AMPHIPODS 



243 



aquilibra Say, but it differs from Say's species in having no spine on 

 the ventral side of the body between the bases of the second gnathopods, 

 in having the ischium of these appendages armed in front with a very 

 prominent spinous process, and in having the palm devoid of a spine at 

 the upper end. Owing to the two latter characteristics, this species is 

 one which is especially well marked. 



CAPRELLA SCABRA sp. nov. 



Type from Orca, Prince William Sound, Alaska (numerous specimens 

 found among specimens of the Hydroid Thuiaria turgida). 



Adult male; Body robust, narrowed in front of the insertion of the 

 second gnathopods, and scabrous with minute spinules which become 

 larger on the posterior segments. Head armed above with a prominent 

 spine, behind which there may be a smaller spine or tubercle. First an- 



FIG. 126. Caprella scalra. The three figures of the second gnathopods are drawn 

 from male specimens of different ages. 



tennse scarcely a third the length of the body, the peduncle very stout, the 

 first joint about two thirds the length of the second and a little longer than 

 the comparatively slender third joint ; flagellum shorter than the peduncle 

 and composed of about eleven segments. Second antennae slender, much 

 shorter than the first, and fringed with long hairs posteriorly ; flagellum 

 two-jointed and a little longer than the last joint of the peduncle. First 

 segment of the thorax about twice as long as deep and sometimes armed 



