IN THE ESNA-IDFU REGION, NILE VALLEY, EGYPT 167 



Horizon and locality. Holo- and paratypes from sample No. 64, Gebel 

 Owaina section. 



Stratigraphical range. The species is common to abundant throughout the 

 Middle and Upper Paleocene of the sections studied, and is rare in the uppermost part 

 of the Danian. 



Globigerina inaequispira Subbotina 



(PL 15, figs. 8a-c) 



1953 Globigerina inaequispira Subbotina : 69, pi. 6, figs, \a-\c. 



Description. Test large, almost triglobular, coiled in a low trochospire, and 

 strongly inflated especially on the ventral side ; equatorial periphery almost trilobate, 

 radially elongate, with each lobe perfectly rounded at the end and distinctly separa- 

 ted from the others ; axial periphery rounded ; chambers on the dorsal side 15, 

 arranged in 3 dextrally coiled whorls ; the initial chambers are extremely small, 

 globular, inflated, very tightly coiled ; they increase slowly in size, and are followed 

 by relatively much bigger, globular and strongly inflated chambers which increase 

 gradually in size towards the beginning of the last whorl ; the chambers increase 

 slowly to moderately in size within the same whorl, but very rapidly from one whorl 

 to another ; the last whorl, which constitutes most of the test, is composed of 

 4 very large, roughly globular, inflated chambers, which increase rapidly in size ; 

 the last chamber is strongly elongated radially and constitutes more than one-third 

 of the test ; on the ventral side the chambers are 4, globular, strongly inflated and 

 increase rapidly in size ; intercameral sutures on both sides straight, radial and 

 strongly incised ; spiral suture roughly angular, almost rectispiral and strongly 

 depressed ; umbilicus roughly quadrate, wide, deep and open ; aperture interio- 

 marginal, umbilical, with a thin lip of which remnants are still preserved ; wall 

 calcareous, perforate ; surface delicately pitted, with the raised parts between the 

 minute pits giving the surface a fine sugary texture. 



Dimensions of described specimen. 

 Maximum diameter = 0-50 mm. 

 Minimum diameter = 0-36 mm. 

 Thickness = 0-27 mm. 



Remarks. Globigerina inaequispira is distinguished from other species by the 

 great difference in size between the successive whorls ; its large, triglobular, radially 

 elongate test ; its small, closely coiled early chambers, and large, loosely coiled, 

 rapidly increasing later ones ; its large, ovoid, radially elongate last chamber ; its 

 roughly angular, depressed spiral suture, and straight, radial, depressed intercameral 

 ones ; its distinctly lobate periphery, and finely pitted surface. 



The forms described as G. inaequispira by both Loeblich & Tappan (1957a) and 

 Olsson (i960) are completely different from Subbotina's original description and 

 figures, while that described by Hillebrandt (1962) lacks the radially elongate 

 terminal chamber characteristic of the species. The form described by Gartner & 

 Hay (1962) as G. inaequispira, may be G. stonei Weiss. 



