Northeast Gulf Science Volume 1 Article 6 Number 1 Number 1

6-1977 The olM luscan Fauna of the Middle Grounds with Comments on its Zoogeographical Affinities Thomas S. Hopkins University of Alabama

Deborah R. Blizzard University of Alabama

Douglas K. Gilbert University of Alabama

DOI: 10.18785/negs.0101.06 Follow this and additional works at: https://aquila.usm.edu/goms

Recommended Citation Hopkins, T. S., D. R. Blizzard and D. K. Gilbert. 1977. The oM lluscan Fauna of the Florida Middle Grounds with Comments on its Zoogeographical Affinities. Northeast Gulf Science 1 (1). Retrieved from https://aquila.usm.edu/goms/vol1/iss1/6

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Northeast Gulf Science Vol. 1, No.1. p. 39-47 June 1977

THE MOLLUSCAN FAUNA OF THE FLORIDA MIDDLE GROUNDS WITH COMMENTS ON IT'S ZOOGEOGRAPHICAL AFFINITIES!

Thomas S. Hopkins, Deborah R. Blizzard, and Douglas K. Gilbert

Marine Science Program University of Alabama Dauphin Island, Alabama 36528

ABSTRACT: Recent studies have indicated that the Gulf of Mexico is bom1ded by a discontinual series of hard substrates which support faunal and floral assemblages of both temperate and tropical Ol'igins. This substrate distTibution has had a significant impact on molluscan fauna in the Gulf of Mexico. An investigation of the molluscan fauna of the Florida Middle Grounds has produced 75 associated with this high relief substrate which is also chamcterized by herma­ typic COl'als, Although the molluscan fauna is comprised of forms which are predominantly "Caribbean eurythermic" and "Caribbean Restricted" (76%) which is similar in composition to the West Flower Garden Bank of Texas, their species composition is quite dissimilar (only 23% similaTity). For these and other reasons, it is proposed that the zoogeographic status of the Gulf of Mexico should be seriously l'econsidered by specialists in other faunal groups.

INTRODUCTION (21°08'N, 097°13'W) and Enmedio (19°06'N, 095"56'W) which are 100 km The Gulf of Mexico is bounded by southeast of Tampico and 15 km south­ a discontinual series of hard, sometimes east of Veracruz respectively have been moderately high relief rocky substrates studied by Tunnel (1974). Lipka (1974) which bear faunal and floral assemblages investigated the reef associated molluscan of both temperate and tropical origins fauna of the West Flower Garden Bank (Figure 1). Bright and Pequegnat (1974), (WFGB) located at 27"52'N, 093°48'W and Bright and Rezak (1976) have re­ which is 172 km south of Galveston, viewed both biological and geological as­ Texas. The molluscan fauna reported pects of these topographical features on herein is assoicated with the hermatypic the western gulf continental shelf. Brooks reef community briefly described by ( 19 7 3) has dealt with topographic Hopkins (1974) at the Florida Middle features in the eastern Gulf. Grounds (28o35'N, 084°29'W) approxi­ The zoogeography of bivalve molluscs mately 137 km southeast of Apalachi­ and of mollusks in general , in the Gulf cola, Florida. See Figure 1 for spatial of :Mexico has been discussed by Pulley relations for the various topographic (1952) and Rehder (1954) respectively. structures. Hopkins (op. cit.) has es­ Collard and D'Asaro (1973) have dis­ tablished the the FMG hermatypes are cussed zoogeographic relationships of domina ted by Millepom along with benthic invertebrate communities in the Madracis and Dic!zocoenia in contrast eastern Gull' of ivlcxico, and Hedgpeth to the Di!Jlom-Monastrea formations (1953, P. 201-205) and Briggs (1974, of the WFGB. For this reason as well p. 214-221) have given their views on as the significant spatial separations of the status of provinces and zones in the these reef areas, a comparative character­ Gulf of Mexico. ization of their molluscan faunas should The molluscan faunas of Lobos Reef be of value in gaining a better under-­ lContribution number 012, Dauphin Island standing of these deep reef communities. Sea Lab. The only known previous report on the 39

