IN THE ESNA-IDFU REGION, NILE VALLEY, EGYPT 153 



Family GLOBIGERINIDAE Carpenter, Parker & Jones 1862 



Subfamily GLOBIGERININAE Carpenter, Parker & Jones 1862 



Genus GLOBIGERINA d'Orbigny 1826 



Type species. Globigerina bulloides d'Orbigny 1826. 



1826 Globigerina d'Orbigny : 277 (Type species : Globigerina bulloides d'Orbigny 1826). 

 1956 Globoconusa Khalilov : 249 (Type species : Globoconusa conusa Khalilov, 1956). 

 1961 Subbotina Brotzen & Pozaryska : 160 (Type species : Globigerina triloculinoides Plummer 

 1926). 



Emended diagnosis. Test free, trochospirally coiled, multiglobular ; dorsal side 

 evolute, low trochospire or turreted ; ventral side umbilicate, strongly inflated ; 

 equatorial periphery subcircular to ovoid, moderately to distinctly lobate ; axial 

 periphery rounded ; chambers arranged in 2-4 whorls, dextrally or sinistrally coiled ; 

 all chambers seen on dorsal side, only those of last whorl seen on ventral side ; 

 chambers generally spherical, ovate, slightly elongated radially or in direction of 

 coiling, strongly inflated, but occasionally slightly compressed or gently appressed ; 

 inter-cameral sutures on dorsal side curved or straight, depressed ; on ventral side 

 generally radial and strongly depressed ; spiral suture curved, or rectispiral, depres- 

 sed ; umbilicus very small or large, open ; aperture interiomarginal, umbilical, 

 sometimes extending slightly towards the periphery, not as much as in Globorotalia, 

 and sometimes provided with apertural lip ; previous apertures remain open into 

 the umbilicus ; wall calcareous, perforate, radial in structure ; surface smooth, 

 cancellated, pitted, reticulate, papillose, hispid or spinose. 



Discussion. d'Orbigny's original description of the genus Globigerina was so 

 brief that several other genera, e.g. Globorotalia, Hedbergella, Rugoglobigerina and 

 Globotruncana, were included in it, thus obscuring its stratigraphical range. How- 

 ever, Globigerina is distinguished by its globular, non-truncated chambers ; interio- 

 marginal, umbilical apertures (which may in some cases extend slightly towards the 

 periphery), its simple, open umbilicus and rounded axial periphery. Recent 

 studies have defined the range of this genus as Danian-Recent, although it was 

 previously extended to the Lower Cretaceous or even to the Upper Jurassic. How- 

 ever, the fact that no typical Globigerina has yet been recorded from the Upper 

 Cretaceous makes the stratigraphical gap between the first appearance of Globigerina 

 in the Lower Danian and the so-called Globigerina in the Upper Jurassic and the 

 Lower Cretaceous too big, and casts doubt on the identification of the latter forms. 

 Whether Globigerina is a polyphyletic genus which in the Upper Jurassic, branched 

 off from a particular ancestor to die out in the Lower Cretaceous, and again from 

 another ancestor in the basal Danian branched off to continue living up to now 

 (as suggested by Bolli, Loeblich & Tappan 1957), or whether the Upper Jurassic- 

 Lower Cretaceous forms are not true globigerinas are questions still unanswered, 

 although the latter proposition seems most probable. 



Khalilov (1956) described Globoconusa as a new genus, with Globoconusa conusa 

 Khalilov as type species. It was distinguished by its high conical, turret-like test, 



