The Shell-Collector’s Handbook. 69 
another, and elevated into a spiral cone, (= Helix cochlea. 
Brown. Wern. Trans. ii., t. 24, £. 10—Hela terebra. 
Turton. Conch. Dict. p. 62, f. 55). 
PLANORBIS CORNEUS, LINN. 
SuHeEtt reddish brown in colour, sometimes white, glossy, 
nearly opaque, obliquely striate; whorls five to six, rounded 
above and below; periphery not keeled; suture deep; » 
mouth semilunar; umbilicus broad and shallow. Dia- 
meter of shell 3-1 inch. Animal nearly black. 
Habitat——Muddy streams, marshes, ponds, and ditches. 
1. v. albina (Jeff:): Shell perfectly white. (B. C., vol. 
1., p. 94.) 
2. v. albinos (Mogq.): Shell whitish, very transparent. 
(Mog. Tand. Hist. Nat. Mollusques de France, p. 445.) 
PLANORBIS CONTORTUS, LINN. 
SHELL nearly flat above, with a deep concavity in the 
middle, deeply umbilicate below, solid, opaque, yellowish 
or brown-horn colour; whorls eight, compact and narrow; 
suture deep; mouth crescent-shaped, very narrow; um- 
bilicus large and deep. Diameter of shell ;4ths inch; 
thickness ;oth inch. Animal grey or blackish. 
Habitat.—Lakes, ponds, and ditches. 
v. albida (Jeff.): Shell nearly white. (B. C, vol. 1, 
p. 95.) 
v. excavata (7. D. A.Cockerell): Shell much depressed, 
and sunken above. 
PLANORBIS DILATATUS, GOULD. 
“Tus shell is about the same size as P. nautileus, which 
may be considered its nearest ally; but it has one whorl 
