HELIX. 215 



profusion, as to give a saffron tinge to the trace whicli it 

 leaves on objects over whicli it crawls. It is distributed 

 over the animal, and arranged in minute points, which 

 are most thickly clustered on the margin, and on the 

 glandular tubercles of the surface. 



The shell varies in being more or less depressed, and 

 in having the striae more or less rough. In the young 

 shell the margin is carinated, especially at its junction 

 with the second whorl. On many individuals there is a 

 distinct, uncolored line on the centre of the outer whorl, 

 dividing the rafous bands of the superior surface from 

 those on the lower surface. There is a variety in which 

 the shell is destitute of color ; another in which the spire 

 is sunk below the last whorl, leaving a projecting shoul- 

 der ; a third which remains carinate when mature ; and a 

 fourth in which the striae of increase are replaced by dis- 

 tinct, prominent, sharp ribs, placed rather widely apart. 



This species was described and published by Mr. Say, 

 in 1818, as H. alternata. In 1822, Lamarck gave it 

 the specific name of scabra, a name pre-occupied by a 

 species of Chemnitz. Say's name has the priority and 

 is adopted in this country, as it should be elsewhere. 



Lister's figure, Synops. t. 70, f. 69, represents this 

 species. It is also noticed in the London Philos. Trans- 

 actions, XX. (1698) No. 246, p. 395. 



