Ill 



Clausilia. 



Singular land shells, of a produced spiral form. 

 Mouth provided with teeth, and having within the 

 throat an elastic testaceous val?e, which closes when 

 the animal retires within it, as a trap-door. 



The animal is broad, but not long ; has four tenta- 

 cles, the lower pair of which are very short. 



Clausilia nigricans [The Dark Close Shell]. 



Maton and Rackett. 



Figure 80. 



80, 



The common Clausilia, as it is usually called, was 

 first described by Dr. Lister, in the year 1678. Although 

 a generally distributed species throughout Great Bri- 

 tain, yet it is but little known, save to the conchologist, 

 its habits and colour rendering it an object easily to be 

 passed over. It is the only species of this interesting 

 family found in this neighbourhood. 



Long, narrow, and spiral ; slender, yet strong ; shin- 

 ing; aperture nearly oval; peristome white, and 

 scarcely reflexed. Colour, deep brown. The shell is 

 covered with raised strioe, placed longitudinally. There 

 are from seven to eleven convolutions. The animal is 

 not operculaled, but in place of this appendage it is 

 provided with an elastic valve for its protection when 

 retired within the shell. 



