240 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



DEPTH IN METERS 



400 M 500 M 1000 M 



FtCIES I I FACIES 2 



FAUNAL DEPTH 



FACIES 3 



FACIES 



RQTALIA ROLSHAUSENI 



MARGINULINA PLANATA 



1 h 



BIGENERINA IRREGULARIS 



CIBICIDES 10 



ELPHIDIJM DISCOIDALE 



I I 



REUSSELLA ATLANTICA 



LX 



J L 



ELPHIDIUM MEXICA NUM 

 \ - 



A ^ 



PLANULINA FOVEOLATA 



VALVULINERiA LAEVIGATA 



CYCLAMMINA 



CANCEL|.ATA | 



PARRELLA CULTUR 



PARRELLA 



CASSIDULINA CARINATA 



BULIMINA SPICATA 



i h 



PSEUDOPARRELLA DECORATA 



PLANULIN A WUELLERStIjRFI 



BOLIVINA LOWMANI 



H h 



+ 



500 M 1000 M 



BOTTOM WATER 



Figure 59. — Generalized chart showing depth biofacies of benthonic Foraminifera in the Gulf of Mexico and correlation 

 between depth biofacies and temperature. Depth range lines are of benthonic Foraminifera used to illustrate types 

 of depth distributions found. 



below the bottom of the permanent thermochne 

 at about 800-1,000 m. 



Living specimens have been collected of 78 

 benthonic species. The greatest number of living 

 specimens were found of the following species, 

 all of which are characteristic of the facies above 

 100 m.: 



Bifarina advena (Cushman). 



Bolivina lowmani Phleger and Parker. 



B. strialula Cushman var. spinata Cushman. 



Butiminella cf. bassendorfensis Cushman and Parker. 



Cancris oblonga (Williamson). 



Cibicides concentricus (Cushman). 



Elphidium discoidale (d'Orbigny). 



Nonionella atlantica Cushman. 



Proleonina comprima Phleger and Parker. 



Rolalia beccarii (Liim6). 



Virgutina pontoni Cushman. 



The highest production rate of benthonic 

 Foraminifera is in the upper facies, although the 

 largest population of accumulated empty tests 

 in bottom sediments usually is at intermediate 

 depths. 



Calcareous areas. — The Foraminifera fauna of 

 the calcareous areas is quite distinctive from that 

 of the clastic areas and is dominated by Amphiste- 

 gina lessonii d'Orbigny, a typical calcareous 

 species. 



Cushman (1922) described the Foraminifera 

 from several environments of the Dry Tortugas 

 area off the southwest coast of Florida. The 

 sampling was too scattered to give dependable 

 results of the distribution in these environments, 

 some being represented by only one or two sta- 

 tions. For this reason, the following description 



