132 UPPER CRETACEOUS-LOWER TERTIARY FORAMINIFER A 



truding ; periphery subcircular in outline, nearly continuous, transversely acute, 

 with a single well-developed beaded keel ; chambers on the dorsal side 20, arranged 

 in 4 dextrally-coiled whorls ; the initial chambers are very small, slightly inflated, 

 globigerine, and are followed by nearly crescentic chambers which increase very 

 slowly in size till near the beginning of the last whorl where they enlarge very rapidly ; 

 the last whorl is composed of 4, large, angular conical chambers which are narrow and 

 strongly elongated in the direction of coiling ; the first one is typically crescentic on 

 the dorsal side, while the last 3 are roughly trapezoidal ; on the ventral side the 

 chambers are 4^, typically quadrangular with blunt corners and roughly parallel 

 curved sides ; they are strongly overlapping, distinctly outlined, and strongly 

 inflated especially around the umbilicus, with the surface somewhat steeply sloping 

 towards the thinned-out periphery ; sutures on the dorsal side very slightly curved 

 or nearly straight, angular, limbate, raised and heavily beaded ; on the ventral side 

 they are strongly curved forward, limbate, raised and heavily beaded ; umbilicus, 

 narrow, roughly pentagonal in outline, relatively deep, surrounded by thickened, 

 raised, beaded ridges, 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 smooth and finely porous. 



Dimensions of described specimen. 

 Maximum diameter = 0-46 mm. 

 Minimum diameter = 0-36 mm. 



Thickness = 0-26 mm. 



Main variation. 



1. Chambers on the dorsal side 15-20 arranged in 3-4 whorls, usually dextrally 



coiled (of 75 specimens picked at random, 2 coiled sinistrally) . 



2. Chambers in the last whorl 4-5, the first one or two usually crescentic, the last 



three trapezoidal and much bigger. 



3. The surface is generally smooth but in some specimens small scattered papillae 



cover the surface of the initial chambers. 



Remarks. Globotrnncana stuarti parva Gandolfi has always been confused with 

 G. stuarti stuarti (de Lapparent), from which it is believed to have evolved. How- 

 ever, it can be clearly distinguished by its much smaller size, fewer chambers in the 

 last whorl, its nearly straight sutures on the dorsal side, its strongly protruding 

 umbilical side, and by the fact that the last whorl is always much larger than the rest 

 of the test. 



Hypotype. P. 45555- 



Horizon and locality. Figured specimen from sample No. 23, W. El- 

 Sharawna section. 



Stratigraphical range. Globotruncana stuarti parva Gandolfi is recorded 

 from the lower part of the G. gansseri Zone of the studied sections, where it is found 



