GULF OF MEXICO 



471 



DEEPER WATERS 



The first work on the fauna of the deeper waters 

 of tlie Gulf of Mexico was carried out in 1878 by 

 the United States Coast Survey steamer Blake 

 under the direction of Professor Alexander Agas- 

 siz. The molhisks gathered during this cruise 

 were reported on by Dall (1886-89). Subse- 

 quently, the steamer Albatross of the United 

 States Fish Commission made numerous stations 

 in the eastern part of the Gulf, the results of 

 which have been referred to in various scattered 

 papers. More recently, the Fish and Wildlife 

 Service vessels Pelican and Oregon have been 

 carrying out investigations in the Gulf of Mexico 

 in the course of which they have gathered many 

 interesting mollusks which have been only partly 

 reported on. The commercial shrimp fishermen 

 have been initiated by the amateur shell collectors 

 into the practice of saving the mollusks brought 

 up in their nets, and in this way they are con- 

 tributing many interesting finds. A preliminary 

 report on some of these mollusks has recently 

 been published by Rehder and Abbott (1951). 



ECOLOGY 



Under this heading are listed what seem to be 

 the most important biotopes present in the lit- 

 toral zone of the Gulf of Mexico. No attempt 

 has been made to go into a detailed description of 

 the various facies, zones, and a.ssociations. 



Some of the species listed as occurring in one 

 province or in one kind of habitat may, of course, 

 be found also in other areas. It should likewise 

 be pointed out that because of the lack of careful 

 collecting along much of the coast line of the Gulf 

 the extent and exact position of the transition 

 areas between the Caribbean and Carolinian prov- 

 inces is at the present time still largely a matter 

 of speculation. This is especially true of the fauna 

 of the moderate depths between the shore and the 

 deeper waters. 



CARIBBEAN PROVINCE 



This zoogeographical area includes the north- 

 west coast of Cuba from Cabo San Antonio to 

 Habana, the west coast of Florida from the Dry 

 Tortugas and Key West north to probably Tampa 

 Bay (the northern limit of this province is some- 

 what doubtful here but lies somewhere between 

 Sanibel Island and Cedar Keys), and the coast of 



Mexico from Cabo Catoche to the vicinity of Port 

 Isabel, Texas, and possibly beyond to Corpus 

 Christi Bay. 



As is to be expected, the mollusks of this area 

 show an obvious relationship with those of the 

 West Indies and the entire Caribbean region. 



The list of species has of necessity been taken 

 largely from our knowledge of the Floridian mol- 

 luscan fauna. An interesting and more extended 

 discussion of these associations can be found in 

 a report by Bartsch (1937). 



1. Coral reefs, rocky outcrops, and jetties: 



Here we find a rich fauna of which I list only 

 a few species. 



Acanthopleura granulata Gmelin. 

 Acmaea pustulata Helbling. 

 Fissurella cayenensis Lamarck. 

 Astraea americana Gmelin. 

 Nerita peloronta Linnd. 

 Nerita versicolor Gmelin. 

 Nerita tesseltata Gmelin. 

 Littorina ziczac Gmelin. 

 Tectarius muricatus Linn6. 

 Cerithium literatum Born. 

 Batiltaria minima Gmelin. 

 Thais rustica Lamarck. 

 Cantharus tinctus Conrad. 

 Conus mus Hwass. 

 Siphonaria pectinata Gmelin. 

 Area zebra Swainson. 

 Barbatia barbata Linn6. 

 Brachidonles exustus Linn6. 

 Lima scabra Born. 

 I sognomon alatum Gmelin. 



2. Shallow water sandy stretches, shallow grassy 



bays, muddy flats: 

 Here the sand-burrowing mollusks are at home, 

 and hence we find more pelecypods than in the 

 preceding habitat. 



Cerithium variabile C. B. Adams. 



Epitonium lamellosum Lamarck. 



Sinum perspectivum Say. 



Natica canrena Linn6. 



Busycon contrarium Conrad. 



Melongena corona Gmelin. 



Oliva saya?ia Ravenel. 



Olivella floralia Duclos. 



Marginetta apicina Menke. 



Conns pealei Green. 



Terebra dislocata Say. 



Aplysia witlcoxi Heilprin. 



Cardila floridana Conrad. 



Anodontia alba Link. 



Lucina floridana Conrad. 



Trachycardium egmontianum Shuttleworth. 



Dosinia elegans Conrad. 



