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Mr, RDN DEMS aN oP eae st 2) fl i” a oy \ like Ce i il ihe i, 7 nn ' Rae _w - = oi oe ‘ke ss 0 Le ee ONO Canis ali) TN Le pt BPR EAg E wen | Ey LAL OL! NY: F Pe ee es ts) a et Bt ah Pk a, hint sa R Ba \ WR ai roe, ee AY fd pie 3 % re MENUS, Pact Werle VELIGER A Quarterly published by CALIFORNIA MALACOZOOLOGICAL SOCIETY, INC. Berkeley, California Volume 9 July 1, 1966 to April 1, 1967 Volume 9 TABLE OF CONTENTS A checklist of mollusks for Guaymas, Sonora, Mexico HELEN DUSHANE & Roy PoorRMAN ........... 413 Additional remarks on the range of Trivia myrae Camp- BELL | DER? DONOR “SoobboonopoodocunoooooodNC 355 Additions to the molluscan fauna of Clipperton Island Lro Grorce HERTLEIN & Epwin C. ALLIson .. 138 A description of a new species of Dirona from the North- East Pacific ANRINS, IGN occondd0coc00c00n0b 000000000000 9 Age and environment of a marine terrace fauna, San Cle- mente Island, California 2B Jal, INMPAS 6 cocsodcccbodeo0dHa0KDOG0NOD 388 A new genus and species of Buccinidae from the Fiji Islands (Mollusca : Gastropoda) WALTER OLIVER CERNOHORSKY ..........e00- 229 A new name for Acmaea mitchelli Liprs |(ais IGG IUTRRS SooondoonoudbooHdbcc0DGOnDOOUD 250 A new name for Mitra sanguinolenta Lamarck, 1811 SSAIN@MICEREERVACATE, fj «7s forsee «2 cise © 239 A new species of Morum from Brazil, with remarks on related species (Gastropoda: ‘Tonnacea) WinrnrAniIGrInHe EMERSON) (sc). elclerelleleie «i 289 A new subspecies of Volutoconus hargreavesi (ANGAS, 1872) from central Western Australia (Gastropoda : Volutidae ) CIETON STOKES) WEAVER) aoacsccsse ess + os cee 301 A note on three species of Mitridae (Mollusca : Gastro- poda ) WALTER OLIVER CERNOHORSKY ...........00. 441 A remarkable snail fauna from Coahuila, México DWIGHT WILLARD TAYLOR ..........0.00000- 152 A review of Amoria damonii Gray, 1864 and two new spe- cies names proposed for the homonyms Voluta bullata Swainson, 1829 and Voluta lineata Leacu, 1814 (Gastropoda : Volutidae) CiirTon S. WEAVER & JOHN ELEUTHERE DUPONT 382 Aspects of the biology of Donax gouldi and a note on evo- lution in Tellinacea (Bivalvia) IROSSBEI ss ROHL O vs. spevafateco ieteiencyetss aiebel siaieleielter=:steus 330 A study of mitrid radulae and a tentative generic arrange- ment of the family Mitridae (Mollusca: Gastropoda) WALTER OLIVER CERNOHORSKY ..........-500- 101 A technique for observing ctenidial and mantle currents in limpets (Aspidobranchia ) PETER VAUGHN FANKBONER ..........2++000- 251 Bryozoan-mollusk relationships OLUWAFEYISOLA SYLVESTER ADEGOKE ........ 298 Burial experiments on marine pelecypods from Tomales Bay, California Maurer, Don THE VELIGER Page III California Late Miocene records of Swiftopecten HERT- LEIN, 1935 (Pelecypoda : Pectinidae) OLUWAFEYISOLA SYLVESTER ADEGOKE ........ 337 Confirmation of Haliotis sorenseni Bartscu at Isla Gua- dalupe, Mexico ENMERYAPERKINS) GHAGE feels crecte eel ere cles ois 250 Elevation of clams in coral sand J ACKMIEPROMEINSONE etc ect se slesine oie sie tte 67 Erroneous range extension for Tivela stultorum (MaweE, 1823) ELEVEN DUSHANE scccie sc cccisis cee sce s scenes 86 Filtering experiments on marine pelecypods from Tomales Bay, California DOS IMUNOIIS. | 6 jolsbondd sooo seoueObAdadoUD US 305 First Canadian report of the sacoglossan Elysia chlorotica GouLp KAaniAuLono H. Baitey & J. S. BLEAKNEY ..... 353 Foot autotomy in the gastropod Gena varia (Prosobran- chia : Trochidae) LEv FIisHELSON & GULIETTE QWRON-LAZAR ...... 8 Function of labial spines, composition of diet, and size of certain marine gastropods INOBERT- MREATS PAINE — 15, 2ccvaiei Gach: AHS aie eas WD ee an aS ay Rumina decollata (Linnazus, 1758) (Achatinidae) Discovered in Southern California (1 Text figure) ‘Ts WAL LEVSTETST Ey G56, UNG eu Oleh a ae MT Ean MS RR fees UR LL (= Function of Labial Spines, Composition of Diet, and Size of Certain Marine Gastropods (2 Text figures) Rosert T, Paine SM peer NE ARIS! ack wih Sei egy usa NeO hve canara ela Me llghlhc Se eaian Ee Muscular System of Achatina fulica (Plate 3) KrisHna C GuHo a - 25 RISHNA CHANDRA GHOSE EMIT HSON ES 5 v™ On Donax and Other Sandy-Beach Inhabitants tur. 9.1966 . } 7) IN ABRARIES. Puy us T, JoHNson [Continued on Inside Front Cover Distributed free to Members of the California Malacozoological Society Inc. Subscriptions (by Volume only) payable in advance to Calif. Malacozoological Soc., Inc. Volume 9: $12.- Domestic; $12.60 in the Americas; $12.80 all other Foreign Countries. Price single copy, this issue, $5.80, Postage extra. Send subscriptions to Mrs. Jean M. Cate, Manager, 12719 San Vicente Boulevard, Los Angeles, California 90049. 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 CONTENTS — Continued The Higher Taxa of Cowries and their Allies Franz ALFRED SCHILDER 31 The Range of Trivia myrae CAMPBELL (1 Map) Jerry DonoHuE 35 The Terebridae of Fiji (Mollusca: Gastropoda) (Plates 4-7; 13 Text figures) Wa.TeR OLIver CERNOHORSKY «& ALBERT JENNINGS |) -5\200 A Rees ms 37 Elevation of Clams in Coral Sand Jack T.ToMEInson 1.00) 0 0 ab eee, 2 se New Distributional Records of some Northeastern Pacific Opisthobranchiata (Mollusca : Gastropoda) with Descriptions of Two New Species (12 Text figs.) James R. Lange 06000600 0) a alee a aa or Notes on the Mollusca of Prince William Sound, Alaska Roser R. ‘Farmaper, 30.63.) 2) a ea er NOTES & NEWS) 50.0 GSS le. a Range Extension for Tlodina fungina Gasp, 1865 HELEN DuSHANE Erroneous Range Extension of Tivela stultorum (MaweE, 1823) Heten DuSHane Gift from San Diego Shell Club BOOKS, PERI@ODICAIES 6. BANIP ENCES a) ines iin ae Note: The various taxa above species are indicated by the use of different type styles as shown by the following examples: ORDER, Suborder, DIVISION, Subdivision, SECTION, SUPERFAMILY, FamiLy, Subfamily, Genus, (Subgenus). New Taxa Vol. 9; No. 1 THE VELIGER Page 1 West American Mollusk Types at the British Museum (Natural History) ITI. Atcipe p’Orsicny’s South American Collection A. MYRA KEEN Department of Geology, Stanford University, California © (Plate 1) Acie DEssALinEs D’OrsIcNny was born September 6th, 1802, at Couéron, France, near Nantes, in the north- western part of the country and thus not far from the seacoast of the Bay of Biscay. He was son of a physician of broad interests who had begun the study of marine life, especially Foraminifera. When the father’s eyesight began to fail, Alcide assisted him at the microscope and thus early developed his talents for observation and drawing. He continued an interest in natural history during school training at La Rochelle. By the time he was 23, Alcide had constructed a set of models of Fora- minifera (carved from wood and reproduced in plaster) and had published a classification of the group in tabular form. Soon after this he was appointed as travelling natu- ralist to the Muséum d’Histoire Naturelle de Paris. His first assignment was a zoological expedition to South America. He left France in 1826 and did not return until 1833, by which time he had explored parts of Brazil, Uruguay, Patagonia, Chile, Bolivia, and Peru. On the West Coast, in 1833, he collected at Callao and Islay, Peru, and at Arica, Cobija (then in Bolivia), and Val- paraiso, Chile. Back in France he devoted himself to the preparation of several large reports on his work in ethnology and zoology -— not only on the “Voyage dans l’Amérique Méridionale .. ” but also on the mollusks of the West Indies and invertebrates from the Canary Islands. Com- pleting these large works on the Recent faunas, he turned to work in paleontology for the rest of his life and pub- lished a number of monumental reports in this field also. When a Chair in Paleontology was established at the Muséum in 1853, he was elected as its first incumbent. Busy with this new responsibility, he shut himself off from the rest of the world until his work was terminated by death in June 1857, a few months before he would have been 55 years old. The quality and the quantity of his published work give ample evidence of the great energy and ability that he had. In the early 1850’s Orbigny transferred his molluscan collections to the British Museum (Natural History), and an inventory of the South American portion was published by Gray, the curator, in 1855. Because of its historic significance, the collection has been kept intact and has been left as Orbigny mounted and labelled it, the shells being glued to heavy cardboard blocks. In a neat hand, Orbigny had lettered the names and the locality informa- tion. He also had indicated the collector if other than him- self (all lots from north of Callao had been taken by a Monsieur Fontaine). The collection has not been arranged in any systematic order, although it is separated into three geographic suites — West American, Cuban, and Canary Island. There has been some disassociation of specimens and cards, what with the transfer of the materi- al from cabinet to cabinet during the 110 years since it was sent to London. I found little difficulty in reassemb- ling the lots when I had occasion to examine this material. In 1964, when I was at the Museum for some months, I