INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. SSO" 



In the female the liands of the first and second pairs of legs are 

 smaller and slenderer, aud the iiropodi somewhat oval and nearly alike 

 in both pairs; otherwise the females do not differ from the males, except 

 that the rami of the posterior caudal stylets are, perhaps, a very little 

 shorter and broader in proportion. 



Length, 10-12""". 



Vineyard Sound, in vast numbers at the surface of the water, usually 

 among floating sea- weeds and eel-grass. Also from stomach of mackerel^ 

 May 1*0. 



G-AMMARUS MARINUS Lcach. (p. 480.) 



Traus. Linoeau Soc, London, vol. xi, p. 359, 1815; Bate, Catalogue Ampbip. 



Crust., Brit. Mus., p. 215, P1.38, fi^. 4 ; Bate and Westwood, Brit. Sessile-eyecl 



Crust., vol. i, p. 370, wood-cut. 

 A species which I cannot distinguish, by the published figures and 

 descriptions, from this common species of Europe, was not uncommon, 

 associated with Amphithoe maculata, under stones at the Wepecket 

 Islands, Gull Island, Cuttyhunk Island, and at other places on Vine- 

 yard Sound and Buzzard's Bay. It has also been found at Watch Hill, 

 Rhode Island, and at New Haven, Connecticut, by Professor VerrilL 

 It is at once distinguished from all the other species of our coast by its- 

 slender form, slender antenna?, by having the sides of the second and 

 third segments of the abdomen narrow and not produced or acute at the 

 postero-iuferior angle, aud by having the outer rami of the posterior 

 caudal stylets four or five times as long as the inner. 



Gammarus mucronatus Say. (p. 479.) 



Log. cit., p, 376, 1818; De Kay, op. cit., j). 37. Gammaracanthtis mucronatus Bate, 

 op. cit., p. 203. 



Readily distinguished from the other species of the coast by having 

 the x)OSterior margin of each of the anterior segments of the abdomen 

 produced into a slender, spiniform, dorsal tooth. In life, it is translu- 

 cent, tinged with green, or yellowish green, minutely specked with brown 

 or black; these black or brown markings and the green color being fre- 

 quently so arranged as to give the antenn;ii and legs a banded appear- 

 ance. Our species cannot be referred to Bate's genus Gammaracanthus, 

 for the dorsal margin is not distinctly carinated, and the third, fourth, 

 and fifth segments of the abdomen are furnished with fascicles of spines. 



Usually in brackish water, North Carolina to Cape Cod, and, accord- 

 ing to Say, from Florida also. 



McERA LEVIS Smith, sp. nov. (p. 315.) 



Eyes nearly round; black in alcoholic specimens. Antennula two- 

 thirds as long as the body ; first and second segments of the peduncle 

 ecpial in length, third about two-thirds as long as the second ; flagellum 

 about as long as the peduncle. Antenna about as long as the peduncle 

 of the antennula ; ultimate and penultimate segments equal in length, 

 antepenultimate very short ; flagellum ranch shorterthan the peduncle. 

 Legs of the first pair small ; carpus as broad as the propodus, but little 



