J-^" THE vm\ VELIGER ?/, A Quarterly publbhad by ^tel^' \\ CALIFORNIA MALACOZOOLOGICAL SOCIETY, INC. ^^ \\ Barkolay, California VOLUME 18 OCTOBER I, 1975 NUMBER 2 CONTENTS Quaternary Larval Gastropods from Leg 15, Site 147, Deep Sea Drilling Project. Preliminary Report. (20 Plates) PETER JUNG 109 Reprint ?> Structures of Recent Cephalopod Radulae. (4 Plates) ALAN SOLEM & CLYDE E E. ROPER 127 Two Pleistocene Volutes from the New Hebrides (Mollusca : Gastropoda). (2 Plates; 1 Map) HARRY S. LADD 134 Feeding and the Radula in the Marine Pulmonate Limpet Trimusculus reticulatus. (1 Plate; 4 Text figures) JOHN R. WALSBY 139 Reproduction in the Giant Octopus of the North Pacific, Octopus dofleini martini* (1 Plate) SUSAN HOFFER GABE ? 146 Egg and Larval Development in the Green Mussel, Mytilus viridis Linnaeus (2 Plates) W. H. TAN ? 151 A Seasonal and Histologic Study of Larval Digenea Infecting Cerithidea californicd (Gastropoda : Prosobranchia) from Goleta Slough, Santa Barbara County, California. (2 Plates; 2 Text figures) TIMOTHY P. YOSHINO ? 156 Notes on the Structure and Habits of Myadora (Pelecypoda). (1 Plate; 2 Text figures) MICHAEL J. S. TEVESZ ? 162 Notes on the Spawning and Larval Development of Mitra idae Melvill (Gastro- poda : Mitridae). MICHAEL G. KELLOGG & DAVID R. LINDBERG ? 166 [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, FAMILY, Subfamily, Genus, (Subgenus) New Taxa CONTENTS ? Continued New Tertiary and Recent Naticidae From the Eastern Pacific (Mollusca : Gastro- poda). (2 Plates; 3 Text figures) LOUIE MARINCOVICH ? 168 An Illustrated List of the Phyllidiidae from Seto, Kii, Middle Japan (Nudibranchia : Doridoidea). (5 Text figures) KlKUTARO BABA & I\VAO H.MWATANI ? I 74 Two New Cone Species from Senegal, West Africa. (i Plate; i Text figure) EDWARD J. PETUCH ? 180 Studies on the Mytilus edulis Community in Alamitos Bay, California. V. The Effects of Heavy Metals on Byssal Thread Production. (6 Text figures) J. MICHAEL MARTIN, FRED M. PILTZ & DONALD J. REISH 183 The Essential Amino Acids of Mytilus californianus (2 Text figures) CRAIG HARRISON ? 189 Growth in the Black Abalone, Haliotis cracherodii. (4 Text figures) MARY BERGEN WRIGHT ? 194 Aspidosiphon schnehageni (Sipuncula) inhabiting Tornatina Shells. (4 Text figures) ANTONIO S. E DITADI ? 200 Ecological Aspects of Zooplankton (Foraminifera, Pteropoda and Chaetognatha) of the Southwestern Atlantic Ocean. (7 Text figures; 3 Tables) DEMETRIO BOLTOVSKOY ? 203 NOTES & NEWS 217 Range Extensions for Two Tropical West American Gastropods. DONALD R. SHASKY BOOKS, PERIODICALS & PAMPHLETS ? 221 The Recent Mollusk Collection Resources of North America ALAN SOLEM ? 222 Distributed free to Members of the California Malacozoological Society, Inc. Subscriptions (by Volume only) payable in advance to Calif. Malacozool. Soc, Inc. Volume 18: $25.- Domestic; $26.50 in all Spanish Speaking Countries and Brazil; $27.- in all Other Foreign Countries (including Canada) Single copies this issue $18.-; postage additional. Send subscription orders to Mrs. JEAN M. CATE, P.O. Drawer 710, Rancho Santa Fe, California 92067. Address all other correspondence to Dr. R. STOHLER, Editor Department of Zoology, University of California, Berkeley, California 94720 Vol. 18; No 2 THE VELIGER Page 127 Structures of Recent Cephalopod Radulae BY ALAN SOLEM Department of Zoology, Field Museum of Natural History Roosevelt Road at Lake Shore Drive, Chicago, Illinois 60605 AND CLYDE F. E. ROPER Department of Invertebrate Zoology, National Museum of Natural History Smithsonian Institution, Washington, D. C. 20560 (4 Plates) ATTEMPTS TO DETERMINE the possible affinities of the iso- lated Carboniferous nautiloid radula recently described as Paleocadmus herdinae Solem & Richardson, 1975 have led first to an examination of a few recent cephalopod radulae, and then, on the basis of these results, to a systematic re- view of radular patterns in the Cephalopoda. Scanning electron microscope (hereafter SEM) photographs from the extended survey, including observations on the pat- tern of variation found in sympatric congeneric species, will be published subsequently. Here we present examples from most major systematic groups, selected to show typi- cal overall structural patterns and to indicate deduced functional differences. SEM photographs of cephalopod radulae have been published previously by ALDRICH, BARBER & EMERSON (1971), who surveyed 