FAMILY COLIMACEA. 107 



Pupa nmscorum. (Much enlarged.) 



Genus XI. PUPA, Lamarck. 



Animal ; body rather short, slenderly acuminated towards the tail, 

 carrying a horny narrow-whorled shell, mostly brownish or 

 slate-grey, dark-streaked on the neck and back, pale towards 

 the sides ; upper pair of tentacles rather short, lower pair very 

 short. 

 Shell ; cylindrical, narrowly umbilicated, composed of from six to 

 nine semitransparent homy glossy whorls, mostly smooth, 

 rather obtuse at the apex, rounded at the base ; aperture some- 

 what triangularly ovate, generally more or less toothed within, 

 the teeth having a parietal form, winding in thread-like ridges 

 into the interior. 

 Land snails are suppbed with two pairs of tentacles ; water snails 

 with only one pair. In the genera on the confines of these two 

 primary divisions, Pupa and Vertigo on the one hand, CarycMum 

 and Auricula on the other, an intermediate state of these organs 

 exists. The lower tentacles lessen until they are reduced to rudi- 

 mentary protuberances ; finally they are represented by mere 

 specks, and disappear without a trace of any kind. 



In Pupa, the lower tentacles are always present, but they vary 

 considerably in their development between short symmetrical ten- 

 tacles and blunt protuberances. Pupa fives chiefly in damp places 

 among moss or under stones. Vertigo is almost amphibious in 

 habit. It fives, with rare exception, at the roots of grass in wet 

 places, and the lower tentacles are either represented in the most 

 rudimentary form or are wanting. 



We have only four Pupa in Britain, outlying forms of a generic 

 type which, like Clausilia, has its centre of creation in Southern 



