NO. 4 PLANKTONIC FORAMINIFERA — CIFELLI 29 



Specimens the last chamber completely covers the umbilicus, and the 

 primary aperture is a small, rounded opening symmetrically located 

 above 2 earlier chambers. The last chamber is compressed and 

 flattened in appearance. In the early stages this species has an open 

 umbilicus and in coiling closely resembles species of Glohigerina. The 

 specimen that Bradshaw (1959, pi. 7, figs. 16, 17) figured as Globig- 

 erinoides sp. is considered here to be an early stage of G. conglobatus. 

 The wall of this species is relatively thick for a Glohigerinoides and 

 the surface is coarsely spinose. 



Distribution. — This is a characteristic species in the subtropical as- 

 semblages but was found mostly at frequencies of less than 5 per- 

 cent. However, at Sargasso Sea summer station KK it was recorded 

 at a frequency of 15 percent and was the dominant species of 

 Globigerinoides. 



