ISOPOD8 OF xNORTH AMEKIOA. 449 



//. First pair of antenna' well develoju'd; llageiluiii iiiulti-articnlate. Second pair 

 of antenme with scale outside of third article of peduncle. rVo{)oda largely 

 developed. 

 c. Eyes laterally placed. First pair of legs in male nearly twice the length 

 of the body, enlarged distally, forming a club-like hand armed with trian- 

 gular processes, to which is articulated a movable finger, the propodus, 



armed also with triangular processes Genus ('arpias Kichardson 



(/. Eyes sub-dorsal. First pair of legs in male not twice as long as body; j)ro- 

 podus not armed with triangular processes. 

 d. Maxillipeds with the second and third articles of the i)alp very much 

 exj^anded. Distal extremity of the peihincle and the branch of the first 

 pleopoda in the male fused and produced and dilated at the tip. 



Genus Jantrop^ix G. O. Sars 

 d\ Maxillipeds with the second and tliird articles of the palp not expanded. 

 Distal extremity of the peduncle and the branch of the first pleopoda in 

 the male generally not fused nor produced and not dilated at the tip. 

 e. Terminal segment of body with post-lateral angles produced into a trian- 

 gular expansion, one on either side. Segments of thorax with lateral 



parts produced, laciniate Genus lolrllu, new name. 



e^. Terminal segment of body with jiost-lateral angles not produced in a tri- 

 angular expansion, one on either side. Segments of thorax with lateral 



parts not produced, not laciniate Genus Janirn Leach 



f/. Second pair of antennae short, with articles of peduncle dilated; flagellum rudi- 

 mentary. Second antenn;e ecpial in length to the width of the head. Cutting 

 part of mandibles comjiosed of five teeth Genus Jieropsis Koehler 



71. Genus J^^RA Leach." 



Body broad, depressed. Lateral parts of thoi'acic segments laiiiinarly 

 expanded. 



Head without rostrum. Terminal segment with median emargina- 

 tion, within which the uropoda are placed, E3'es dorsal. 



First pair of antennie extremely small, with rudimentary flagellum. 

 Second pair of antenn{\j long and well developed, without a scale 

 attached to the peduncle of the second antenna?; flagellum multi-articu- 

 late. 



Uropoda extremely small; branches short, nodiform. 



Legs of all seven pairs ambulatory in structure; dactylus tri- 

 unguiculate. 



Distal extremity of the pedtuic^le and the branch of the first pleopoda 

 in the male fused and dilated at the tip. 



ANALYTICAL KEY TO THE SPECIES OF THE (iEXrS .I.F-RA. 



<^ Anterior margin of the head broadly excavated on either side of a median lobe. 

 Extremity of terminal segment of body notched for the insertion of the uropoda, 

 the median point being almost imperceptible Jtrra marina (Fabricius) 



.(/. Anterior margin of the head nearly straight. Extremity of terminal segment of 

 body with a double excavation, the median point not extending beyond the 

 extremity of the sides Jsera wakkhiana Spence Bate 



« See Sars for characters of genus, Crust, of Norway, II, 1899, pp. 103-104. 

 28589—05 ^29 



