MACROSTOMATA. MOLLUSCA. VELUTINA. 243 



State Coll., No. 12G. Soc. Cab., No. 2409. 



Shell tbia, opake, white, and in some places pellucid, minutely 

 striated both ways ; whorls less than three, the first two minute, 

 and not seen when the shell is viewed in front ; the last, widening 

 with great rapidity, becomes large, though it is not tumid, but 

 appears rather dejiressed as it lies upon the aperture ; the surface 

 is covered with a chalky incrustation, deposited by the animal, 

 apparently instead of an epidermis ; it is white, or flesh-colored, 

 and generally with nur\erous zones of brown, of various widths ; 

 when this is removed, the shell is left pellucid ; aperture ovate, 

 ample, nearly the whole length of the shell, more than double the 

 size of the body of the shell ; outer lip sharp and spreading ; 

 inner lip sharp-edged, but margined by a flattened, crescent- 

 shaped, white, channelled space ; the sharp edge is lost as it re- 

 volves within the shell, and a thin plate of enamel covers the 

 space between it and the junction of the outer lip. Length ^% 

 inch, breadth ^^ inch. 



Specimens have been found on Chelsea Beach, but are most 

 easily obtained from fishes. 



It is readily distinguished from the preceding by its more sohd struc- 

 ture, its flattened form, its expanded aperture, the flattening of the 

 left lip, and the peculiarity of the surface. Mr. Sowerby sent a speci- 

 men from a raised beach on the Frith of Clyde, labelled " Galericulimi 

 undatum, Brown," which is partly fossilized, but bears a very close re- 

 semblance to our shell. The most marked difl^erences in the shell 1 

 received are, the greater breadth and excavation of the flattened lip, 

 and a more irregular exterior, which, from the name it bears, I sup- 

 pose to be constant. It may also be the shell figured in Brown's 

 " Conchology of Great Britain," as Galericulum oiiatum, but nowhere 

 described. The peculiar coating of the shell adheres very closely, 

 and might not be detected except by accident. Perhaps it does not 

 always exist ; but in the striped specimens it will always be found. I 

 should think that specimens entirely white, or flesh-colored, are as 

 often found as the zoned ones. In one fish, caught off Cape Ann, I 

 found about a dozen very large and beautiful specimens. 



