502 



BULLETIN OF THE BUREAU OF FISHERIES. 



T-- 



Gammarus anntdalus, male. Woods Hole, Mass, 



size and similar in shape. The palm in the first pair is, however, more oblique than in the second, 

 and in both pairs the palms are more even than in the male sex and have laminate edges marked 



with fine vertical lines; pera?opods slender, 

 first and second pairs armed with only a 

 very few weak spines but furnished with 

 long slender hairs, which are especially abun- 

 dant on posterior margins of carpus and 

 mcrus; last three [■airs with fascicles of spines; 

 postero-lateral angles of second and third ab- 

 dominal segments produced and acute; tilth 

 and sixth abdominal segments with both me- 

 dian and lateral fascicles of spines; third 

 segment with only a median fascicle; last 

 uropods elongate!, rami narrowly lanceo- 

 late, the margins furnished with long, plu- 

 mose hairs; outer margin of outer ramus 

 with several spines, the terminal article nar- 

 row and tapering to an acute tip; inner 

 ramus equaling or exceeding end of first joint 

 of i inter, both margins armed wit li a few spines; 

 telson with a variable number of spines near 

 outer margin and several at the tip. 

 Length, 15 mm. Abundant in Vineyard Sound; Gloucester. This species of Gammarus is pecu- 

 liar on account of its habitat at the surface, where it is often taken in great numbers. 



Professor Smith has kindly sent me the types of his Gammarus annulatus. They prove to be the 

 same species as the one he has described as Gammarus natator. 



Gammarus marinus Leach. 



Body slender; lateral lobe with a rather deep emargination below; eyes reniform; first antenna' 

 about half as long as body; second basal joint a little shorter than first, but twice the length of third; 

 flagellum longand slender; second, 

 ary flagellum about 7-jointed and 

 scarcely half as long as peduncle; 

 second antenna? shorter than first : 

 last two joints of peduncle of sub" 

 equal length, flagellum longer than 

 peduncle; first four coxal plates no) 

 large, the fourth deeper than broad; 

 first gnathopods in the male some 

 what stouter and larger than the 

 second; carpus about three-fourths 

 the length of band; hand narrowly 

 oval; palm very oblique, continu- 

 ous, with posterior margin a little 

 concave in the middle, where there 

 is a stout spine on the outer side 

 which is the first of a row of three 

 spines, the last one of which is near 

 distal end of palm; see 1 gnatho- 

 pods of the male with carpus a little 

 longerthan hand; osterior margin with 10-12 short tranversc rows of long -eta-; hand subrectangular. 

 ali' mt twiee as long as \\ ide, posterior margin densely clothed with long setae arranged in about 13 trans- 



' rows palm oblique, concave in the middle; first gnathopods of the female nearly as large as those of 

 the male and resembling them in form; first pair stouter than second, hand subquadrate, broaderthan in 



tarinus, male. Woods Hole, Mass. 