put aside what seemed to be all the lots that Orbigny had credited to himsclf as author and made record photo- graphs of most of them. Reviewing my work later, at home, I realized that I had stopped a little short of completeness. At the Museum again in 1965 for a few days, I searched out several lots I had overlooked, but a crowded schedule prevented the page-by-page review of Orbigny’s published work and direct comparison of this with the collection itself. Thus, I now find that there Page 2 THE VELIGER Vol. 9; No. 1 were a few items for which I did not search. However, I did succeed in spotting most of the types. Among the material in the so-called Cuban collection (actually from several islands of the West Indies), I noted and photographed a few forms that have been identified by authors as also occurring on the West Coast of the Americas - Vermetus corrodens, Trigonulina ornata (now Verticordia), Perna chemnitziana (now Isogno- mon), and Crenella divaricata. These will not be re- viewed in the present paper, for they were not described as “South American.” The volume on Mollusca published by Orbigny in the “Voyage dans Amérique Méridionale .. ” comprised some 758 pages of text and 85 colored plates. The work was issued irregularly over a period of years, completed in 1847, Collation of the pages and plates has been difficult for bibliographers. Libraries of that day did not always mark the dates of receipt of separate parts or keep the original wrappers. Early references to the work . therefore were apt to be incomplete or inaccurate. Charles Sherborn, compiler of that greatest of nomenclators, the “Index Animalium,” in 1902 - 1933, expressed dissatis- faction with the then-available evidence as to dates. Later, however, he had access to a set of the work in original wrappers and published a tabular collation (SHERBORN & GriFFIN, 1934). For the present list I have adopted the revised dates. Under “References” I have quoted the evidence given by SHERBORN & GriFFIN but have re- arranged it into chronologic order. Dates on three plates still are lacking, but this affects only one name, which therefore will have to be dated as 1847 under Article 22 (c) of the International Code. Many of the date changes in the present list are caused by the validation of names in the plate explanations, which often were issued in advance of the text. The format adopted here is to cite the species names in their original generic combination but in a modern sys- tematic sequence rather than that followed by Orbigny. His name as describer is to be understood and is not repeated for each entry. An asterisk preceding the species name indicates a change in date from that in most lists. Then, in order, follow: date; page, plate, and figure reference; type locality; British Museum registry number (note that most of these were assigned December 4th, 1854) ; remarks, including notes on nomenclature; mod- ern allocation, if different from Orbigny’s; references to a figure, either in a more modern work or in this paper. Because the “Voyage .. ” is a rare work and not avail- able in most libraries, I have cited reproductions of his figures by later authors (notably Tryon and Pivssry in the Manual of Conchology) and discussions in more accessible modern works. Although I photographed most of the types, I am including in my plate mostly the forms that have not been well understood by authors. A few minor gastropod groups (pteropods, heteropods, and nudibranchs) have been omitted in this canvass, and it does not cover Cephalopoda. Non-marine forms of course are excluded. A comment as to the spelling of D’Orbigny’s name is in order, for authors have variously recorded it. Dall adopted the spelling Orbigny in 1909, and I have followed this precedent for two reasons: in indexes, according to the Style Manual for Biological Journals, the entry would be “Orbigny, Alcide d’”; and, for formation of scientific names from personal names, the International Code re- commends dropping of the nobiliary particle de, so that a name dedicated to him should be spelled orbignyz. It is, of course, correct to use it in connection with the Christian name: “Alcide d’Orbigny,” and, in writing of him as a person, when not citing the Christian name, one pre- sumably would use the spelling “D’Orbigny.” As species authority, he is Orsicny. One must admit, though, that he, on his labels and in his book, used the abbreviation “dO.” or “d’Orb.”. GASTROPODA PATELLACEA * Patella araucana. 1839: p. 482, pl. 65, figs. 4-6. Val- paraiso, Chile. B. M. no. 54.12.4.244, 11 specimens. Refigured by Pirssry, 1891, Man. Conch., v. 13, p. 35, pl. 16, figs. 21, 22. Acmaea. Patella ceciliana. 1841: p. 482, pl. 81, figs. 4-6. Falkland Islands. Range to Antofagasta and Valparaiso, Chile, fide Dati, 1909. Not searched. Acmaea. Patella parasitica. 1841: p. 481, pl. 81, figs. 1-3. Valpa- raiso and Arica, Chile. B. M. no. 54.12.4.300, 302, 15 specimens. Scurria. Patella pretrei. 1841: p. 481, pl. 78, figs. 15-17. Payta, Peru; Valparaiso and Arica, Chile. Not searched. Re- figured, Pispry, op. cit., p. 33, pl. 34, figs. 9, 10. = Acmaea viridula (Lamarck, 1819). Patella maxima. 1841: p. 482 (no fig.). Payta, Peru. B. M. no, 54.12.4.437, 1 specimen. = P. mexicana Brop- ERIP & SOWERBY, 1829. “Acmaea scutum Esch.” of Orbigny, 1839 (not of RATHKE ex EscuscuHo.tz, MS, 1833): p. 479, pl. 64, figs. 8 to 10. Cobija and Arica, Chile. B. M. no. 54.12.4.304, 12 specimens. Refigured, Pitssry, 1891, op. cit., p. 32, pl. 4, figs. 77, 79. The identity of the species Vol. 9; No. 1 THE VELIGER Page 3 remains unclear. D’Orbigny had first labelled this subgenus Broderiptella Ousson, 1964. (Plate 1, Lottia punctata Gray, a preoccupied name, then Figure 21). changed to Acmaea scutum Escu. A new name has been provided for his misidentification: Acmaea or- CERITHIACEA bignyi Dat, 1909. FISSURELLACEA Fissurella fontainiana. 1841: p. 477, pl. 78, figs. 12-14. Islay, Peru, 18 fms. B. M. no. 54.12.4.613. Very close to Diodora alta (C. B. AvaMs, 1852) and to Fissur- ella aspera SowERBY, 1835 (non RATHKE ex Escu- scHoLttz MS, 1833) = Fissuridea asperior Da.u, 1909, the former from Panama, the latter from Peru. Diodora. (Plate 1, Figure 13). TROCHACEA Trochus araucanus. 1840: p. 410, pl. 55, figs. 5-8. Valpa- raiso, Chile. Not searched. = Monodonta nigerrima (Gmeuin, 1791), fide Prssry, 1889, Man. Conch., v. 11, p. 97. Trochus luctuosus. 1840: p. 409, pl. 76, figs. 16-19. Val- paraiso, Chile, 12 fms. B. M. no. 54.12.4.390, 14 specimens. Tegula (Chlorostoma). Trochus microstomus. 1840: p. 410, pl. 76, figs. 20, 21. Valparaiso, Chile. Not searched. = Chlorostoma tridentatus (PotrEz & Micuaup, 1838), fide Pitssry, 1889, op. cit., p. 175. Littorina umbilicata. 1840: p. 394, pl. 76, figs. 1-3. Arica and Cobija, Chile. Not searched. Refigured, Stronc, 1928, Proc. Calif. Acad. Sci., ser. 4, vol. 17, no. 6, p. 200, pl. 10, figs. 16, 17, as a phasianellid. Tricolia. NERITACEA Neritina fontaineana. 1840: p. 406, pl. 76, figs. 14, 15. Guayaquil, Ecuador. B. M. no. 54.12.4.382, 8 speci- mens. Refigured, Tryon, 1888, Man. Conch., vol. 10, p. 76, pl. 23, figs. 92, 93, as N. latissima BRoDERIP, 1833, var. A later synonym is: N. guayaquilensis “Ors.” of Sowersy, 1849. LITTORINACEA Littorina araucana. 1840: p. 393, pl. 53, figs. 8-10. Chile. Not searched. Refigured, Tryon, 1887, op. cit., vol. 9, p. 250, pl. 48, figs. 95, 96. TURRITELLACEA Turritella broderipiana. 1840: p. 388 (no fig.). Payta, Peru. B. M. no. 54.12.4.356, 1 specimen. ‘Type of * Cerithium montagnei. 1839: p. 443, pl. 63, figs. 3, 4. Guayaquil, Ecuador, in brackish water. B. M. no. 54.12.4.504, 4 specimens. Cerithidea. Cerithium peruvianum. 1841: p. 443, pl. 77, figs. 9, 10. Payta, Peru; Arica, Chile. B. M. no. 54.12.4.511, 6 specimens. Refigured, Tryon, 1887, op. cit. p. 153, pl. 30, fig. 21. Bittiwm. (Plate 1, Figures 12a-b). Rissoina inca. 1840: p. 395, pl. 53, figs. 11-16. Arica and Cobija, Chile. “Cobija, Bolivia,” on original la- bel. B. M. no. 54.12.4.367, 13 specimens. Type of genus Rissoina. (Plate 1, Figures 6a-c). NATICACEA 1840: p. 401, pl. 76, figs. 10, 11. Callao, Natica cora. Peru. B. M. no. 54.12.4.375, 7 specimens. Poli- nices. (Plate 1, Figures 10a-c). HiPPONICACEA Pileopsis ungaricoides. 1841: p. 457, pl. 78, fig. 4. Payta, Peru. B. M. no. 54.12.4.554, 1 broken specimen. Refigured, Tryon, 1886, op. cit., vol. 8, p. 131, pl. 40, figs. 82, 83. Capulus. (Plate 1, Figures 14a-b). CALYPTRAEACEA * Calyptraca intermedia. 1839: p. 463, pl. 59, figs. 4-6. Islay, Peru, 20 fms. B. M. no. 54.12.4.566, 3 speci- mens. Refigured, Tryon, 1886, op. cit., vol. 8, p. 122, pl. 35, figs. 89,90. (Plate 1, Figures 1la-b). CyYMATIACEA Ranella kingii. 1841: p. 451 (no fig.). Mocha, Chile, 10 fms. B. M. no. 54.12.4.533, 3 specimens. Pro Triton ranelliformis Kinc & Broperip, 1832, which also was renamed Janella vexillum SowErBy, Oct. 1841. Argobuccinum. MuRICACEA 1841: p. 454, pl. 78, figs. 1, 2 [non Sowersy, 1841]. Payta, Peru. B. M. no. 54.12.4. 