ISOPODS OF NORTH AMERICA. 



477 



Legs simple, siinllar in structure; dactylus hi-unguiculate. 

 Uropoda short, extremely small. 



ANALYTICAL KKY TO THE Sl'ECIES OF THE GEN'I'S .J.EKOPSIS. 



(I. Head, second, third, fourth, and seventh thoracic segments and abdomen brown. 

 First, fifth, and sixth thoracic segments jierfectly white and colorless. Median 

 lobe of terminal segment of body rounded. Frontal process of head as long as 



side of head. Eyes moderately large fnropnh lobatu Richardson 



a^. Color uniformly white. Median lobe of terminal segment of V)ody acute. Frontal 

 process of head about half as long as lateral margin of head. Eyes small. 



Jivropsis rathbunx Richardson 



JiEROPSIS LOBATA Richardson. 



Jxropsis lohata Richardson, Proc. U. S. Nat. Mus., XXI, 1899, pp. 859-860; 

 Ann. Mag. Nat. Hist. (7), IV, 1899, pp. 326-827; American Naturalist 

 XXXIV, 1900, p. 300. 



Locality. — Monterey l^ay, California. 



Surface of body smooth. 



Color very peculiar and striking. The head is l)rown. The first 

 thoracic segment is perfectly white, without any markings. The 

 second, third, and fourth seg- 

 ments are brown. The tifth and 

 sixth arc white. The seventh 

 thoracic segment and the caudal 

 segment are brown. This pe- 

 culiar marking gives the body a 

 striped appearance. 



Head large; front produced 

 into two prominent triangular processes, on either 

 side of a deep median excavation in which is placed a 

 small lobe; this gives the head the appearance of being 

 produced in a large rounded median lobe. The antero- 

 lateral angles of the head are acutely produced on either 

 side to a distance equal to one-third the length of the 

 frontal process. The eyes, which are small, are situ- 

 ated on the extreme lateral margins of the head. The 

 first pair of antennse are extremely small, equal in 

 length to less than half the width of the head; flagellum 

 obsolete. The second pair of antenna^ are also ex- 

 tremely short, equal in length to the width of the 

 head, with rudimentary flag(dlum. composed of about 

 tive joints, and with peduncular joints dilated. Man- 

 dibles have the cutting part composed of five teeth; 

 palp, three-jointed. 



The thoracic segments are subequal in length, with lateral edges 

 produced, but not laciniate, and separated from each other by lateral 

 incisions. 



¥Ui. 533. — J.EROPSIS LOBATA. 



Head, x 27i. 



Fig. 534.— J.EROPSIS 



LOBATA. MAXIL- 



LiPED AND Man- 

 dible. 



