IN THE ESNA-IDFU REGION, NILE VALLEY, EGYPT 251 



marginal, extraumbilical-umbilical ; wall calcareous, perforate ; surface distinctly 

 papillose or even nodose with the nodes tapering out sometimes to form stout, spine- 

 like projections, especially along the periphery. 



Dimensions of described specimen. 



Maximum diameter = 0-41 mm. 

 Minimum diameter = 0-28 mm. 



Thickness = 0-20 mm. 



Remarks. Globorotalia wilcoxensis is distinguished by its medium-sized, plano- 

 convex, roughly ovoid, distinctly lobate test ; its axial periphery which is subrounded 

 in the early part, angular in the last chamber ; its curved depressed spiral suture ; 

 its curved, depressed, dorsal intercameral sutures, which are radial and strongly 

 incised on the ventral side, and its heavily nodose or even spinose surface. 



The species is believed to have evolved from G. whitei Weiss in uppermost Paleo- 

 cene time by the slight increase in the size of test, the close coiling of the early 

 chambers which become crescentic rather than globular, and by the development of 

 the more acute axial periphery of last chamber. On the other hand, it has possibly 

 evolved into G. quetra Bolli by the increase in the size of test, compression of the 

 dorsal side, and the development of the acute axial periphery and the partially 

 developed spinose keel. 



Subbotina (1953) included G. wilcoxensis in the synonymy of G. crassata (Cushman) 

 in spite of their marked difference. However, her G. crassata actually belongs to 

 G. aequa Cushman & Renz which is also quite distinct from the present species. 



Said & Kenawy (1956) described as Truncorotalia wilcoxensis (Cushman & Ponton) 

 from the Paleocene of Nekhl section, northern Sinai, Egypt, a form which has nothing 

 in common with G. wilcoxensis but most probably belongs to G. aragonensis Nuttall, 

 thus proving their Paleocene to be of Lower Eocene age. 



Bolli (1957&) described as G. wilcoxensis Cushman & Ponton, a form which appears 

 to be more closely related to G. whitei Weiss, while the form described by Hamilton 

 & Rex (1959) cannot be assigned to any known species. 



Berggren (1960a) described as G. wilcoxensis from the Lower Eocene of Denmark, 

 forms which may be related to G. esnaensis (LeRoy). 



Hypotype. P.45643. 



Horizon and locality. Figured specimen, from sample No. 64, Gebel Owaina 

 section. 



Stratigraphical range. Cushman & Ponton (1932) described G. wilcoxensis 

 from the Lower Eocene Wilcox group of Alabama, and it was recorded from the same 

 group by Cushman & Garrett (1939) and Cushman (1944). It was also recorded 

 from the Lower Eocene Wilcox group of Virginia and Maryland (Cushman 1944& 

 and Shifflett 1948) ; the Middle Eocene of the Mississippi (Cushman & Todd 1948) ; 

 the Paleocene Madruga formation of Cuba (Cushman & Bermudez 1949) and the 

 Lower and Upper Eocene of the same area (Bermudez 1950) ; from the Eocene of the 

 Gulf of Mexico, the Carribbean region and the Middle East (Grimsdale 1951) ; from 