22 species, covering the sepiolid Rossia, loliginid squids Loligo and Lolliguncula, omma- strephid squids Illex, Todaropsis, and Ommastrephes, and the octopods Octopus, Pteroctopus, and Eledone. Subse- quently SOLEM & RICHARDSON (1975) illustrated the radula of Nautilus and discussed its function. The species reviewed here, their systematic position and the specimens are: CEPHALOPODA Cuvier, 1798 Coleoidea Bather, 1888 TEUTHOIDEA Naef, 1916 Myopsida Orbigny, 1845 LoLiGiNiDAE Steenstrup, 1861 Loligo plei Blainville, 1823 USNM 577080, "Geronimo" Cruise 6, station 7-2, 26 October 1966, 18?25'N, 67?12'W, Caribbean Sea. ML (Mantle Length) =137 mm Oegopsida Orbigny, 1839 HisnoTEUTHroAE Verrill, 1881 Histioteuthis dofleini (Pfeffer, 1912) USNM 729468, Oregon station 6703, 21 May 1967, 16?53'N, 61?53'W, Car- ibbean Sea. ML = 57 mm Page 128 THE VEL1GER Vol. 18; No. 2 VAMPYROMORPHA Pickford, 1939 VAMPYROTEUTHIDAE Thiele, 1915 Vampyroteuthis infernalis Chun, 1903 USNM 729469, Wdther Herwig station 482-HI, 13 April 1971,04?38'N, 19?41' W, North Atlantic Ocean, off western Africa. ML=47mm OCTOPODA Leach, 1817 Incirrata Grimpe, 1916 OCTOPODIDAE Orbigny, 1845 Octopus briareus Robson, 1929 USNM 574777, J. Russell, 10 July 1937, 24?38'N, 82?55'W, Gulf of Mexico, DryTortugas. ML=39 mm When combined with the previously published SEM illustrations of cephalopod radulae, the information pre- sented here permits a definition of the basic strategies of radular function and an indication of patterns within the major groups of extant cephalopods. ACKNOWLEDGMENTS We are indebted to Anne Cohen, Michael J. Sweeney, and Barbara Walden for assistance in the extraction of buccal masses and preparing them for SEM study. The photo- graphs illustrating this paper were made by Alan Solem on a Cambridge S4-10 scanning electron microscope pro- vided to Field Museum of Natural History through Na- tional Science Foundation grant BMS 72-02149 A01. The Explanation of Figures 7 to 6 Loligo plei Blainville, 1823 USNM 577080; 18?25'N; 67?12'W; ML= 137mm Figure /: Part row at posterior end showing newly formed, only partly hardened teeth X 72 Figure 2: Part row of mature teeth X 94 Figure 3: Inner side of outer marginal teeth and inner marginal teeth X 142 Figure 4: Detail of outer marginal teeth and marginal plates X 194 Figure 5: Rachidian tooth showing margin of posterior basal plate and cusps X 480 Figure 6: Outer marginal teeth at artificially curved point of basal membrane to show functional relationship between marginal plates and outer marginal teeth X 136 enlargements were made by Fred Huysmans and mounted by Dorothy Karall. For help with manuscript preparation, we are indebted to Jayne Freshour, Barbara Walden, and Michael J. Sweeney. We thank C. C. Lu, M. J. Sweeney and R. E. Young for reading the manuscript. METHODS Buccal masses were prepared for SEM viewing using the technique outlined by SOLEM (1972). The masses were soaked in a concentrated KOH solution until the beaks could be pulled out and the muscles surrounding the rad- ula itself were weakened enough so that the radula could be removed easily. Frequently the radula was left in KOH for an additional period, until connective tissue and mus- cle fibers were virtually detached. The radular membrane then was soaked briefly in alcohol and plunged into a sonic cleaner for 10 to 20 seconds in order to remove extraneous particles. Rubber cement was used to mount each radula onto an SEM stub. After drying onto the mounts, 6 stubs at a time were given first a coating of carbon and then gold in a vacuum evaporator with continuous rotation and vary- ing tilt of the stubs during the coating processes. This in- sured covering of nearly all surfaces and greatly reduced the problems of charging during SEM viewing. Photo- graphs were made on Polaroid Type 55 P/N film. The accelerating voltage ranged from 3-20 kv, depending upon the condition of individual specimens. DESCRIPTION AND FUNCTION OF STRUCTURES Traditionally the radular teeth of cephalopods have been termed rachidian, first lateral, second lateral and third lateral teeth and marginal plate (or tooth) (see ROB- Explanation of Figures 7 to 12 Hislioleulhis dofleini (Pfeffer, 1912) USNM 729468; 16?53'N; 61?53'W; ML = 57mm Figure 7: Part row in near-vertical view X 123 Figure 8: Anterior view of part row X 200 Figure 9: Rachidian and lateral teeth X 188 Figure 10: Nearly vertical view of outer marginal