168 BULLETIN 15 8, UNITED STATES NATION Ali MUSEUM 



Female. — Posterior corners of fifth segment with processes curv- 

 ing outward and downward ; genital segment only ^slightly swollen ; 

 anal segment asymmetrical and fused with the caudal rami, right 

 ramus twice as wide as left, its outer seta replaced by a broad and 

 flattened spine ; end segment of fifth legs three or four times as long 

 as penultimate segment, curved inward, tapered to an acute point, 

 with both margins smooth and unarmed. Total length, 2-2.25 mm. 



Male. — Body more slender; fourth and fifth segment,s separated 

 with rounded posterior corners, without processes; urosome 5-seg- 

 mented, turned to the right and twisted on its longitudinal axis; 

 genital segment with a rounded process at the left distal corner; 

 first abdominal segment with a pointed process at the right di,stal 

 corner; right caudal ramus larger than the left and constricted near 

 its base; end segment of left fifth leg no longer than penultimate 

 segment ; thumb on chela of right leg conical, blunt, and tipped with 

 a short spine. Total length, 1.75-2 mm. 



Remarks. — Wheeler described this as a new species under the name 

 Coryrmra huni'pusii., but it is evidently identical with the above 

 species. It can be recognized by the peculiar asymmetry of the 

 urosome in both sexes. It is a summer species and is practically 

 confined to the shallower waters along shore, and is nowhere found 

 in any numbers. 



TORTANUS SETACAUDATUS Williams 

 Figure; 115 



Tortanus setacaudatus Williams, Amer. Nat., vol. 40, p. 649, figs. 12-15, 1906. 



Occurrence. — Both sexes, surface tow, Waquoit Bay, Falmouth, 

 July, 1925, a second lot at the same place, August, 1926; a third lot 

 from small pond at the head of the bay, August, 1926. 



Distribution. — Narragansett Bay in winter (Williams). 



Color. — Body transparent, often tinged with blue around the mouth 

 and the bases of the mouth parts on the ventral surface. A blue spot 

 in the center of the last two segments of the metasome; eye dark blue. 



Female. — Body short, stout and symmetrical ; fourth and fifth seg- 

 ments indistinctly separated and smoothly rounded at the corners; 

 urosome half as long as metasome; maxillipeds exceptionally large 

 and carried horizontally at right angles to the body axis; fifth legs 

 consisting of a fused basal portion and 2-segmented rami, the seg- 

 ments of equal length, the distal one broadly rounded, armed with 

 one apical spine, two at the inner distal corner, and one at the center 

 of the outer margin, all about the same size. Total length. 1.25- 

 1.4 mm. 



