2o6 I'PPER CRETACEOUS-LOWER TERTIARY FORAMINIFERA 



side 15, arranged in z\ sinistrally coiled whorls, increasing gradually in size ; the 

 initial chambers are small, inflated, globigerine and are followed by typically crescen- 

 tic, overlapping chambers which increase moderately in size ; the last whorl is 

 composed of 5 relatively large, inflated chambers ; on the ventral side the chambers 

 are 5, large, roughly triangular and strongly inflated ; sutures on the dorsal side are 

 strongly curved, depressed in the early part, short, slightly curved and depressed in 

 the later part ; on the ventral side they are almost straight, radial and depressed ; 

 umbilicus narrow, shallow and open ; aperture interiomarginal, extraumbilical- 

 umbilical, a long, narrow arch bordered above by a narrow delicate lip ; wall 

 calcareous, perforate ; surface rough, nodose. 



Dimensions of described specimen. 

 Maximum diameter = 0.37 mm. 

 Minimum diameter = 0-29 mm. 



Thickness = 0-23 mm. (Of last chamber) 



Remarks. Globorotalia convexa was first described by Subbotina (1953) who 

 mentioned that it had a wide range of variation and a long stratigraphical range. 

 The form described here differs from the holotype of G. convexa in being much larger, 

 in having fewer chambers in the last whorl, a more rounded axial periphery and a 

 more protruding ventral side. It might possibly have evolved into G. convexa, as 

 suggested by their stratigraphical distribution. 



Globorotalia cf. convexa is believed to have evolved from the morphologically 

 similar G. faragi sp. nov. by the development of a more tightly coiled test and by an 

 increase in surface rugosity. 



Globorotalia convexa of Olsson (i960) is probably G. nicoli Martin, that of Berggren 

 (1960a) is possibly G. faragi sp. nov. and the one of Said & Kerdany (1961) is most 

 probably G. angulata abnndocamerata Bolli. The form figured by Gartner & Hay 

 (1962) as G. convexa has triangular chambers on the dorsal side instead of chambers 

 with the alar or semicircular outline described by Subbotina. 



Hypotype. P.45604. 



Horizon and locality. Figured specimen, from sample No. 37, Gebel Owaina 

 section. 



Stratigraphical range. The species was first described by Subbotina (1953) 

 from the " zone of conical Globorotalias " of the northern Caucasus, which she 

 considered as Lower-Middle Eocene, but is regarded by Berggren (1960a 1 ) on the 

 basis of its planktonic Foraminifera, to indicate an Upper Paleocene-Lower Eocene 

 age. 



Subbotina recorded this species to range from the " Danian? " to the Middle 

 Eocene, occuring in the zones of " Rotalia-\ike Globorotalias ", " flattened Globoro- 

 talias ", and " conical Globorotalias " of the northern Caucasus. It was also 

 recorded from the Paleocene- ? Lower Eocene of the Gulf and Atlantic Coastal 

 Plains and from the Velasco formation of Mexico (Loeblich & Tappan 1957a ; Hay 

 i960), and from the Ilerdian " marne bleue " of Mont Cayla, France (Gartner & Hay 

 1962). 



