66 IMUTISli COPEPODA. 



inarticulate posterior antenna, the presence of a small 

 branch on the mandible-palp, the uniformly triarticu- 

 late outer and biarticulate inner branches of the swim- 

 ming-feet, and by the one branched fifth foot. 



1. TETRAGONICEPS MALLEOLATA, nov. sp. PL LXXVIII, 



figs. 111. 



First segment very broad and subtruncate in front, 

 rostrum short ; abdomen nearly as stout and quite 

 as long as the cephalo thorax, 5-jointed, first joint 

 shortest, last longest ; caudal segments slender, as 

 long as the last abdominal segment. Anterior an- 

 tenna (fig. 2) slender, somewhat longer than the first 

 cephalo thoracic segment, 8-jointed; first joint as long 

 as the united lengths of the following five, and pro- 

 duced at the inner apical angle into a large and stout 

 curved prominence somewhat like the claw of a 

 hammer ; second joint about half as long as the first, 

 the following being the relative lengths of the several 

 joints, 14, 8, 4, 5, 2, 3, 3, 4 ; posterior antenna (fig. 3) 

 composed of three elongated, nearly equal joints, to 

 the first of which is attached a small, slender, 1 -jointed 

 branch ; the terminal setse are slender and are attached 

 almost wholly to the apex. The hand of the second 

 foot-jaw (fig. 7) is slender, and has a long slender 

 apical claw. First joint of the inner branch of the 

 first foot slender (fig. 8), longer than the entire outer 

 branch, and having a single plumose seta on its inner 

 margin, second joint short, and bearing two short 



