COPEPODS OF THE WOODS HOLE REGION 195 



shaped, its posterior corner curved backward like a claw, and be- 

 tween the two on either side a small recurved spine. Terminal seg- 

 ment of fourth endopod linear, without lateral setae, with two 

 unequal terminal spines. Inner expansion of basal segment of fifth 

 legs broad and vaulted, with two unequal terminal setae and three on 

 the inner margin ; distal segment linear, extending a little beyond the 

 inner expansion, with a short terminal seta and four longer setae on 

 the outer margin, the distal one elongated. Total length, 0.3-0.4 mm. 



Male. — Smaller than the female, the postero-lateral corners of the 

 head obliquely truncated; first antennae jjrehensile, the fourth seg- 

 ment considerably enlarged, the terminal segment clawlike; fifth legs 

 linear and elongated, the basal segment without an inner expansion, 

 the distal segment tipped with two unequal setae. Total length, 

 0.25-0.35 mm. 



Remarks. — This minute harpactid was reported by Williams from 

 Narragansett Bay, but has not hitherto appeared in any list of the 

 Woods Hole region. It is easily recognized by its black color and 

 its habit of rolling up its body into a ball. 



Family TISBIDAE 

 Genus TISBE Lilljeborg, 1853 



Body considerably depressed; head fused with the first segment, 

 with angular posterior corners; second, third, and fourth segments 

 with broad epimeral plates, obtuse at their tips ; fifth segment greatly 

 narrowed. Urosome sharply defined from metasome; genital seg- 

 ment divided by a dorsal groove across the middle; abdomen 3-seg- 

 mented in female, 4-segmented in male ; caudal rami short and broad. 

 First antennae 8-segmented, geniculate in the male ; exopod of second 

 antennae 4-segmented ; first four pairs of legs with 3-segmented rami, 

 setae on the end segment of the first exopod penicillate at their 

 tips ; fifth legs slender, 2-segmented, the distal segment narrow linear. 



Remarks. — The genus Idya was established by Philippi in 1843, 

 and the genus Tishe by Lilljeborg in 1853, the two being identical. 

 But the name Idya had been preoccupied in 1809, and hence 

 Lilljeborg's name becomes valid, and not the name Idyaea proposed 

 by Sars in 1909. 



KEY TO THE SPECIES (BOTH SEXES) 



1. First antennae short, third and fourth segments each shorter 

 than second ; distal segment of fifth leg four times as long as 

 wide furcata (p. 196) 



First antennae elongate, third and fourth segments each longer 

 than second; distal segment of fifth leg six times as long as 

 wide longicomis (p. 197) 



First antennae long and tapered ; third and fourth segments com- 

 bined shorter than second ; distal segment of fifth leg twice as 

 long as wide wilsoni (p. 198) 



