IN THE ESNA-IDFU REGION, NILE VALLEY, EGYPT 159 



Globigerina bacuana Khalilov 



1956 Globigerina bacuana Khalilov : 235, pi. 3, figs. 4<z-c. 



Remarks. Globigerina bacuana Khalilov is one of three morphologically similar 

 Globigerina species which are distinguished from each other by the surface texture. 

 These three species are : 



1. Globigerina bacuana Khalilov, 1956, with a densely pitted surface. 



2. Globigerina aquiensis Loeblich & Tappan 1957a, with a finely hispid surface. 



3. Globigerina haynesi sp. nov. with a delicately papillose surface. 

 Globigerina bacuana is distinguished by its large, robust test which is coiled in a low 



to moderately high trochospire ; its 4 large, subglobular, chambers in the last whorl 

 which increase rapidly in size ; its almost straight, radial, depressed sutures ; 

 narrow umbilicus ; and distinctly pitted surface. It is believed to have evolved 

 from G. haynesi sp. nov. by the development of the pitted surface. 



Hypotype. P.45572. 



Horizon and locality. Hypotype from sample No. 60, Gebel Owaina section. 



Stratigraphical range. Globigerina bacuana was first described by Khalilov 

 (1956) from the Upper Paleocene and the Lower Eocene of Azerbaidzhan and 

 Turkman, U.S.S.R. 



In the Esna-Idfu region G. bacuana occurs as a rare form in the upper part of the 

 G. velascoensis Zone, the G aequa/G esnaensis Subzone of upper Upper Paleocene age. 



Globigerina belli White 

 1928a Globigerina belli White ; 192, pi. 27, figs. na-c. 



Remarks. Although White's original figures are not clear and his description is 

 incomplete, the present form most probably belongs to this species. 



Globigerina belli White is distinguished by its large, globular, trochospirally coiled 

 test ; raised dorsal side and inflated ventral one ; numerous, large roughly globular 

 chambers which increase moderately in size on the dorsal side (except for the last, 

 which is generally smaller than the penultimate and strongly elongated and curved 

 over the ventral side thus covering most of the umbilicus) ; chambers on the ventral 

 side inflated, globular, slowly increasing in size ; last chamber peculiar in shape ; 

 straight, incised sutures on both sides ; narrow umbilicus ; and sugary-textured 

 surface. 



G belli is probably the ancestral stock from which most of the multilocular, 

 highly-spired Paleocene Globigerina species have evolved. It has possibly evolved 

 directly into G. spiralis Bolli, or indirectly via G arabica sp. nov., although no direct 

 evidence was recorded. 



Hypotype. P.45573. 



Horizon and locality. Hypotype from sample No. 7, Gebel El-Kilabiya 

 section. 



