Formation, Grays Harbor County, Washington. (Turritella porterensis and Exilia lincolnensis oc- cur in the collection.) loc. A-1636 Middle Oligocene. Lincoln Creek Formation, Grays Harbor County, Washington. Type ‘Porter’ Bluffs along northeast side of highway beginning at a point 270 yards southeast of first exposure southeast of Porter station and extending 180 yards. loc. A-3677 Oligocene or Miocene. Twin River Formation, Clallam County, Washington. In shale exposed in sea cliff. About in center of north line of the S. W.} of sec. 23, T.31 N, R. 10W. loc. 681 Upper Oligocene. Blakeley Formation, Bainbridge Island, Kit- sap County, Washington. Generalized locality for fossiliferous strata around Restoration Point. S.U. Rau iG: loc. 1804 Upper Oligocene. Blakeley Formation, Kitsap County, Wash- ington. Conglomerate on south side of Bremerton Inlet, Middle point. Sec. 15, T. 24 N., R. 2E. loc. A-1806 Upper Oligocene. Blakeley Formation, Bainbridge Island. Kit- sap County, Washington. From the sandstone at Restoration Point. Eastern boundary of section 12, T. 24 N., R. 2E. loc. 3055 Oligocene or Miocene. In valley north of Sobrante Ridge, on west fork of Bear Creek 4 mile from source, on north bank in Tuff beds, elevation 800 feet, Contra Costa County, Califor- nia. Long. 122°12’35” W, lat. 37°55’58” N. loc. 9003 Middle Oligocene. Lincoln Creek Formation, Grays Harbor County, Washington. Clemons Logging R. R. 420 - 500 paces northwest of Saginaw Trail, Sec. 6, T. 16N., R. 6W. loc. 9005 Oligocene. Lincoln Creek Formation, Grays Harbor County, Washington. Sec. 6, T. 16 N, R. 6W, M. loc. 5’, Clemons Log- ging R. R. 1050-1100 paces northwest of Saginaw Trail in the NW } of sec. 6. loc. 9013 Middle Oligocene, Lincoln Creek Formation, Grays Harbor County, Washington. Clemons Logging R. R. 1200-1300 paces northwest of Saginaw Trail. (1966) loc. F17 Upper Oligocene. Lincoln Creek Formation, Grays Harbor County, Washington. West fork of Satsop River, 1500 feet north, 400 feet west of S. E. cor. sec. 21, T. 21 N., R 7W. .G.S. United States Geological Survey, Washington, D. C., register loc. 1895 Middle Oligocene. Lincoln Creek Formation, Grays Harbor quadrangle, Washington. Highway south of Porter 4750 feet east, 3510 feet north of S. W. cor. sec. 28, T. 17 N., R. 5 W. Malone quadrangle. loc. 4090 Oligocene or Miocene. Twin River Formation, Clallam Coun- ty, Washington. Lake Crescent, 15 quad. Sea Cliff exposure, west of mouth of West Twin River. Upper part of Twin River Formation. loc. 15329 Middle Oligocene. Yaquina Formation, Lincoln County, Ore- gon. Fossils from concretions on shore of Yaquina Bay. N W. +, N. E. 4 sec. 15; T. 11S, R 11W. United States Geological Survey, Menlo Park, Califor- nia, register loc. 18974 Oligocene. Lincoln Creek Formation, Grays Harbor County, Washington. Grays Harbor quadrangle. Clemons Logging road 3750 feet east, 1750 feet north of S. W. corner sec. 25, T. 17N., R. 7W. Montesano quadrangle WN. loc. M=1729 Oligocene. Lincoln Creek Formation, Grays Harbor County, Washington. Page 204 loc. M- 1979 Upper Oligocene. Lincoln County, Oregon. Waldport 15-min. quad. S. E. 4 sec. 24, T. 13S, R. 12W. West of seawall, south side of Alsea Bay. loc. M-1990 Middle Oligocene. Yaquina quad. (15-min.), Lincoln County, Oregon. N. E. 4, N. E. sec. 4, T. 11S, R. 11W. Jeffreys Creek. loc. M= 2120 Oligocene or Miocene. Nye mudstone. Yaquina quad., Lincoln County, Oregon. 1900 feet north, 700 feet west of S. E. cor. sec. 24, T. 12S., R. 12 W. loc. M.- 2522 Pliocene. Yakataga Formation. Middleton Island, Alaska. Gulf of Alaska. loc. M= 2589 Upper Oligocene. Lincoln Creek Formation, Wahikiakum County, Washington. Grays River quad. N. central sec. 1, T. 9N., R. 8W. North slope of Hill 498, south of South Fork of Crooked Creek. 2700 feet east and 1600 feet south of N. W. corner of the section. loc. M=3191 Upper Oligocene. Alsea Formation, Lincoln County, Oregon. Toledo 15-min. quad. 2550 feet west, 1550 feet south of N. E. cor. sec. 18, T. 11S., R. 1OW. A. West side of West Yaquina Bay Road. loc. M= 3630 Lower Miocene. Nye mudstone. Yaquina 15-min. quad., Lin- coln Creek Formation, Oregon. Fill from access road to trailer park northeast of intersection of Big Creek and U.S. Route 101, 2200 feet south, 1550 feet west of N.E. cor. sec. 32, T. 10S., R. 11 W. loc. M.