ISOPODS OF NORTH AMERICA. 



193 



Fi(.. 17(1.— i: (M I - 

 nki.a cornuta. 

 Head, x 12. 



Length of body two and one-quarter times its greatest breadth. 

 Outline oval; surface smooth, with scattered points of depression. 

 Head subtriangular, having a medium excavation. Its frontal margin 

 is produced forward in a long and broad projection, 

 widely rounded at its extremity, and curving upward. 

 Eyes large and situated some distance apart. The 

 tirst anteiuia reaches the anterior margin of the first 

 thoracic segment; its Hagellum is composed of six 

 articles. The second antenna extends to thc^ posterior 

 margin of the second thoracic segment; its tlagellum is sixteen-jointed. 



The thoracic segments are subequal. The 

 antero-lateial angles of the tirst segment 

 are greatly produced and extend forward a 

 little less than half the length of the head, 

 including the projection. These antero- 

 lateral projections of the tirst segment do 

 not follow closely the lines of the head, but 

 rather extend out straight in a direction 

 which is parallel to that of the frontal pro- 

 jection of the head. The extremities of 

 these projections are rounded. The epimera 

 of all the segments point downward and do 

 not extend beyond the post-lateral angle of 

 their respective segments with the excep- 

 tion of the sixth and seventh 



\ 



Fig. 177. — a, Rocinela cor.ntta. 



MALE, SLIGHTLY REDUCED. 6, 



Leg of first pair, x 4. c, Le(; 



OF FOURTH PAIR. X 4. 



ones. 



The first segment of the 

 abdomen is almost entirely 

 covered by the seventh tho- 

 racic segment. The hist segment is rounded poste- 

 riorly and is faintly crenulate. The two branches of 

 the uropods are similar in shape and size; the inner 

 branch, being the longer, reaches the extremity of 

 the abdomen. The uropods as well as the abdominal 

 segments are furnished with hairs. 



The propodus of the prehensile feet is armed with 

 three spines, and three blunt ones are found on the 

 merus. The gressorial feet are long and slender 

 and covered with spines. 



Type. — The tj^pe specimen was found oft' Shumagin Bank, Alaska, 

 Station 3338, 625 fathoms (Cat. No. 20086, U.S.N.M.). 



28589—05 13 



Fig. 17>s.— Rocinela 



CORNVTA. Ma.\- 

 ILLIPED. X 20^. 



