APPKNDIX. 



AMPH1P0DA. 



NATAT0R1A. 



501 



LYSIANASSIDES. 

 {Vol. I. p. 118.*) 



Genus OP1S. (Kroyer.) 



Generic character. Resembles Anonyx, with the exception tbat 

 the first pair of gnathopoda have the inferior angle of the propodos 

 considerably produced, so that the hand is formed into a didactyle 

 chela. 



OPIS LEPTGCHELA, N.S. 



Specific character. Upper antenna? with the two basal joints large ; lower 

 antennse half as long again as the upper. Both pairs of gnathopoda minute, 

 slender, and subequal. 



Length, about one-fourth of an inch. 



The cephalon is small, not produced anteriorly. The 

 segments of the pereion and pleon are dorsally subequal in 

 length ; the fourth segment of the pleon having a deep notch on 

 the dorsal surface. The eyes are small and round. The first 

 two joints of the superior antennse large ; the flagellum short; 

 secondary appendage short. The inferior antennse are slender, 

 being half as long again as the superior. Coxae deep. Gnatho* 