547, 2 specimens. Refigured and renamed, Tryon, 1880, op. cit., vol. 2, p. 126, pl. 35, figs. 384, 385, as Murex fontainei Tryon, 1880. Ceratostoma. Very close to C. lugubris (BRropErip, 1833), which was erroneously placed in synonymy in “Sea Shells of Tropical West America” as an Ocenebra. The Murex monoceros. Page 4 THE VELIGER Vol. 9; No. 1 varices are heavier than in C. lugubris, of which it may prove to be a variant. There is a small tooth on the outer lip. (Plate 1, Figures 18a-b). Purpura delessertiana. 1841: p. 439, pl. 77, fig. 7. Payta, Peru. B. M. no. 54.12.4.493. Refigured, Tryon, 1880, op. cit., vol. 2, p. 169, pl. 50, fig. 95. Thais (Stramonita). (Plate 1, Figure 15). BucciNACEA Columbella sordida. 1841: p. 430, pl. 77, figs. 2-4. Cal- lao, Peru: Arica, Chile. B. M. no. 54.12.4.450, more than 12 specimens. Refigured, Tryon, 1883, op. cit., vol. 5, p. 117, pl. 47, fig. 42. = Mitrella unicolor (SOwERBY, 1832). * Fusus fontainei. 1839: p. 447, pl. 63, fig. 2. Callao, Peru; Cobija, Chile. B. M. no. 54.12.4.517, 5 speci- mens. Refigured, Trron, 1881. op. cit., vol. 3, p. 137, pl. 56, fig. 379. Synonym: Fusus alternatus Puiipri, 1847, usualy cited as the prior or preferred name. Austrofusus. * Fusus purpuroides. 1839: p. 448, pl. 65, fig. 1. Callao and Payta, Peru, 6 fms. B. M. no. 54.12.4.501, 5 specimens. Refigured, Tryon, 1831, op. cit., vol. 3, p. 149, pl. 42, fig. 217. = Cantharus (Solenosteira) fusiformis (BLAINVILLE, 1832). Murex inca. 1841: p. 455, pl. 78, fig. 3. Callao, Peru, 6 fms. B. M. no. 54.12.4.548, 5 specimens. Re- figured, Trvon, 1881, op. cit., vol. 3, p. 164, pl. 74, fig. 301. Cantharus,s.1. (Plate 1, Figures 9a-b). Nassa fontainei. 1841: p. 433, pl. 77, figs. 5, 6. Payta, Peru. B. M. no. 54.12.4.456-457, 2 specimens. Re- figured, but poorly, Trvon, 1882, op. cit., vol. 4, p. 32, pl. 10, fig. 102, as a synonym of N. exilis, from which the lectotype (here selected) differs by being propor- tionately wider, the axial ribs with beads at the suture. Nassarius. No. 456 is Orpicny’s figured specimen and is here selected as lectotype; no. 457, although mounted and labelled by Orbigny as this species, seems to be closer to N. versicolor (C. B. Apams, 1852). (Plate 1, Figure 3). VOLUTACEA. Mitra inca. 1841: p. 427, pl. 77, fig. 1. Payta, Peru. B. M. no. 54.12.4.434, 1 specimen. Refigured, Tryon, 1882, op. cit., vol. 4, pl. 39, fig. 140. Mitra (?Scabricola). (Plate 1, Figure 17). OPISTHOBRANCHIATA ANASPIDEA Bulla peruviana. 1837: p. 211, pl. 19, figs. 4, 5. Peru. Not searched. Refigured, Prrspry, 1895, op. cit., vol. 15, pl. 43, figs. 3-5. Haminoea. Tornatella venusta. 1840: p. 399, pl. 56, figs. 4-6. Payta, Peru. Not searched. Refigured, Pitssry, 1893, op. cit., vol. 15, p. 164, pl. 18, figs. 100, 101. Acteon (Rictaxis), near A. casta (Hinps, 1844) but with a lower spire and more coloration. Explanation of Plate 1 All specimens in the Type Collection, Mollusca Section, British Museum (Natural History) Figure 1: Lima pacifica Orpicny. SOwERBY. x 0.8. Figure 2: Mytilus “falcatus’ Orsicny = M., strigatus HANLEY. Syntype, from Brazil. X 0.5. Figure 3: Nassa fontainei Orsicny. Holotype of Lima arcuata Lectotype. X 1.5, Figure 4, a-c: Auricula globulus OrBicny. 3, syntypes. xX 2. Figure 5, a-b: Mytilus soleniformis ORBIGNY. 2 syntypes. x 0.8. Figure 6, a-c: Rissoina inca OrsicNny. 3 syntypes. x 1.7. Figure 7, a-b: Pectunculus “minor’ OrsicNy = Glycymeris chem- nitzii DALL. Exterior and interior of holotype. x 0.8. Figure 8, a-b: Venus paytensis OrBIGNY. Exterior and interior of 2 syntypes of Cytherea affinis BropERIP. x 0.7. Figure 9, a-b: Murex inca OrBIGNY. Back and apertural views, 2 syntypes. 53 le Figure 10, a-c: Natica cora Orsicny. apertural views. x I. Figure 11, a-b: Calyptraea intermedia Orsicny. Interiors of 2 syntypes. x2: (Actually, specimens are circular in 3 syntypes, back and outline but appear oblique because of the necessary camera angle). Figure 12, a-b: Cerithium peruvianum OrsiGNy. 2 syntypes X 5.5. Figure 13: Fissurella fontainiana OrpicNy. Holotype. x 1.3. Figure 14, a-b: Pileolus ungaricoides OrpicNy. a) above, interior, x 1.3; b) below, exterior, x 2.2. Figure 15: Purpura delessertiana ORBIGNY. Figure 16, a-b: Ostrea aequatorialis OrBIGNY. 2 syntypes. a) left, exterior, b) right, interior X 0.5. Figure 17: Mitra inca Orpicny. Holotype. X 2. Figure 18, a-b: Murex “monoceros” Orsicny = M. fontainet TrYON. a) back, b) apertural views. 2 syntypes. x 1.1. Figure 19, a-d: Anomia peruviana OrBIGNY. Above, 2 broken syntypes showing the perforate valve; below, 2 other syntypes showing exterior sculpture. x 0.8, Figure 20, a-c: Cyclas fontainet ORBIGNY. syntype, exterior of another. X 0.5. Figure 21: Turritella broderipiana ORBIGNY. Syntype. x1. Interior views of one Holotype. x 0.4. Tue VELIGER, Vol. 9, No. 1 [KEEN] Plate 1 uN f t " “s = \ 4 y Vol. 9; No. 1 THE VELIGER Page 5 PyRAMIDELLACEA Chemnitzia cora. 1840: p. 398, pl. 76, figs. 7-9. Payta, Peru. Not searched. Turbonilla. CEPHALASPIDEA * Aplysia inca. 1836: p. 207, pl. 19, figs. 1-3. Callao, Peru. Not searched. Refigured, Prrssry, 1895, op. cit., vol. 16, pl. 19, figs. 29-31. * Aplysia nigra. 1836: p. 209, pl. 18, figs. 1, 2. Callao, Peru. Not searched. Refigured, Pitssry, loc. cit., pl. 22, figs. 10, 11. * Aplysia rangiana. 1835: p. 210, pl. 17, figs. 11-13. Payta, Peru. Not searched. Refigured, Prissry, loc. cit., pl. 19, figs. 34-36. PULMONATA Auricula acuta. 1835: (Magasin de Zool., vol. 5, p. 23) ; figured, 1837, p. 327, pl. 42, figs. 4, 5. Guayaquil, Ecuador. Not searched. Marinula. Auricula globulus. 1835 (Magasin de Zool., p. 22, ex Ferussac, MS?) ; cited, 1837, p. 327, as “d’Orb.”, but not figured. Guayaquil, Ecuador. B. M. no. 54.12.4.243, 3 specimens. Original label credits the name to Ferussac; one syntype figured by REEVE, 1878, Conchologia Iconica, vol. 20, Auricula, pl. 6, fig. 43. Detracia. (Plate 1, Figures 4a-c). * Auricula reflexilabris. 1837: p. 326, pl. 42, figs. 1-3. Lima and Callao, Peru. Not searched. Tralia. Auricula stagnalis. 1835 (Magasin de Zool., p. 23); figured, 1837: p. 325, pl. 42, figs. 7, 8. Guayaquil, Ecuador. B. M. no. 54.12.4.240, 2 specimens. Ellobium. AMPHINEURA Chiton bicostatus. 1841: p. 486, pl. 81, figs. 7-9. Peru; Arica, Chile. Not searched. =C. pulchellus Gray, 1828. Callistochiton, fide Datu, 1909. * Chiton inca. 1839: p. 486, pl. 65, figs. 20-24. Islay, Peru. Refigured, Pirssry, 1894, op. cit., vol. 14, pl. 27, figs. 52-54, as Ischnochiton. PELECYPODA NuUCULACEA * Leda sowerbyana. 1845: p. 544 (no fig.). Xipixapi, Ecuador. New name for Nucula lanceolata “La- MARCK, 1819” of G. SowerBy, 1833 [non J. SowEr- BY, 1817]. Probable holotype at B. M., registry number not yet assigned. Adrana. (Species fig- ured and discussed by Oxsson, 1961, p. 69, pl. 3, fig. 3). * Leda ornata. 1845: p. 546, pl. 82, figs. 4-6. Payta, Peru. Not searched. Nuculana (Saccella). (Spe- cies discussed by Otsson, 1961, op. cit., p. 60, pl. 2, fig. 3). ARCACEA Arca aequatorialis. 1846: p. 636 (no fig.). Santa Elena, Ecuador. New name for Arca ovata Reeve, 1844 [non GMELIN, 1791]. REEVE’s type searched but not yet located at B. M.; cited as from Cuming Collec- tion by Reeve. Anadara (Cunearca). (Species figured and discussed by Otsson, 1961, op. cit., p. 95, pl. 9, figs. 4, 5. Arca reeveana. 1846: p. 635 (no fig.). Payta, Peru. B. M. no. 54.12.4.786, 2 specimens. New name for “Arca helblingii BrucutiRE” of Reeve, 1844 [not of Brucutzre, 1789]. Barbatia (Cucullaearca). Arca sowerbyi. 1846: p. 637 (no fig.). Atacama, Co- lombia, 7 fms. Holotype searched at B. M., 1964, but not found. Unneeded innovation for Arca biangulata SowerBy, 1833, non A. biangula Lamarck, 1805. Species figured and discussed by Oxsson, 1961, op. cit., p. 98, pl. 8, fig. 5, as Anadara (Caloosarca), a new subgenus by Oxsson, 1961. Pectunculus minor. 1846: p. 628 (no fig.). Isla Plata, Ecuador. Homonym (non Lea, 1833); renamed Glycymeris chemnitzii Dat, 1909. Based on a figure in Reeve, Conchologia Iconica, vol. 1, Pectunculus pl. 6, fig. 28. Holotype, B. M. registry number not yet assigned. Considered a synonym of Tucetona strigilata (SowERBY, 1835) by Oxsson, 1961, p. 108, pl. 11, fig. 3. Glycymeris. (Plate 1, Figures 7a-b). MyTILACEA Mytilus americanus. 1846: p. 648 (no fig.). Callao, Peru. Not searched. Probably a synonym of M. (Aulacomya) ater Mouna, 1782. * Mytilus falcatus. 1846: pl. 84, figs. 38, 39 (as M. char- ruanus). [Non Gotpruss, 1837]. Rio de Janeiro, Brazil; Maldonado, Uruguay. B. M. nos. 54.12.4. 812-813, 6 or more specimens, labelled as M. falcatus. Allocated to Mytella by Soot-RYEN, 1955, p.50, and reported as ranging from Bahia de Petitlan, Mexico to Ecuador and the Galapagos Islands. OLsson, 1961, however (p. 113-114) cites only Mytilus arci- formis (Dat, 1909) and rejects Mytella “falcata” by implication from the West Coast fauna, citing the range of Mytilus arciformis (which he does not con- sider to be a Mytella) as El Salvador to Guayaquil, Page 6 Ecuador. The identity of material north of El Sal- vador thus remains in doubt. Soot-RyEN had syn- onymized M. arciformis with Mytella “falcata.” The name M.charruana (Orsicny, 1847), printed in the plate explanation, is available as replacement for the homonymous M. “falcata.” However, there seems to be an earlier synonym, as Dr. L.G. Hertlein has pointed out to me — Mytilus strigatus HaNLEY, 1843 (Illustrated and descriptive catalogue of bivalve Shells, pp. 251, 388, pl. 24, fig. 34), which was described without locality from a Hinds MS and figured in 1847 with the statement that Orbigny had described the species as M. falcatus. Thus, it would seem that if West Coast representatives of this form do occur, they should take the name Mytella strigata (Haney, 1843). (Plate 1, Figure 2). * Mytilus chenuanus, spelling error for M. chenui Réctuz, 1842. 