202 I'PPER CRETACEOUS-LOWER TERTIARY FORAMINIFERA 



Globorotalia bollii sp. nov. 

 (PL 22, figs. $a-d, 6a-d) 

 1 11576 Globorotalia rex Martin ; Bolli : 75, pi. 18, figs. 10-12. 



Diagnosis. A Globorotalia with medium-sized test ; perfectly flat dorsal side and 

 protruding ventral one ; distinctly well-developed, very broad, heavily beaded keel ; 

 narrow umbilicus and thick, curved, raised, heavily beaded dorsal sutures. 



Description. (Holotype, PL 22, figs. $a-d). Test medium sized, plano-convex, 

 umbilico-convex, coiled in a very low trochospire ; dorsal side flat ; ventral side 

 strongly protruding ; equatorial periphery roughly quadrate, distinctly lobate with a 

 well-developed, broad, heavily beaded marginal keel ; axial periphery acute ; 

 chambers on the dorsal side about 10, arranged in 2 dextrally coiled whorls ; the 

 initial chambers are small, globular, compressed, almost masked by the surface 

 rugosity, and are followed by typically crescentic chambers which increase gradually 

 in size ; the last whorl is composed of 4 1 , large, crescentic chambers which increase 

 rapidly in size ; on the ventral side the chambers are 4^, large, angular conical 

 and strongly protruding, with their distal ends meeting closely around the small 

 umbilicus ; sutures on the dorsal side are thickened, raised, curved and heavily 

 beaded ; on the ventral side the sutures are radial and strongly depressed ; umbilicus 

 small, deep and open ; aperture interiomarginal, extraumbilical-umbilical ; wall 

 calcareous, perforate ; surface delicately papillose on the dorsal side, more heavily 

 so on the ventral. 



Dimensions of holotype. 



Maximum diameter = 0-46 mm. 



Minimum diameter = 0-35 mm. 



Thickness = 0-21 mm. 



Remarks. Bolli (19576) described as Globorotalia rex Martin from the upper 

 Lizard Springs formation of Trinidad, a form which differs from the holotype of 

 Martin in its perfectly flat dorsal side ; extremely well-developed, much wider, 

 heavily beaded marginal keel ; thick, raised, beaded dorsal sutures and more tightly 

 coiled chambers. Bolli stated that this form characterizes the G. rex Zone at the base 

 of the Eocene. 



Globorotalia rex Martin is closely related to G. aeqna Cushman & Renz, and may 

 be a junior synonym of G. simulatilis (Schwager) although very little is known about 

 Schwager's species. On the other hand, the form figured by Bolli (19576) appears to 

 be more closely related to the G. velascoensis group, especially to G velascoensis parva 

 Rey. It differs from the latter, only in being smaller, having a rougher surface, a 

 much smaller umbilicus, a less protruding ventral side and a weaker, less ornamented 

 umbilical shoulder. 



Careful examination of G. rex as described and figured by Martin (1943) from the 

 Lodo formation of California, and by Mallory (1959) from the same formation, 

 showed that the form described by Bolli (19576) as G. rex Martin is different and 

 should be considered separately. It is here named G. bollii n.sp. after Dr. Hans M. 

 Bolli. 



