On the MoUusca of Long Island. 155 



aid I have so often been indebted in the preparation of this 

 paper. 



34. Yerm^tus radicula Stimpson. Only the tip of a single 

 specimen occurred. 



35. Littorina rxidls Gould. Very abundant. Animal white 

 or greyish above, head dark brownish grey, becoming bright 

 red or purple at each pulsation. Tentacles of same color, short 

 and blunt, bearing the eyes on bulgings at their outer bases. 

 Muzzle large and prominent. Foot white below, about two- 

 thirds the length of the shell, broad, rounded at both ends, 

 grooved along the middle. 



36. Littorina littoralis Forbes <& Hanley. Not so abundant 

 as the preceding. There appear to be at least two species in- 

 cluded under this name, the shells of which appear to have no 

 invariable marks of distinction, both having most of the varie- 

 ties of color ascribed by Gould to the species. The animal, 

 however, is in one whitish or yellowish, with yellow or orange 

 head ; and in the other, the head and tentacles vary from dark 

 grey to jet black, the darkest shades being the commonest. 

 This second variety or species is three or four times as abun- 

 dant as the other. If this should not prove to be a sexual 

 difference, which I think is hardly probable, though I have 

 been unable to completely satisfy myself on the subject, the 

 original name might be retained for the first species, which cor- 

 responds most nearly with Gould's description of the animal, 

 whilst I would propose for the second the name of L. PeGonica 

 from the locality in which it occurs. I subjoin more detailed 

 descriptions. 



Littorina littoralis. Animal white to light reddish yellow. 

 Head reddish orange, becoming deeper at each pulsation. Ten- 

 tacles lighter, about quarter the length of the shell, blunt, 

 bearing the eyes on bulgings at their outer bases. Foot 

 rounded at both ends, translucent white below, with the ante- 

 rior edge opaque white; about two-thirds the length of the 

 shell. 



