FORAMINIFEKA OF THE ATLANTIC OCEAN. 



27 



the material I have examined shows, in cool waters, being best 

 developed in the cold water off the northeastern coast of the United 

 States. It does not appear to be common either in the Arctic or 

 Antarctic. It is more characteristic of deep waters, nearly all 

 stations at which it was really abmidant being over 1,500 fathoms 

 (2,743 meters) with the greatest development around 2,000 fathoms 

 (3,658 meters). 



Both microspheric and megalospheric specimens evidently occur. 

 In tlie former the proloculum is very small and the number of 

 chambers reaches the maximum, five to six. In the megalospheric 

 specimens the proloculum is large and the number of chambers is 

 from one to three. In the extreme cases where a single chamber is 

 produced it is as large as the final chamber in the adult of three 

 chambered specimens. This accords with what Schlumberger 

 showed in the development of various species of Biloculina. 



Outside this character of developmental stages there is little varia- 

 tion in the species except perhaps in the fineness of the material of 

 the chamber walls and the relative amount of the cement used in 

 the waU. Altogether it is a very constant and satisfactory species. 



Hormosina globulifera — material examined. 



