242 INVERTEBRATA OF MASSACHUSETTS. 



shells, renders the aperture nearly circular ; interior smooth and 

 shining. Diameter about ^V inch, length a little more. 



Found among the sea-weed on the sea-beach, and in the stomachs 

 of fishes. Mr. Conrad states, on the authority of Dr. Pickering, 

 that it dwells on rocks, with habits like the Pate'lla. But the 

 fact of so fragile a shell being usually found entire in the stomachs 

 of fishes, rather forbids this idea. It could not be detached by 

 them without being fractured. 



This shell, as hitherto found, is extremely fragile, seeming to con- 

 sist almost entirely of epidermis, with a small deposition of calcareous 

 matter within. The ordinary English specimens are said to be of about 

 the size of a pea, or perhaps twice as large ; but it sometimes becomes 

 three fourths of an inch in diameter. I sent our ordinary specimens to 

 Mr. G. B. Sowerby, who sent larger ones in return, assuring me of 

 their identity. These differ from the shell as we find it, in being more 

 solid, the epidermis more wrinkled lengthwise, the surface shining 

 where this is removed, and the lowest whorl is disunited from the pre- 

 ceding one at the aperture. These changes may all be attributed to 

 age. We may anticipate finding specimens of equal size here, since 

 we have already found them four times as large as the one described 

 by Mr. Conrad, who allows the very close affinity of his minute one 

 to the Icevigaf.a of Europe. 



The quoting of Bulla velutina by Lamarck as a synonym to his 

 Sigaretus haliotoideus is plainly erroneous. The Helix halioloidea 

 of Fabricius, which is the Bulla velutina of Miiller, is not the H. hal- 

 ioloidea of Linnaeus and others ; and hence the probable misquotation. 



The figure in Pennant's " British Zoology " is poor ; that of Blain- 

 ville represents the common appearance when arrived at that size, the 

 transverse wrinkles becoming more conspicuous than the revolving 

 ones, which evidently become obsolete with age. The white zone 

 which he represents, however, I have never seen. Brown's figure is 

 very good for a shell of the size, and Conrad's is sufficiently character- 

 istic for specimens as we usually find them. 



Velutina zonata. 



Shell oval-orbicular, compressed, pellucid, covered with a 

 striped, calcareous incrustation ; inner lip flattened and channelled. 



Figure 160. 



