230 UPPER CRETACEOUS-LOWER TERTIARY FORAMINIFERA 



3. The last whorl is usually composed of 5-6 chambers, but 4 or 7 are sometimes 

 found. 



Remarks. Globorotalia pusilla laevigata is characterized by its small, roughly 

 lenticular test ; strongly protruding ventral side ; acute axial periphery ; weakly 

 developed keel ; strongly curved, slightly raised dorsal sutures, and radial, depressed 

 ventral ones ; its crescentic chambers which increase slowly in size on the dorsal 

 side, and its triangular, conical, strongly protruding ones on the ventral ; its small 

 umbilicus ; characteristic aperture and smooth to delicately papillose surface. 



Loeblich & Tappan (1957a : 194) mentioned that G. pusilla laevigata is very 

 similar and undoubtedly related to G. pseudoscitida Glaessner. However, although 

 they did not include it in the synonymy of the latter, they described as G. pseudo- 

 scitida, forms which most probably belong to G. pusilla laevigata. These authors 

 (pi. 45, figs, ja-c) also described, as G. angidata (White), a form with a faintly 

 developed keel, which is most probably a 4-chambered G. pusilla laevigata. 



As previously mentioned by Bolli (19576) G. pusilla laevigata is believed to have 

 evolved from G. pusilla pusilla ; transitional stages between these two subspecies 

 were recorded, and their stratigraphical distribution substantiates this suggestion. 



Hypotype. P.45623. 



Horizon and locality. Figured specimen, from sample No. 48, Gebel Owaina 

 section. 



Stratigraphical range. Bolli (19576) described G. pusilla laevigata, from the 

 Paleocene, lower Lizard Springs formation of Trinidad, where he showed it to range 

 through his G. pseudomenardii Zone only. It was also recorded from the same zone 

 of the Paderno d'Adda section of Northern Italy (Bolli & Cita 1960a, 6). Hille- 

 brandt (1962) extended its range to cover strata which he referred to the Lower and 

 Middle Paleocene (Montian-Landenian) of Austria. Some of the specimens which 

 Loeblich & Tappan (19576) described under G. pseudoscitida Glaessner and G. 

 angidata (White), from the Landenian of the Gulf and Atlantic Coastal Plains, 

 probably represent this subspecies. 



In the Esna-Idfu region, G. pusilla laevigata appears in the basal part of the 

 Upper Paleocene G. velascoensis Zone. It continues as a common form in the lower 

 part of this zone, the G. pseudomenardii Subzone, and fades out gradually, dying out 

 completely in the basal part of the overlying G. aequa/G. esnaensis Subzone. 



Globorotalia pusilla mediterranica subsp. nov. 

 (PI. 19, figs. 3a-c) 



Diagnosis. A Globorotalia pusilla with relatively larger, papillose test ; more 

 chambers and whorls ; more protruding ventral side and moderately convex dorsal 

 one ; roughly quadrangular last chambers on dorsal side, very narrow and very 

 strongly elongated in direction of coiling ; very high, angular conical chambers on 

 ventral side, strongly protruding from the periphery, leaving it as a thick, marginal 

 pseudo-keel. 



