THALESTEIS. 121 



claw, and bearing three or more setiferous marginal 

 lobes. Second pair forming a strong prehensile hand. 

 Both branches of the first pair of feet form strong pre- 

 hensile organs with terminal claws, and are 3-jointed ; 

 first joint of the inner branch much elongated, second 

 and third very short ; first and third joints of the 

 outer branch short, the middle joints greatly elongated. 

 The second, third, and fourth pairs have both branches 

 3-jointed, and adapted for swimming, except in the 

 second pair of the male, where the inner branch has 

 the third joint wanting or very much reduced in size, 

 and converted into two or three strong spines. Fifth 

 pair of feet 2-branched, foliaceous ; both branches 

 in the male usually much reduced in size, the inner 

 often almost obsolete. Ovisac single. 



1. THALESTEIS MYSIS, Claus. PI. LVIII, figs. 1 13. 



Thalestris mysis, Claus. Die frei lebenden Copepoden, p. 130, 



t. xviii, figs. 1216 (1863). 

 Boeck. Ovevsigt Norgea Copepoder, p. 44(1864). 



Body elongated, slender; abdomen very long, the 

 first two segments much longer than the rest ; ros- 

 trum of moderate size, sharp and slender. Anterior 

 antennae (fig. 2) 9-jointed ; the first four subequal 

 and considerably longer than the following joints. 

 Inner branch of the second pair of antennas 2-jointed 

 (fig. 4), armed with stout setse. Mandible-palp well 

 developed and strongly setose (fig. 5) ; maxilla also 



