GULF OF MEXICO 



241 



includes only tlie outstanding characteristics of 

 the area. 



The area sampled is in shallow water with a 

 maximum depth of 33 m. but chiefly 20 m. or 

 less. The bottom sediment at the majority of 

 stations is described as "fine white sand" or 

 "sand" ; this is calcareous sand. The fauna closely 

 resembles that of the general West Indies region 

 which, in turn, is similar to the warm, shallow 

 faunas of the Indo-Pacific. Cushman described 

 about 150 species from the area. The following 

 list incUules many of the most widely distributed 

 and common species described: 



Amphistegina lessonii d'Orbigny. 

 Archaias angulatus (Fichtel and Moll). 

 A. compressus (d'Orbigny). 

 Asterigerina carinala d'Orbigny. 

 Bigenerina irregularis Cushman and Parker. 

 Botivina piilchella (d'Orbigny). 

 Cymbalopora squammosa (d'Orbigny). 

 Discorbis candeiana (Cushman). 

 D. mira Cushman. 



D. subaraucana Cushman. 

 Elphidium discoidale (d'Orbigny). 



E. poeyanum (d'Orbigny). 

 Trilociilinella circiilaris (Bornemann). 

 Nonion grateloupi (d'Orbigny). 

 Pyrgo siibsphaerica (d'Orbigny). 

 Quinquelocidina agglulinans d'Orbigny. 

 Q. lamarckiana d'Orbigny. 



Q. laevigata d'Orbigny. 

 Rolalia rosea (d'Orbigny). 

 Spiroloculina anlillarum d'Orbigny. 

 Teitularia agglulinans d' Orbigny. 

 T. candeiana d' Orbigny. 

 Triloculina rotunda d'Orbigny. 

 Virgulina punctata d'Orbigny. 



The Amphistegina fauna also is reported from 

 an isolated calcareous reef area in the northwest 

 Gulf of Mexico. 



PLANKTONIC FORAMINIFERA 



Planktonic Foraminifera are abundant in oft'- 

 shore areas of the northwest Gulf of Mexico ofT 

 the continental shelf both as accumulations of 

 tests in the sediments and as living members of 

 the planktonic population. Occasional concen- 

 trations of planktonic specimens are found in 

 shallow water. The planktonic fauna is domi- 

 nated by great abundance of Globigerinoides rubra 

 (d'Orbigny) and contains the following additional 

 species in the surface bottom sediments: 



Candeina nitida d'Orbigny. 

 Globigerina bulloides d'Orbigny. 

 G. eggeri Rhumbler. 



G. inflala d'Orbigny. 



Glohigerinella acquilateratis (H. B. Brady). 



Globigerinoides conylobata (II. B. Brady). 



G. sacculifera (H. B. Brady). 



Globorotalia menardii (d'Orbigny). 



G. punetulata (d'Orbigny). 



G. scitula (H. B. Brady) 



G. truncalulinoides (d'Orbigny). 



G. tumida (H. B. Brady). 



Orbulina universa d'Orbigny. 



Putleniatina obliquiloculata (Parksr and Jones) 



Sphaeroidina bulloides d'Orbigny. 



Sphaeroidinella dehiscens (Parker and Jones). 



Living specimens of all but 6 of these species 

 have been found in serial plankton tows taken 

 from various depths of water at 27 stations occu- 

 pied during February and March 1947. The 

 average living planktonic Foraminifera popula- 

 tion from these samples is about 5-6 specimens a 

 cu. m. of water at 25-50 m. water depth, and 

 much larger shallow-water populations are found 

 in certain localities. Living specimens were col- 

 lected at all depths of water sampled down to 

 about 1400 m., but the largest population is in 

 the upper layers at most stations. At a few sta- 

 tions there was a larger population collected at 

 considerable depth than from near the surface. 

 Nine specimens of planktonic Foraminifera, com- 

 prising six species, were found living on the surface 

 of the bottom sediments. 



LITERATURE CITED 



Cushman, J. A. 



1918-31. The Foraminifera of the Atlantic Ocean. 



U. S. Nat. Mus. Bull. 104, pts. 1-8. 

 1922. Shallow water Foraminifera of the Tortugas 

 region. Carnegie Inst. Washington Pub. 311, 17: 

 1-8.5, pis. 1-14. 



and Bermudez, P. J. 



1946. A new genus of Cribropyrgo and a new species of 

 Rotalia. Contr. Cushman Lab. Foram. Res., pt. 4, 

 22: 119-120. 

 Flint, J. M. 



1899. Recent Foraminifera. Ann. Rep. U. S. Nat. 

 Mus., 1897, pp. 249-349. 



KORNFELD, M. M. 



1931. Recent littoral Foraminifera from Texas and 



Louisiana, Contr. Dept. Geol. Stanford Univ., 



no. 3, 1: 77-101. 

 Phleoer, F. B. 



Ecology of Foraminifera, northwest Gulf of Mexico, 



Pt. 1, Foraminifera distribution. Geol. Soc. Amer. 



Mem. 46: 1-88. 



and Parker, F. L. 



Ecology of Foraminifera, northwest Gulf of Mexico, 



Pt. 2, Foraminifera species. Geol. Soc. .\mer. Mem. 



In press. 



