98 UPPER CRETACEOUS-LOWER TERTIARY FORAMINIFERA 



Horizon and locality. Figured specimen, from sample No. 20, W. El- 

 Sharawna section. 



Stratigraphical range. Globotruncana convexa was first recorded by Sandidge 

 (1932) from the Maestrichtian Ripley formation of Alabama. 



In the Esna-Idfu region G. cf. convexa ranges throughout the Maestrichtain, 

 being common to abundant in the G. fornicata and the G. gansseri Zones, gradually 

 fades out towards the top part of the latter zone and completely dies out in the 

 overlying G. esnehensis Zone. 



Globotruncana esnehensis Nakkady & Osman 



(PI. 12, figs, za-d) 



1950 Globotruncana area (Cushman) var. esnehensis Nakkady : 690, pi. 90, figs. 23-26. 

 1954 Globotruncana esnehensis Nakkady & Osman : 79, pi. 19, figs. 3a— c. 

 ? 19566 Marginotruncana stuarti (de Lapparent) ; Hofker : 332-333, text-fig. 23. 

 1956 Globotruncana caliciformis Vogler ; Said & Kenawy : 150, pi. 5, figs. i8a-c. 

 1956 Globotruncana intermedia Bolli ; Said & Kenawy : 151, pi. 5, figs, i^a-c. 

 1961 Globotruncana esnehensis Nakkady, Said & Kerdany : 331, pi. 2, figs. i2a-c. 



Emended diagnosis. A Globotruncana with large, spiroconvex test ; broadly- 

 domed dorsal side and flat to slightly convex or even slightly concave, undulating 

 ventral one ; well-developed beaded, single keel ; chambers increasing slowly in size, 

 almost petaloid on dorsal side and subglobular to ovoid on ventral side ; slightly 

 curved, raised, beaded dorsal sutures and radial depressed ventral ones ; large 

 umbilicus and distinctly beaded umbilical ridge ; slightly to moderately lobulate 

 equatorial periphery and angular, acute axial one; peculiar apertural face of last 

 chamber and delicately papillose surface. 



Description. Test large, almost circular in outline, spiroconvex, coiled in a 

 relatively high trochospire ; dorsal side broadly domed ; ventral side almost flat or 

 even slightly concave, although the chambers are weakly inflated ; equatorial 

 periphery circular, moderately lobate with a single well-developed, beaded keel ; 

 axial periphery angular, acute ; chambers on the dorsal side 19, arranged in three 

 whorls which are coiled dextrally and very tightly ; they increase slowly and 

 regularly in size, except the last, which is slightly smaller than the penultimate ; 

 initial chambers small, inflated, globigerine, followed by relatively large, subglobular, 

 moderately inflated ones ; the last whorl is composed of 6 large, typically petaloid 

 chambers which moderately overlap and increase slowly in size ; on the ventral side 

 the chambers are 6, large, roughly ovoid, slightly inflated and increase so slowly in 

 size that they all appear to be roughly equal ; each chamber is weakly inflated at its 

 centre and slopes gently towards the suture on each side giving the ventral surface a 

 gently undulating appearance ; sutures on the dorsal side are very slightly curved or 

 almost straight in the early part, very gently curved in the later part, raised and 

 distinctly beaded ; on the ventral side they are radial, depressed and delicately 

 beaded ; umbilicus hexagonal in outline, wide, relatively deep, surrounded by a 

 beaded umbilical ridge and covered by complex tegilla of which remnants are still 



