18 AMERICAN MARINE CONCIIOLOGY. 



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

 ing the e3'es on prominences near their bases, outside ; foot short, 

 angular in front; branchial plume single, long. 

 Subgenus Arrhoges, Gabb. 

 Am. Jouru. Couch., iv. 145. 18G8. 

 Shell fusiform, anterior canal nearl}' obsolete, no posterior canal, 

 outer lip expanded, simple. 



1. A. occiDENTALis, Bcck. Fig. 125. 



Gueriu, 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 dusk}^; beneath 



bluish-white. Length 2.25 ; width 1.5 inches. 



Maine, northwards. 



Family MURICID^. 

 Animal with a broad foot ; e^'es sessile on the tentacles, or at 

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

 Teeth in three scries (M'l) 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. 



Synoxisis of Genera. 



1. Not umhilicated. Outer Up thickened. 



Lip tcithout folds ; ichorls tcith varices. 



Shell ornamented with three or more continuous longitudinal varices ; 



aperture rounded ; beak often very long ; canal parti}' closed ; operculum 



concentric ; nucleus sub-apical. Murex, Linn. 



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



Ranella, Lam. 



2. Not uinhilicatcd. Columellur lip icith folds ; no varices. 



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

 open ; coluniellar lip tortuous with several oblique folds. Operculum 

 claAV-shaped. Fasciolaria, Lam. 



Shell cancellated ; aperture channelled in front ; columella with several 

 strong oblique folds ; no operculum. Cancei.laria, Lam. 



3. Umhilicated. Shell spirally furroiced ; columella without folds. 



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



columella obliquely truncated ; operculum lamellar, nucleus external. 



Trichotropis, Bred. 



