ANODONTA. 17 



i. ANODONTA CYG'NEA,* LINN. PL. III. 



Body longish oval, compressed, grey, with sometimes a 

 yellowish or reddish tint ; foot dirty yellow, more or less tinged 

 with orange or red ; mantle brownish at the edges ; gills (lower 

 orifice) grey, or reddish-grey, somewhat resembling gauze. 



Shell oblong, somewhat swollen, thin, rather glossy, greenish- 

 yellow, sometimes brown, with irregular grooves formed by the 

 lines of growth, strongly wrinkled on the posterior and lower 

 sides ; epidermis thin ; beaks straight, placed away from the 

 centre ; iimbonal region strongly plaited, compressed ; ligament 

 long ; hinge line straight ; anterior side rounded, sloping 

 abruptly downwards, not gaping ; posterior side somewhat com- 

 pressed above, sloping gently, ending in a rounded wedge-shaped 

 point, gaping ; lower margin straightish ; inside white, pearly, 

 iridescent ; hinge small, sharply ridged in both valves on the 

 posterior side ; scars very indistinct. 



Inhabits sluggish rivers, canals, ponds, &c., in most 

 parts of Great Britain, as far north as the counties of 

 Banff and Perth. 



Var. i. radiata. Shell larger, yellowish-green, beautifully 

 marked with longitudinal rays or streaks of the same colour ; 

 beaks placed at a distance of only one-third from the anterior 

 side. Bog of Allen, Ireland, Clumber Lake, Notts, B.C. Near 

 Birmingham (G. Sherriff Tye), near Wakefield (J. Hebden), J.C. 



Var. 2. incrassata. Shell more swollen and solid, olive- 

 brown ; upper margin or hinge line rather curved on the pos- 

 terior side. Scarborough, Otterspool, Lancaster, Oxwich Marsh, 

 Swansea, B.C. Near Birmingham (G. Sherriff Tye), J.C. River 

 Earn, Perthshire (F. Buchanan White), S.N. River Irvine, 

 Ayrshire (McMurtrie). 



Var. 3. Zellensis. Shell broader, yellowish-brown, having the 

 upper and lower sides nearly parallel ; posterior side much pro- 

 duced. Bog of Allen, Ireland, Clumber Lake, Notts, B.C. 

 Near Birmingham (G. Sherriff Tye), J.C. 



Var. 4. pallida. Shell light yellow or fawn-colour ; hinge 



* Of or belonging to swans, as those birds feed upon it. 



C 



