IN THE ESNA-IDFU REGION, NILE VALLEY, EGYPT 91 



Description. (Specimen, PI. 7, figs. za-c). Test large, robust, spiroconvex with 

 a sharply angular, polygonal outline and a peculiarly shaped, folded surface ; 

 dorsal side highly trochospirally coiled, with bluntly curved convex folds radiating 

 from the apex and shallowly concave, broader depressions running between the 

 radiating folds, and widening away towards the base ; ventral side concave ; 

 equatorial periphery roughly pentagonal with blunt corners, gently undulating and 

 very weakly, if at all, lobate ; periphery with two well-developed, heavily beaded 

 keels, enclosing a relatively wide, almost horizontal, slightly depressed peripheral 

 band ; axial periphery subangular, distinctly truncate ; chambers, on the dorsal 

 side 23, arranged in 4 dextrally coiled whorls ; they increase moderately and regu- 

 larly in size till shortly before the beginning of the last whorl where they start to 

 enlarge very rapidly and to change in shape ; the initial chambers are small, inflated, 

 globigerine ; they increase moderately in size and are followed by relatively large, 

 globular, inflated chambers which increase more rapidly in size, and become highly 

 undulating and strongly elongated in the direction of coiling towards the end of the 

 penultimate whorl ; the last whorl is composed of 4, very long, very narrow, 

 broadly curved, roughly oblong, undulating chambers which are extremely elongated 

 in the direction of coiling ; on the ventral side the chambers are 4, very large, 

 angular, roughly oblong, very narrow, strongly elongated in the direction of coiling 

 with their surfaces gently sloping towards the umbilicus ; sutures on the dorsal side 

 slightly curved, faintly raised and delicately beaded in the early part, strongly 

 curved, undulating, raised, thickened and heavily beaded later ; on the ventral side 

 the sutures are straight, radial and depressed ; umbilicus rhombodial in outline, 

 relatively wide, deep, surrounded by beaded umbilical ridges 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 keels, peripheral band and tegilla ; surface 

 delicately papillose especially on the early part and on the ventral side. 



Dimensions of described specimen. 

 Maximum diameter = 070 mm. 

 Minimum diameter = 0-50 mm. 



Thickness = 0-45 mm. 



Main variation. 



1. Chambers 16-25, arranged in 3-4 or rarely 5 whorls, usually dextrally coiled, 



but sinistral forms also occur (out of 25 specimens picked at random, 1 

 coiled sinistrally) . 



2. Chambers in the last whorl 4-5. 



3. The two keels are either equally developed throughout or the ventral one 



becomes slightly reduced on the last chamber. 



Remarks. Globotruncana contusa contusa was first described by Cushman (1926) 

 as a variety of Pulvinulina area Cushman = Globotruncana area (Cushman), but 

 no figures were given until 1946, when Cushman figured the dorsal and lateral views 

 of the holotype. 



