i2b UPPER CRETACEOUS-LOWER TERTIARY FOR AMINIFER A 



curved, raised, beaded sutures, wide umbilicus and horseshoe-shaped ridge of beads 

 bordering each chamber on ventral side. 



Description. Test large, almost circular in outline, coiled in a relatively high 

 trochospire ; dorsal side broadly convex, ventral side flat although the chambers are 

 very slightly inflated ; equatorial periphery almost circular, slightly lobate ; axial 

 periphery angular, acute, with two heavily beaded keels on the early chambers of the 

 last whorl, reduced to a single, well-developed, distinctly beaded keel in the last 

 chambers ; chambers on the dorsal side 18 (17 -+- 1 broken), arranged in 3 dextrally 

 coiled whorls and slowly and regularly increasing in size ; the initial chambers are 

 small, inflated and globigerine, while later chambers are typically crescentic, slightly 

 flattened and elongated in the direction of coiling, the last whorl is composed of 6 

 large, typically crescentic chambers ; on the ventral side the chambers are 6, ovoid, 

 very weakly inflated, slightly overlapping, distinctly outlined with heavily beaded 

 horseshoe-shaped rims, and increase so slowly in size that they all appear to be roughly 

 equal ; sutures on both sides curved, raised, thickened and heavily beaded ; umbili- 

 cus roughly hexagonal in outline, wide, deep, surrounded by slightly raised, heavily 

 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 imperforate keels, 

 peripheral band and tegilla ; surface generally smooth. 



Dimensions of holotype. 



Maximum diameter = 0-50 mm. 



Minimum diameter = 0-45 mm. 



Thickness = 0-25 mm. 



Main variation. 



1. Chambers on the dorsal side 18-21, arranged in 3-3^ whorls, generally dextrally 



coiled. 



2. The last whorl is composed of 5-7 chambers which are large, crescentic and 



increase slowly in size. 



3. In some specimens the ventral keel is completely reduced and the test becomes 



entirely single keeled at least throughout the last whorl. 



Remarks. Globotruncana orientalis is morphologically similar to G. leupoldi 

 Bolli, G. conica White, G. esnehensis Nakkady & Osman and to G. sharawnaensis 

 sp. nov. However, it is distinguished from G. leupoldi by its flat ventral side, much 

 narrower peripheral band and less lobate equatorial periphery. It differs from G. 

 conica White by its less conical dorsal side, its early double keel and the horseshoe- 

 shaped ridges on the ventral side. Globotruncana esnehensis is entirely single keeled 

 and has strongly depressed ventral sutures, while G. sharawnaensis sp. nov. is single 

 keeled in the early part becoming double keeled later, has depressed ventral sutures 

 and a rougher surface. 



The forms desribed by Cita (1948) and Pessagno (1962) as G. conica White most 

 probably belong to tne present species. 



