RHIZOPODA. 19 



that all the apertures are visible when looking into the common vestibule. But in 

 the light of more recent investigations, Mr. Brady has found it desirable to enlarge 

 the scope of the family to include many new species. He has, therefore, divided the 



Fig. 18. — Globigerina bulloides, greatly enlarged. 



GlobigerinoB into three groups, according to the position and appearance of the aper- 

 tures, as follows : — 



1. Forms with an excavated cavity (umbilical vestibule) into which the orifices of 

 all the segments open, such as Olobigerina bulloides, Fig. 18. 



2. Those with only one external orifice, situated on the face of the terminal segment, 

 at its point of junction with the previous convolution, as in Globigerina inflata. 



