

GAMMARIDEA. 355 



pair; g, leg of seventh pair.— A, female, side view of head; i, extre- 

 mity of leg of first pair; k, ibid, of second pair; I, leg of seventh pair. 



Abundant among the sea-weed thrown up on the shores of Nassau 

 Bay, Tierra del Fuego. 



Length, three-fourths to seven-eighths of an inch. Colour, greenish 

 brown. The large peltate plates on either side of the body posteriorly, 

 pertaining to the basal joint of the posterior legs, give the males a 

 singular appearance. These plates, in a side view, conceal much of the 

 abdomen and the appendages below ; they are concave within. The 

 superior antennae are short, they extend beyond apex of penult joint 

 of base of inferior pair ; the flagellum is about six-jointed. The fla- 

 gellum of the inferior antennae contains sixteen to eighteen joints. 

 The setae of the flagella are about one-fourth the diameter of the 

 joints in length; the base of this pair is quite short in males as well as 

 females. Eye round. Mandible has a large molar prominence, which 

 is minutely granulous at apex. The terminal setae of the inner 

 maxillae are toothed within. The penult joint of first pair of feet in 

 males is subtriangular like the hand, and nearly of the same size ; 

 lower apex of hand and also of preceding joint rounded and promi- 

 nent. The hand of the second pair in males is large ; the palm is 

 nearly straight and almost naked, with a low triangular prominence 

 just above its centre ; the third joint of this pair is a little oblong and 

 rectangulate below. In females, the second pair of legs has the fourth 

 and fifth joints subequal in length, and longer than the third; the 

 third and second subequal ; the fourth is articulated with the third by 

 nearly one-half of its lower side, the other half being regularly ar- 

 cuated below. The first pair in females is nearly as in Talitrus; yet 

 the claw does close so as to hit the lower apex of the preceding joint 

 by its inner surface ; the fifth joint has its two margins nearly parallel, 

 and is sparsely scabrous below. 



This species has many of the characters of the 0. chilends of Ed- 

 wards; but the terminal segment of the abdomen is not longer than 

 broad, and is D-shape (fig. 2 m) instead of being long and pointed ; 

 moreover, the finger of the hand has but a single curvature. 



217 



