110 RatJih}iii — Synopsis of the American Species of Etlinsa. 



Ethusa tenuipes Rathbun, new species. 



Closely allied to J<J. uiicrophthulma Smith, but a much smaller species. 

 The shai)e of the carapace and the outline of the front are sinnlar to those 

 of micropJttltaltntf ; the cardiac I'egion is more elevated and surrounded by 

 a deeper groove. The eye-stalks are shorter than in microp]il]iabiia, the 

 first segment of the antenna reaching the cornea. 



The aI)domen of the male is narrow ; the penultimate segment is slightly 

 narrower at its distal than its j)roxinial end, and is sliorter than its distal 

 width. The appendages of the fii'st segment have a lanceolate, foliaceous 

 extremity, and sheathe the appendages of the second segment, which ex- 

 tend far beyond those of the first, and have slender, converging tips. 



Chelipeds of the male very unequal, the right the larger. Right manus 

 with upper and lower margins convex. Dactyli of first and second ambu- 

 latory legs more slender than in inicrophtJialina, not vertically compressed, 

 and having four carime, one above, one below, one anterior, and one 

 posterior; dactyli a little wider in a dorsal than in a horizontal view. 



Dimensions. — rf: length, 6 mm.; width, 5.5. 



Type locality. — Off Key West, Florida, station 2316, steamer 'Albatross,' 

 50 fathoms (U. S. Nat. Mus., No. 19855). 



Distribution. — .\lso dredged at station 2388 in the Gulf of Mexico, oft' 

 the Delta of the Mississippi, 35 fathoms. 