-4038 Oligocene or Miocene. Twin River Formation, Clallam Coun- ty, Washington. Lake Crescent 15-min. quad., sea cliff ex- posure above dirt road leading westward to quarry and loading dock, 2100 feet north, 1250 feet east of S. W. cor. sec. 23, T. 31N, R. 10W. loc. M- 4043 Upper Oligocene. Blakeley Formation, Kitsap County, Wash- ington, Duwamish Head 73-min. quad. Uppermost part of intertidal zone N. W. of Restoration Point. 600 feet west, 450 feet north of intersection of E. line sec. 12, T. 24N., R. 2E. and shore line. loc. M.-4168 Upper Oligocene. Lincoln County, Oregon. Toledo quad. West side of city of Toledo at bend in Yaquina River. Center sec. 18, T. 11S., R 10W. loc. M-4272 Pliocene. Middleton Island, Alaska. Gulf of Alaska. Meas- ured sec. at southwest end. 2845 to 2910 feet above base of measured portion. loc. M-4392 Pliocene. Trinity Islands, Alaska. Trinity Islands quad. Meas- ured section on northwest coast of Tugidak Island, approxi- mately 230 to 260 feet above base. THE VELIGER Vol. 15; No. 3 loc. M.-4394 Pliocene. Trinity Islands, Alaska. Trinity Islands quad. Meas- ured section on northwest coast of Tugidak Island, approxi- mately 580 to 610 feet above base. loc. M- 4402 Pliocene, Trinity Islands, Alaska. Trinity Islands quadr. Meas- ured section on northwest coast of Tugidak Island, approxi- mately 1690 to 1720 feet above base. U. W. University of Washington, Seattle, Washington loc. A-52 Oligocene. Twin River Formation, Clallam County, Washing- ton. East of West Twin River, T. 30N., R. 10W. loc. A-395 Middle Oligocene. Lincoln Creek Formation, Grays Harbor County, Washington. Along east side Highway 12 in bluffs just south of Porter Creek. N. 4 sec. 6, T. 16N., R. 6W. loc. A-575 Middle Oligocene. Lincoln Creek Formation. Grays Harbor County, Washington. Along bluffs of Highway 12 just south of Porter. Secs. 27, 28, T. 17N, R. 5W. loc. A-1603 Middle Oligocene. Lincoln Creek Formation. Grays Harbor County, Washington. From bluffs along Highway 12. 600 feet south of road along south side of Porter Creek, sec. 28, T. 17N., R. S.W. loc. A-3282 Middle Oligocene. Lincoln Creek Formation. Grays Harbor County, Washington. Along bluffs of Highway 12 just south of Porter, secs. 27, 28, T. 17N., R. S. W. loc. A-3299 Middle Oligocene. Lincoln Creek Formation. Grays Harbor County, Washington. Along bluffs of Highway 12 just south of Porter, secs. 27, 28, T. 17N., R. S. W. loc. A-3314 Middle Oligocene. Lincoln Creek Formation. Grays Harbor County, Washington. Along bluffs of Highway 12 just south Porter, secs. 27, 28, T. 17N., R. S.W. loc. B-0058 Upper Oligocene. Siltstone of Alsea, Toledo Quarry, Yaquina Bay, Oregon. Large quarry along Yaquina Bay road. 14 miles south of junction at Bay road with Highway 20 at Toledo. On west side of road. S. E. 31, N. W. i sec. 18, T. 11S., R. 11W. loc. B-0273 Upper Oligocene. Lincoln Creek Formation, Grays Harbor County, Washington. South side of Canyon River at base of high cliff just west of Canyon River bridge. S. E. 4, S. E. + sec. 13, T. 21N., R. 6W. loc. B-0356 Upper Oligocene. Lincoln Creek Formation, Mason County, Washington. South side of middle fork of Satsop River along base of high cliff running along E - W tracc of river. S. W. 1, N. W.4 sec. 20, T. 21N., R. 6W. loc. B-0357 Upper Oligocene. Lincoln Creek Formation, Mason County, Washington. West side of meander bend of Middle Fork of Satsop River along base of high cliff. N. W. 4, S. W. i sec. 20, T. 21N., R. 6W. Vol. 15; No. 3 loc. 256 Oligocene in railroad cut on O. W.R. R. and N. Co. One mile north of Galvin station in sec. 27, T. 15N., R. 3W. loc. 258 Oligocene or Miocene. One half mile west of Twin post office, Clallam County, Washington. In sea cliff in sec. 27, T. 31N., R. 10W. loc. 271 Oligocene or Miocene. Twin River Formation, Clallam Coun- ty, Washington. Cliff, south shore of Straits of Juan de Fuca, about 1000 feet west of locality 258 which is 4 mile west of Twin post office, sec. 22, T. 31N., R. 9W. loc. 489 Oligocene or Miocene. Twin River Formation, Clallam Coun- ty, Washington. Literature Cited AppicotT, WARREN OLIVER 1966. New Tertiary marine mollusks from Oregon and Washington. Journ. Paleont. 