211 



SCALARIA. 



turbo scal/uus. — Linn, 



Sowerby's Genera, No. 1 1, pi. 2. 



The Scalariae are marine shells, very easily distinguish- 

 ed from the G. Cyclostoma, (though they have, a circu- 

 lar aperture), not only as to habitat, and their turreted 

 form, but by their longitudinal, elevated ribs, which are 

 never connected together, rather oblique, and almost 

 sharp: these ribs are only the thin reflected margins of 

 previous terminations of the opening, each exhibiting 

 the growth and addition made by the animal to the 

 shell, at successive periods of enlargement: these ter- 

 minations are very different in terrestrial shells, never 

 being left at a former stage of growth. The spire of 

 theScalaria is more or less elongated in the different spe- 

 cies, but in all yet known the succeeding whorl is always 

 larger than the preceding, which occasions the turreted 

 form of these shells to differ from the cylindrical shape 

 of the Pupae, to which they may be said to bear some re- 

 semblance; they, like the Scalariae, having numerous 

 ribs on the whorls, though their form is much more cy- 

 lindrical. The aperture of the Scalariae, is round or 

 nearly so, the edge of it thickened, sharp, and outward 

 p2 