teeth and rem- nants of marginal plate X 158 Figure //: Outer marginal teeth bent outwards, inner marginal teeth, and marginal tooth ligament (arrows) X 176 Figure 12: Detail of marginal plate remnant X 875 THE VELIGER, Vol. 18, No. 2 [SOLEM & ROPER] Figures 1 to 6 THE VELIGER, Vol. 18, No. 2 [SOLEM & ROPER] Figures 7 to 12 Vol. 18; No 2 THE VELIGER Page 129 SON, 1932; Voss, 1956). We alter the terminology some- what by calling the second and the third lateral teeth, re- spectively, the inner and the outer marginal teeth. This terminology parallels that applied in other molluscan groups and is equivalent to that of taenioglossate gastro- pods which also have seven rows of radular teeth (FRETTER & GRAHAM, 1962: 169, 171; fig. 105D). More importantly, the designation of inner and outer marginal teeth takes into account the close functional relationship of these two teeth in the process of compaction or folding (Figures 1, 8, 16, 23). In the majority of taxa examined (unpublished survey) the inner and ou ter marginal teeth are structurally much more similar to each other than they are to the lat- eral tooth (Figures 1, 8,18, 20). We define "cusp" more narrowly than previous authors. We consider it to be an elevated, pointed projection from the base of a tooth or laterally from a main cutting projec- tion. We distinguish a cusp from a lower, laterally extend- ing support ridge, which may appear cusp-like from some angles of viewing. This difference is demonstrated by Loligo plei. For example, in Figure 3 the lateral teeth, lower right, show an elevated "wing-like" lateral cusp, that when viewed from directly above (Figure 1) appears as a pointed projection. In contrast, the inner marginal tooth in Figure 3 (second tooth row from right) has a raised laterally extending edge that effectively is a low, unpointed version of the cusp on the lateral tooth. When it is viewed from directly above (Figure 1), this is clearly a support ridge rather than a cusp. As can be seen in the upper right of Figures 1 and 3, the outer marginal teeth can fold down on top of the inner marginals, with the support ridge of the inner marginals fitting into the groove on the median side of the outer marginal teeth (see left of center in Fig- ure 3). Both support ridge and cusp share a common deri- vation, but their functions have diverged - cusps operate in holding, tearing, or conveying particles of food, while the support ridges function during the process of com- paction, i. e., when the teeth are folded down, Marginal Plate: Marginal plates long have been recogn-zed as discrete structures, but this is the first attempt to define functional differences. In Nautilus (SOLEM & RICHARDSON, 1975: figs. 14, 15, 17, 18) the outer marginal plate functions as a mechanism for tooth erection through interaction be- tween the free inner edge of the plate and the laterally curved posterior tip found on the basal plate of the outer marginal tooth. The series of teeth shown from upper right to the middle of fig. 15 (loc. cit.) suggests the sequence of moves in tooth elevation in Nautilus through shifting alignment between the marginal plate and the base of the outer marginal tooth. The inner marginal plate that occurs in nautiloids does not exist in recent coleoids. A function equivalent to that in Nautilus apparently is served by the (outer) marginal plates in myosid squids such as Loligo (Figures 2, 4, 6), with interactions between the basal flare of the outer marginal tooth and the free edge of the plate. The marginal plate is reduced to a rem- nant (Histioteuthis dofleini, Figures 10, 12, 13) or is lost (unpublished data) in most oegopsid squid (except, e.g., Cranchia) and sepiolids (unpublished; also ALDRICH, BAR- BER & EMERSON, 1971). In Vampyroteuthis infernalis (Fig- ures 15,16, 18) and incirrate octopods (Octopus briareus, Figures 19, 20, 23), the marginal plate seems to act as a "stress support" buttress, rather than as an erection de- vice. The plate itself is without a free edge, has a truncated inner margin and articulates with an indentation (Figure 23 for Octopus) or a truncation (Figure 18 for Vampyro- teuthis) on the outer marginal tooth. The change between an erectional and supporting function for the outer marginal plate is of uncertain phylogenetic significance. SOLEM & RICHARDSON (1975: 239) hypothesized that in the Carboniferous genus Paleo- cadmus the outer marginal plate had a support