40 (3): 635 - 646; plts. 76 - 78 Bartscu, Pau 1945. Distribution list of the West Pacific species of the mollusk genus Aforia. Journ. Wash. Acad. Sci. 35 (12): Burcu, JoHN Quincy 1942-1946. Distributional list of the West American marine mollusks from San Diego to the Polar Sea. Conch. Club So. Calif., minutes; 2 parts; pag. by issue; 3 plts. Crark, Bruce LAWRENCE 1918. The San Lorenzo series of middle California, Univ. Calif. Publ. Geol. Sci. 11 (2): 45 - 234; plts. 3- 24; 4 text figs. (16 July 1918) THE VELIGER Page 205 Dai, WILLIAM HEALEY 1921. Summary of the marine shellbearing mollusks of the northwest coast of America, from San Diego, California, to the Polar Sea, mostly contained in the collection of the United States National Museum, with illustrations of hitherto unfigured spccies. U. S. Nat. Mus. Bull. 112: 1 - 217; plts. 1 - 22 (24 February 1921) DurHaAM, JoHN WyatTT 1944. Megafaunal zones of the Oligocene of northwestern Washing- ton, - Univ. Calif. Publ. Geol. Sci. 27 (5): 101-212; plts. 13 - 18; 7 text figs.; 1 map (14 November 1944) Moorg, ELLEN JAMES 1963. Miocene marine mollusks from the Astoria Formation in Oregon. U.S. Geol. Surv. Prof. Paper 419: 1-109; plts. 1-33 O.proyp, IpA SHEPARD 1927. The marine shells of the west coast of North America. 2 (1): 297 pp.; 22 plts. Stanford Univ. Press, Stanford, Calif. PowELL, ARTHUR WILLIAM BADEN 1966. The molluscan families Speightiidae and Turridae. An evaluation of the valid taxa, both Recent and fossil, with lists of characteristic species. Bull. Auckl. Inst. & Mus. No. 5: 1 - 184; plts. 1 - 23; text figs. (1 November 1966) Rau, WELDON W. 1966. Stratigraphy and Foraminifera of the Satsap River area, South- ern Olympic Peninsula, Washington. Wash. Div. Mines & Geol. Bull. 53: 1- 66 (24 June 1966) TEGLAND, NELLIE May 1933. The fauna of the type Blakeley upper Oligocene of Washington. Univ. Calif. Publ. Geol. Sci. 23 (3): 81-174; plts. 2-15; 2 maps (11 October 1933) Tryon, GeorcE WASHINGTON, Jr. 1884. Manual of Conchology. WEAvER, CHarLES EDWIN 1916. Tertiary faunal horizons of western Washington. Publ. Geol. 1 (1): 1-67; plts. 1-5 Philadelphia, ser. 1, 6: 413 pp.; illust. Univ. Wash. 1916. The Tertiary formations of western Washington. Geol. Surv. Bull. 13: 1942. Paleontology of the marine Tertiary formations of Oregon and Washington. Washington Univ. (Seattle) Publ. Geol. 5 (1-3): 789 pp.; 104 plts. Page 206 THE VELIGER Vol. 15; No. 3 The Intertidal Behavior of the Bean Clam, Donax gouldit Dall, 1921 THOMAS H. IRWIN Department of Biology, Victor Valley College, Victorville, California 92392 (2 Plates; 3 Text figures) INTRODUCTION PELECYPOD MOLLUSKS of the family Donacidae, genus Donax, occur throughout the world mostly within the intertidal zone on sandy beaches in tropical and temperate climates. Most species of intertidal Donax inhabit only wave washed beaches and are found at various levels of the littoral where many are exposed at low tide and sub- merged at high tide. They occupy only the surface of the sand to a depth of about 5 cm and are easily observed in areas of great population density. Studies of these organisms and their adaptations that allow them to successfully occupy this unstable habitat are far from complete. One of the many possible adaptations of Donax that deserves additional attention is a contro- versial behavioral phenomenon known as tidal migration. In exhibiting this behavior, the organism follows the rising tide up the beach and then retreats down the beach as the tide subsides. The possession of anatomical devices for extended movement need not be present as the animal could position itself to make use of the surge of the waves to change its position. The following species of Donax have been reported to migrate or exhibit some form of tidal movement: Donax semigranosis Dunker, 1877 (Mort, 1938, 