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40 T. S. Hopkins, D. R. Blizzard and D. K. Gilbert

~ : ,..---.... \ ___ / '',,,\ )

THREE ~,_,/-'/ FLORIDA \ • HICKEY ROCKS J MIDDLE G~,~~ ND • ; .. ---- •• -- __ .. - ~ .. -··J 1 \ } : .':: / \ . ·:, \ ..:/: ! . ·~:: \ \,::;4) '~-- .. \ ~~ ...... Q ...... DRY TOf!"':_~~~~--::~~FLORIDA /~ KEYS / ~~~ : ,.' ' .. , 'I .,..-.- ' 'I .•! ,-'/ ~ ALACRAN \, 22° •-, ,------;_c;;O AR~·NA:EEF '··\, 0 . .. '·~'LANQUILLA REEF NUEVO REE[ • BANCO INGLESES :·\ : ISLA DE LOBOS 1 : '.\·,. \,, TR IANGULOS ~ .. ' OBISPO SHOALS: ·:•.':, 'J ARGAS CAYS'• ,·;, ", I . :·;. 't.. ENMEDIO REEF t"" • REEFS/ >= ·\·.::·~.~VERACRUZ ,soo GRAND .. ··.~... '- ...... "' 4oo.,..-, -- __ ...... CAYMAN <-'l,lfSTERIOSA BANK

Fig. 1. Map of the Gulf of Mexico showing locations of known coral reefs. (After Bright & Pequegnat, 1974)

molluscan fauna from the Florida Middle stem thermometers, and these data are Grounds is that of Lyons (1976). in agreement with the mean monthly temperatures published by Cheney and METHODS Dyer (197 4).

Because of the depth and topography RESULTS of the Florida Middle Grounds (23-36m), open circuit SCUBA (non-recirculating The present study reports 75 species self contained underwater breathing from the FMG which includes 42 species apparatus) was used for specimen collec­ of gastropods, 24 species of pelecypods, tion at six sampling sites during June and three species of cephalopods; two species September 1975 and February- March, of chitons and of particular, note four 19 7 6. Each sampling site encompassed species of opistobranch gastropods one of a rectangular area of the approximate which just recently has been described dimensions 15 x 75 meters. Representa­ by Marcus and Gallagher (1976) from tive specimens of the materials described shallow water. The molluscan species herein are currently in residence at the encountered on the Florida Middle Dauphin Island Sea Lab. Grounds are displayed along with their Routine temperature measurements noted occurence by Lipka (op. cit.) or were recorded (uncorrected) with mercury Tunnel (op. cit.) in Table 1.

https://aquila.usm.edu/goms/vol1/iss1/6 2 DOI: 10.18785/negs.0101.06 Hopkins et al.: The Molluscan Fauna of the Florida Middle Grounds with Comments o