function, but that in the recent Nautilus it serves a "triggering func- tion!' The function of the plate in such octopods as Ele- done and Octopus salulii (ALDRICH, BARBER S; EMERSON, 1971: figs. 18, 19) is uncertain, but the appearance sug- gests reduction toward a remnant state, while in taxa such as Bathypolypus (unpublished) the plate may serve partly as a triggering mechanism, rather than a support system. Quite probably the change has occurred repeatedly within major lineages as selection for more efficient feeding on differing prey organisms has proceeded. In taxa with greatly reduced marginal plates, a new structure frequently is present. A strand of ligamentous tissue extends from the anterior tip on the base of the outer marginal tooth to either the posterior edge of the base of the next outer marginal tooth anteriorly (Eno- ploteuthis, unpublished), or to the basal membrane itself (Histioteuthis, see arrows in Figures 11, 14). Equivalent structures are known for the carnivorous land snail Oophana (SOLEM & RICHARDSON, 1975: fig. 24) and are a normal part of the radular complex in the fn.sh water pulmonate family Physidae (BAKER, 1928: 414). We are not aware that this has been reported in other mollusks. Similar structures in other taxa with long slicing teeth can be predicted, but because of the unusual viewing angle required to detect this structure, it easily can be over- Page 130 THE VELIGER Vol. 18; No. 2 looked. We call this structure in cephalopoda the marginal tooth ligament. The inner marginal support plate in Nautilus (SOLEM & RICHARDSON, 1975: figs. 17, 18, 21) is a uniquely nautiloid feature, and it functions both as a trigger for the erection of the inner marginal tooth and as a folding support for the outer marginal tooth. It also is found in Paleocadmus (loc. cit.: 239; fig. 25), but has not been observed in other cephalopods. Outer Marginal Tooth: Structure of the outer marginal tooth differs drastically with the apparent function of the marginal plate. The outer marginal tooth in all taxa is unicuspid, but its shape and basic angle or alignment varies greatly. In taxa with a strong lateral basal flare on the outer marginal tooth which correlates with the triggering or erectional function of the marginal plate, distinct grooves occur on the medial side of the tooth (Nautilus, SOLEM & RICHARDSON, 1975: fig. 20), or the medial side is indented (Loligo, Figure 3). In taxa in which the basal plate of the tooth is greatly reduced or lost, such as Hislioleuthis (Figure 11), the medial edge of the outer marginal tooth lacks these grooves. The func- tional difference basically involves the way in which teeth are folded when they are not being used for feeding. The type of folding pattern represented by Loligo involves interlocking of the outer marginal tooth onto the inner marginal tooth during folding, whereas in Hislioleuthis the pattern of folding does not involve such an interlock- ing with the adjacent inner marginals. The degree of curvature of the outer marginal teeth varies greatly from species to species, both in those in which the marginal plate functions as a trigger and those that possess greatly reduced marginal plates. For taxa in which the marginal plate functions as a support, the ten- dency is for the outer marginal tooth to be a simple, only slightly curved shaft, that tapers slightly from tip to base (Figures 15, IS, 20, 23) and that folds down (medially) against the inner marginal tooth. The inner marginal tooth can be very strongly extended laterally via a deep groove into which the outer marginal tooth fits (Octopus, Figure 23), or the outer marginal tooth can fold against the grooved side of the inner marginal (Vampyroteuthis, Figure 18). None of the outer marginal teeth of cephalopods exam- ined so far demonstrate a "slicing" form equivalent to that seen in carnivorous land snails such as Euglandina, Sys- trophia, and Haplolrema (see SOLEM, 1974). Instead they are of the "stabbing" or "tearing" form. Inner Marginal Tooth: The inner marginal teeth in nautiloids are very similar in form and function to the outer marginal teeth (see SOLEM & RICHARDSON, 1975: figs. 1, 15, 17, 25) and quite different from the lateral and central teeth. In the coleoid species discussed and illustrated here, the cusped portion of the inner marginal tooth is of the same size as the lateral tooth and much shorter than the outer marginal. Very great differences