1842: p. 649, pl. 85, figs. 14-16. Brazil. B. M. no. 54.12.4.810, 1 specimen. Gray’s list cites the locality as Payta, Peru. The B. M. specimen closely resembles Gregariella denticulata (Datu, 1871). Thus, Orbigny’s material may not be correctly identified. Gregariella. * Mytilus soleniformis. 1842: p. 649, pl. 85, figs. 17, 18. Payta, Peru. B. M. no. 54.12.4.811, 2 specimens. Type of genus Adula. Oxsson, 1961, p. 132, ex- tends the range north to Panama. _ (Plate 1, Figures 5a, b). Lithodomus inca. 1846: p. 651 (no fig.). Payta, Peru. B. M. no, 54.12.4.789, 1 specimen. Holotype figured by Otsson, 1961: p. 135, pl. 15, fig. 1, as Lithopha- ga (Labis). (The species was considered a synonym of Modiola attenuata DresHayEs, 1836 by Soor- Ryen, 1955, p. 99). Lithodomus peruvianus. 1846: p. 651 (no fig.). Callao, Peru. B. M. no. 54.12.4.788, 3 specimens. One syn- type figured by Otsson, 1961, p. 135, pl. 15, fig. 2a. Lithophaga (Labis). PECTINACEA Pecten inca. 1846: p. 663 (no fig.). Santa Elena, Ecuador. New name for Pecten tumidus SowErsy, 1835, non Turton, 1822. = Aequipecten circu- laris (SowERBy, 1835). Pecten tumbezensis. 1846: p. 663 (no fig.). Tumbez, Peru. New name for Pecten aspersus SowErBy, 1835, non LAMaRCK, 1819. Type searched at B. M. in 1964 but not found. Species figured and discussed by Otsson, 1961, p. 164, pl. 21, fig. 2. Aequipecten (Pacipecten). [Type of subgenus Pacipecten Ors- son, 1961). : THE VELIGER Vol. 9; No. 1 Lima pacifica. 1846: p. 654 (no fig.). Lord Hood’s Island, Panama, Guayaquil, Guacomayo (Cuming Collection). New name for Lima arcuata SowEREY, 1843, non Getnitz, 1840 of authors, non Ostrea arcuata Broccut, 1814, a Lima. Sowerby’s probable holotype, B. M., not yet assigned a registry number. Species figured and discussed, Otsson, 1961, p. 170, pl. 17, fig. 1. Lima (Promantellum). (Plate 1, Figure 1). OSTREACEA Ostrea aequatorialis. 1846: p. 672 (no fig.). Isla de la Luna, Guayaquil, Ecuador. Holotype, B. M. no. 54. 12.4.823. Probably a synonym of O. columbiensis Han ey, 1846. (Plate 1, figs. 16a-b). ANOMIACEA Anomia peruviana. 1846: p. 673 (no fig.). Payta, Peru. B. M. no. 54.12.4.824, 4 specimens; syntypes thin and somewhat broken, showing variation in color. Species figured and discussed by Otsson, 1961, p. 177, pl. 24, fig. 2. (Plate 1, Figures 19a-d). CorRBICULACEA * Cyclas fontainet. 1842: p. 569, pl. 83, figs. “16-17” (actually, 14-15). Guayaquil, Ecuador. B. M. no. 54.12.4.750, 2 specimens. Neocyrena. (Plate 1, Figures 20a-c). VENERACEA * Venus cycloides. 1845: p. 562 (no fig.). Payta, Peru. New name for Cytherea gigantea Putiprl, 1844, ex SowerBy, MS; not a homonym of Venus gigantea GMELIN, 1791 cited as Cytherea by Lamarck, 1818. = Dosinia ponderosa (Gray, 1838). * Venus cumingit. 1845: p. 563 (no fig.). Xipixapi, Ecuador. Type material not searched. Unneeded new name for the supposed homonym Cytherea mod- esta SowERBY, 1835, non Venus modesta Dusols, 1831. Species figured and discussed by Oxsson, 1961, p. 280, pl. 46, fig. 4, as Transennella modesta (SowErsy). * Venus mariae. 1845: p 563 (no fig.). Isla la Plata, Ecuador. New name for Venus cypria SowERBY, 1835, non Broccut, 1814. Holotype, B. M., registry number not yet assigned. Species figured and dis- cussed by Oxsson, 1961, p. 296, pl. 49, figs. 2, 8. Chione (Lirophora). * Venus paytensis. 1845: p. 565 (no fig.). Payta, Peru; Cuming Collection, Xipixapi, Ecuador. Syntype lot, Vol. 9; No. 1 THE VELIGER Page 7 B. M., labelled “West Colombia” (i.e. Ecuador), without assigned registry number. New name for the secondary homonym Cytherea affinis Broperip, 1835, non Venus affinis GMELIN, 1791 (both species now regarded as belonging in Pitar, s. l.). Apparently separable from Pitar concinnus (Sowersy, 1835), as Oxsson, 1961, p. 288, has shown, ranging north at least to Panama. Pitar (Lamelliconcha). (Plate 1, Figures 8a-b). * Venus solangensis. 1845: p. 564 (no fig.). Ecuador. Type lot in B. M., registry number not yet assigned. New name for the secondary homonym Cytherea radiata SoweERBy, 1835, non Trigona radiata MEGER- LE VON MUHLrFELp, 1811, both species now regarded as Tivela. However, there is an available prior syn- onym. = Tivela byronensis (Gray, 1838). MACTRACEA * Donacilla chilensis. 1845: p. 530 (no fig.). Not searched. == Mesodesma donacium (LAMARCK, 1818, fide Otsson, 1961, p. 335. TELLINACEA * Donax obesus. 1845: p. 541, pl. 81, figs. 28-30. Payta, Peru. B. M. no. 54.12.4.702, 1 specimen. Holotype figured, Otsson, 1961, p. 344, pl. 85, fig. 3. * Donax paytensis. 1845: p. 541 (no fig.). Payta, Peru. B. M. no, 54.12.4.703, 4 specimens. Interior of one syntype figured by Oxsson, 1961, pl. 85, fig. 4. = Donax dentiferus HANLEy, 1843. ACKNOWLEDGMENTS Iam grateful to the John Simon Guggenheim Foundation for a grant that covered travel expenses to Britain and to the authorities and staff of the British Museum (Natural History) for the privilege of studying this historic mate- rial. I wish to thank Dr. Leo G. Hertlein and the Califor- nia Academy of Sciences for assistance in reference work and for the opportunity to examine a copy of d’Orbigny’s “Voyage .. ” in their library. REFERENCES CITED Dati, WILLIAM HEALEY 1909. Report on a collection of shells from Peru, with a sum- mary of the littoral marine Mollusca of the Peruvian zoological province. Proc. U.S.N. M. 37 (1704): 147 - 294; plts. 20 to 28 (24 November 1909) Gray, Joun Epwarp 1855. List of the shells of South America in the collection of the British Museum collected and described by M. Alcide d’Orbigny in the “Voyage dans l’Amérique Méridionale.” London: pp. 1 - 89. Otsson, AxEL ADOLF 1961. | Panamic-Pacific Pelecypoda: Mollusks of the Tropical Eastern Pacific. Paleontological Research Institution: Ithaca, N. Y. Pp. 574, pls. 86 (10 March 1961) Orsicny, ALciwE DEssALINES D’ 1834-1847. Voyage dans l’Amérique Méridionale. Mollusques. Paris, vol. 5, pt. 3, xliii + 758 pp., atlas, 85 plts. 1835. Synopsis terrestrium et fluviatilium molluscorum, in suo per Americam meridionalem itinere. Magasin de Zoologie, Ann. 5 (5), nos. 61-62, pp. 1-32. Pitssry, H. A., in Tron & Pirspry, vol. 10-. See under Tryon. SHersorn, Cuarzes Davies & Francis J. Grirrin 1934. On the dates of publication of the natural history portions of Alcide d’Orbigny’s “Voyage Amérique méridionale.” Ann. Mag. Nat. Hist. (10) 13 (73): 130-134 (Jan. 1934) {In the following tabulation, the data on pages 131-132, on mollusks, are put into chronologic order instead of the order of the separate parts]: Year Pages 1834 1-48; 73-128 1835. 49-72; 129-176 1836 177-184 Plates 1-2, 9-13, 15-16, 56 3-8, 17-23, 25, 55 14, 24, 26-28, 30-32, 34-35, 37, 58 [no dates on 33, 36] 1837 185-376 29, 38-52, 57 1838 — — 1839 — 54, 59-66, 68-69 1840 377-424 1841 425-488 53, 67, 70-71 72-76, 79, 80 [possibly the “79” is a typographical error for 77, as there is a second 79 in 1847] 1842 — 83, 85 [no date on 84] 1843 — — 1844 — — 1845 529-600 = 1846 489-528, 601-728 _— 1847 729-758 [no 78-79, 81-82 exact record of date] Soot-RyEN, TRON 1955. A report on the family Mytilidae (Pelecypoda). Allan Hancock Pacific Expeditions, vol. 20, no. 1 (Univ. S. Calif. Press, Los Angeles), 175 pp., 10 plts., 78 text figs. (10 November 1955) Tryon, GeorceE WASHINGTON, Jr. 1879-1913. Manual of Conchology. vols, 1-17 Philadelphia: ser. 1, (continued by H. A. Prtssry). Page 8 THE VELIGER Vol. 9; No. 1 Foot Autotomy in the Gastropod Gena varia (Prosobranchia: Trochidae) LEV FISHELSON AND GULIETTE QIDRON-LAZAR Department of Zoology, Tel Aviv University, Tel Aviv, Israel (1 Text figure) LARGE CONCENTRATIONS OF Gena varia A. Apams, 1850, a prosobranch gastropod usually typical for tropical re- gions, are encountered among the animals occurring under stones in the infratidal zone at Eilat (Red Sea, Israel). These gastropods are markedly photophobic and the slightest disturbance, e. g. merely trying to lift the stones under which they hide, puts them to flight. In attempting to escape, they plunge downwards and disappear among the algae and stones at the sea-bottom. A prominent morphological feature of this genus is the large foot which extends posteriorly and cannot retract under the small ear-like shell (Figure 1). A phenomenon rather unusual for mollusks was detec- ted during collection of these prosobranch gastropods: when touched, they reacted by autotomy of that part of their foot which extended past the posterior margin of the shell. Immediately after, they attached firmly to a nearby stone, now completely covered by their shell. The amputated part of the foot continued to exhibit movements for two to six hours after autotomy. Prelimi- nary observations