Florida Middle Ground Molluscs 41

Tunnel (op. cit.) reported 290 mulluscs as B. cancellaria a speices which was (211 gastropods, 73 bivalves, 4 chitons, collected by Lipka (oJI. cit.) from the and 2 cephalopods) in his study vvhich \Vest Flower Garden. Litho p/wga bisu/­ ranged from supratidal to 2 3 1VI. the cata was found in abundance in both dominant gastropod genera were: reef ecosystems, although L. aristata was Trip!zora ( 12 species), Caecum (11 more abundant from the Middle Ground. species), Ccrithiopsis (10 species), Malleus candcanus collected from the Turbanilla (7 species) and Cymatuim Flower Garden was found only attached (6 species). The dominant bivalve genera to hard substrates, not in (Lipka, were Li I lzoplzaga and Lima (4 species Of!. cit.) vvhile some of the fvliddlc each) and Barbatia, Chama and Tcllina Ground specimens were collected from with 3 species each. Lipka (op. cit.) sponges. M. candeanus was abundant collected 65 species of molluscs from the from the Florida Middle Grounds as was (WFGB) and included 41 species of Chlamys benedicti. SjJondy!us amcri­ gastropods, 21 species of pelecypods, CCI!Il!s, Pteria colymhus, chama macem­ two species of cephalopod and one plzylla, and Lo;J/W fi·ons. species of chiton. Two species of the Octo;JUs The molluscan assemblage of the comprised two of the three cephalopods Florida Middle Ground is quite dissimilar collected from the Florida Middle to the WFGB as measured by the Bray­ Grounds (Table 1). The only specimen Curtis similarity index (1957) where: collected from the Flower Garden was a juvenile and could not be identified be­ yond the genus Octopus. Only one species of squid, Lo/igo f!Ca/ei, was col­ lected from the water column over both where a is the number of species common of the two reefs studied. to two sites; band c arc the total number Lipka (1974) did not mention the of species at each site. In comparing the collection or identification 0 f any opisto­ similarity of these data to Lipka (ofJ. branches from the West Flower Garden; cit.) a value of 24% was obtained. four species were collected from the or the specimens presently identified, Florida Middle Grounds (Table 1 ). only eight species of gastropods collected from the l'vliddle Ground also occurred DISCUSSION from the Flower Garden (Table 2). One \VFGB species of Calliostonw was a For the purposes of the ensuing dis­ juvenile and not identified to determine cussion, we think it is important to re­ if it occurred on the Middle Ground. view pertinent information from Ceritlzium litteratl/111 was the most Hedgpeth (1953), Briggs (1974), and abundant gastropod surveyed in situ Valentine (1973). Hedgpeth (ofJ. cit. p. from both the Flower Garden (Lipka, 195-205) is a comprehensive treatment Ufi. cit.) and the Florida !'diddle Ground. of "Biogeographical and Ecological Con­ Of the 24 Florida i\liddle Ground siderations" based on the knowledge species of pelecypods collected, only available to him at that time. Our inter­ seven were found to be common to both pretation of this cf'fort leads us to con­ reefs (Table 1). Some specimens of clude that Hedgpeth's conclusions con­ Barbatia collected form the J\Iiddlc cerning the Gulf fauna were in rluencecl Ground have tentatively been identified the greatest by (a) littoral and sub-

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42 T. S. Hopkins, D. R. Blizzard and D. K. Gilbert

Table l. Comparison of the Molluscan fauna of the Florida Middle Ground with the data of Lipka (1974) and Tunnel (1974). A= alive; D ~shell only;* indicates a new record for the easlern Gulf of l'vlexico.

West Florida Flower Middle Gardens Grounds Bank Lobos Enmcdio

CLASS Family FISSURELIDAE (Fleming) EmarKinula pumila (A. Adams) A* A D octoradiata (Gmclin) A cayenensis (Lamark) A A A Diodora dysoni (Reeve) A Lucapina sufji1sa (Reeve) A* D A Lucapina ac1ds (Reeve) :\ ll A

Family TROCHIDAE (Rafinesque) Calliostoma roseo/um (Dall) A Ca/liostoma harbouri (Clench & Aguayo) A* Calliostoma jujubinium (Gmelin) A Family (Rafinesque) Astraea phoebia (Roding) A A Astraea tecta americana (Gmelin) A* A A A Astraea cj: tuber (Linne) A Family CYCLOSTREMA!DAE (Fisher) Arene cruentata (Miihlfeld) A A Family TURRITELLIDAE (Clarke) Turritella exo/eta (Linne) A* Vermicularia knorrii (Deshayes) A Family CERITHIDAE (Fleming) Cerithium atratum (Born) A Ccrithium litteratum (Born) A A A A Family TRIPHOR!DAE (Gray) Triphora turristhomae (Holten) A* A A A Family CREPIDULIDAE (Fleming) Crepidula aculeata (Gmelin) A Crepidula plana (Say) A Family ERATOIDAE (Gill) Tril1ia pediculus (Linne) A Family CYPRAEIDAE (Rafinesque) Cypraea spurca acicularis (Gmelin) A A A A Family OVULIDAE (Fleming) Simnia uniplicata (Sowerhy) A Cyphoma macgintyi (Pilsbry) A Family MURlCIDAE (de Costa) florifir dilectus (A. Adams) A* Urosalpinx cf. cinerea (Say) A Ocenebra minirosea (Abbott) A* Muricopsis oxytatus (M. Smith) A D D ostrearum Con'rad) A Family CORALLJOPIIIL!DAE (Chenu) Corallioplzila ahbrel'iata (Lamarck) A A A Coralliophila carihaea (Abbott) A* A A Family COLUMBELLIDAE (Swainson) Anachis j7oridana (Rehder) A Family BUCCJNIDAE (Rafinesque) Bailya illtricata (Dall) A' A A Bailya pan•a (C. B. Adams) A Engina corinnae (Crovo) A* Engbza turbinella (Kiener) A* A A Pisania tincta (Conrad) A A A A Alltilloplzos ade/us (Schwengel) A Family (Gray) nassa (Gmelin) A D A Leucozonia ace/lata (Gmelin) A* Latirus cariniferus (Lamarck) A

