PLANORBIS, 119 
There is no mistaking this elegant little shell, which is 
found on weeds and on the underside of decaying leaves 
in ponds and ditches throughout Great Britain. 
The variety cvzsta which is commonly found with the 
type, is an exceedingly beautiful object under a lens. 
Var. I. crista (Linné). Ridges of epidermis exagger- 
ated to points, 
Var. Il. Jlevigéta (Adami). Without ridges. 
3). Px DIEATATUS (expanded) Gould. PIs VI.;, f.. 12; 
Flattish above, extremely convex beneath; zw/or/s 2 to 23, dull ; 
nearly opaque ; #zouth exceedingly expanded and very large ; sztzvre 
distinct ; zzbz/¢cus narrow, but deep. A. Imm. B. 2 mm. 
This little shell was imported from America in cotton 
bales. It was first noticed by Mr. T. Rogers, of Man- 
chester, in 1869. The only places where it has yet been 
observed to have made itself at home are the Bolton 
Canal, and the Reddish Canal (between Stockport and 
Manchester), where there are cotton mills, and at Burnley 
in a mill “lodge” or small reservoir adjoining the mill. 
g J g 
An Be ALBUS Conic) Ataller. PlioVisy £4 
Flattish above, with sfzrve depressed; dull white, very finely 
striated in line of growth, but more distinctly marked with raised 
strice spirally ; microscopically hispid ; wov/s5. A.2mm. B. 7mm. 
This little shell often belies its name, being frequently 
found black with dirt. Under a powerful lens its delicate 
striations are visible, as well as rows of minute hairs 
