146 VALVATIDA. 
I. V. PISCINALIS (2ahabeting fish ponds) Miller. P\. VIII, f. 9. 
Globular, nearly opaque, brownish yellow ; wor/s 6, cylindrical ; 
spire blunt; szture very deep; mouth circular; wmbzlicus deep ; 
operculum concentrically spiral. A. 64mm. B. 65 mm. 
This species is found in lakes, canals, and _ rivers, 
throughout the British Isles, as far north as Perth. It 
is nearly always covered with a green confervoid crust 
which is very difficult to remove. ‘The largest specimen I 
have seen is one that I took at Norwich, measuring 
7?mm. I have some from Doxey Brook near Stafford, 
with the whorls disconnected. 
Var. I. depréssa (C. Pfr.). Flatter, umbilicus larger. 
Var. II. antigua (Sow.). [=var. subcylindrica (Jeff.). | 
Spire more raised. 
Var. III. pusilla (Mill.). Smaller, striz stronger, 
whorls 43. 
Var. IV. adlbina (Taylor). White. 
Monst. szzzstrorsum (Jeff.). Reversed. 
2. V. CRISTATA (crested, t.e. with branchial plume) Alitller. 
Pe VEE, iro, 
In shape a circular coil; glossy, light horn-colour; whorls 5; 
mouth circular; operculum concentrically spiral. A. 3mm. B3§ mm. 
This pretty little shell frequents canals, lakes, and 
ponds, especially among the roots of flags. It is rather 
local, but is distributed from Orkney to the south of 
England. In Ireland it is still more local, and has not 
been recorded for the south-west. 
Var. dlba (Rowe). White. 