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Florida Middle Ground Molluscs 43

Table 1 (cont.)

West Florida Flower Middle Gardens Grounds Bank Lobos Enmedio

Fasciolar/a tulipa (Linne) A A A Family APLYSIIDAE (Rafinesque) Aply>ia pan•ula (Morch) A Family DORIDIDAE (Rafinesque) .·. Hypselodoris edenticulata (White) A Chromodoris elenchi (Russell) A Family DENDRODORIDIDAE (Pruvot-Fol) Dendrodoris warta ~~Iarcus & Gallagher A* CLASSPLOYPLACOPHORA Family JSCHNOCHITONIDAE (Dall) Stenoplax floridana (Pilsbry) A Family CHlTONIDAE (Rafinesque) Tonicia schrammi (Shuttleworth) A A CLASS PELECYPODA Family ARCIDAE (Lamarck) Area zabra (Swainson) A D A A Area imbricata (Brugui~re) A A A Barbatia cf. cancellaria (Lamarck) A A Barbatla domingensis (Lamarck) A A A A Arcopsis adamsi (Dall) A A A Family MYTILIDAE (Rafinesque) Musculus latera/is (Say) A A Lithophaga nigra (Orbigny) A* A A Lithophaga an til/arum (Orbigny) A A Lithophaga bisulcata (Orbigny) A A A A Lithophaga aristata (Dillwyn) A A A A Botttla fusca (Gmelin) A A Family PTERIDAE (Gray) Pteria columbus (Roding) A A Pinctada imbricata (Roding) A Family MALLEIDAE (Lamarck) Malleus candeanus (Orbigny) A A A A Family PECTINIDAE (Rafinesque) Chlamys benedict/ (Verrill & Bush) A A Argopecten gibbus (Linne) A Family SPONDYLIDAE (Gray) Spondylus americanus (Hermann) A A

Family OSTREIDAE (Rafinesque) Lopha frons (Linne) A A A Family CHAi\HDAE (Lamarck) Chama macerophylla (Gmelin) A A A Family TRAPEZIIDAE (Lamy) Coralliophaga coralliophaga (Gmelin) A A D Family VENERIDAE (Rafinesque) Ventrico/aria rugathla (Heilprin) A* Family GASTROCHAENIDAE (Gray) Gsatrochaena !lions (Gmelin) A Spengleria rostra/a (Spengler) A* A Family HlATELLIDAE (Gray) Hiatella arctica (LinnC) A* CLASS CEPHALOPODA Family LOL!GlNIDAE (Lesueur) Loligo pea/ei (Lesueur) A A Family OCTOPODIDAE (Rafinesque) Octopus l'Ulgaris (Cuvier) A A A A Octopus joubini (Robson) A

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44 T. S. Hopkins, D. R. Blizzard and D. K. Gilbert

