238 Lamarck's Genera of Shells. 



being contiguous to the axis of the shell, whereas, in that ge- 

 nus, it is very remote from it. Lastly, the right margin, in the 

 adult helix, is reflected outwards, which it never is in aquatic 

 shells. The Helix is readily known by the projection of the 

 penultimate whorl into the aperture, whence Linnaeus described 

 it, " aperturd intus lunatd ; segmento circuli dempto." 

 The animal has great resemblance to the limax. 

 The species of this genus are almost innumerable — Lamarck 

 describes only those in his own collection. 



Type. Helix gigantea *. (Helix cornu militaire. Linn.) 

 Shell orbicular-convex, imperforate, solid, white; epidermis 

 red-brown ; whorls transversely striated, aperture wide ; lip 

 white within ; margin reflected. Germamj. PI. VIL Fig. 130. 

 107 species. 



2. Carocolla. 



Shell orbicular, more or less convex, or conoldal, on the 

 upper part, with a sharp, angular periphery. Aperture trans- 

 verse, contiguous to the axis of the shell ; right lip subangular, 

 often toothed on the lower part. 



The sharp edge of the last whorl, their being always orbicu- 

 lar, and sometimes considerably depressed, are the principal 

 characteristics of the shells of this genus. 



Type. Carocolla acutissima t. 



Shell discoidal, convex on both sides, imperforate ; periphery 

 compressed and very acute ; tawny; strise small, oblique, very 

 minutely granular; margin reflected, bidentate at the lower 

 part, Jamaica. PI. VII. Fig. 131. — 18 Species. 



3. Anostoma |. 



Shell orbicular, spire convex and obtuse. Aperture rounded, 

 toothed within, ringent, turned upwards ; margin of the right 

 lip reflected. 



The singular position of the aperture, directed upwards, to- 

 wards the spire of the shell, is the characteristic of this genus, 

 and peculiar to it. 



* Gigantic. Lamarck's second species — his type is H, vesicatis. 

 t Very acute, t From av», upwards, and tfhf**, a numth. 