occur in the degree of lateral extension of the inner marginal tooth. In Octopus briareus (Figure 23) and Vampyroteuthis infernalis (Figure 16) a very strong lateral extension exists on the inner marginal tooth onto which the outer marginal tooth lies in the folded position. In Loligo plei (Figures 1, ?) the lateral extension of the inner marginal tooth is shorter than in the two previous taxa, but the function appears to be the same (although the outer marginal tooth may not lie as flat), fjistioteuthis dofleini (Figures 8,9,11) has a very short, ridged extension on the inner marginal tooth, a structure that is typical of taxa with reduced marginal plates. Lateral Tooth: The lateral teeth are equal in height to the inner mar- ginal teeth (e.g., Figures 1, 7), except in Octopus (Figure 19). They may be unicuspid (Vampyroteuthis, Figure 17), or have a very slightly elevated lateral "cusp" that is more of a shoulder than a projection (Hislioleuthis, Figure 9). or have a markedly elevated lateral cusp that is distinctly lower in elevation than the main cusp (Loligo, Figures 1, Explanation of Figures 13 to 18 Hislioleuthis dofleini (continued) Fisrure 13: Outer marginal teeth and marginal plate remnants X 200 Figure- 14: Detail of marginal tooth ligament (arrow) X 550 Vampyroteuthis infernalis Chun, 1903 USNM 729469; 04?38'N; 19?41'W; ML = 47mm Figure 15: Detail of marginal plates and outer marginal teeth X 96 Figure 16: Part row of teeth X 48 Figure 17: Rachidian and lateral teeth X 169 Figure 18: Marginal teeth and marginal plates X 95 THE VELIGER, Vol. 18, No. 2 [SOLEM & ROPER] Figures 13 to 18 Vol. 18; No 2 THE VELIGER Page 131 )). In octopods (Figures 19, 20, 22), the lateral tooth is rudimentary, consisting of a small lateral cusp and a me- dial extension (see also ALDRICH, BARBER & EMERSON, 1971: figs. 18, 19). The lateral tooth appears so underde- veloped compared with the cusps on the neighboring teeth, that it is difficult to imagine how it could take part in the feeding process. Rachidian Tooth: Rachidian teeth are equally variable, ranging from the almost equally tricuspid structure with narrow base found in Loligo (Figure 5), to the very large multicuspid struc- ture seen in Octopus (Figures 21, 22; also ALDRICH, BAR- BER & EMERSON, 1971: figs. 18, 19). All of the squid species examined by ALDRICH, BARBER & EMERSON (1971: figs. 2-8, 12-17) had tricuspid rachidian teeth, although these au- thors document considerable intraspecific variation in tooth width and relative size of the cusps. They found species of the sepiolid Rossia to have unicuspid rachidian teeth (loc. cil.: figs. 9-11). Every degree of variation seems to exist between the tricuspid and unicuspid structures. In Histioteuthis dofleini (Figures 7,8,9) there are "pointed shoulders" to the rachidian tooth that equal the weak ex- tensions of the lateral teeth (Figure 9). The low degree of elevation is such that they must play a secondary role in actual feeding. Vampyroteulhis (Figures 16, 17) has a sharply pointed unicuspid rachidian tooth, that tapers gradually at first, then flares to a broad base. The strong grooves on the lateral surface of both rachidian and lateral teeth in Vampyroteuthis are clearly visible in Figure 17. In contrast, the large, highly variable rachidian teeth in Octopus have a very different orientation and cusp struc- ture. The well-known pattern of variation in number and position of subsidiary cusps on successive rachidian teeth is shown clearly in Octopus briareus (Figures 20, 22). The pattern occurs over 4 teeth, with an initial two side-cusps (fourth tooth from bottom in far left of Figure 20), one high and one very low cusp. This is followed by loss of the upper, then size increase and upwards migration of the lower cusp on the next two teeth, then size reduction of the upper and reappearance of a lower cusp in the 4th tooth, thus duplicating the first state. ROBSON (1929: 12, 28) discusses this phenomenon in detail. ALDRICH, BARBER & EMERSON (1971: figs. 18, 19) report a similar two-tooth change in Octopus salutii. The angle of the rachidian teeth, concave anterior margins, and very crowded posi- tions contrast greatly with the shape and spacing in the other cephalopods. One additional structural pattern requires comment. When the radula of virtually all coleoid cephalopods, whether octopods or teuthoids is viewed from the anterior end, the teeth have a characteristic