CLAUSILIA. 249 



Pupa. — As is the case with most of the genera and species 

 of molkisca^ the name has reference to the shell, which is 

 very much like the chrysalis of a butterfly, being cylindri- 

 cal and pointed at the top. The shell is formed of. many 

 whorls, and the aperture has teeth or folds on its edge. The 

 animals are shorter in proportion than those of snails, and 

 their lower tentacles are very little, sometimes hardly at all 

 developed. All our British species are small, and their 

 distinctions minute ; the number and form of the teeth in 

 the aperture being important. Some of them are reversed 

 or sinistral shells. The species are — P. iimhilicataj the com- 

 monest species, found under stones, among lichens, near 

 the sea, or inland, on high and low grounds, in every posi- 

 tion ; P. muscorum, P. Anglica, P. secale, P. edentula, with- 

 out any teeth in the aperture ; P. minutissima and P. pi/g- 

 mcea, both very minute; P. suhstriata, having six teeth; 

 P. aniivertigo, with quite a labyrinth of them ; P. pusilla, 

 reversed, with six to eight teeth ; and P. Venetzii, also re- 

 versed. 



BALEA/m^^7^5 has a small, dull-coloured, many-whorled, 

 pyramidal shell, and in the character of the soft parts re- 

 sembles Bulimus. 



Clausilia. — The shells of Clausilice are long and narrow. 