have clearly shown that the autotomy is not haphazard but always follows a well-defined course, occurring along the fine white line that traverses the foot. The region along this transverse line is histologically different from adjacent regions of the foot. Regeneration of the foot commences several days after autotomy. Figure 1 A living specimen of Gena varia A. ADAMS The arrow points to the narrow line of autotomy. x 2 Further histological and biological investigations should elucidate the cytological basis of this phenomenon as well as its biological importance. This study is supported by contract 62558-4556 from the U.S. Office of Naval Research with the Department of Zoology, Tel Aviv University. Vol. 9; No. 1 THE VELIGER Page 9 A Description of a New Species of Dirona from the North-East Pacific ANNE HURST University of Washington Friday Harbor Laboratories, Friday Harbor, Washington 98250 (Plate 2; 7 Text figures) INTRODUCTION THE FAMILY Drronmae was first described by CockERELL & Exior (1905) and later by MacFartanp (1912) giving a full account of two new species, Dirona picta MacFar- LAND in CockERELL & Exiot, 1905 and D. albolineata MacFarianp, 1912. Two more species have been added to the family: D. pellucida by VotopcHenKo (1941) and D. akkeshiensis by Basa (1957), the latter species having been tentatively called D. albolineata in an earlier publication (Basa, 1935). A further note on D. picta has been made by VoLopcHENKo (1955) and additional in- formation on this species and on D. albolineata has been provided by Marcus (1961). A new species from the Puget Sound area possesses all the characters outlined for the family Dironidae and the genus Dirona but is clearly different from the previously established species in the following respects: general coloration, distribution of white markings, morphology of the egg mass, veligers, cerata, reproductive system (particularly the penis), size and proportions of radular teeth. It does not interbreed with the other local species, D. albolineata. Dirona aurantia Hurst, spec. nov. The type specimens were collected by dredge between 11 and 30 fathoms west of Blakely Island and in West Sound in the vicinity of Friday Harbor Laboratories. Dirona au- rantia has been previously dredged in the region at similar depths and one was observed on a float near the shore. Specimens have been most numerous in the winter months (September onwards) and have laid eggs in aquaria in January, February and March. They have sometimes been dredged with D. albolineata but in aquaria the two species do not associate and lay dissimilar egg masses (that of D. albolineata was described by O’DoNocHUE & O’Dono- GHUE, 1922) giving rise to readily distinguishable veligers. (It is intended to discuss further the eggs and veligers of these species in a later publication.) The narrow pink egg string of D. aurantia is laid in a loose coil, part of which appears in Plate 2, Figure 4. The range of food taken by Dirona aurantia is wide. In one animal some apparent vegetable matter was found, in others were remains of hydroids and bryozoans, another’s stomach was crammed with gammarids and caprellids, several being longer, though narrower, than the buccal region of the gut. It is likely that these crustaceans were eaten as dead or dying matter. Dirona aurantia lives well scavenging in aquaria. Unhealthy and dead specimens may be found with the buccal region protruded as described by CockKERELL & Etiot (1905) in D. picta. This is an unnatural phenomenon: the feeding apparatus is such that it could not be effectively used in this position unlike that of some other opisthobranchs (Hurst, 1965). Size: Specimens have ranged in length from 3 to 12 cm. In an animal 7 cm long, the foot measured 6 cm and the oral veil 1 cm, the latter being wider than the foot (Plate 2, Figure 3). Thus Dirona aurantia may be longer than the greatest size recorded for other dironids (CockE- RELL & Exiot, 1905, MacFarianp, 1912); however D. albolineata up to 12 cm has also been collected locally so that the length of 4.2 cm quoted for it by MacFarLAND (1912) is not maximal. Color: The ground color is orange throughout (Plate 2, Figures 1, 2, 3, 4). Some specimens have occurred which were of a deeper reddish orange than those photographed here, but none were lighter. The body is scattered with white, granular spots (Figure 1, gr) though none appear on the underside of the foot or oral veil (Plate 2, Figure 3). A few isolated specks occur on individual cerata but here almost all the granules are concentrated in a tapering white line (Figures 1, 2, ce, gr), extending from a short distance above the ceratal base, up the median side and Page 10 THE VELIGER Vol. 9; No. 1 surrounding the translucent tip completely. White gran- ules are absent or scarce on the rhinophores (Figure 1, th). The radiating white lines on the cerata are prominent in the living animal (Piate 2, Figures 1, 2, 4). The viscera may be seen by transparency through the underside of the foot as a dark brown mass (Plate 2, Figure 3). General appearance: The animal is limaciform with a broad foot, rounded anteriorly and tapering posteriorly to a bluntly pointed tail (that part of the foot posterior to the bases of all cerata) which has a distinguishable dorsal ridge. This ridge is always white in Dirona albolineata but not in D. aurantia. The head is bluntly rounded (Figure 1) and around its anterior margin is the oral veil (or). This veil is thin, with very undulating edges, usually curving upwards mediaily (Plate 2, Figures 1, 3, 4). The mouth is a longitudinal slit mid-ventrally placed at the base of the oral veil (Plate 2, Figure 3). The rhinophores (Figure 1, rh) point forwards and outwards at angles of about 120° with the back and with each other. The lower half of each rhinophore is stout and a little wider than the perfoliate terminal part. The Figure 1 Right antero-dorsa! view of the head region of Dirona aurantia. ce — ceras dbw —- dorsal body wall gr — granules or — oral veil rh — rhinophore extreme tip is blunt and the rhinophore leaves are fairly regular and oblique, sloping forward and up from a mid- dorsal posterior separation. There are usually a few more than 20 leaves. The cerata (Figures 1, 2, ce) are very numerous except in unhealthy specimens, in which they readily drop off (although they may be quickly regenerated). They are 5 mm Figure 2 Median postero-lateral view of three cerata (a, b, c) of the right side of Dirona aurantia. ce — ceras gr — granules based in a continuous series (but for a median anterior gap between the rhinophores) from anterior to the rhi- nophores along the sides and meeting over the dorsum at the base of the tail. The outermost cerata are abundant and very small. Median to them the cerata are larger and fewer, slightly flattened antero-posteriorly (less markedly than in Dirona albolineata) and much swollen above the narrow base. The largest occur on the posterior half of the body and often obscure this region of the back (Plate 2, Figure 2). Sometimes a few small cerata occur amongst the innermost cerata, unlike D. picta and D. albolineata (MacFarzanp, 1912). They are probably regenerating after the loss of some large cerata. A few cerata may be bifid (Figure 2,a) and some (rarely) are bluntly branched or very irregularly swollen (Figure 2c). All are smooth and muscular, continuing to contract vigorously when detached. The reproductive openings lie about + of the way back from the head, on the right side below the cerata. The female opening is surrounded by radiating folds and is Tue VELIcER, Vol. 9, No. 1 [Hurst] Plate 2 Figure 2 Figure 1: Dirona aurantia Hurst. Dorsal view of holotype. Figure 2: Collection of six Dirona aurantia Hurst from off Blakely Island and from West Sound. Figure 3: Dirona aurantia Hurst, ventral view. Figure 4: Dirona aurantia Hurst and part of its egg mass. The parent was disturbed when only a small part of the mass was laid. Vol. 9; No. 1 stretched widely during egg laying. Halfway along the right side immediately below the outermost cerata is the small renal aperture. The anus, as in other dironids, is raised on a stout papilla amongst the most posterior cerata of the right side. The papilla is cylindrical with longitu- dinal folds allowing considerable expansion during passage of faeces. Internal anatomy: The mandibles (Figure 3) are large, completely enclosing the sides of the buccal region of the gut (Figures 3, 7, wj), closely hinged anteriorly (aj, al). Figure 3 Left mandible of Dirona aurantia in a) outer lateral view b) median lateral view aj — articular region of jav al — articular ligament of jaw wj —- lateral wing of jaw They are very stout and of similar form to those of Dirona picta and D. albolineata described and drawn by Mac- FarLanp (1912). In all dironids the jaws serve as an important area for attachment of muscles concerned in the feeding process. The radula from which Figure 4 was drawn has the formula 2:1:2:x24-26. Some specimens have less rows of functional teeth, the minimum observed being 2:1:2:x12- 15. As in other dironids the short horizontal radular sac lies dorsally, above the bulk of the buccal mass. That part of the radular membrane bearing functional teeth curves down anteriorly and is folded longitudinally forming a THE VELIGER Page 11 deep groove at the base of which are the median teeth (Figure 4, mt). They are widely separated from the rows of lateral teeth (11t, 21t) situated at the upper edges of mt Figure 4 Radular teeth of Dirona aurantia. 