APPENDIX. 



AMPHIPODA. 



NATATORIA. 



501 



LYSIANASSIDES. 



[Vol. I. p. 118.*) 



Genus— OPIS. [Krorjer.) 



Generic character. Resembles Anoiiyx, with the exception that 

 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 LEPTOCIIELA, N.S. 



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

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

 slender, and siibequal. 



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 supei'ior antennae large ; the flagellum short; 

 secondary appendage short. The inferior antennge are slender, 

 being half as long again as the superior. Coxte deep. Gnatho^ 



