[559] INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 265 
In the female the hands of the first and second pairs of legs are 
smaller and slenderer, and the propodi 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 20. 
GAMMARUS MARINUS Leach. (p. 486.) 
Trans. Linnean Soc., London, vol. xi, p. 359, 1815; Bate, Catalogue Amphip. 
Crust., Brit. Mus., p. 215, PJ. 38, fig. 4; Bate and Westwood, Brit. Sessile-eyed 
-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 Amphithoé 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 antenne, by having the sides of the second and 
third segments of the abdomen narrow and not produced or acute at the 
postero-inferior angle, and by having the outer rami of the posterior 
caudal stylets four or five times as long as the inner. 
GAMMARUS MUCRONATUS Say. (p. 479.) 
Loe. cit., p, 376, 1818; De Kay, op. cit., p.37. Gammaracanthus mucronatus: Bate, 
op. cit., p. 203. 
Readily distinguished from the other species of the coast by having 
the posterior 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 antenne 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. 
MGRA 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 
equal 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 much shorterthan the peduncle. 
Legs of the first pair small; carpus as broad as the propodus, but little 
oa 
