140 POPULAR BRITISH CONCHOLOGY. 



II. BiTHiNiA. — We have two species of this genus, which 

 differs from the last in two respects : — first, the operculum 

 is testaceous ; second, the animal is not vivij}arous, but ovi- 

 parous. Not having an opportunity of consulting the work 

 of M. Bouchard-Chantereaux, for his account of the repro- 

 ducing habits of the Bitliinia, I must be content to give an 

 outline taken second-hand from the work of Messrs. Torbes 

 and Hanley ; so that, if it be considered in the light of a 

 robbery to avail ourselves of tlie labours of others, I shall 

 only incur the pains and penalties of a ^^ receiver." 



''The Bithinia tentaculata lays from May to August. 

 There are usually from thirty to seventy globular, yellowish, 

 hyahne eggs, which are united together in a band, and at- 

 tached to stones or the stems of aquatic plants. When the 

 animal desires to lay, it seeks some smooth place, and begins 

 to clean the surface with its mouth before commencing. 

 That being done, it contracts its foot, so as to render itself 

 a third shorter than its usual dimensions when creeping, but 

 also a third broader. Then, ceasing to use its mouth, it raises 

 the centre of the anterior extremity of its foot, so as to form 

 a little canal, intended to receive the eg^. It next with- 

 draws its head a little within the shell, and directs its 

 muzzle towards the branchial orifice, where an ^^^ appears, 



