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The Shell-Collector’s Handbook. 65 
PLANORBIS LINEATUS, WALKER. 
SHELL quoit-shaped, depressed, glossy, semitransparent, 
yellowish horn-coloured; whorls four, with two to five 
curved transverse plates inside the last whorl which 
appear as whitish lines when seen from the exterior ; 
periphery obtusely carinated; mouth obliquely cordate. 
The last whorl is larger than the rest of the shell, and 
conceals nearly two-thirds of the penultimate whorl. 
Animal brown with a reddish or violet tinge, sparsely 
speckled with black. 
Haiitat.—Slow streams and ponds in the home and 
eastern counties of England. 
v. albina (Taylor): Shell milk-white and transparent. 
PLANORBIS NITIDUS, MULLER. 
SHELL depressed, discoid or quoit-shaped, thin, glossy, 
semi-transparent, yellowish horn-coloured, more or less ~ 
reddish; upper surface more convex than the lower 
surface ; whorls four to five, the outer whorl being very 
large in proportion to the rest, covering one-half of the 
preceding whorl, and obtusely carinated in the middle; 
suture deepish; umbilicus small, shallow. Diameter of 
shell, 23 lines. Animal reddish-brown marked with fine 
grey specks. 
Hatitat.—On fallen leaves of trees, also on aquatic 
plants, in ponds and ditches. 
v. albida (Nelson) : Shell white. 
v. minor (Jeff. MS.) : Shell small. 
PLANORBIS NAUTILEUS, LINN. 
SHELL depressed, thin, subpellucid, rather concave above, 
rather convex below, dull light brown or grey, not glossy ; 
periphery bluntly and indistinctly carinated; whorls 
three, the outer whorl strongly marked with transverse 
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