1950) ; D. vitta- tus La Costa (STott, 1937, 1938) ; D. vartabilis Say, 1822 (Pearse et al., 1942; TuRNER & BELDING, 1957; LorscH, 1957; AtpricH, 1959; Tirrany, 1971); D. fossor Say, 1822 (= D. variabilis [ApBott, 1954; CHANLEy, 1969]) (Jacopson, 1957); D. denticulatum Linnaeus, 1767 (WapE, 1964, 1967a) ; D. gould Dall, 1921 (Jounson, 1966a, 1966b); D. striatus Linnaeus, 1767 (WapE, 1967b); D. aemulus (Pichon, 1967) ; D. elegans (Picuon, 1967) ; D. incarnatus Gmelin, 1791 (ANSELL & TREVALLION, 1969); D. spiculum Reeve (ANSELL & TREVALLION, 1969). In contrast, the following species of Donax have been observed not to exhibit migration or tidal movement: Donax gouldu (HEpcretH, 1957; Porto, 1967) ; D. vari- abilis (EpGREN, 1959); D. faba (Picton, 1967) ; D. vit- tatus (ANSELL & TREVALLION, 1969). It should be noted that several other beach-dwelling marine organisms have been observed to migrate. The sand crab, Emerita analoga Stimpson, 1857 (MacGinimiz, 1938; Cuxir, 1969) and the gastropods Terebra salleana Deshayes (Kornicker, 1961) and Bullia melanoides Des- hayes (ANSELL & TREVALLION, 1969) have been observed to migrate with the tides. JoHNson (1966a) has sug- gested that the gastropod Olivella biplicata Sowerby, 1825 might also move landward during the rising tide. The purpose of this study is to examine a population of Donax to find if tidal migration does occur and, if so, what factors are responsible or influential in this behavior pat- tern. An attempt will also be made to examine the poten- tial advantages to the organism of such behavior. MATERIALS anp METHODS Observations were made on a population of Donax gouldu at Estero Beach (approximately 31°45’N, 116°38’ W) near Ensenada, Baja California, Mexico. This particular location was selected because it usually maintains a high population density of these clams. Beaches in this area are also easily accessible by traveling by boat in the estero and crossing over a sand bar to the beach. Observations on this population began in August, 1961 and continued through August, 1969. Detailed observa- tions were made in August of each year, but shorter in- spections of one week or less were conducted in other months of the year whenever possible. Vol. 15; No. 3 Four stations were selected so that there were at least noticeable variations in the beach elevations between the stations. An attempt was made to use the same stations during the 8 year period of study. This was difficult, however, because the beach contours and sand dunes of the backshore changed considerably during the 8 year period of study. A concrete bench marker about 4 feet square was used as a base stake for one station, but upon returning 7 months later, it was found that this marker had been undercut by the surf and moved into the inter- tidal zone from high on the dunes behind the beach. 'The other stations were even more difficult to keep track of during this period, and it was possible only to estimate their location from year to year. At each station a stake was placed above the high water line. From this stake a line graduated in meters was run down the intertidal zone at low tide to the low water line. The daily position of the population of Donax gould was noted by taking one-quarter square meter samples every 2 meters in the area occupied by the clams (Figure /). Sample areas to be collected were marked by using a wooden frame measuring 4 meter on each side. This included an area of + square meter. All the clams were removed from this area and placed in a wood- en-framed sieve with } inch hardware cloth bottom. This sieve was then used to separate the sand from the clams by washing the collection in the surf. Each sample of clams was then counted to obtain a quantitative estimate of the population and its position on the beach. If the sample contained only small numbers of clams each was counted individually. Samples containing large numbers were esti- mated by volume using a 350 ml can. When this method was used, 4 cans-full of clams were counted, and an aver- age was taken to figure the number of clams per can. At monthly intervals the number