180 



Pupa quadridens 



polyodon 



variabilis 



frumentum 



secale 



Pupa avena 



granum 



fragilis 



dolium. 



umbilicata 



Pupa muscorum. 



CLAUSILIA. 



TURBO TRIDEtfS. 



Chem.9, tah. 112,^.957. 

 The characteristic name of Clausilia was, in the first in- 

 stance, given to shells in which the entrance of the open- 

 ing was closed at a certain depth by a moveable ovate 

 testaceous lid, performing the office of an operculum, 

 and supported by a thin elastic pedicle, inserted in the 

 columella: the lid closes upon the animal when it re- 

 treats within its dwelling, by means of the pedicle acting 

 as a spring. Lamarck has not been able to ascertain that 

 all the examples he has given of this genus are so pro- 

 vided, but concludes they should be, and has consti- 

 tuded the present genus, from the other constant and 

 similar characters to be observed in them ; the most 



