Abstract
This study is based on samples of palaeotaxodont bivalves obtained from the deeper aspects of the Gulf of Mexico by the Texas A&M University Research Vessel ALAMINOS during the years 1964-1969. Approximately 300 live specimens and 2,800 valves were collected from a total of 91 stations of which 46 were located between 183 and 1,999 meters and 45 were at depths between 2,000 and 3,800 meters. The collection comprises 34 species representing 11 gen era. Ten of these species are considered to be new to science. Of the 24 previously described species, 10 are reported in the Gulf for the first time, horizontal ranges of eight are extended over 2,000 nautical miles, and five are illustrated for the first time. Predation and food are discussed for some species, while systematic notes and photographic illustrations are given for each species. Revisional notes are given for some of the deep-sea palaeotaxdont species collected by previous investigations. A comparison of pertinent type specimens has revealed the following three sets of subjective synonyms: Nucula pemambucensis Smith, 1885 and N. cymella Dall, 1886; Tlndaria amabilis (Dall, 1889) and T. lata Verrill & Bush, 1898; Nuculana semen (Smith, 1885) and N. aspecta (Dall, 1927). The vertical distributions of specimens are examined with the main emphasis on benthic zonation. The distributions of live and dead specimens are separately examined. Some probable displaced valves are noted and possible causative agents are discussed. Data on the distribution of live specimens show a distinct faunal change at around 2,000 meters. Most of the previously described species found living below a depth of 2,000 meters in the Gulf have been considered abyssal species outside the Gulf. Thus it is concluded that the Gulf has an abyssal zone.
James, Bela Michael (1972). Systematics and biology of the deep-water Palaeotaxodonta (Mollusca: Bivalvia) from the Gulf of Mexico. Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -184679.