1lt — first lateral tooth 2 1t -second lateral tooth mt — median tooth P — posterior A — anterior the groove where the radular membrane is reflected over the buccal mass. The teeth are larger than their counter- parts in Dirona picta and D. albolineata, measured by MacFar.anp (1912) and Marcus (1961), but as Mar- CUS noted tooth size varies with that of the whole animal. The form of the teeth is similar to that of other dironids. Each median tooth (mt) has a peg-like, back-pointing spine arising from a roughly rectangular base. Each first lateral tooth (11t) has a simple spine pointing medially and backwards, converging at its tip with that of the adjacent second lateral tooth (2 It) of the same row. The large second lateral tooth is flattened and hamate, bluntly pointed and curves slightly backwards towards the median line. The penis (Figures 5A, 6, pe) is large and wide except at the tip which narrows abruptly to a short smooth papilla (pp). It is readily distinguishable from those of Page 12 THE VELIGER Vol. 9; No. 1 Figure 5 a pa 2.5 1m fap Figure 5 b Figure 5 Penis of a) Dirona aurantia (retracted) b) Dirona albolineata (extended) A -— anterior P -— posterior fap - female aperture ma — male atrium pa -— penial armature pe-- penis pp -_penial papilla Dirona picta drawn by Marcus (1961), D. akkeshiensis drawn by Baza (1935) and D. albolineata (Figure 5B, pe). The reproductive tract (Figure 6) is of essentially the same plan as that of these two species as described by MacFarianp (1912) and further by Marcus (1961). The spermatheca (Figure 6, sp) is large, its duct contin- uous with the very large muscular female atrium (fa). The oviduct (ov) is narrow and short, closely applied to the female gland mass (fg) and joining the wide terminal part of the hermaphrodite duct (hd). The long coiled vas deferens (vd) is stout but narrow and passes between the fibres of the penial retractor muscle (Figures 6, 7, pr) before entering the penis (Figures 5 A, 6, pe). The penial retractor (Figures 6, 7, pr) passes anterior to the digestive gland (Figure 7, dg) to its origin on the left side of the body wall (bw). Its insertion on the muscular male atri- um (Figures 5A, 6, ma) lies among the muscle fibres (Figure 6, am) surrounding the genital region (Figure 7, ge) of the body wall (bw). The nervous and digestive systems (Figure 7) are rather similar in disposition to those of Dirona picta, described by MacFartanp (1912). The destinations of the nerves are almost identical and apart from cerebral nerves 5 (Figure 7, 5), their paths are alike. In D. picta cerebral nerve 5, the optic nerve, “is closely attached to the anterior margin of c6 (or pl. 1)” (MacFartanp) but in all specimens of D. aurantia examined, this was only true of the nerves of the right side, while on the left side the optic nerve (c5) was separate for its entire length. Pleural nerve 1 (pl 1), as noted by MacFartanp in D. picta, may have a cerebral origin. The ganglia lie very close to the dorsal body wall. The thin-walled oesophagus (oe) is usually flattened on top of the buccal region of the gut as in Figure 7, passing back shortly to the stomach (st) on the Icft side of the body. The buccal ganglia lie below it, con- cealed in Figure 7. The buccal nerves are similar in distribution to those of D. picta figured by MacFarLanp. The collection of specimens of Dirona aurantia from which the above description is taken is deposited at the California Academy of Sciences, Invertebrate Zoology Type Series, Holotype no. 273. Geographical locations in Puget Sound from which specimens were taken: W. Blakely 16-18 fathoms 48° 33’ N 122° 49.9’ W W. Blakely 30 - 23 fathoms 48° 34.5’'N 122° 50.6’ W West Sound 22 fathoms 48° 36.1’N 122° 57.9’ W Broken Point 11 - 12 fathoms 48° 35.4’N 122° 57.4’ W Vol. 9; No. 1 THE VELIGER Page 13 = Figure 6 Dissection of the reproductive system of Dirona aurantia: penis opened by a longitudinal cut; only part of the hermaphrodite gland shown. am — atrial muscles fap - female aperture hg - hermaphrodite gland pe — penis bw — body wall fg - female gland ma — male atrium pp — penial papilla fa — female atrium hd —- hermaphrodite duct ov — oviduct pr — penial retractor sp - spermatheca vd — vas deferens Vol. 9; No. 1 THE VELIGER Page 14 hg pr dg Figure 7 Vol. 9; No. 1 THE VELIGER Page 15 ACKNOWLEDGMENTS Hurst, ANNz 1965. Studies on the structure and function of the feeding . eae apparatus of Philine aperta with a comparative consideration I am indebted to Dr. R. L. Fernald for the use of facilities of some other opisthobranchs. Malacologia 2(3) : 281 - 347; at the Friday Harbor Laboratories and to the National 31 text figs. (29 April 1965) Science Foundation for financial support. Thanks are due NACEARVANDER Ne ENKAce to Dr. K. M. White who confirmed identification of the 1912) “The nudibranch family Dironidae. Zool. Jahrb. animal described. Suppl., 15: 515-536; plts. 30-32 Marcus, Ernst 1961. | Opisthobranch mollusks from California. The Veliger LITERATURE CITED 3 (Suppl.) (I): 1-85; plts. 1-10 (1 February 1961) O’Donocuue, CHartes Henry « E. O’DonocHUE 1922. Notes on the nudibranchiate mollusca from the Van- couver Island region. II. The spawn of certain species. Trans. Roy. Canad. Inst. 14: 131 - 143 VoLopcHENKo, N. I. Basa, KikuTARO 1935. The fauna of Akkeshi Bay. 1. Opisthobranchia. Journ. Fac. Sci. Hokkaido Univ. 6, Zool. 4 (3): 115-125 1957. __A revised list of the species of Opisthobranchia from the northern part of Japan. Journ. Fac. Sci. Hokkaido ; 1941. | New nudibranchiate molluscs from seas of the far east Bai Zool, 13 (1-4) 2-8-4 of the U.S.S.R. Moscow 1: 53-68 OR SEU, EOS SS DET EABEOD O CERES Be 1955. Atlas of the invertebrates of the eastern seas of Russia. 1905. Notes on a collection of Californian nudibranchs. Russian Acad. Sci. Moscow and Leningr. (Opisthobranchia: Journ. Malacol. 12 (3): 31-53; plts. 7, 8. 181 - 185). Figure 7 (facing page) Dorsal view of a dissection of Dirona aurantia to show the major part of the nervous system and the anterior part of the gut in situ. (The numbering of the nerves follows MacFarLanp’s (1912) description of the nerves of Dirona ficta.) aj — articular region of jaw ce — cerebral commissure h —- haemocoel pg — pedal ganglion al - articular ligament of jaw cg -— cerebral ganglion hg —- hermaphrodite gland pl1,pl2 - pleural nerves bw — body wall dg —- digestive gland i - intestine plg - pleural ganglion cl-c5 — cerebral nerves1-5 € — eye oe — oesophagus pr -— penial retractor muscle cbc — cerebro-buccal connective ge - genital region Pi, p2 — pedal nerves st — stomach stc - statocyst wj - lateral wing of jaw Page 16 THE VELIGER Vol. 9; No. 1 Rumina decollata (LinNaEus, 1758) (Achatinidae) Discovered in Southern California BY T. W. FISHER Department of Biological Control University of California, Riverside, California 92502 (1 Text figure) Rumina decollata is of Mediterranean origin and probably was introduced into the United States in the early 1800’s. Prior to the present finding it was known to occur at many localities across the southern United States from the Atlantic seaboard to Yuma Mesa in Arizona. It is an omnivorous plant feeder and is cannibalistic on its own and other mollusk species. The decollate snail is not easy to detect because of its rather inconspicuous size (partic- ularly of juveniles) and earth color, and because it burrows into the soil presumably to avoid dehydration and to feed on subterranean plant tissue. The quarantine status of Rumina decollata as a poten- tial pest in California is set forth in the State of California Department of Agriculture Quarantine Memorandum E-83 (1958). The main reason for submitting this note is to solicit the assistance of those with malacological interests in reporting the occurrence of R. decollata else- where in the State. The first infestation to be reported in California was in the city of Riverside. On January 12, 1966, Mr. Gilbert L. Challet, a technician in this Department, brought in four dormant specimens for determination which he had picked off the wall of his garage after a rain. County and state agricultural inspectors at once surveyed the immedi- ate area and found that the infestation was restricted to seven properties in the same block. No snails had crossed the streets to adjacent city blocks. Soon thereafter a press release with pictures of the snail was made and during the next week reports from interested citizens led to two more infestations in Riverside. Write-ups also appeared in ad- joining counties, and the presence of colonies of Rumina decollata was verified in East Los Angeles, La Habra Heights, Claremont, Los Alamitos, and Costa Mesa. So far, positive findings have been reported only from areas where the news stories carried the picture of the snail. Snails