176 UPPER CRETACEOUS-LOWER TERTIARY FORAMINIFER A 



of chambers, and in the height of the dorsal spire, by an increase in the rate of growth 

 in the last whorl and by the development of a delicately papillose surface. 



Hypotype. P.45584. 



Horizon and locality. Figured specimen, from sample No. 53, Gebel Owaina 

 section. 



Stratigraphical range. Globigerina spiralis was first described from the 

 lower Lizard Springs formation of Trinidad, where it was found to be restricted to the 

 G. uncinata Zone. Bolli & Cita (1960a, b) recorded it from the Paleocene of the 

 Paderno d'Adda section of northern Italy, where they considered its range as 

 Danian. However the stratigraphical range of G. spiralis as interpreted from the 

 charts of Bolli (1957&) and Bolli & Cita (1960a, b) is Upper Danian-lower Middle 

 Paleocene. 



Hay (i960) recorded G. spiralis throughout the Upper Danian G. uncinata Subzone 

 of the Velasco formation of Mexico, and Hillebrandt (1962) recorded it throughout 

 the Upper Danian and the overlying Lower, Middle and Upper Paleocene of Austria. 



In the Esna-Idfu region, G. spiralis appears as a rare to common form in the top 

 part of the Danian ; it increases gradually in number upwards in the section to the 

 basal part of the G. velascoensis Zone where it reaches its acme : it then fades out 

 gradually and dies out completely in the lower part of the G. aequajG. esnaensis 

 Subzone (uppermost Paleocene). 



Globigerina stonei Weiss 

 (PI. 16, figs, za-d) 



1949 Globigerina cf. pseudobulloides Plummer ; Cushman & Stone : 57, pi. 10, figs. 15a, b. 



1955a Globigerina stonei Weiss : 18, pi. 5, figs. 16-21. 



19556 Globigerina stonei Weiss ; Weiss : 308-309, pi. 2, figs. 1-3. 



19576 Globigerina primitiva (Finlay) ; Bolli : 71, pi. 15, figs. 6-8. 



Description. Test medium sized, coiled in a low trochospire ; dorsal side slightly 

 convex with the last chambers inflated and the early ones depressed in the form of a 

 sharply cut, slightly sunken, oblong mass ; ventral side strongly inflated ; equatorial 

 periphery roughly ovoid, distinctly lobate ; axial periphery rounded ; chambers on 

 the dorsal side about 9, arranged in 2 sinistrally coiled whorls, increasing moderately 

 in size in the early part and very rapidly later ; initial chambers very small, depressed, 

 tightly coiled and masked by the surface rugosity ; the last whorl is composed of 4 

 relatively large, subglobular chambers with almost straight inner margins and 

 distinctly curved outer ones ; the first two chambers in the last whorl are roughly 

 quadrangular, elongated in the direction of coiling and slightly inflated, while the last 

 two are roughly globular, much bigger in size and strongly inflated ; on the ventral 

 side the chambers are 4, globular, inflated and rapidly increasing in size ; sutures on 

 both sides straight, radial and strongly incised ; spiral suture angular, rectispiral and 

 strongly depressed ; umbilicus roughly rectangular in outline, relatively wide, deep 

 and open ; aperture interiomarginal, umbilical, a small narrow slit with a delicate 



