IN THE ESNA-IDFU REGION, NILE VALLEY, EGYPT 139 



s.l. from the Campanian-Maestrichtian of the northwestern Caucasus, forms which 

 are probably G. stuarti stuartiformis Dalbiez as can be seen from her figures. 

 Because she lumped together the various subspecies of G. stuarti under G. stuarti s.l. 

 she stated that G. stuarti is a characteristic Senonian species and occurs in the Cam- 

 panian and Maestrichtian of the northwestern Caucasus and various other places in 

 the Soviet Union. She also mentioned that Agalarova (1949) had recorded G. 

 stuarti in the Santonian and the Lower Campanian of Azerbaydzhan (Kabristan- 

 Unusdagskaya range). Such forms, most probably belong to G. stuarti stuartiformis. 



Pessagno (i960 : 89, chart 1, 91, chart 2 and 101 ; 1962 : 354 charts 1, 2, 355 

 charts 3, 4, and 362) recorded G. stuarti stuartiformis as ranging from the late San- 

 tonian to the base of the Middle Maestrichtian (base of the G. gansseri assemblage 

 subzone) of Puerto Rico. 



In the Esna-Idfu region, G. stuarti stuartiformis Dalbiez occurs as a common 

 form in the Lower Maestrichtian G. fornicata Zone and continues to the basal part 

 of the Middle Maestrichtian G. gansseri Zone, where it dies out completely. 



Globotruncana stuarti subspinosa (Pessagno) 

 (PL 10, figs. 2a-3c) 



i960 Globotruncana (Globotruncana) subspinosa Pessagno : 101, pi. 1, figs. 1-9, pi. 5, fig. 5. 

 1962 Globotruncana (Globotruncana) stuarti subspinosa (Pessagno) Pessagno : 362, pi. 2, 

 figs. 7-9. 

 ? 1963. Globotruncana undulata Lehmann : 148, pi. 9, figs. $a-c ; text-figs, it, u. 



Description. (Specimen, PI. 10, figs. 3«-c.) Test large, subcircular in outline, 

 umbilico-convex, coiled in a very low trochospire ; dorsal side slightly raised, ventral 

 side strongly protruding ; equatorial periphery nearly circular, weakly lobate to 

 almost entire ; axial periphery strongly acute, with a single, well-developed, pinched- 

 out, faintly beaded keel ; chambers on the dorsal side 23 arranged in 4 dextrally 

 coiled whorls ; the initial chambers are very small, slightly inflated, globigerine ; 

 they increase slowly in size and are followed by crescentic chambers which increase 

 more rapidly in size ; the last whorl is composed of 5^ large chambers, the early ones 

 of which are crescentic, elongated in the direction of coiling and slightly crenulate, 

 while the last three are roughly trapezoidal and relatively much bigger ; on the 

 ventral side the chambers are 5|, large, overlapping, typically stuarti-form, distinctly 

 outlined, strongly inflated around the umbilicus and somewhat steeply sloping 

 towards the pinched-out marginal keel ; sutures on the dorsal side distinct, much 

 thickened and raised, slightly curved and heavily beaded in the early part, straight 

 and limbate later, giving the chambers their roughly quadrangular shape ; on the 

 ventral side the sutures are slightly curved, thickened, raised and beaded ; umbilicus 

 large, roughly hexagonal in outline, relatively deep, surrounded by raised, beaded 

 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 keel and 

 tegilla ; surface generally smooth, with a few small papillae on the early part of the 

 ventral side. 



