276 HELICID^E. 



prominent : umbilicus very slight, and consisting of a narrow 

 and oblique slit behind the pillar lip. 



The Clausilice are herbivorous. Some species inhabit 

 rocks, stony places, and old walls, while others seem to 

 prefer woods and shady spots, and are to be met with on 

 trunks of trees and under stones among herbage. They 

 bury their bodies and three-fourths of their shells in the 

 earth, and excavate a small oblique tunnel, for the pur- 

 pose of depositing their eggs. 



The malacological relations of this genus are with 

 Bulimus and Pupa. In the form of the shell it is allied 

 to both of those genera, setting aside the circumstance 

 of the spire in the present genus being reversed ; but 

 the spire in Bulimus and Pupa is shorter than in Clau- 

 silia. As in most of the species of Pupa, the laminar 

 teeth in Clausilia are never formed until the last whorl 

 has been commenced. 



A peculiar and characteristic feature of the present 

 genus is that the animal is provided with an internal 

 process called the " clausilium" It is analogous to the 

 testaceous appendages of Teredo, called " pallets ; " al- 

 though they are not homologous organs, nor is the clau- 

 silium attached to the body of the snail, like the pallets 

 to that of the Ship-worm. This remarkable process acts 

 as a valve or spring-door in closing the shell against all 

 intruders, and has been well described by Mr. J. S. 

 Miller, in the ' Annals of Philosophy ' for 1822 (vol. iii. 

 p. 378), in the following words : 



" Independently of the various contrivances which 

 Nature has resorted to for the protection of the otherwise 

 vulnerable Mollusca, it has taken peculiar care to guard 

 the apertures of many univalves from the intrusion of 

 enemies ; hence the apertures are sometimes peculiarly 

 contracted and provided with numerous folds and teeth. 



