18 AMERICAN MARINE CONCHOLOGY. 



Animal with a broad short muzzle; tentacles cylindrical, bear- 

 ing the eyes on prominences near their bases, outside ; foot short, 

 angular in front; branchial plume single, long. 



Subgenus Arrhoges, Gabb. 

 Am. Journ. Conch., iv. 145. 1868. 



Shell fusiform, anterior canal nearly obsolete, no posterior canal, 

 outer lip expanded, simple. 



1. A. OCCIDENTALS, Beck. Fig. 125. 



Guerin, Mag. Zool., t. 72. 1836. 



Whorls eight to nine, convex, with numerous waving vertical 

 folds and regular conspicuous revolving lines; lip expanded, with 

 a blunt process above. Epidermis thick and dusky; beneath 



bluish-white. Length 2.25 ; width 1.5 inches. 



Maine, northwards. 



Family MURICHXE. 



Animal with a broad foot ; eyes sessile on the tentacles, or at 

 their base ; branchial plumes two. Lingual ribbon long, linear. 

 Teeth in three series (I'I'I) the central broad, the lateral versatile. 

 Mantle inclosed, the margin producing varices at intervals across 

 the shells, and extended in front, forming a straight, more or less 

 elongated siphon. Foot simple in front. 



Synopsis of Genera. 



1. Not umbilicated. Outer lip thickened. 

 Lip without folds ; whorls with varices. 



Shell ornamented with three or more continuous longitudinal yarices ; 

 aperture rounded ; beak often very long ; canal partly closed ; operculum 

 concentric ; nucleus sub-apical. MUBEX, Linn. 



Shell with two rows of continuous varices, one on each side. 



RANELLA, Lam. 



2. Not umbilicated. Golumellar lip with folds ; no varices. 



Shell fusiform, elongated ; not cancellated ; whorls round or angular ; canal 

 open ; columellar lip tortuous with several oblique folds. Operculum 

 claw-shaped. FASCIOLABIA, Lam. 



Shell cancellated ; aperture channelled in front ; columella with several 

 strong oblique folds ; no operculum. CANCELLARIA, Lam. 



3. Umbilicated. Shell spirally furrowed ; columella without folds. 



Thin, umbilicated ; spirally furrowed ; the ridges with epidermal fringes ; 



columella obliquely truncated ; operculum lamellar, nucleus external. 



TRICHOTROPIS, Brod. 



