66 BRITISH COPEPODA. 
triarticulate 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. LXXVITI, 
figs. 1—11. 
First segment very broad and subtruncate in front, 
rostrum short; abdomen nearly as stout and quite 
as long as the cephalothorax, 5-jointed, first joimt 
shortest, last longest; caudal segments slender, as 
long as the last abdominal segment. Anterior an- 
tenna (fig. 2) slender, somewhat longer than the first 
cephalothoracic 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 lke 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 setz 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 
