A MONOGRAPH OF THE FORAMINIFERA OF 

 THE NORTH PACIFIC OCEAN. 



ASTRORHIZID.E AND LITUOLID.E. 



By Joseph Augustine Cushman, 



Of the Boston Society of Natural History. 



GENERAL ACCOUNT. 



The Foraminifera are for the most part minute animals varying in 

 size from a fraction of a millimeter to several millimeters in length, 

 but may develop a test several inches across; these, however, are 

 rare exceptions. A few species live in fresh or brackish water, but 

 the great majority live in the ocean. They occur at all depths, but 

 are most frequent at moderate depths in the ocean basins, where they 

 form characteristic deposits — the so-called "globigerina ooze." In 

 the vicinity of tropical coral islands many species occur in great 

 abundance. 



The animal itself is a single-celled form with one or many nuclei, 

 as will be later explained. The test, in many cases at least, is really 

 an internal structure, as the thin film of protoplasm which covers it 

 in the perforate forms, and probably in others, is capable of secreting 

 the material of the test, to repair breaks, etc. 



Comparatively little is known concerning the animal of the Foram- 

 inifera except in certain littoral species. The great mass of the work 

 on the group has been confined to a study of the empty tests. In 

 the present work the material has been dried in almost all cases. As 

 a result little has been noted in regard to the animal itself. 



As single-celled animals the Foraminifera are especially interesting, 

 and their structures do not need explanation on the basis of organs 

 or tissues. There is much beauty in the curves of the test and in its 

 ornamentation, the patterns of the latter often being very intricate. 



For some time after their discovery the Foraminifera were thought 



to be a group of the cephalopods, and many of the coiled species have 



the appearance of minute nautiloid cephalopods. Many of the 



generic names were applied before the true relationships were known. 



16777— Bull. 71—10 1 



