THE AETHROPODA OF THE DEEP SEA 127 



take into consideration tlie depth, the character of the 

 bottom, and the temperature from which they are 

 supposed to have been dredged, be taken to support 

 very strongly the view that these species are really 

 abysmal in habit. 



Among the Isopoda we have several very charac- 

 teristic forms — no fewer than nine distinct genera 

 peculiar to the abysmal zone have been described by 

 Beddard — and of these two, Bathynomus and A71U- 

 ropus, are to be regarded as types of sub-families. 

 They seem to be very unevenly distributed over the 

 floor of the ocean, some regions, such as the whole 

 of the Central and Southern Atlantic and the Cen- 

 tral and Western Pacific, produce none ; whilst 

 the waters of the east coast of New Zealand, the 

 Crozets, and others, produce a great many varieties. 

 Many of the deep-sea Isopoda exhibit characters that 

 are usually associated with the bathybial life. Thus, 

 according to Beddard, thirty-four of the deep-sea 

 species are totally blind, and eighteen have well- 

 developed eyes. In four species there are eyes 

 which are evidently degenerating. If we compare, 

 for instance, the structure of the eye of Serolis sclujtheij 

 a species found in shallow water ranging from 4 to 

 70 fathoms, with the eyes of Serolis hromleyena, a 



