238 
LIMNJSADiE. 
t. 16. f. 89. (not 87.); Leach^ Syn, Moll. 114.; Tories and 
Hanley., B. M. iv. 153. t. 127. f. 4, 5. ; Bossm. Icon. i. f. 60. 
- — Helix carinata. Mont. T, B. 451. t. 25. f. 1. — Helix 
planala. Linn. Trans, viii. p. 189. t. 5. f. 14.. — Helix pla- 
norbis. Linn. S. Nat. i. 1242. ; Turton., Diet. p. 45. (not 
Da Costa'). — Helix complanata. Mont. T. B, 450. t. 25. 
f. 4. — Planorbis complanatus. Turton., Man. ed. 1. f. 89. 
(not description). — Planorbis lutescens. Jeffreys., Linn. 
Trans, xvi. 385. (not Lam.). — Planorbis planatus. Turton., 
Man. ed. 1. 110. f. 92. — Helix limbata. Da Costa, B. M. 
63. t. 4. f. 10., t. 8. f. 8. — Planorbis acutus. Poir. Prod. 91. 
(not Drap.) — Planorbis nmbilicatus. Studer., 92. (not 
Muller). 
Var. 1., keel more central, lower disk ratber more convex : 
Planorbis disciformis. Jeffreys, Linn. Trans, xvi. 521.; 
Alder, Mag. Z. and B. ii. 113. 
In stagnant waters. 
Animal brown. 
The animal, according to Montagu, differs from 
P. marginatus in the tentacles being somewhat longer, 
and particularly in their being pellucid, yellow, and 
not darker in the middle. ( T. B. 453.; Sturm, t. 43.) 
Shell hardly half an inch in diameter, with five 
volutions, the outer one growing suddenly larger, 
above nearly fiat, beneath rather convex, gradually 
shelving to the outer edge ; in the older specimens 
the hinder or upper part of the whorls becomes rather 
convex ; colour pale horn-colour and transparent, 
often covered with a brownish coat ; aperture con- 
tracted to a point above, in consequence of the keel. 
This species is immediately known from Planorbis 
complanatus by the under or front side of the whorls 
not being so convex and ventricose, by their shelving 
gradually to the outer edge, and by the hinder or 
upper part of the whorls of the older shells being 
rather convex, somewhat like the lower, which has 
