ISOPODS OF NORTH AMERICA. 79 



abrupt!}' narrower tliuii tlio sixth, not as wide as iho abdominal seg- 

 ments and devoid of lej^s. 



The first three pairs of legs are subchelate, the three following 

 pairs ambidatory. 



The al)doniinal segments are well defined and distinct from one 

 another. The terminal abdominal segment is rounded, entire. The 

 inner branch of the uropoda is likewise rounded; the outer -and supe- 

 rior ])raneh arches over the telson. 



This genus agrees with both IIy(<><u/'a Norman and Stebbing and 

 Cruregans Chilton in the absence of the seventh pair of legs, but dif- 

 fers from the first named in the structure of the antenna>, both pairs 

 of antennae in ITyssiird having nuilti-articulate flageUa; in the structure 

 of the outer branch of the uropoda, which in JlysKi/ni does not arch 

 over the telson; and in th(! structure of the mouth parts. (Jolanthura 

 differs from Crureg<uis in the presence of e^'es, which are wanting in 

 (^ruregans^ and in the structure of the outer l)ranch of the uropoda, 

 the outer branch in Cniregans being very narrow and not arching 

 over the squanuform telson, while in Colanthura the outer branch is 

 broad and arches over the rounded terminal segment. The structure 

 of the mouth parts is the same as found in the genera Pararithura^ 

 Calathara^ and Crartgan-'^. 



COLANTHURA TENUIS Richardson. 



Cokinthurn tmuiii Richardson, Trans. Conn. Acad. Sciences, XI, 1902, pp. 287- 

 288, pi. XXXVIII, figs. 23-28. 



Localif y.^Bermndns. 



Body narrow, elongate; surface smooth; color light yellow. Head 

 with a prominent median process extending between the first pair of 

 antenna^. Antero lateral angles prominent, produced, reaching the 

 distal end of the first joint of the peduncle of the first pair of antenna^. 

 Eyes large, conspicuous. 



First pair of antennae consist of foui- joints, the terminal or flagel- 

 lar joint being fringed with long hairs. The second pair of antenna? 

 are composed of five joints, the terminal joint being fringed with 

 hairs. 



The first three thoi'acic segments are about equal in length. The 

 fourth and fifth segments are each much longer than an}' of the three 

 preceding segments, and are about alike in size. The sixth segment 

 is short, not quite as long as any one of the first three segments. 

 The seventh is ver}'" short, being one -third the length of the sixth 

 segment, and in both specimens exauiined is devoid of legs. 



The segments of the abdomen are distinct, the first five together not 

 being as long as the sixth thoracic segment. The last thoracic seg- 



