VALVATA. 



37 



a, animal ; b, gill ; 

 c, operculum. 



Mr, Alder observes (Mag. Zool. and Sot. ii. 117.), 

 " Dr. Turton has introduced two other species, 

 V. planorbis Drap. (f. 116.), and V. minuta Drap. 

 (f. 117.), into his Manual, but no specimens of them 

 are now to be found in his cabinet." Mr. Alder 

 says he took some pains to Fig. 9. 



investigate these two species 

 when in Paris, on examining 

 three of the principal collec- 

 tions there ; those of the Jar- 

 din des Plantes, the Baron 

 de Ferussac, and the Due de 

 Rivoli. "In the latter only, 

 I found any thing under the name of V. pla- 

 norbis. The specimens (which were originally La- 

 marck's) were V. cristata Miiller. M. de Ferussac 

 had specimens, under the name of V. minuta, from 

 two different individuals. Those from M. Pfeiffer 

 are, I think, the young of V. cristata, and the others 

 (I forget from whom, but with the name of Dra- 

 parnaud) the young of V. piscinalis. Mr. Miller in- 

 troduced V. minuta into his catalogue of the land and 

 freshwater shells of the environs of Bristol, but no 

 specimen of it is preserved in the Bristol Museum. 

 Dr. Turton says that his V. minuta is the Helix 

 serpuloides of Montagu. This is well known to be 

 a marine shell, referrible to the genus Skenea of 

 Fleming. Mr. Thompson of Belfast has, however, 

 favoured me," continues Mr. Alder, " with the ex- 

 amination of a shell which may possibly turn out to 

 be the V. minuta Drap., though I suspect it to be 



marine.' 



D 3 



