CRENELLA. 195 



pied by the ligament. Length, five twentieths of an inch ; height, 

 nine twentieths of an inch ; breadth, three tenths of an inch. 



This very pretty and singularly shaped CrencUa was first found 

 by Colonel Totten, in Provincetown Harbor, It is one of the most 

 common shells found in the stomachs of fishes caught in Massachu- 

 setts Bay. The shell is not often so large as above mentioned. 



Marblehead, seven fathoms mud {Haskell} ; Halifax ( Willis) ; East- 

 port {Cooper}; Stonington {Linsley}; Montreal, fossil (Daivson}. 



Its rounded-oval and regularly convex form, with its radiating 

 lines, forbid that it should be confounded with any other shell ex- 

 cept an English species, the Crenella elliptica of Brown {Conch. 

 Illust. of Great Brit., SfC. pi. 31, f. 12 to 14), the Mytilus decussa- 

 tus of Montagu. For my own part, in comparing a small specimen 

 of this shell with one of ours of a similar size, I must confess I can 

 discover no difference, though Mr. Sowerby supposes they are dis- 

 tinct. In giving the dimensions, I have supposed the shell to be 

 placed in the ordinary position of other species, with the beaks 

 placed laterally. 



Crenella pectinula. 



Fig. 85. 



Shell obovate, ventricose, with about forty equal, radiating ribs ; beaks promi- 

 nent, projecting as far as the anterior margin ; epidermis brownish yellow. 



MocUola pectinula, Gould, Inv. Mass. 127, fig. 8.5. — Mighels, Catal. in Best. Journ. 



iv. 326. — De Kay, Nat. Hist. New York, 18.5. 

 Mytilus pectinulus, Stimpson, Shells of New England, 11 (1851). 

 Crenella pectimda, Stimpson, Smith. Inst. Check Lists (1860), 2. 



Shell small, strong, of a strictly ovate form, excepting that a very 

 short portion of the hinge-margin is straight ; broadly rounded at 

 both extremities, but most so behind ; valves convex, with- 

 out any marked ridge passing from the beaks, and very 

 little compression at the hinge-margin ; beaks rather 

 prominent, blunt, and in contact with each other, reach- 

 ing forward as far as the anterior extremity ; surface cov- 

 ered with about forty equal, rounded, radiating ribs ; epidermis a 

 dark gamboge-yellow ; lines of growth minute ; within pearly, of a 

 livid or leaden color ; entire margin crenulated by the ribs ; cavity 

 of the beaks considerable. Length, seven tenths of an incli ; height, 

 one half uich ; breadth, seven twentieths of an inch ; another speci- 

 men, nineteen twentieths by thirteen twentieths of an inch. 



