IN THE ESNA-IDFU REGION, NILE VALLEY, EGYPT 123 



them appear slightly depressed towards the inner whorl ; on the ventral side the 

 sutures are radial and strongly incised ; umbilicus roughly hexagonal in outline, 

 moderately wide, deep and covered by complex tegilla of which remnants are still 

 preserved ; primary apertures interiomarginal, umbilical ; tegilla, with accessory 

 apertures, only poorly preserved ; wall calcareous, perforate, except for the imperfo- 

 rate keel and tegilla ; surface rough, heavily nodose in the early part especially on 

 the ventral side, with the roughness decreasing gradually towards the last chamber. 



Dimensions of described specimen. 

 Maximum diameter = 0-43 mm. 

 Minimum diameter = 0-34 mm. 



Maximum thickness = 0-26 mm. (Thickness of last chamber) 



Main variation. 



1. Chambers 13-18, arranged in 2J-3I whorls, generally dextrally coiled (all 



specimens studied coiled dextrally). 



2. Chambers in the last whorl 4-7. 



Remarks. Bronnimann & Brown (1956) followed by Berggren (1962) considered 

 this species to be a junior synonym of G. gansseri gansseri Bolli. However, the 

 present study showed clearly that the two forms are morphologically distinct and 

 should be treated separately. 



The evolutionary history of G. lugeoni Tilev is not clear, but it might have evolved 

 from G. gansseri gansseri, although no direct evidence was recorded. 



Tilev (1951, 1952) also described as G. lugeoni var. angulata, a form which appears 

 to be quite distinct from the holotype of G. lugeoni and the studied hypotypes. It 

 appears to be more closely related to G. stuarti stuarti (de Lapparent), although it 

 lacks the characteristic shape of the chambers of the latter species on the ventral side. 

 Forms identical with this variety were recorded in the samples studied, but being very 

 rare they are not described for the time being. 



Hypotype. P. 45546. 



Horizon and locality. Figured specimen, from sample No. 15, Gebel Owaina 

 section. 



Stratigraphical range. Tilev (1951, 1952) recorded G. lugeoni from the 

 Maestrichtian of southeastern Turkey stating that its range is more precisely 

 considered as Middle Maestrichtian. In the Esna-Idfu region, G. lugeoni Tilev 

 occurs as a rare form in the G. gansseri Zone. It gradually increases upwards in the 

 section to flood the upper part of this zone and then fades out gradually in the basal 

 part of the overlying G. esnehensis Zone, where it dies out completely. 



Globotruncana mariai Gandolfi 



1941 Rosalinella globigerinoides Marie : 239, pi. 36, figs. 338a-c. 



1941 Rosalinella globigerinoides var. sublaevigata Marie : 240, pi. 36, figs. 339<z-c. 



1955 Globotruncana mariai Gandolfi : 33. 



