IN THE ESNA-IDFU REGION, NILE VALLEY, EGYPT 229 



Stratigraphical range. The species was first described by Bolli (1957&) from 

 the Paleocene lower Lizard Springs formation of Trinidad, where it characterizes the 

 G. pseudomenardii Zone, to which it is restricted. Bolli did not relate his faunal 

 zones to any classification of the Paleocene, but Bolli & Cita (1960a, b) considered the 

 G. pseudomenardii Zone of the Paderno d'Adda section of northern Italy to be of 

 Upper Montian age. Reliable records show that G. pseudomenardii is of lower 

 Upper Paleocene age. All records of this species from strata younger or older than 

 the lower Upper Paleocene (e.g. Loeblich & Tappan 1957a) are erroneous. 



In the Esna-Idfu region Globorotalia pseudomenardii Bolli appears with the first 

 representatives of G. velascoensis velascoensis (Cushman) in the basal part of the 

 Globorotalia velascoensis Zone. It floods the lower part of this zone, thus defining 

 the G. pseudomenardii Subzone, here considered to be of lower Upper Paleocene age ; it 

 dies out before the first appearance of G. esnaensis and G. aequa which characterize 

 the overlying subzone. 



Globorotalia pusilla laevigata Bolli 

 (PI. 17, figs, zza-c) 



!957& Globorotalia pusilla laevigata Bolli : 78, pi. 20, figs. 5-7. 

 19606 Globorotalia pusilla laevigata Bolli ; Bolli & Cita : 27-28, pi. 32, figs. 6a~c. 

 1962 Globorotalia (Globorotalia ?) pusilla laevigata Bolli ; Hillebrandt : 128-129, pi- IJ i 

 figs. 17a, b. 



Description. Test small, roughly lenticular, coiled in a very low trochospire ; 

 dorsal side slightly raised, gently convex ; ventral side strongly convex, moderately 

 protruding ; equatorial periphery circular, slightly lobate ; axial periphery acute, 

 with a very thin, faintly developed, delicately beaded marginal keel ; chambers 19, 

 arranged in 3, sinistrally coiled whorls ; the inital ones are very small, slightly 

 inflated, globigerine, and are followed by relatively large, almost crescentic, over- 

 lapping chambers which increase slowly in size except for the last, which is often 

 slightly smaller than the penultimate ; the last whorl is composed of 6, large, 

 roughly crescentic chambers which increase slowly in size ; on the ventral side the 

 chambers are 6, relatively large, roughly triangular, conical, inflated, almost equal 

 in size ; sutures on the dorsal side strongly curved, faintly raised and very delicately 

 beaded ; on the ventral side they are almost straight, radial and depressed ; umbilicus 

 small, shallow and open ; aperture an elongated arch, covered by a prominent, 

 delicate lip, interiomarginal, extraumbilical-umbilical ; wall calcareous, perforate ; 

 surface smooth or very delicately papillose. 



Dimensions of described specimen. 



Maximum diameter = 0-30 mm. 



Minimum diameter = 0-26 mm. 



Thickness = 0-16 mm. 



Main variation. 



1. Chambers 12-18, arranged in 2J-3 whorls. 



2. Coiling tends to be dextral (of 15 specimens picked at random, 11 coiled 



dextrally) . 