indention on the an- terior base (compare Histioteuthis, Figure 8, and Octopus, Figure 20; also ALDRICH, BARBER & EMERSON, 1971: figs. 2-6, 9-10, 12-16 for various sepiolids and teuthoids). The only exception noted to date in our survey is Vampyro- teulhis (Figures 15-18) in which the rachidian and lateral teeth have a prolongation of the anterior basal support. This is the same type of extension seen in the radulae of carnivorous land snails such as Ptychorhytida (SOLEM, 1974: fig. 14), marginal teeth of Haplotrema (SOLEM, loc. cit.: fig. 6), and Torresiropa (SOLEM, loc. cit.: figs. 23, 24). It is analagous to the stress support flare seen in many land snails (SOLEM, 1972: figs. 22, 23), although the latter is not attached to the radular membrane, while in Ptychorhytida and Vampyroteulhis the anterior flare is anchored to the basal membrane. This prolongation functions as support against stress from bending during feeding. It effectively locks the tooth into a fixed angle, whereas the anterior margin of the rachidian and lateral teeth in other cephalo- pods permits more flexibility in tooth orientation. The presence of grooves on the teeth is most marked in the nautiloid cephalopods (see discussion in SOLEM & RICH- ARDSON, 1975), but they are also quite prominent in the coleoid taxa that have prominent marginal plates, whether of the trigger-erection (Loligo, Figure 3) or support func- tion (Vampyroteuthis, Figure 17 and Octopus, Figure 23). These grooves are greatly reduced or absent in taxa with reduced or missing marginal plates (Histioteuthis, Figure 11). The grooves function during the compaction or in- folding of the teeth toward the midline of the radula, Their presence is to be expected in taxa with a marked radial (to and from midline of radula) shift in tooth erec- tion and folding. Their reduction or loss in taxa where tooth movement is more "up and down" (i.e., non-fold- ing) rather than "out and up, then in and down" is reason- able. SUMMARY OF STRUCTURAL PATTERNS On the basis of the observations outlined above, the pat- tern of teeth in radulae of recent cephalopods is relatively simple. The largest number of structural elements occur in Nautilus which has the following teeth in order from radular midline to outer margin: one rachidian, two lat- erals, one inner marginal, one outer marginal, and one each of inner and outer marginal support plates. A total of 9 teeth and 4 support plates occur in a transverse row of teeth. Both marginal teeth are much larger and very dif- ferent in shape from the lateral teeth. The generalized pattern in extant coleoids appears to be a rachidian, one lateral, one inner marginal, and one Page 132 THE VELIGER Vol. 18; No. 2 outer marginal tooth, plus the marginal plate. The inner marginal tooth tends to be different in size from the outer marginal tooth, but similar instead to the lateral tooth. Reduction and loss of the marginal plate is frequent in teuthoids. Unicuspid, bicuspid, and tricuspid rachidian teeth and unicuspid or bicuspid lateral teeth are seen in many groups. The shape of the inner marginal tooth is correlated with the function of compaction and support against stress of the outer marginal tooth. Octopods differ in having the lateral tooth on each side reduced to a small remnant, the rachidian tooth enlarged ?often with variable cusps, and, usually, a massive outer marginal plate. Once the clear distinction is made between cusp-bearing teeth and the marginal plates, which function for erection, support against stress, or compaction (folding), or both, then much of the discussion concerning numbers of teeth in a transverse row in the Cephalopoda becomes irrele- vant. The nautiloids do differ in having 9 teeth and 4 plates in each row, that is, an additional pair of lateral teeth and an additional pair of support plates over those found in typical coleoids. The coleoids characteristically have 7 teeth and 2 plates in each row, with the support plates re- duced or lost in sepiolids and many oegopsid squids. Some gonatids have only 5 teeth per row. The inner marginal tooth of teuthoids is more modified than the outer mar- ginal. Octopods generally are characterized by having a modified and enlarged rachidian, greatly reduced laterals, and very large marginal plates. Some cephalopoda lack radulae altogether. Thus the coleoids have rather limited variations on a basic plan, rather than showing the more radical