MARINE MOLLUSCA OF THE UNITED STATES. 25 



* Shell ventricose, rounded. Nos. 1, 2, 3. 

 * Shell angulated by revolving ribs. ISTos. 4, 5. 



1. F. ISLANDICUS, Ginelin. Fig. 34. 



(Murex.) Syst. Nat., 3555. 1790. 



Murex corneus, Pennant, Brit. Zool., iv. 124, t. 76, f. 99. 1777. 

 Fusus corneus,S&j, Amer. Conch., t. 29. 



Shell elongated, symmetrically fusiform ; spire regularly atten- 

 uated to the apex; volutions eight, slightly convex ; body-whorl 

 equally inflated, its surface covered with between forty and fifty 

 small revolving ribs which are conspicuous through the epidermis ; 

 these become almost effaced towards the outer lip, when the ver- 

 tical, sinuous striae appear in their place. These ribs, or revolving 

 elevated lines, are reduced to fifteen on the next whorl above, dimi- 

 nishing in numbers as they ascend, the intervening furrows becoming 

 more profound, with very faint traces of vertical lines. Aperture 

 oblong-ovate, half the length of the shell ; canal short, sinuous and 

 wide. Callus on the columella broad ; lip sharp, very minutely 

 impressed by the terminations of the revolving lines. Color 

 Epidermis horn-colored or soiled brown ; surface beneath whitish 

 opalescent ; within, pearly white. 



Length of shell 2.9 inches. 



Animal white, with irregular black spots ; foot rounded, rectan- 

 gular ; eyes black. 



Massachusetts, northward. . 



2. F. PYGM^EUS, Gould. Fig. 35. 



Invert. Mass., 1st edit., 284, f. 199. 1841. 



Shell same shape and similarly marked as F. Islandicus^ but 

 having only'six whorls and only one-fourth the size, being about 

 three-quarters of an inch in length. Animal pure white, with large 

 foot, broadly truncate in front. 



Maine, northward. 



3. F. VENTRICOSUS, Gray. Fig. 36. 



Zool., Beechy's Voyage, 117. 

 Fusus Islandicus (Yar.), Kiener, Sp. t. 15, f. 2. 



Shell subfusiform, ventricose ; whorls five, rounded, rapidly at- 

 tenuating to a blunt apex ; body-whorl much inflated, composing 

 the greater part of the shell. Surface covered with a velvety 

 epidermis, under which numerous minute and regular revolving 

 lines, with a few vertical wrinkles, are apparent. Spire short, not 

 exceeding .4 above the body-whorl ; lip simple, smooth ; colu- 