littoral collections, (b) the large degree Island and Cedar Keys), and "the coast of disjunct distributions which he attri­ of Mexico from Cabo Catoche to the buted in part to insufficient sampling vicinity of Port Isabel, Texas and pos­ effort, and (c) his evaluation and conclu­ sibly beyond to Corpus Christi Bay". sions concerning the amounts and validity He further observed that the mollusks of of endemism reported. 0 f particular the area described "show an obvious consequence, his treatment did not con­ relationship with those of the West sider the more recently investigated hard­ Indies and the entire Caribbean region." substrate communities ringing the Gulf In dealing with the Carolinian Province on the coastal shelf. The question of he states: provincial definitions has been reviewed "This area extends from Cape Hatteras, by Briggs (otJ. cit., p 16) who asks the North Carolina, south to about Cape Canaveral question " how much does a on the east coast of Florida, and from about local fauna have to differ from the Tampa Bay on the Florida west coast north­ parent in order to merit formal recogni­ ward and westward along the shore of the Gulf tion as a province?" I-Ie goes on to admit to about Corpus Christi Bay, Texas." an "arbitrary" value of 10 per cent Lastly and of importance to this dis­ endemism for designation as a separate cussion, Rehder op. cit. calls attention to provirice. He further makes a case for the fact that the fauna of deeper water usmg "shelf " in developing shows relationships with topical ele­ provmces, an admitted shortcoming ments of the Caribbean and of even m Hedgpeth's treatment. Valentine's more pertinence, there are species vvhich (19 73) treatment of the "province" appear to be peculiar to the Gulf. question has an entirely different The often cited contribution by Work approach, e.g. "it is in fact theoretically (1969) updates the efforts cited above, possible that a province could possess no but further opens the question of the endemic species at all and yet have dis­ validity of conclusions about provincial tinctive communities". Thus Valentine boundaries based on shallower water (op. cit., p. 337) defines provinces "as observations. For example, the work of regions in which communities maintain J'vicrrill and Petit, 19 65; Cerame- Vivas characteristic taxonomic compositions". and Gray, 1966; lVIcnzics et. a!. 1966, are Furthermore, "since communities arc all cited as examples that indicated West polythetic units, it is necessary that only Indian species have invaded the Caro­ enough of the species differ so as to linian Province. Work (op. cit.) should form distinctive characterizing sets of also be credited with observing that the species in each province". area off-shore from Clearwater to ncar Rehder (1954) has provided a summary St. Marks on the upper big-bend coast review of the molluscan literature for of Florida has an extraordinary tropical the Gulf and provides some zoogeo­ assemblage, and he refers to it as the graphic implications. This work generally "disjunct Astraea zone" because of the outlines the Caribbean Province as apparent abundance of Astmea fJ/webia including the northwest coast of Cuba and A. tecta ssp. His observations and from Cabo San Antonio to Ilabana, the hypothesis have been verified hydro­ west coast of Florida from the Dry graphically by Austin and Jones (1974) Tortugas and Key West north to pro­ and biologically by Hopkins (1974) and bably Tampa Bay (the northern limit Smith and Ogren (1974). Furthermore, of this province is somewhat doubtful the cxistance of West Indian species in here but lies somewhere between Sanibel deeper areas of the western Gulf has

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Florida Middle Ground Molluscs 45

