MARINE OSTRACODA 



By Willis L. Tressler, United States Navy Hydrographic Office 



The marine Ostracoda of the Gulf of Mexico 

 region are very imperfectly known at the present 

 time. George S. Brady, one of the earliest workers 

 in this group to report ostracods from the Gulf 

 region, published a series of papers from 1866 to 

 1887 and described a number of new species. 

 Some of these descriptions were later incorporated 

 into the report of the Challenger expedition, and 

 many of them were published in the Marquis de 

 Folin's work, Fonds de la Mer, which included 

 four volumes published between 1867 and 1887. 

 These volumes are very difficult to obtain, partic- 

 ularly the fourth volume which contains descrip- 

 tions of several species of Ostracoda from the 

 Gulf region. Unfortunately, almost all of Brady's 

 descriptions are made from the valves alone, and 

 for this reason many of his descriptions cannot 

 be identified definitely with present day, living 

 forms. Although his illustrations are beautifully 

 executed, his descriptions are very brief and give 

 little or no ecological data; not even the depth or 

 exact location is given for most descriptions. 

 Miiller (1912), in his masterly compendium of the 

 known species of Ostracoda, both marine and 

 fresh-water, has allowed several of Brady's 

 species, but for the most part his forms have 

 been relegated to the doubtful species category 

 or even to the "dubious genera and species" 

 section of his book. 



With the exception of Brady's work, only two 

 other publications which deal with marine ostra- 

 cods of the Gulf of Mexico are known despite the 

 efforts of several geologists and zoologists who have 

 been working on recent and fossil ostracods from 

 this region. Dr. Henry V. Howe of Louisiana 

 State University and his students, for example, 

 have done considerable work on this group. The 

 two publications referred to above both appeared 

 in 1949 and consist of a preliminary report on 

 ostracods obtained from bottom and core samples 

 taken by the Woods Hole Oceanographic Institu- 

 tion research vessel Atlantis in 1947 by W. T. 



Rothwell, Jr. (1949), and a short report on some 

 marine ostracods from Tortugas by the present 

 author (Tressler 1949). 



Rothwell's report was merely an abstract of 

 his findings, but tlirough the kindness of this 

 worker, the present author was able to use his 

 data sheets which give the location and depth of 

 all species which he had taken from the bottom 

 sediment samples. Rothwell distinguished 126 

 distinct forms but was not able to identify all of 

 these to species. Some 40 of this number, which 

 had been identified to species, were selected as 

 being readily enough identifiable from the valves 

 alone to leave no doubt as to their validity. Only 

 five species were recovered with inner body parts 

 intact, plus tliree other forms which were not 

 definitely identified to species. The remainder of 

 Rothwell's species were determined from the 

 valves alone. Without these data this report 

 would have been meager indeed. It is to be hoped 

 that Dr. Rothwell will be able to complete his 

 identifications, many of which will undoubtedly 

 turn out to be new species, and publish a report on 

 the complete collection at an early date. 



The author has not been able to obtain a copy 

 of Folin and Perier's Fonds de la Mer contain- 

 ing many of Brady's reports, but all species enu- 

 merated in volumes 1, 2, and 4 have been eval- 

 uated in Miiller's (1912) comprehensive report. 

 Also, it has not been possible to go through the 

 paleontological literature which undoubtedly con- 

 tains references to forms which are living today. 

 One paper (Van den Bold, 1946) is cited in the 

 literature as an example of such reports. Pal- 

 eontological material is, of course, restricted by 

 its very nature to identifications based upon shell 

 structure alone. The short literature list also 

 includes all other known reports on marine 

 Ostracoda for the whole eastern Atlantic coast, 

 because, while some forms are definitely restricted 

 by temperature conditions, many, which are 

 found at high latitudes, will also be found at 



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