differ- ences implied by counting the outer plates as teeth or by overlooking the minute lateral tooth of most octopods. Some cephalopods, such as Spirula and cirrate octopods e.g., Opisthoteuthis (Solem & Roper, unpublished), totally lack a radula (see also ROBSON, 1932: 9). A thorough discussion of the phylogenetic implications of the radula will appear in our later work. Although the topic has been discussed in the literature (ROBSON, 1932: 7-12), no conclusions have been reached, nor is there agreement on which type of radula represents the primi- tive form. We do know, however, that the radula of nauti- loid cephalopods is a very conservative structure that has persisted nearly unchanged in basic structure for about 300 million years (SOLEM & RICHARDSON, 1975). The radula in the orders of living coleoids also is similar in basic struc- ture. The details of structure do vary at different taxo- nomic levels, even to the extent that some congeneric sympatric species have dissimilar radulae. The variations on the conservative structural plan of the radula appear to be an overlay imposed by the evolution of a variety of feeding characteristics throughout the cephalopods. SUMMARY A review of published scanning electron micrographs of cephalopod radulae, together with illustrations of the radula of Loligo plei, Histioteuthis dofleini, Vampyroteu- this infernalis, and Octopus briareus permit identification of different functions for marginal plates, clear distinction between teeth and plates, and clarification of the basic number and patterns of teeth and plates in major taxo- nomic categories. Marginal plates may function either to erect outer marginal teeth or to support them against stress. Nautiloid cephalopods differ from coleoids in hav- ing two extra lateral teeth and two inner marginal support plates. Coleoids vary in cusp patterns on the rachidian and lateral teeth, with the teuthoids varying from possession of strong marginal plates to their complete loss. Octopods are characterized by a greatly reduced lateral tooth, a very en- larged and usually multicuspid rachidian tooth, and mas- sive marginal plates. Vampyroteuthis is unique among examined species in having an anterior prolongation of the rachidian that provides support against stress during feeding. The conspicuous grooves present on the teeth of many cephalopods function during compaction or infold- Explanation of Figures 79 to 23 Octopus briareus Robson, 1929 USNM 574777; 24?38'N; 82?55'W; ML = 39mm Figure 19: Part row of teeth Figure 20: Anterior view of teeth Figure 21: Rachidian teeth in lateral view Figure 22: Cusp variation on rachidian teeth Figure 23: Details of folding pattern of marginal teeth X90 X96 X189 X 189 X 194 THE VELIGER, Vol. 18, No. 2 [SOLEM & ROPER] Figures 19 to 23 Vol. 18; No 2 THE VELIGER Page 133 mg of the teeth towards the midline of the radula. These grooves cause the outer teeth to "lock" down either on the support plates (Nautilus) or against the inner marginals and laterals (coleoids). When the outer marginal plates are greatly reduced or lost, the grooving on the teeth often is reduced or lost and a different pattern of tooth folding or erection, or both, is evolved. In some teuthoid taxa that lack marginal plates an entirely new structure is present, a marginal tooth ligament that extends from the anterior basal plate of the outer marginal tooth to either the basal membrane or the posterior part of the basal plate of the next anterior outer marginal tooth. This structure was not reported previously Literature Cittd ALDRICH. M. M., V. C. BARBER & C. J. EMERSON 197 1. Scanning electron microscopical studies of some cephalopod ra- dulae. Canad. Journ. Zool. 49 (12): 1589- 1594; pits. I-V (December 1971) BAKER, FRANK COLLINS 1928. The fresh water Mollusca of Wisconsin. Part I. Gastropoda.. Bull. Wise. Geol. Nat. Hist. Survey 70 (1): i - xvii + 1 - 507; pits. 1-28; 202 text figs. FRETTER, VERA t ALASTAIR GRAHAM 1962. British prosobranch molluscs, their functional anatomy and eco- logy. London, Ray See. xvi-t- 755 pp.; 317 text figs. ROBSON, GUY COBURN 1929. A monograph of the recent Cephalopoda. Part I. Octopodinae. Brit. Mus. (Nat. Hist.) v-xi + 1 -236; 7 pits.; 89 text figs. (27 July 1929) 1932. A monograph of the recent Cephalopoda. Part 11. The Octo- poda, excluding the Octopodinae. Brit. Mus. (Nat. Hist.) 2: 1 -359; 6 pits ; 79 text figs. (23 January 1932) SOLEM, ALAN 1972. Malacological applications of scanning electron microscopy -- II. Radular structure and functioning. The Veliger 14 (4): 327 to 336; 6 pits.; I text fig. (1 April 1972) 1974. Patterns of radular tooth structure in carnivorous land snail The Veliger 17(2): 81-88; 7 pits. (1 October 1974) SOLEM, ALAN & EUGENE 5. RICHARDSON 1975. Paleocadmus, a nautiloid cephalopod radula from the Pennsyl- vanian Francis Creek Shale of Illinois. The Veliger 17 (3): 233 - 242; 5 pits.; 1 text fig. (1 January 1975) Voss, GILBERT LINCOLN 1956. A review of the cephalopods of the Gulf of Mexico. Bull. Marine Sci. Gulf & Carib. 