CLAUSILIA. 169 



those upon which moss and lichens grow, such as the 

 apple, crab, and thorn ; also in the crevices of rocks. 

 The shells of this species might easily be mistaken 

 for immature or half-grown specimens of Claiisilia 

 riigosa, were it not that the periphery of Balia is 

 rounded, and has scarcely any trace of angularity, 

 while that of the young of C. riigosa is sharply 

 angulated. 



These little snails are gregarious. During the day- 

 time, especially in dry weather, they conceal them- 

 selves under the bark of trees or in the fissures of 

 rocks, and sally forth in the evening, or after a shower 

 of rain. When unable to find them in any other 

 way, I have frequently succeeded in obtaining speci- 

 mens by examining the rotten branches of trees 

 which after a gale are strewn upon the ground. 

 According to Eouchard-Chantereaux, their eggs, 

 which are large in proportion to the size of the 

 animal, are laid in early autumn, and vary in number 

 from fifteen to twenty. The young are hatched about 

 fifteen days afterwards, and attain maturity at the 

 end of the first year. Mr. Rich says that this species 

 is viviparous. 



Var. viridida. — Shell greenish-white, transparent. Near Cork 

 (Humphreys), B.C. 



GENUS IX.—CLAUSI'LIA* DRAPARNAUD. 



Body slender, elongated, capable of being entirely contained 

 within the shell ; tentacles 4, upper pair long, lower pair very 

 short ; foot long, slender. 



* So named because of the clausium^ or apparatus by which the 

 aperture of the shell is closed. 



