FOEAMINIFERA OF THE ATLANTIC OCEAN. 



19 



flattened and extended laterally so that they form nearly the whole 

 surface of the test; wall strongly reticulate, the angles between the 

 reticulations often being almost spinose; aperture at the inner margin 

 of the chamber near the umbilicus and with several rounded secondary 

 apertures along the contact between the last-formed chamber and the 

 previous ones to which it is adjacent. 



Diameter up to or exceeding 1 mm. 



Distribution. — This is essentially a pelagic species and its distribu- 

 tion seems to be largely determined by ocean-current movements, 

 especially of those currents which sweep away from tropical regions. 

 The Gulf Stream distributes this species, which is most abundant and 

 best developed in the Caribbean. Specimens found farther north 

 are often somewhat smaller and few, if any, of them show the large 

 fine tests developed in the Tropics. 



This species has the test well modified for a pelagic existence. The 

 generally spherical shape of the test with the large aperture and num- 

 erous accessory openings allow free egress of the protoplasmic con- 

 tents which seems necessary to the floating of the somewhat heavy 

 test. 



The early development of the test is a trochoid spire which soon 

 becomes modified to the subspherical form. It is one of the most 

 easily recognized species of the genus. 



Globigerina conglobata — material examined. 



