IN THE ESNA-IDFU REGION, NILE VALLEY, EGYPT 199 



in all horizons from the base of the Velasco up into the lower part of the middle 

 portion of the formation ". Apparently, he had confused this species with its 

 ancestor G. uncinata uncinata Bolli or with similar forms in the Lower Velasco and 

 thus misinterpreted its range. Contrary to White's observation, Hay (i960) 

 recorded this species throughout the upper part of the Velasco formation with only 

 a rare occurrence in the uppermost part of the Lower Velasco, (from the top of the 

 G. uncinata Subzone to the top of the Globorotalia velascoensis Zone). 



In the Esna-Idfu region, G. angulata angulata (White) appears at the basal part of 

 the Middle Paleocene. It is taken as a stratigraphical marker for the Lower-Middle 

 Paleocene boundary (i.e. it separates the Danian from the overlying Middle Paleo- 

 cene) as it has not been found in the type Danian or in the Danian (of reliable 

 references) elsewhere. Moreover, the first appearance of G. angulata angulata 

 coincides with the disappearance of the index species of the Danian rocks below, and 

 with the first appearance of the " Globigerina [truncated Globorotalia assemblage " 

 which is clearly distinguished from the underlying " Globigerinaj rounded Globorotalia 

 assemblage ", characteristic of the Danian in its type section and elsewhere. 



The subspecies ranges throughout the Middle and Upper Paleocene of the sections 

 studied. It floods the Middle Paleocene, constituting the main element in plank- 

 tonic foraminiferal fauna, and characterizes the Globorotalia angulata Zone. It 

 continues as an abundant to rare form in the overlying G. velascoensis Zone, at the 

 top of which it dies out completely. 



All reliable references show clearly that G. angulata angulata occurs neither in the 

 Danian nor in the Lower Eocene. 



Globorotalia apanthesma Loeblich & Tappan 

 (PI. 21, figs, la-c) 



1957a Globorotalia apanthesma Loeblich & Tappan : 187-188, pi. 59, figs, ia-c only ; non 

 pi. 48, figs, za-c ; pi. 55, figs. la-c ; pi. 58, figs. ^a-c. 

 ? i960 Globorotalia apanthesma Loeblich & Tappan, Olsson : 45, pi. 8, figs. 17-19. 



Description. Test large, planoconvex, umbilico-convex, coiled in a very low 

 trochospire ; dorsal side almost flat, slightly imbricate ; ventral side strongly 

 protruding ; equatorial periphery subcircular, moderately lobate ; axial periphery 

 subacute with the thick, stout, spine-like projections simulating a marginal keel ; 

 chambers on the dorsal side about 16 in number, increasing gradually in size and 

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

 almost masked by the surface rugosity ; they are followed by relatively large crescen- 

 tic chambers ; the last whorl is composed of 6 large, almost flat, slightly imbricate 

 chambers (one of which is broken) ; these are roughly crescentic in the early part, 

 quadrangular to hemispherical later ; on the ventral side the chambers are 6 (5 + 1 

 broken), large, inflated, angular conical and strongly protruding ; sutures on the 

 dorsal side curved, depressed ; on the ventral side they are radial, strongly incised ; 

 umbilicus very wide, deep and open ; aperture interiomarginal, extraumbilical- 

 umbilical, a broad, arched opening with a narrow delicate lip (only seen in well- 

 preserved specimens) ; wall calcareous, perforate ; surface rough, distinctly nodose, 



