57 



ON THE RADUL^ OF VITREA HELVETICA, BLUM., AND THE 

 ALLIED SPECIES. 



By Rev. E. W. Bowell, M.A. 



Read IQth January, 1908. 



The radulaof V. helvetica, Blum. (Fig. 2), is a very characteristic organ, 

 and by it the species may be distinguished from other Vitrew, so far 

 as my own investigations have gone. The central tooth is small, and 

 its basal plate remarkably quadrate ; central cusp long, with sides 



F.-3 2- 



Each divisiou of the scale represeuts teu micra. 



nearly parallel. There are but two well-developed laterals (admedians), 

 and these are also remarkable for the squared character of their basal 

 plates. Their mesocone and endocone together are of a compactly 

 rounded shape, somewhat suggestive of the appearance of a half-closed 

 fist ; the ectocone is closer than usual to the mesocone, on account of 



VOL. vm. — MAiicH, 1908. 5 