of clams filling the can was recalculated to consider possible change in the population. Observations were also made during high tides when the population was submerged. Quantitative sampling was difficult, but by using the transect line and a glass face plate the position of the population could be recorded. The physical factors of the habitat which may have some influence on the migratory behavior of Donax were also recorded, including: 1. Air and water temperatures were taken during each ob- servation with a laboratory grade thermometer. Read- ings corresponded to air and water temperatures found by Fores (1965) for this area. 2. Surf conditions were recorded throughout the time of observations. Unusual conditions during other periods were recorded by residents of Estero Beach Resort. The surf height was estimated using a meter stick. THE VELIGER Page 207 3. Salinity data were taken from published data for the area (FLores, 1965). 4. Tidal conditions were taken from United States Coast and Geodetic Survey tide tables for 1961 through 1969. The 0.90 ratio was applied to the San Diego Data given to convert to readings for Todos Santos Bay. Time dif- ferences of —19 minutes for low tides and —17 minutes for high tides were used. on . Sand was fractioned using standard 8 inch soil sieves from 40 mesh (0.42mm) to 200 mesh (0.074 mm). Samples of 100 gr were shaken for 30 minutes by a mechanical shaker and the fractions were weighed to 0.01gr. The density of the sand was calculated using water displacement. The water-holding capacity of the sand was found by saturating dry sand with distilled water. As soon as water stopped dripping from the sand it was weighed, then oven-dried at 100°C for 4 hours and reweighed. The percentage of water to sand was then figured. 6. The beach contour was measured at the beginning and at the end of each observation period. The contour of the beach was measured at 2 m intervals by sighting through a transit located over the base stake upon a long graduated pole. All contours and distances were converted into feet so that they could be easily com- pared to the tidal data published by the United States Coast and Geodetic Survey. The contour measurements for each station were then drawn, and the daily posi- tion and population density of the clams at this station were plotted upon the contour drawing. With these data plotted, the vertical position of the clams with relation to the water or tidal level could easily be seen. 7. The presence of local currents was recorded by ob- serving floating debris in the water. Characteristics of this population of Donax gouldii that might influence migration were also studied. Clams from different levels of the beach were measured to determine if size segregation was present. Clams were also tested to determine their ability to withstand exposure by placing them on dry and damp sand under direct sunlight for various lengths of time. Tagging and transplanting ex- periments were also attempted. DESCRIPTION or tHE WORK AREA AND Donax POPULATION Estero Beach represents an isolated strip of sand situated between the rocky coast north of Ensenada and the cliffs Page 208 THE VELIGER Vol. 15; No. 3 at Punta Banda. An entrance to the estero (estuary) produces another barrier that separates the beach just south of Ensenada from the work area. The mountains surrounding the area and the islands in the entrance to Todos Santos Bay shelter the beach and work area from excessive winds and surf. Days are relatively calm with little overcast except during the late spring and early summer. The conditions representing the work area were noted as follows: 1. For the year 1964, which was typical, air temperatures ranged from a low of 9.5° C on November 20 to a high of 23.0° C on October 20. Water temperatures within the surf were fairly constant, with winter temperatures averaging 16°C and summer temperatures averaging near 20° C. 2. Surf conditions were very stable. The surf along this protected beach seldom exceeds 3 feet in height. There were, characteristically, 4 or 5 rows of continuous break- ers ranging in height from a few inches to 2 feet with a weak wash produced every 5 to 10 seconds. Storms or heavy winds produced little change in these conditions. 