IN THE ESNA-IDFU REGION, NILE VALLEY, EGYPT 145 



fades towards the inner whorl ; on the ventral side the sutures are straight, 

 radial and strongly depressed ; umbilicus pentagonal in outline, wide, deep and 

 covered by complex tegilla of which remnants are still preserved ; primary apertures 

 interiomarginal, umbilical ; tegilla with accessory apertures, only poorly preserved ; 

 wall calcareous, perforate except for the imperforate keel and tegilla ; surface rough 

 in the early part, heavily papillose or even nodose with the papillae decreasing 

 gradually towards the last chamber. 



Dimensions of holotype. 



Maximum diameter = 0-54 mm. 



Minimum diameter = 0-43 mm. 



Thickness = 0-31 mm. (of last chamber) 



Main variation. 



1. Chambers 11-21, arranged in 2-3 whorls which are generally dextrally coiled. 



2. Chambers in the last whorl 4-6, most commonly 5. 



Remarks. Globotruncana youssefi sp. nov. is morphologically similar to both G. 

 lugeoni var. angulata Tilev and G. arabica sp. nov. It is distinguished from the 

 former by its typically crescentic chambers throughout, peculiarly shaped last 

 chamber, strongly curved, raised, beaded dorsal sutures and more strongly developed 

 marginal keel. It differs from G. arabica by its almost flat to slightly raised dorsal 

 side, its longer, more curved, raised and beaded dorsal sutures and its perfectly 

 marginal keel. 



This species is named after Professor M. I. Youssef, of the Department of Geology, 

 Ain Shams University, Cairo. 



Holotype. P.45564. 



Paratypes. P. 45565. 



Horizon and locality. Holo- and paratypes, from sample No. 16, Gebel 

 Owaina section. 



Stratigraphical range. Globotruncana youssefi sp. nov. appears in the upper 

 part of the Middle Maestrichticn G. gansseri Zone. It increases upwards in the 

 section to flood the uppermost part of this zone and the lower part of the overlying 

 G. esnehensis Zone where it dies out completely. 



Globotruncana sp. 



(PI. 1, figs, 6a-c) 



Description. Test large, weakly biconvex, coiled in a slightly high trochospire ; 

 dorsal side broadly arched, ventral side slightly inflated ; equatorial periphery 

 subcircular, distinctly lobate, with two well-developed, beaded keels reduced to one 

 on the last chamber ; axial periphery truncate ; chambers on the dorsal side 21, 

 arranged in 3 dextrally coiled whorls ; they increase slowly and regularly in size ; 

 initial chambers very small, subglobular, weakly inflated, and followed by subcircular 

 to crescentic flattened chambers ; the last whorl is composed of 6| large, crescentic to 