were plentiful at all sites, usually on the surface of the ground or shallowly to partially buried beneath cover plantings such as ivy (Hedera), Mesembryanthemum, or in weed growth along fences. The largest infestation oc- curred over a recently subdivided 80-acre avocado or- chard in La Habra Heights. Here, R. decollata coexists with Helix aspersa MULLER and occurs mainly in beds of Mesembryanthemum. Laboratory testing of various molluscicides is being con- ducted by Mr. Joseph Pappas (Department of Entomol- ogy, University of California, Riverside), and he has found that Rumina decollata is not killed by presently available commercial baits with metaldehyde, guthion, or zectran as the active ingredients. From the size and distribution of the known infesta- tions, and because of the known ages of housing develop- ments on some of the sites, it is thought that Rumina decollata has been in southern California for at least 7 to 10 years. Consequently, eradication is no longer thought to be practical, and Californians will be obliged to learn to live with the decollate snail. Its chief mode of entry into the State is not difficult to deduce, particularly when the occupant of one property admitted bringing in potted ferns from an infested area in Arizona. A few such instances of smuggling past border quarantine inspectors, followed by exchanging of plants among gardening en- thusiasts within the state, and enough said. Figure 1 Rumina decollata (LINNAEUS, 1758): Sketch of shell from three aspects. The decollate shell is the “tip-off.” Vol. 9; No. 1 THE VELIGER Page 17 Function of Labial Spines, Composition of Diet, and Size of Certain Marine Gastropods BY ROBERT T. PAINE Department of Zoology, University of Washington, Seattle, Washington (2 Text figures) INTRODUCTION THE MORPHOLOGICAL BASIS of prey capture and penetra- tion in many predatory marine prosobranch gastropods is fairly well documented: shell drilling by radular action and accessory boring organ (CarrikEr, 1955, 1961), har- pooning with poisonous barbs (Koun, 1959), and the use of the shell margin as a wedge (Pane, 1962; WELLs, 1958b). It is surprising that little is understood of the functional significance of the most conspicuous external trait of apparent use in feeding: the single spine or labial tooth on the outer margin of the shell lip characterizing certain species in the Thaididae, Muricidae and Fascio- lariidae. Generalizations in the literature, apparently un- supported by data, state that the spine is thrust between the prey’s valves, preventing closure and hence facilitating consumption by the predator (MacGinitie & MacGInImTE, 1949). The data given below suggest that this generaliza- tion, while possibly correct in some instances, does not appear to hold for those species with the most conspicuous spines. An understanding of spine function is closely re- lated to the effects that organism size and behavioral capabilities have on food consumption. Field data on both intra- and inter- specific dietary variations have been as- sembled to provide a basis for comparisons of different spine-bearing species. I wish to acknowledge the able field assistance of Charles King, Garrett Paine, and especially Fay Wolfson. Dr. Rudolf Stohler kindly identified the gastropod species and has generously loaned specimens in the collections of the Department of Zoology, University of California at Berkeley. The manuscript has benefited from the critical comments of Dr. A. J. Kohn. The University of Washing- ton, through the offices of the Organization for Tropical Study financed the trip to Costa Rica. The field work in Baja California, Mexico, was supported in part by the National Science Foundation (GB-341). Specific Use of the Spine Direct observations of spine use in the natural setting are difficult and tedious to make, and most of the present conclusions are based on inference, though wherever pos- sible, supported by laboratory observation. Acanthina brevidentata (Woop, 1828) This species, on the basis of 80 observations at two stations on the Pacific coast of Costa Rica, was seen to feed mainly (75%) on Chthamalus sp., although small individuals of other barnacle species may well be con- sumed. The remainder of the observed diet consisted of small mussels. The spine is well formed, though relatively short, being about 1mm in length in individuals 2cm long. The snail penetrates barnacles by drilling between their opercular plates. No evidence was obtained for spine use, although both drilling and prying the prey open with the spine would be redundant acts. Acanthina tuberculata (SoweErBy, 1835). Despite the local abundance and large size (to 6- 7cm) of this intertidal species in the upper Gulf of California, I have rarely found it feeding. The spine is short (1-2 mm), often just a fold in the margin. In eight of fourteen feeding observations (57%) the carnivorous gastropod Acanthina angelica was the prey. There was no evidence of shell drilling in these prey; rather parts of the prey’s operculum appeared to have been rasped away. In four instances limpets, Crucibulum sp., were being consumed. Again there was no evidence of drilling but in these cases the outer margin of the prey’s shell had been shattered, probably by the Acanthina’s shell. Casual observations on a 6cm individual maintained in captivity for over 2 years indicate no deviation from the field pattern: operculate gastropods seem to be the preferred food of a variety offered, and are penetrated by having a corner of their operculum rasped away while being held in the A. tuber- Page 18 THE VELIGER Vol. 9; No. 1 culata’s foot. I have never obtained any evidence that large individuals can drill, or that the spine is used. In fact, most gastropod prey withdraw so deeply into their shells that the short labial spine would be functionless. Acanthina angelica (I. Otproyp, 1918). This species is widely distributed in the upper Gulf of California in intertidal waters (KEEN, 1958), and I have observed it at San Felipe, Puertocitos, and Puerto Pefiasco. All observations to date suggest that it is a barnacle “spe- cialist”; of 432 records of prey only two non-barnacles (both 10 mm individuals of the gastropod Cerithium ster- cusmuscarum VALENCIENNES, 1833) have been found. I have no data to indicate any strong prey preference being exercised within the abbreviated spectrum usually con- sumed, as is true for Thais lapillus (LinNaEus, 1767) (ConNELL, 1961). For instance, at San Felipe in March, 1963 Acanthina angelica was observed eating the barna- cles Chthamalus sp., Tetraclita squamosa, and Balanus am- phitrite. These karnacles occupy recognizable zones and an estimate was obtained of the percent of Acanthina feeding in each area. There was no difference in feeding intensity where Chthamalus and Balanus, both small species, were abundant, 14/26 (54%) and 28/45 (62%) respectively of Acanthina picked at random actually feeding. On the other hand, only 48/120 (40%) of the individuals ad- jacent to Tetraclita were feeding. The reduced incidence may reflect some greater difficulty in penetrating these larger, thicker shelled, barnacles, but say little about food preference, since if the reward to the predator in terms of nourishment attained per unit time was greater, as might be expected from much larger prey, Tetraclita would be the optimal food. In every instance the prey were being drilled, and characteristic holes were noted between the barnacles’ opercular valves or in their lateral plates. Although Acan- thina was observed during all stages of the feeding process, no function was noted for the apertural spine. Another Acanthina angelica population was observed in March, 1964, at Puerto Pefasco, Mexico, on the opposite shore of the Gulf from San Felipe. The basic environ- mental situation appeared quite similar except that Acan- thina appeared to be polymorphic for spine length. The majority of individuals were characterized by short (3 mm or less) spines and were eating Chthamalus. A number, however, characterized by immense (6-10mm) spines were devouring Tetraclita, and it is from these latter individuals that a definite indication of the spine’s func- tion was obtained. Notice that all logical relationships between where the hole was drilled and the spine’s posi- tion were encountered, although in far from equal fre- quency (Table 1). These data indicate that in only about 35% of the observations was the spine actually inside the opercular cavity of the barnacle, and that only 25% of the snails were feeding through the opercular plates. In the remaining instances both the spine and the point of active drilling were removed from the barnacle’s natural opening. Five examples were noted (not recorded in Table 1) in which the spine was hooked around or in one barna- cle, and the snail was feeding or drilling on a second. The conclusion seems inescapable that in these large-spined individuals the spine is used for purchase and is not directly involved in penetrating the prey. Table 1 The relationship between spine position and hole position in a population of long-spined Acanthina angelica feeding on Tetraclita