3. Salinity in the surf averaged 34.4%, with a range be- tween 33.9 and 35%, (Fiores, 1965) 4. Tidal conditions in the area are typical of the west coast of California. There are usually 2 high and 2 low tides each day. The mean tide level for Todos Santos Bay is 2.7 feet, with a mean tidal change of 3.6 feet. During the period when observations were made, tidal changes ranged from 0.3 feet on August 27, 1963, to 7.8 feet on August 25, 1965. The mean high and low tides are 4.7 and 0.9 feet respectively. This represents a 0.2 foot greater tidal change than the actual mean. The mean tide level was 2.8 feet, 0.1 foot higher than the actual mean for this area. 5. Sand within the intertidal zone was found to be ex- tremely fine as compared to parts of the east coast (Pearse et al., 1942) and to the optimum particle size favored by Donax denticulatus (Wave, 1964). Sand fractions showed that over 95% was between 0.177 mm and 0.074 mm. This is similar to the sand on the Texas coast (HepcpetH, 1953). The density of the sand was 2.72, as compared to a density of 1.89 for the Donax gouldu. Water holding capacity was found to be 22.5%. 6. Variations in beach contour between the 4 stations are shown in Table 1. Local currents appeared to cause great changes in the beach profile from year to year (Table 2). The breakers rolled in at a slight oblique angle producing a weak local current toward the inlet of the estero. During tidal changes, a stronger current was produced by the exchange of water in the estero. This current was, perhaps, most responsible for the un- stable conditions observed near the inlet of the estero. Table 1 Comparison of Stations in August, 1962 — oO 2s & 3.8 BS 3 oO SEN = omg o § ae Gs ae =e a 2355 <8 me ae g SRS o2 1 8 =r a § Ley 38 o°8 Dy Beas i} 3 8 5 Ss SS ac nA ro > 48 LQ FS 1 1: 40 80 6400 2 1. 28 54 7600 3 1-222 42 2600 4 1: 28 54 3400 Table 2 Comparison of Variations in Station 3 from 1961 to 1967 ms o gs ionene RZ 8 be 8. N a) & 2 3 5 iy OS Ry Se ee a. ow S| se as © § 27S Date ae oe gc ms P ca g y (<3) > cl a F Nee : Ue : eae Vol. 15; No. 3 from each microhabitat, were marked in situ for the track- ing part of the study. The identification procedure con- sisted of marking small colored tags (white, red, and yellow) with consecutive numbers, using India ink. These were attached to the shells with a quick-drying water- proof adhesive. On previous tests this adhesive, Aron Alpha no. 202, proved to be a non-toxic substance and also was found to be superior to the painted coding system used in the initial study. In addition to the tagged limpets, 2 dummy clusters were positioned on the rock face with the above mentioned adhesive. A dummy cluster consisted of limpet shells filled with plaster of paris and mechanically adhered to the rocks to simulate a natural living cluster. Ten shells were boiled to remove all chemical traces, and another 10 were positioned on the rocks without any pre-conditioning. Both dummy clusters were placed in close proximity to the 3 selected microhabitats, but in unoccupied spaces. It is interesting to note that both of these pseudocluster sites were previously occupied by living clusters used in the previous summer’s study. After marking, and noting their original positions, the limpets were observed each day at low tide, for 10 consec- utive days. Two additional periods were also used to ob- serve movement and clustering behavior at high tide. The 10 tagged members of each microhabitat were traced to their resting positions each day with distance and direction in degrees measured. The position and orientation of each marked limpet was noted along with orientation of all other limpets in each of the 3 microhabitats. On the third day of observation, a number of the marked limpets within the clusters appeared to be pro- longing their resting period, and it was suspected that they were not moving during either of the 2 high tide periods. These limpets were then tethered to the