36 
VALYATID^. 
that all conoid shells are more depressed in their 
young state, have, from the peculiarity of their forma- 
tion, regarded the young as a distinct species under 
the name of Valvata depressa, (See f. 8. a. b, c.) 
The animal and operculum are Avell described by 
Montagu {Test, Brit, 351.), who justly compared 
the animal to that of the next species, though in his 
arrangement one shell is a Turbo and the other a 
Helix; but he saw the difficulty of this arrange- 
ment. See his note at p. 367., and also at p. 461., 
where he describes the animal of V. cristata. 
8. 2,Y aIjY XT K cristata. Crested Valve Shell. — Shell 
discoid, flat above, and umbilicate beneath; 
whorls 3. (t. 10. f. 115.) 
Yalvata cristata. Gray, Man, 98; Muller, Verm. 198. ; Alder, 
Mag. Zool. and Bot. ii. IIG. ; Tories and Hanley, B.M.m. 
20. t. 71. f. 11. 12, 13. — Yalvata spirorbis. Drap. p. 41. t. 
1. f. 32, 33. ; Brard, p. 187. t. 6. f. 15, 16. ; Turton, Man.^A 
1. 131. f. 115. — Valvata Miilleri. Leach, Syn. Moll. 205. 
Kerita valvata. Gmel. 3675. — Helix cristata. Mont p. 46. ; 
Vign. 1. f. 7, 8. — Planorbis cristatus. Flem. Ed. Ency. vii. 
69. — Trocbus cristatus. Maton and JEtachet, Linn. Trans. 
viii. 167. — Turbo cristatus. Turton, Diet. p. 227. — Yalvata 
planorbis. Moll. 42. ; Drap. Tab. 41. t. 1. f. 34, 35.; Tur- 
ton, Man. ed. 1. 132. f. 116. (?) — Yalvata pulcbella. Studer, 
Coxe's Trav. iii. 436. — Valvata brancbialis. Gruithuisen, 
Nov. Act. Nat. Cur.x. 1821, 437. t. 38. f. 13. — Junior. Yal- 
vata minuta. Drap. 42. t. 1. f. 36 — 38. ; Turton, Man. ed. 1. 
f. 117. 
In ditches and canals, on aquatic plants. 
Shell about the tenth of an inch in diameter, pale 
horn-colour, striate transversely, with three volu- 
tions ; the upper surface a little sunk, the under side 
umbilicate, so as to expose the interior volutions. 