squamosa. Position of spine Inside Outside opercular opercular opening opening ‘Totals Outside Where opercular 8 30 38 barnacle opening Was Inside drilled opercular 10 4 14 opening Totals 18 34 a2 Twenty to thirty short-spined individuals from the upper Gulf have been maintained at Seattle, Washington, and laboratory observation obtained. After a varied period of starvation, these were offered Balanus glandula and the ensuing events were studied. The snails invariably spent some time orienting themselves on the barnacles. Then the spine, located between the eyes of a crawling snail, was hooked over the outside rim of the barnacle or in some convenient cranny, after which the barnacle was drilled. Although data were obtained from 15 different individuals, little variation in this procedure was noted, and never was the spine forcibly thrust between the prey’s opercular plates. Seemingly the spine, as in the larger individuals, is used solely for purchase. Spine length is quite labile in this species and varies from area to area. The relationship between shell length and spine length is compared in Figure 1 for the two most different populations yet examined and a third characterized by the longest spines. The former two Vol. 9: No. 1 @= NEAR SAN FELIPE o= NEAR SAN FELIPE x= PUNTA PENASCO 1959 1963 1964 (MM) SPINE LENGTH SHELL LENGTH THE VELIGER Page 19 Y=.25X — 2.92 Y= 16X— 1.45 30 35 40 45 50 (MM) Figure 1 Spine-shell length relationships of three populations of Acanthina angelica. The significantly different regression lines were fit by least squares. samples were collected approximately 30 miles south of San Felipe by Dr. R. Stohler. Regression lines fit by least squares indicate significantly different relationships between shell length and spine length within a local area, but sampled four years apart. Such would occur if spine length varied in response to barnacle size, and the barna- cle species composition had changed gradually in this local area from 1959 to 1963. Both curves have similar origins, reflecting the shell length at which the spine can be measured. The situation at Puerto Penasco is rather different. Inspection of Figure 1 suggests a curvilinear relationship between the variables. However, the few points could also be interpreted as a composite of two linear relationships, one from approximately 10 to 30mm shell length, the other from 30 to 37 mm. It is tempting to suggest that the shorter spined individuals were probably Page 20 I | eating small barnacles while the longer spined ones were consuming mature Tetraclita. Further field data are needed to resolve the reality of such a polymorphism. Opeatostoma pseudodon (Burrows, 1815) KEEN (1958, p. 416) has stated that this member of the Fasciolariidae has “. . . perhaps the longest apertural tooth developed by any gastropod,” and of the species for which I have data, this assertion is borne out by high spine-shell length ratios. For instance, a shell 40mm long may bear a 14mm spine. My observations were all made at El Coco Beach on the Pacific coast of Costa Rica in July, 1964, where Opeatostoma was found living under rocks semi-buried in coral sand. Observations suggest it to be active nocturnally. THE VELIGER Vol. 9; No. 1 The species seems to be mainly verminivorous, although other items may well be eaten. In an examination of about 85 individuals during daylight hours, only 3 were found feeding. One of these was definitely consuming a serpulid polychaete. The remaining two were both firmly anchored in the sandy substrate by their immense spines, apparently feeding on “sand tubes,” although no worm remnants were observed. Nocturnal observations added three more instances of feeding on tubiculous polychaetes plus one example of a small bivalve being taken. In the cases of positively observed feeding, there was no indication that the spine had ever been brought directly to bear on the prey, and in fact, the spine’s length (up to 15mm) would mitigate against this. I feel that the spine Table 2 New and literature accounts of size-feeding relationships of the Fasciolariidae. (G) indicates gastropod prey; (B), bivalve prey. PainE (1963) gives a breakdown to species of the categories listed. % of Adult total diet length incate- |§ Number of Species (cm) Natural diet gory observations Source Fusinus spp. 4 polychaetes 100 11 this paper * Opeatostoma pseudodon (BuRRows) 4.8 polychaetes 86 7 this paper small bivalves 14 Fasciolaria hunteria (PERRY ) 8 polychaetes 41 gastropods 13 76 Paine, 1963 small bivalves 32 carrion 13 Pleuroploca (Fasciolaria) 10 Calliostoma (G) filamentosa (R6p1Nc) and a murex (G) 2 Rissec, 1932 Pleuroploca (Fasciolaria) trapezum LINNAEUS 13 Marganitifera (B) fide GraHam, 1954 Fasciolaria tulipa LinNAEUS 17 bivalves 25 52 large gastropods 67 Paine, 1963 carrion 8 Strombus (G) frequent Rosertson, 1961 RanpaLt, 1964 Fasciolaria princeps SOWERBY 23 - 30 Hexaplex (G) Sorenson, 1943 Pleuroploca gigantea KIENER 35 bivalves 20 66 Paine, 1963 large gastropods 80 Melongena (G) * spine bearing species HatTHAaway & Woopsurn, 1961 Vol. 9; No. 1 functions in anchoring the animal to the coral rubble substrate, and is not directly involved in prey penetration. Size and Diet The basic fact that, other things being equal, larger organisms need more energy for maintenance, is expressed at both inter- and intra- specific levels when dietary comparisons are made. The Fasciolariidae are carnivorous gastropods lacking any drilling apparatus, which penetrate prey by forcefully inserting the proboscis into the prey, often accompanied by mild rasping with the radula or use of the shell margin (Wetts, 1958a; Paine, 1963). The family is well suited for studies on size-diet relationships because it includes Pleuroploca gigantea (KieNeER) reputed to be the largest living carnivorous gastropod. Table 2 summarizes all available comparisons of size and diet. The Fusinus, ob- served near Puertocitos, consumed small serpulids by in- serting the proboscis down the worm tube, a food-getting stratagem also characterizing Fasciolaria hunteria (PAINE, 1963). The observations on Opeatostoma indicated that tubiculous worms were its principal prey. In the 6 larger species the diet is composed of either bivalves or gastro- pods and no worms are consumed. In the Fasciolariidae, then, smaller species eat polychaetes, and an increasing reliance on bivalves and gastropods, both more substantial food items, occurs with increasing size. Similar interspecific trends characterize the Thaididae and Muricidae, considered jointly in Table 3 because of their close taxonomic position and common possession of a shell-boring mechanism. These data include only my THE VELIGER Page 21 observations from the Pacific coast of Costa Rica (Acan- thina brevidentata, Thais kiosquiformis (Ductos, 1832), Thais biserialis (BLAINVILLE, 1832), Thais melones (Du- cLos, 1832) ) and the northern end of the Gulf of Cali- fornia (the remaining species named in Table 3). The general impression that the smaller species are barnacle specialists, or at least eat few other gastropods, would be supported by the work of ConneLt (1961) on other Thais species, and Hewatt (1934) on Acanthina sp. The very high percentage of gastropods in A. tuberculata’s diet may be due to relatively few observations on mainly large individuals, or may fairly indicate the high degree to which this species preys on A. angelica. The differences between Hexaplex and Muricanthus in regard to the pro- portion of barnacles taken is due to subtle habitat differ- ences: although they are often found together, small Muricanthus live in cobble patches wherein barnacles abound. When only adults of both species are considered there is no change in the Hexaplex data whereas for Muricanthus the barnacle feeding incidence drops to 0% and the percentage of gastropods rises to 43%. Both the above size-diet correlations include the tacit assumption that a particular species’ post-larval diet is a fixed entity. The assumption is partially false, gastropod diets being known to vary geographically (THompson, 1964) and presumably also during post-larval develop- ment. Enough data are available to examine intraspecific dietary changes related to size increase only in Murican- thus nigritus (Puitippr, 1845). Observations made near Puertocitos in March 1962 and 1963, although pooled in Table 3 The relationship between adult shell length and the relative contribution of barnacles and gastropods to a species diet. The asterisk indicates a spine-bearing species. shell length Number of Jo To Species (cm) observations barnacles gastropods Morula ferruginosa (REEVE) 2.5 39 100 0 * Acanthina brevidentata (Woop) 3.0 80 80 0 * Acanthina angelica OLDROYD 3.9 432 99 1 Thais kiosquiformis (Ductos) 4.3 84 100 0 Thais melones (Ductos) 4.8 17 0 17 Pterynotus erinaceoides (VALENCIENNES) 5.0 7 0 14 * Acanthina tuberculata (SowERBY) 6.2 14 0 89 Thais biserialis (BLAINVILLE) 75 99 23 18 Hexaplex erythrostomus (SwaInson ) 10.0 63 0 23 Muricanthus nigritus (PHILiPPt) 2.0 - 15.0 118 34 29 6.0 - 15.0 20 0 43 Page 22 THE VELIGER . Vol. 9; No. 1 100 4 \ \ \ ps \ & \ \ (7p) \ WwW \ = \ Oo \ < \ é 50 :