STUDIES IN FOBAMINIFERA 



69 



Figure 13. — Direction of coiling of some Globigtrina and Globorotatia species in the Paleocene - lower Eocene Lizard Springs formation of Trinidad, 



B. W. I. 



Systematic Descriptions 



Fourteen species of Globigerina and twenty-four 

 species of Qlohorotalia are described or listed. Most of 

 the Lizard Springs Globigerina have ab"eady been 

 accurately described by Bronnimann (1952) ; for these, 

 reference is made to that publication. Although some 

 of the Qlohorotalia species had already been described, 

 all species, whether new or previously established, are 

 here described in full, to present a uniform picture. 



The principal difference between the genera Globi- 



gerina and Qlohorotalia lies in the position of the aper- 

 ture. In Qlobigerina it is interiomarginal, umbilical 

 (leading from each chamber into the open umbilicus). 

 In Qlohorotalia it is interiomarginal, extraumbilical — 

 umbilical (on the imibilical side of the last chamber 

 along the suture with the first chamber of the last 

 whorl, and leading from near the equatorial periphery 

 into the umbUicus). Chambers in Qlohigerina are 

 always globular or only slightly compressed; in Qlobo- 



