GULF OF MEXICO 



431 



Rothwell labels his barren zone as a region of 

 lower salinity situated as it is along the coast 

 where it receives inflow from several large rivers 

 (Rio Grande, Brazos, Atchafalaya, and others). 

 The species found within this zone are mainly 

 forms whose close relatives have also been found 

 in the brackish waters of the Solomons, Md., 

 region at shallow depths. 



Some ostracods are restricted bj' temperature 

 in their world-wide distribution and are found only 

 in northern latitudes or in deep water in other 

 areas. Bythacypris bosquefiana, for example, al- 

 though widely distributed, apparently prefers 

 cold water. Other species, such as Cythereis 

 echinata, appear to be widely tolerant of temper- 

 ature variations and in the Gulf of Mexico, as in 

 other localities, are found at all depths and tem- 

 peratures. In the Gulf of Mexico Rothwell gives 

 the limits of seasonal variation in bottom tem- 

 peratin-e as 75 meters which, in the region between 

 Galveston, Tex., and Atchafalaya Bay, La., places 

 its outer limits at the inner portion of the Upper 

 Continental Slope. Beyond this depth bottom 

 temperatures are cold the year round which ac- 

 counts for the large number of species found be- 

 yond 75 meters as compared with the number 

 found in the shallower areas where ostracods and 

 other animals must have wide temperature 

 tolerances. 



The section following deals with the individual 

 species which have been reported from the Gulf of 

 Mexico up to the present time. Further details 

 of taxonomy, structure, and individual habits 

 may be obtained for many of these species by 

 consulting references listed, particularly the mon- 

 umental work of Georg Ossian Sars on the 

 Crustacea of Norway, volume 9, Ostracoda (Sars 

 1928). Of all the references cited, this work 

 should prove as helpful as any one report in 

 identifying a large majority of the Gulf species. 

 Miiller's (1894) Ostracoda of the Gulf of Naples 

 will also be found useful. Brady's papers, if used 

 in connection with Miiller's (1912) synopsis, will 

 be of some help, particularly where one must 

 depend upon identification from shells alone. 



Suborder Myodocopa 



Family CYPRIDINIDAE 

 Cypridina squamosa Miiller, 1894 



This large active swimmer lives on the bottom 

 and has been reported only from the Tortugas 



Islands in the Gulf region. It was found at 

 depths of from 20 to 22 meters. It is also known 

 from the Gulf of Naples. 



Cypridina flatus Tressler, 1949 



A single female was taken at a depth of 1,200 

 meters near Tortugas. It has not been reported 

 elsewhere in the world. 



Asterope tnariae (Baird, 1850) 



Of all tlie known ostracods this genus alone 

 possesses gills. Females usually stay close to the 

 bottom; the males, however, may be taken in 

 plankton tows close to the surface. Two females 

 belonging to this species were found in shallow 

 water near the Tortugas Islands. It is known 

 from widely scattered places such as the coasts of 

 Sweden, British Isles, France, Norway, the 

 Mediterranean, North Atlantic, South Atlantic, 

 Pacific, and off Vineyard Sound. 



Asterope elliptica Philippi, 1840 



This species is similar to A. mariae but has a 

 shorter shell. Specimens have been reported 

 from shallow water (4-5 meters) near Tortugas. 

 Its distribution includes the Mediterranean and 

 North Atlantic. 



Cyclasterope priacanthus Tressler, 1949 



The genus Cyclasterope, although closely related 

 to Asterope, differs from it in having much higher 

 shells some of which are almost spherical when 

 seen from the side. C. priacanthus was reported 

 from the stomach of the glass-eyed snapper, 

 Priacanthus cruentatus, near Tortugas. 



Cyclasterope sphaerica Tressler, 1949 



In water 20 to 22 meters deep near Tortugas. 

 Unknown elsewhere. 



Cyclasterope tripla Tressler, 1949 



Found in shallow water (on rocks at low tide 

 and 18-20 meters) near Tortugas. 



Family HALOCYPRIDAE 

 Conchoecia atlantica (Lubbock, 1856) 



Members of the genus Conchoecia are true 

 pelagic ostracods and although often found on the 

 bottom, they are active swimmers. The genus is 

 a large one of nearly 100 species and is widely 

 distributed throughout most of the oceans of the 

 world. One specimen of C. atlantica was taken 