rock so that on later observations a shift or change of position would be evident (Figure 2). Metal pegs were driven into the rocks approximately 2} to 5 cm from each limpet suspected of remaining stationary. A 4-pound monofilament line was tied to the peg and weakly taped to the animal’s shell. The tether had enough strength to withstand the force of the waves, but could easily be parted by the limpets on their shifting position or moving away from the cluster site. In order to determine the stability of the 3 clusters in terms of continued membership, it was necessary to locate the resting site of each marked Acmaea digitalis on a daily basis. The observations revealed that 3 activities were oc- curring within each of the microhabitats. First, there was a periodic turnover of limpets with some moving out of the cluster while others would return to recluster during the period of low water. A residual number of limpets extended their resting period from one observation to the THE VELIGER Page 225 next (see Figure 3), and apparently did not respond to the stimuli of the incoming tide. The third factor ob- served was that some of the cluster members rotated or reoriented themselves in each of their respective sites. It is believed by this observer that by repositioning them- red microhabitat yellow microhabitat — hee ND) Goo HS LOU On) 1) (CO! 6) (© white microhabitat days 3 2 5 6 7 8 YF 1 limpets active during the N stationary during the EB high tide periods NN high tide periods Figure 3 A 10-day observation of the movement and resting behavior of 30 marked individuals of Acmaea digitalis illustrated in consecutive days within 3 studied microhabitats Page 226 THE VELIGER Vol. 15; No. 3 selves, they would either benefit from improved locations, or they moved to make contact with other individuals or groups of limpets. The question of contact will be con- sidered later. VILLEE & Groopy (1940) reported that Acmaea digita- lis as a group demonstrated high rates of replacement. They interpreted this phenomenon as when one animal moved out, another moved in to take its place. Although a number of specific cases could be cited of this phenomen- on, one prime example took place on the 9" and 10™ days of the study. Two limpets, marked number 9 and number 10 from the white microhabitat had been resting in relatively the same cluster orientation and position for 8 consecutive days. Number 10 rested in a solitary position on the edge of the cluster 10 cm above number 9, which was in contact with 3 other A. digitalis. Each limpet was tethered to verify movement or rotational change. On August 13, number 9 moved up and into exactly the same position of number 10’s resting site. Number 10 moved into the center of the cluster and made contact with one other limpet. The following day number 10 returned to exactly the same location and orientation as of August 13. Limpet number 9 returned approximately to the position held initially and made contact with 2 other members of the cluster. It appears that limpet number 10 had left its scar after an extended resting period, and upon returning had found its scar occupied by another member of the cluster. The permanency of cluster membership was the next behavioral characteristic to be considered. Figure 4 focuses attention on the residual makeup of the clusters. Approxi- mately 20% of the marked limpets from a specific micro- red microhabitat yellow microhabitat habitat returned to their original cluster site where first observed. The figure correlates favorably with my findings of the initial study at the same location in August, 1970. During that investigation 47 limpets were marked, 15 of which were for the individual tracking. Of that number, 25% of the marked limpets returned to the original micro- habitat. The cluster membership remained remarkably stable during the course of the investigation. Even though there was a consistent turnover with new members, and re- grouping of some old members on a daily basis, the num- ber in each cluster remained essentially about the same. Table 1 primarily reflects contact data, but also