been more than substantiated by Bright sidering it as Carolinian because of its and Pequegnat (1974). shallow temperate fauna along the upper Tum1el (19 7 4) developed a terminology Gulf Coast, found that it is easily off-set and an approach not unlike that of by tropical occurrences even in embay­ Hedgpeth (1953) in order to numerically ments (Work, 1969). It can be seen that characterize the molluscan fauna. Granted the Middle Grounds molluscan fauna has there are aspects of the classification a predominantly Caribbean heritage as that may be regarded as arbitrary, we we might expect based on the work of feel that their use herein will help expose Collard and D'Asaro (1973). We are them to the kind of critical review ne­ puzzled by Briggs (op. cit., p. 218-221) cessary to either have them stand the who in placing the northern Gulf of scrutiny of our peers, or pass from the Mexico in the Carolinian Province pre­ scene because they were indefensibly sents clear evidence for numerous arbitrary. We use the following terms examples of papers emphasizing tropical defined accordingly: or Caribbean biota and even concludes Carolinian Restricted -organisms whose range that the probable overall level of endem­ is limited to north of mid- Florida either side of ism for fishes and invertebrates is in the penisular Florida. vicinity of 10 per cent. (Recall that Carolinian Eurythermic -organisms whose range Briggs op. cit., p. 16 established an extends from the eastern seaboard southward admittedly arbitrary 10% endemism for to Brazil and with possible occurrence in Ber­ considering provincial areas). However, muda along with the northern Gulf of Mexico. we agree that the presence of West Caribbean Eurythermic -organisms whose major distribution center involves Mexico, the Baha­ Indian forms does not necessarily make mas, Cuba, the West Indies; but with extensions it a Caribbean Province. However, we do into the Gulf of Mexico and up the eastern sea­ feel that the two major current systems board to North and South Carolina. operating, e.g. the Loop Current (Maul, Caribbean Restricted -organisms whose ranges 1974) and the Mexican Current (Sturges are limited to south of mid- Florida. and Blaha, 1976) coupled with the Gulf Restricted -organisms endermic to the vagaries of river and embayment dis­ Gulf of Mexico. charges are providing oportunities for Using range data from Abbott (1974) the development of a unique molluscan and Andrews (1971) we can summarize faunal assemblage in the Gulf of Mexico. our molluscan fauna as follows: We believe there is an insurmountable amount of evidence that indicates that Carolinian Carolinian Restricted Eurythermic the Gulf of Mexico contains a number of No. of Species 2 15 communities with remarkable dissimilar­ ity, but still contain some common char­ Caribbean Carribbean Gulf acteristic lineage other than "Carolinian". Eurythermic Restricted Restricted This position is in agreement with 31 25 2 Valentine ( 19 7 3), and we predict it will As a result of the preceeding discussion, be further supported by other wm:k on the findings herein and supported by the the Florida lVIiddle Ground and from conclusions of Smith (1976), we have dredging/trawling and box- coring in the arrived at a point where we can best eastem Gulf. Consequently, we urge support a contention that as regards the other faunal investigators to carefully molluscan fauna, the Gulf of Mexico can examine their speciality and determine best be delineated as the Gulf Province. whether their faunal assemblages do not We have examined the evidence for con- better fit the category of a Gulf Province

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46 T. S. Hopkins, D. R. Blizzard and D. K. Gilbert