6(2): 85 - 178; 18 figs. 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, distributional, ecological, histological, morphological, phys- iological, taxonomic, etc., aspects of marine, freshwater or terrestrial mollusks from any region, will be considered. Even topics only indi- rectly concerned with mollusks may be acceptable. In the unlikely event that space considerations make limitations necessary, papers dealing with mollusks from the Pacific region will be given priority. However, in this case the term "Pacific region" is to be most liberally interpreted. It is tile editorial policy to preserve the individualistic writing style of the author; therefore any editorial changes in a manuscript will be sub- mitted to the author for his approval, before going to press. Short articles containing descriptions of new species or lesser 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 geographical longitudes and latitudes added. Short original papers, not exceeding 500 words, will be published in the column "NOTES & NEWS"; in this column will also appear notices of meetings of the American Malacological Union, as well as news items which are deemed of interest to our subscribers in general. Articles on "METHODS & TECHNIQUES" will be considered for publication in another column, provided that the information is complete and tech- niques and methods are capable of duplication by anyone carefully fol- lowing the description given. Such articles should be mainly original and deal with collecting, preparing, maintaining, studying, photo- graphing, etc., of mollusks or other invertebrates. A third column, en- titled "INFORMATION 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 in- vited. The column "BOOKS, PERIODICALS, 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, 8'/2" by II", double spaced and accompanied by a carbon 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 accom- modate the pamphlet (which measures 5V2" by 8&i"), with double first class postage, should be sent with the request to the Editor. EDITORIAL BOARD DR. DONALD E ABBOTT, Professor of Biology Hopkins Marine Station of Stanford University DR. WARREN O. ADDICOTT, Research Geologist, U. S. Geological Survey, Menlo Park, California, and Consulting Associate Professor of Paleontology, Stan- ford University DR. JERRY DONOHUE., Professor of Chemistry University of Pennsylvania, Philadelphia, and Research Associate in the Allan Hancock Foundation University of Southern California, Los Angeles DR. J. WYATT 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. CADET HAND., Professor of Zoology and Director, Bodega Marine Laboratory University of California, Berkeley, California DR: JOEL W. HEDGPETH, 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. T. E. THOMPSON., Reader in Zoology University of Bristol, England DR. VICTOR LOOSANOFF, Professor of Marine Biology Pacific Marine Station of the University of the Pacific DR. JOHN MCGOWAN, Associate Professor of Oceanography Scripps Institution of Oceanography, La Jolla University of California at San Diego DR. FRANK A. PITELKA, Professor of Zoology University of California, Berkeley, California DR. ROBERT ROBERTSON, Pilsbry Chair of Malacology Department of Malacology Academy of Natural Sciences of Philadelphia DR. PETER U. RODDA, Chairman and Curator, Department of Geology California Academy of Sciences, San Francisco MR. ALLYN G. SMITH, Research Associate Department of Geology California Academy of Sciences, San Francisco DR. RALPH I. SMITH, Professor of Zoology University of California, Berkeley, California DR. CHARLES R. STASEK, Bodega Bay Institute Bodega Bay, California EDITOR-IN-CHIEF DR. RUDOLF STOHLER, Research Zoologist, Emeritus University of California, Berkeley, California ASSOCIATE EDITOR MRS. JEAN M. CATE Sanibel, Florida