CLAUSILIA. 177 



Shell about a quarter of an inch long, slender, and 

 tapering to a rather sharp point, transparent yellowish 

 horn-colour, slightly striate longitudinally ; spire 

 consisting of from six to nine raised and well-defined 

 volutions ; aperture roundish-oval ; the peristome 

 thin, simple, and a little reflected at the pillar, so as 

 to form a slight umbilicus. In old and full-grown 

 shells there may be observed a slight fold or tooth 

 about the middle of the pillar, but which is seldom 

 to be met with. 



These shells vary considerably in their size, colour, 

 and shape, some being more ventricose than others. 

 Mr. Jeffreys, probably forgetting that these animals 

 are all hermaphrodite, observes, " The females have 

 their shells much more ventricose and with fewer 

 volutions." (Linn. Trans, xvi. 351.) 



13. CLAUSILIA. (Close Shell.) 



The animal like Bulimus ; but the shell is reversed, 

 with an elongated, slender, fusiform spire, the 

 last volution less tumid than the one before it, 

 with an obtuse or papillary summit; aperture 

 oval, oblique, united all round and margined, 

 toothed ; throat furnished with an internal spi- 

 ral shelly plait, or clausium, fixed on an elastic 

 pedicle, which closes the cavity when the animal 

 is withdrawn. 



Jaw lunate, narrow, with a slight central pro- 

 minence, nearly smooth. 



The elegant spindle-shaped outline of the shell of 

 this family having the last volution slenderer than the 



N 