rather than the uncertainties of such ental shelf. Final report, Contract No. 08550- titles as "relict West Indian fauna", CT5 -4 to the Bureau of Land Management, U.S. Department of the Interior. 377 pp. "impoverished West Indian fauna", and Brooks, H. K. 1973. Geological Oceanography. "fauna of mixed Carolinian West Indian In: A summary of knowledge of the Eastern affinities". Gulf of Mexico 1973. State University System of Florida Institute of Oceanography, ACKNOWLEDGEMENTS St. Petersburg, Fla. Cerame-Vivas, !VI. J. and I. E. Gray. 1966. The The authors wish to express thanks to distributional pattern of the benthic inverte­ brates of the Continental shelf off North Dr. K. B. Meyer for aiel in identification Carolina. Ecology, 47(2):260-270. and verification of the opistobranchs, Cheney, D.P. and J.P. Dyer, III. 1974. Deep­ Dr. R. C. Bullock, the University of water benthic algae of the Florida Middle Rhode Island, for help with the chitons, Ground. Mar. Bioi. 2 7:185-190. and Dr. Joseph Rosewater and his staff, Collard, S. B. and C. N. D'Asaro. 1973. Benthic Division of Molluscs, Smithsonian Insti­ invertebrates of the Eastern Gulf of lVlexico. tution, for verification, of several In: A summary of knowledge of the Eastern Gulf of Mexico 19 7 3. State University Sys­ specnnens. tem of Florida Institute of Oceanography, At DISL we are grateful to Ms. Linda St. Petersburg, Fla. Lutz for contributions in scientific illus­ Hedgpeth,]. W. 1953. An introduction to the tration for formating, and to several zoogeography of the northwestern Gulf of colleagues representing other faunal Mexico with reference to the invertebrate fauna. Pub!. Inst. Mar. Sci. Univ. Tex. groups who helped formulate some 3:107-224,46 figs. opinions expressed herein. Hopkins, T. S. 1974. Observations on the The work from the Florida l'vliclclle Florida ?vliddle Ground through the use of Grounds was carried out under the open-circuit SCUBA. pp. 227-228. In: Bureau of Land Nlanagement Contract Proceedings of Marine State University No. 08550-CT5 -30. System of Florida Institute of Oceanography, St. Petersburg, Fla. LITERATURE CITED Lipka, D. A. 1974. !Vlolluscs. pp. 143-196. In: Biota of theW est Flower Garden Bank. T. J. Abbott, R. T. 1974. American Seashells. Van Bright and L. H. Pequegnat, Ed. Gulf Pub!. NostrandReinholdCo.,New York,New York. Co., Houston, Texas. 663 pp. Lyons, W. G. 1976. Distribution of Cerithium Andrews J. 19 71. Seashells of the Texas Coast. litteratum (Born) (Gastropoda: Cerithidae) Univ. of Texas Press. Austin, Texas. 298 pp. off Western Florida. Veliger, 18(4):375-377. Austin, H. andJ. I. .Jones. 1974. Seasonal varia­ Marcus, E. and S. B. Gallagher. 1976. A new tion of physical oceanographic parameters species of Dendrodoris from Florida. V eliger, on the Florida 1'1'1iddle Ground and their re­ 18(4):353-356. lation to zooplankton biomass on the West Maul, G. A. 1974. The Gulf Loop Current. pp. Florida shelf. Quar . .J. Fla. Acad. Sci., 37(2): 87-96. In: Proceedings of Marine Environ­ 16-32. mental Implications of offshore drilling Bray, J. R. and J. T. Curtis. 1957. An ordina­ eastern Gulf of 1'1'lexico. State University tion of the upland forest communities of System of Florida Institute of Oceanography, southern Wisconsin. Ecol. Monogr., 27: 325· St. Petersburg, Fla. 349. l'dcrrill, A. S. and R. E. Petit. 1965. i\Jolluscs Briggs, J. C. 1974. lVlarine Zoogeography. new to South Carolina. Nautilus, 79(2):58- lVlcGraw-Hill, New York. 475 pp. 66. Bright. T. J. and L. H. Pequegnat. 1974. Biota Menzies, R . .J., 0. H. Pilkey, B. W. Blackwelder, of the West Flower Garden Bank. Gulf. Pub!. D. Dexter, P. Htding and L. McCloskey. Co., Houston, Texas. 435 pp. 1966. A submerged reef off North Carolina. Bright, T . .J. and R. Rczak. 1976. A biological Int. Revue. ges. Hydrobiol. Hyclrogr., 51 (3): and geological reconnaisance of selected 393-431. topographical features on the Texas Contin- Rehder, H. A. 1954. Molluscs. In: Gulf of https://aquila.usm.edu/goms/vol1/iss1/6 8 DOI: 10.18785/negs.0101.06 Hopkins et al.: The Molluscan Fauna of the Florida Middle Grounds with Comments o

Florida Middle Ground Molluscs 47

.Mexico, its orgin, waters, and Marine Life. boundary current in the Gulf of Mexico . Fishery Bull. Fish Wild!. Serv. U.S., 89:469- Science, 192:367-369. 474. Tunnel,]. W. 1974. Ecological and geographical Smith, G. A. and L. H. Ogren. 1974. Comments distribution of of Lobos and on the nature of the Florida Middle Ground Enmedio Coral reefs, southwestern Gulf of reef ithhyofauna. pp. 229-232. In: Proceed­ JVlexico. Ph. D. Dissertation, Texas A & M ings of rl'larine Environmental Implications University, College Station, Texas. of offshore drilling eastern Gulf of Mexico. Valentine, J. W. 1973. Evolutionary palaeo­ State University System of Florida Institute ecology of the marine biosphere. Prentice­ of Oceanography, St. Petersburg, Fla. Hall, Inc., Englewood Cliffs, New Jersey. Smith, G. B. 1976. Ecology and distribution of 511 PP· Eastern Gulf of Mexico fishes. Fla. Mar. Res. Work, R. C. 1969. Systematics, ecology and dis­ Pub!. No. 19, 78 pp. tribution of the molluscs of Los Roques, Sturges, W. T. and J.P. Blaha, 1976. A western Venezuela. Bull. Mar. Sci., 19(3):614-711.

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