valvatid^:. 97 



These animals have been well described by Miiller, 

 Montagu, Nilson, Hartmann, and others. Montagu 

 showed that Turbo fontinalis, which Miiller had refer- 

 red to Nerita, should be placed in the genus which 

 Miiller had established under the name of Valvata, 



5. 1. Valvata Miiller, (Valve Shell.) 



Shell with the spire a little elevated, or flat and disk- 

 like ; aperture quite circular, united all round, and 

 furnished with a horny operculum marked with a 

 single raised spiral membranaceous line. (p. 78. f. 14.) 

 So named from the valve or lid which covers the 



orifice of the aperture. 



7. 1. Valvata piscinalis. Stream Valve Shell, (t. 8. f. 



114.) Shell globular, with an elevated obtuse 



spire, and a deep central umbilicus. 

 Nerita piscinalis. Miiller ', 172. 

 Valvata obtusa. Brard, p. 190. t. 6. f. 17. ; Turton, 



Man. ed. 1. 130.; Pfeiffer, 198. t. 4. f. 32. t. 1. 



f. 13. 

 Cyclostoma obtusum. Drap, p. 33. t. 1. f. 14. 

 Turbo fontinalis. Mont. p. 348. t. 22. f. 4. 



thermalis. Dilhvyn, p. 852. 



Helix piscinalis. Gmel. 3627. 



Valvata piscinalis. Lam. vi. 172. ; Kenyon, Mag. 



N. Hist. iii. 425. f. b. c. d. ; Alder , Mag. Zool. and 



Bot. ii. 116. 

 Lymnea fontinalis. Flem., Ed. Ency. 



Young rather depressed, umbilicus rather wider. 

 Helix fascicularis. Alien Syst. 74. t. 8. f. 16. 

 Valvata depressa. Pfeiffer. 



minuta. Pfeiffer. ? 



F 



