370 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvm. 



long hairs. The second pair of antenna are composed of Hve articles 

 and have the tirst article aliout three times as long as the second; the 

 third is twice as long as the second; the fourth is one and a half times 

 longer than the second; the tifth article is minute and terminates in a 

 bunch of hairs. 



The tirst segment of the thorax is united with the head to form a 

 carapace. The second or first free segment is the shortest of all; the 

 third and fourth or second and third free segments are nearly equal in 

 length, the third being perhaps a little longer; the lifth and sixth or 

 fourth and lifth free segments are subequal and are the longest; the 

 sixth or seventh free segment is about equal in length to the third free 

 segment. 



The abdomen is composed of six segments. The first three are sub- 

 equal in length and carrj^ on the ventral side three pairs of well- 

 developed pleopoda. The two following segments are sul)equal, and 

 each about one-half as long as any of the three preceding segments 

 and about one-half as wide, being abruptly narrower. These seg- 

 ments do not carry pleopoda. There are thus only three pairs of 

 pleopoda. The sixth or terminal segment is as wide as the two pre- 

 ceding segments and is rounded posteriorly. The uropoda are single 

 branched; the peduncle is followed )jy a five-articulate branch. 



The tirst pair of legs or gnathopods are chelate. The following six 

 pairs of legs are ambulatory. 



Oidy three specimens of this species were collected by Mr. Harold 

 Heath at Monterey Bay, California. 



The types are in the U. S. National Museum. Cat. No. 30615, 

 U.S.N.M. 



This species difl'ers from Tanais alascensis Richardson in having the 

 abdomen composed of six segments, while in T. alascensis it is com- 

 posed of five segments; in having the uropoda composed of a peduncle 

 and five articles, while in 7\ alascensis the uropoda are composed of a 

 peduncle and six articles; and in the smaller size of the specimens. 



