NO. 1586. NEW ISOPODS FROM THE PACIFIC OCEAN— RICHARDSON. 695 



Fig. 6.— Arthrophkyxis beringanus. Adult fe 

 MALE. a. Dorsal VIEW. /<. Ventral view. X65. 



ARTHROPHRYXUS BERINGANUS, new species. 



The body of the adidt female (hg. (i) is irregular in outline, oblong 

 oval in shape, broadest in front, and slightly narrower behind. It is 

 14 nun. long and 9 unn. wide at its greatest breadth. The lateral 

 parts of the body are expanded, but do not project beyond the head. 

 The head is very large, with the anterior margin irregular in 

 outline and with a transverse 

 fold about the middle. It is 

 well defined from the thorax. 

 There are no eyes. 



The middle portion of the 

 dorsal surface of the thorax is 

 distinctly segmented into five 

 segments. 



The abdomen is distinctly seg- 

 mented into five segments, the 

 terminal one being minute and 

 triangular in shape posteriorly. 

 There are no uropoda or pleopoda. 



On the ventral side of the body the oral area is snudl, rounded, but 

 not contracted l)ehind. There are five pairs of legs, on the outside of 

 which are the five pairs of coxal plates. Issuing from the bases of 

 the five pairs of legs are the five pairs of incubatory lamelhe, partly 

 overla2;)ping each other, the last pair being the largest, 

 meeting along the middle ventral line of the body. 



The adult male has the head lai-ge, without eyes, the 

 thorax divided into six distinct segments, the first 

 being fused with the head. There are seven pairs of 

 prehensile legs, the first pair being attached to the first 

 segment, which is coalesced with the head. The 

 abdomen is indistinctly divided into about six seg- 

 ments, the last segment being minute and triangular 

 posteriorly. (Fig. 7.) 



There are no uropoda and appai'ently no pleopoda. 



Owing to the fact that the body is hunched and the 



abdomen is curved under the thorax, it was difficult to 



place the male in a position to draw the doral surface. 



Onh' the female and one male were taken at Station 4793, Topor- 



kov Island, harbor of Nikolski, Bering Island, north 58° east, 44 



miles (54° 48' north, 1G4° 54' east), at a depth of 2,700 fathoms. It 



is parasitic on Eiicopia australis Dana. 



The type is in the U. S. National Museum. Cat. No. 38338. 



In the segmental character of the abdomen of the male this genus 



is closer to Asindophryxus Sars than to any other of the Dajidse 



Fig. 7.— Aetheo- 

 pheyxus berin- 

 GANUS. Adult 

 MALE. X41. 



