158 On the MoUusca of Long Island. 



appears to be a rare shell. One specimen obtained here mucli 

 exceeded the dimensions stated by De Kay, having a length of 

 1-35 and breadth of 1*2 inches, with a height of 043 in. The 

 shell, as found here, is much less elevated than De Kay's descrip- 

 tion gives an idea of, though, as the figure does not appear to 

 correspond, there may perhaps be a typographical error in the 

 height given. The figure, hovi^ever, represents a more elevated 

 shell than any specimens I have found here. Specimens from 

 Eastport, Maine, have about the same proportions as ours. A3 

 suggested by Mr. Stimpson, in his " Invertebrata of Grand 

 Manan," this may probably form a new species. 



42. Crepidula fornicata Lamarck. The most abundant shell 

 of the bays, occurring in multitudes at every deptli, and on 

 almost every bottom from low water mark to ten fathoms, and 

 even on a bottom of dead shells, where hardly anything else is 

 found alive. The animal varies very much in color. The 

 lower surface of the head, and both surfaces of the foot, are 

 generally, in adults, yellowish white to light reddish yellow, 

 the head being lightest. Sometimes, however, they are cov- 

 ered with a grey or black pigment, and in this case the tenta- 

 cles are generally grey or black also. These differences do not 

 appear to depend upon sex, as the black horn-shaped male 

 genital organ, on the right side of the head, is found in some 

 individuals of all tints. (In one black individual, this organ 

 was white.) Neither does it appear to depend on age, though 

 the young are generally dark colored. The shells of both 

 varieties are exactly alike, and both generally occur in almost 

 every group that may be picked up. Upper side of the head 

 black. Tentacles thick and blunt, bearing the eyes on bulg- 

 ings at their outer bases. Muzzle tipped with opaque white, 

 deeply cleft. Mantle black, with a wide border of translucent 

 white or yellowish, mottled with opaque white. Gill very 

 large, nearly white, but appearing grey from the black mantle 

 beneath. Anus white, on right side, near front of the foot. 

 The horn-shaped male organ is about as long as the tentacles. 



