97. Planorbis alhus. Shell concave on both sides, 

 with fine raised hispid spiral striae. 



Planorbis albiis. Leach, Mollusc, j^- 156. 

 Planorbis hispidus. Drap. p. 43. t. l.f. 45 — 48. 



Brard,p. 159. t. 6.f, 6, 7. 



Helix alba. Mont. p. 459. t. 25, f. 7. 



Shell about a quarter of an inch in diameter, very 

 thin and brittle, pale horn-colour, marked with 

 very fine close-set raised circular striae, which are 

 clothed with deciduous bristles, and crossed with 

 obscure longitudinal lines : volutions five, the first 

 very large and rounded ; the upper surface a little 

 sunk in the middle, the under side more strongly 

 concave : aperture roundish-oval, dilated, higher 

 than wide, with the upper angle much produced. 



When quite fresh, this beautiful species is clothed 

 with a fine velvety pile composed of short points 

 seated on the raised concentric striae, and which fall 

 off with the epidermis ; and in its depilated state 

 may be the Helix Spirorbis of Linne, as he no 

 where also mentions so very common a species, 

 Gmelin having probably quoted it twice, both as 

 H. Spirorbis and H. alba. In this state it answers 

 well to his character of //. Spirorbis, in the Fauna 

 Suecica, " testa utrinque concava^ plana, albida : 

 anfractibus quinque teretibus." 



