22 



UNITED STATES NATIONAL MUSEUM BULLETIN 215 



TENTATIVE STRATIGRAPHIC RANGES OF 

 PLANKTONIC FORAMINIFERAL GENERA 





/. 



/ /^/fA%/f/ / 



U/^/-iM/i/fU/< 



'^ /■i/i/i/f/^U/f/- 



7 







EUROPEAN STAGES 



GULF COAST GROUPS 



M/^/^7^V^'/<^/'i'V<^V<^7^/^'/^/'^'/^V^°/^'/^ 



/ 



o 

 6 



N 

 O 



z 



m 

 V 



■tf 



z 



3 



RECENT 

















































PLEISTOCENE 



TYRRHENIAN 

 SICILIAN 

 CALABRIAN 



UNDIFFERENTIATED 













































>- 



< 



Ul 



PLIOCENE 



~~~-~— ....ASTIAN 

 P L A 1 S A N aAN"~~-~-^^ 



UPPER 

 LOWER 













































MIOCENE 



VINOO 

 BONIA 



SAHELIAN 

 TORTOMIAN 

 HELVETIAN 

 eURDIGALIAN 



UPPER 

 MIDDLE 

 LOWER 













































OLIGOCENE 



STAM 

 PI AN 



AQUITANIAN 

 CHATTIAN 

 RUPELIAN 



LATTORFIAN 



UPPER 

 MIDDLE 

 LOWER 













































UJ 



Z 



o 



UPPER 



PRIABONIAN 



LUDIAN 

 LEDIAN 



JACKSON 



















































MIDDLE 



LUTETIAN 



CLAIBORNE 



















































LOWER 



YPRESIAN 



WILCOX 











































PALEOCENE 



LANDENIAN 

 DANIAN 



MIDWAY 











































U 



O 

 N 



o 



en 



Ul 



</> 



3 

 O 



UJ 



U 



< 

 1- 



lU 



o 



UPPER 

 CRETACEOUS 



MAESTRICHTIAN 



u. 



_l 



z> 

 o 



NAVARRO 



































1 

















z 

 < 



z 

 o 



z 



in 



CAMPANIAN 



TAYLOR 



















































SANTONIAN 



AUSTIN 





















































CONIACIAN 





















































TURONIAN 



EAGLE FORD 





















































CENOMANIAN 

















































WOODBINE 





UJ 



■tf 



E 



WASHITA 









LOWER 

 CRETACEOUS 



ALBIAN 



















































FREDERICKSBURG 





TRINITY 





APTIAN 



- 





1 













































< 

 _l 



=1 

 X 

 < 



o 

 u 



NUEVO LEON 





z 

 < 



o 

 o 

 o 



z 



BARREMIAN 







































HAUTERIVIAN 



DURANGO 













































VALAN6INIAN 





















_ 



















Figure 9. — Tentative stratigraphic ranges of planktonic foraminiferal genera. 



an umbilical extension on each side, connecting the 

 chambers to the previous whorl. In addition, there is 

 a peculiar curvature, almost sinuate, of the later 

 chambers and sutures near the imibilicus, and a ten- 

 dency toward an uncoiled later stage. 



In a new species of Biglobigerinella, described later 

 in the present paper, an ontogenetic sequence is shown 

 from a form much like Glohigerinelloides algeriana, to a 

 stage with two small lateral apertm-es, and finally to a 

 bichambered end stage. A careful study of material 



from the tjrpe horizon of Olobigerinelloides could de- 

 termine whether or not a similar development is present 

 in that form. If so, Biglobigerinella Lalicker would 

 become a synonym of Olobigerinelloides, for the present 

 generic name was published three months prior to 

 Biglobigerinella. Until definite evidence is available 

 both genera are provisionally recognized. 



Types and occuerence: Cushman and ten Dam 

 (1948, p. 42) recorded this genus from the Upper 

 Cretaceous of Djebel Menaouer in western Algeria. 