illust- rates a stability in membership from one day to the next. This phenomenon is of interest, for I never found all the available space within each of the 3 sites fully occupied on any one resting period. The second question of this study concerns the orienta- tion taken by these gastropods as they seek shelter among the folds and crevices of the intertidal rocks. Table 2 ac- counts for the observations of 411 individual limpet orient- ations during an 11-day period. Only the clusters within designated microhabitats were used. As previously indi- cated, Acmaea digitalis prefer vertical rock surfaces, but will position themselves on the horizontal plane if so situated on the vertical surface. No one quadrant of the compass suggests a preferred position; however, in an- alyzing the data there was a slight tendency of the animals to orient with their anterior ends downward as opposed to the anterior ends pointing upward. Rock topography and point of contact with other limpets seemed to account for many of the positions taken. For example, Table 2 100 90 white microhabitat 80 80 70 70 70 = 60 = 60 = 60 oO oO o = 50 2 50 3 50 > 40 A. 40 = 40 30 30 30 20 20 20 10 10 10 a Se OIG) 12 3°4°5°6° 7°89 iO LQ 3° 4s BS" 6" 7 B 9 iO days days days Observations of 30 marked limpets that returned to or remained in designated microhabitats, expressed in percent, August 4 to 14, 1971 Vol. 15; No. 3 Table 1 Frequency and percent of all resting Acmaea digitalis observed having contact with one or more limpets within the three studied microhabitats, and marked Acmaea digitalis observed in contact with other limpets outside the three studied microhabitats. Observations also include those Acmaea digitalis resting without contact both inside THE VELIGER Page 227 reveals that in the white microhabitat a significant per- centage of animals oriented with their anterior ends in the 270° - 360° quadrant. This may be attributed to the fact that the particular microhabitat had a wide, flat angle in its lower right hand quarter. Limpets which were for- aging below the cluster found easy access in returning, as opposed to the steeper slope above and to the left hand and outside of the studied microhabitats. N = 573 margins of the cluster site. Their movements apparently ended within the group when contact was made with the 2 rakes 3 shell of a resting limpet. = “ is) co 5 . : . 2 oe g a5 es) fo z g2 One observation during a receding high tide noted that Bas ae * $3 5 ca one limpet while joining the cluster made contact with 2 ‘ca 0 [e} nn ot Aw b0 G 5 az 5 ag5 FSmnq Flak Acmaea digitalis and one A. scabra, resting at the edge of S +s CN teh oe Sica SAT ON em : . . 4 g& ES oe mae S's 2 Oe the cluster. When these 3 resting limpets were stimulated o o 2 0c o 2 0.4 : ° 26.2 fecal el RAST ae) hes To by the movements of the incoming one, they rotated and Date gos g.3 ge2g ge22 i : me hd E85 88568 8466 shifted their positions slightly to allow it room to position August 4 30 4 = E itself. é pea ik August 5 34 5 es a An obvious phenomenon of this species is its contact August 6 38 2 12 1 behavior; however, as previously indicated, no prior stud- AES 1 34 6 11 ) ies have been found. All of the cluster constituents as well yids see af cs ut 3 as the marked members outside the clusters were observed ee 5 y ¢ for contact. Table 1 reports 573 observations of contact August 10 34 6 14 4 : : : August 11 30 9 13 4 with members of the same species. Approximately 85% of August 12 36 3 12 4 those limpets studied within the microhabitat were in con- August 13 34 7 10 4 tact with one or more other limpets, while approximately August 14 27 11 10 6 74% were in contact with other limpets outside the 3 WEEE BS 5.8 11.7 4.1 specified microhabitats. Again, it is believed that rock percent peu eee Tete 29.8 topography somewhat influences contact. Table 2 Orientation frequencies (expressed in percent) of limpets found in quadrants within three studied microhabitats. Orientation position is determined by the degrees to which the limpet’s anterior end is pointing Yellow Red White Microhabitat Microhabitat Microhabitat =, et