2 i ORCHESTIlDvF, 



A MPIUPODA . ORCHESTIIDJ1. 



SALTATORIA. 



Genus ORCHESTIA, LEACH. 



TALITRUS (part), LATREILLB. 



Generic character. General appearance of Talitrus, but having 

 both pairs of gnathopoda subchelate. The second pair in the 

 male large and powerful ; in the female small and feeble. 

 Telson single and well developed. 



THE superior antennae are as short as in Talitrus, and 

 are often recurved. The inferior antennae, as in that 

 genus, have the two basal articulations incorporated into 

 the anterior or frontal wall of the head, and destitute 

 of the olfactory denticle. The mandibles are without 

 an appendage,* and the whole of the organs of the 

 mouth are largely developed. The two anterior pair of 

 legs are furnished with prehensile hands, the first pair 

 small, the second large and powerful in the male, but 

 small and feeble in the female. The squamiform basal 

 joint of the fifth pair of legs is subequally bilobed, the 

 anterior lobe being as deep as the scale of the preceding 

 legs. The posterior pair of caudal stylets consist only 

 of a single branch. The tail-piece is single and well 

 developed, entire, triangular, w T ith the margin spinous. 



This genus was founded by Leach to receive the Cancer 

 (Gammarus) littoreus of Montagu. That Dr. Leach was 



* A rudimentary palpiform appendage in an Egyptian species of Orchestia 

 is represented by Savigny near the base of the jaw (copied in our figure, 

 p. 27, fig. d), but we have never seen it in any species. 



