91 



CONUS. 



A. Spire nearly truncate or flat. (Plate XllL 



%.l.) 



B. Pyriform. (fig. 2.) 



C. Elongated, (fig. 3.) 



D. Ventricose_, contracted at both ends. 



E. Thin^ ventricose. (fig. 4.) 



Shell univalve^ convolute and turbinate.— Aper- 

 ture effuse, longitudinal, linear, toothless, entire 

 at the base. Columella smooth. Base attenu- 

 ated, often marked with oblique rugose striae. 

 The aperture is sometimes dilated. The whorls 

 are mostly flat, often channelled, rarely crowned. 

 The superior beauty of this genus renders it highly 

 interesting, and the conical form distinguishes it 

 from all others, except the Voluta and Trochus, 

 the former of which has a plaited, and not a smooth 

 columella ; the latter a transverse, and not a lon- 

 gitudinal aperture ; and the conoidal form is erect, 

 and not inverted. 



