528 



THE AMEBIC AN NATURALIST [Vol. XLIX 



Although occurring everywhere except in the Arctic 

 Ocean and in the Mediterranean, Bering. Okhotsk and 

 Japan seas, asymmetrical types are most frequent and 

 most highly developed (1) in warm shallow water from 

 southern Japan southward throughout the Malay Archi- 

 pelago to northern Australia and westward to Ceylon, and 

 (2) in the Antarctic and in the cold abysses. 



Though present among species inhabiting the west 

 Atlantic from North Carolina to Brazil, and characteristic 

 of many forms living at intermediate depths in the west- 

 ern Pacific and in the Indian Oceans, in these it is never 

 more than slightly developed, even though they be very 

 closely related to types in which it is, in other situations, 



In short, 



universal, 



occurring every- 



