SPHyERIUM. 3 



I. Sph^rium cor'neum,* Linn£. Pl. I. 



Body greyish, or occasionally of a reddish or brownish tint ; 

 foot rather longer than the shell, somewhat pointed, of a milky 

 hue, shghtly tinged with rose-colour towards the extremity ; 

 mantle grey at the edges ; siphons longish, truncate, of a pale 

 grey faintly tinged with flesh-colour. 



Shell rather globular, compressed in front, thin, shining, of a 

 pale horn-colour, marked in the hne of growth with lighter- 

 coloured bands, and often with brownish rays which proceed 

 from the beaks towards the front margin ; with very fine close- 

 set striae in the line of growth, which are intersected by still 

 finer lines ; epidermis thin ; beaks nearly central ; ligament 

 short, almost invisible externally ; inside of a faint bluish tint ; 

 hinge thick, with a small double cardinal tooth in each valve, 

 and two double lateral or side teeth in the right valve, and two 

 prominent single teeth in the left valve ; muscular impressions 

 (or scars) faint. 



Inhabits rivers, ponds, canals, &c., in every part of 

 Great Britain. 



Var. I. fiavescens. — Shell of a pale straw-colour, smaller and 

 more globular. Cumberland, Westmoreland, Grand Canal, 

 Dublin, Aberdeenshire, in a lake near Lerwick, B.C. Near 

 Birmingham (G. Sherriff Tye), J.C. Inverness-shire and Kirk- 

 cudbrightshire (F. Buchanan White), S.N. Near Colchester 

 (Laver), Stapleton near Bristol, Hampstead, Watford, Hendon 

 (Rich). 



Var. 2. nucleus. — Smaller and more globular. Crymlyrj, 

 bog near Swansea, Barton Run, Norfolk, Richmond, B.C. 

 Stapleton near Bristol, Bath, Hampstead, Watford, Hendon 

 (Rich). 



Var. 3. Scaldiana. — Shell more oval, and of a paler colour. 

 Oxwich marsh near Swansea, Thames at Clifden, and in many 

 places, B.C. Canal, Acock's Green near Birmingham (G. S. 

 Tye), J.C. Stapleton near Bristol, Bath, Hampstead, Watford, 

 Hendon (Rich). 



* Horn-coloured. 



B 2 



