COPEPODS OF THE WOODS HOLE REGION 



475 



a pair of rudimentary dorsal plates ; fourth and fifth segments fused 

 with the genital segment into a terete trunk six times as long as wide. 

 Abdomen half as wide as the trunk, 1-segmented; caudal rami lan- 

 ceolate, acutely pointed, divergent, and a third as long as the entire 

 body. First antennae 3-segmented; each second antenna made up 

 of a stout basal segment and a strong terminal claw; maxilliped 

 stout, the terminal claw with a sharp spine on its inner margin near 

 the center. First, third, and fourth legs uniramose, 1-segmented; 

 second legs biramose, rami 1-segmented; fifth legs lacking. Total 

 length, 12-16 mm. 



Male. — Carapace ovate, nearly as wide as long, with a small ros- 

 trum; behind the head and more or less fused with it the first seg- 

 ment forms a narrow and short neck; the second segment is wider 



Figure 285. — a, Pseudocycnus appendiculatus, female, dor- • 



sal ; 1), P. huccatus, female, dorsal ; c, Hatschekia hippo- 

 glossi, female, dorsal ; d, H. hippoglossi, male, dorsal 



and at least four times as long as the first; the third segment is 

 wider than the second, but shorter ; the fourth segment is still wider 

 and longer, the fourth legs extending as rigid cylinders from its 

 lateral margins; the fifth and genital segments are fused, as wide 

 as the fourth, with a small spine at the center of each lateral margin. 

 Abdomen l-segmentecl, longer than wide, enlarged at the posterior 

 end; caudal rami longer than the abdomen, divergent, bluntly 

 rounded, each with an apical fringe of minute spines; antennae, 

 mouth parts, and legs similar to those of the female. Total length, 

 3.5-4 mm. 



Remjavhs. — This species is easily identified by its large size and 

 the exceptional length of the caudal rami. 



