56 The Shell-Collector’s Handbook. 
ANODONTA CYGNEA, LINN. 
SHELL very large, oval, compressed in young but ventri- 
cose in old specimens, thin, glossy, dull green, more or 
less tinged with a dusky tint; umbones small, convex ; 
lunule indistinct; umbonal region plaited; hinge-line 
straight ; ligament long; anterior side rounded, not 
gaping, and abruptly sloping downwards; posterior side 
compressed above, gaping, and produced into a rounded 
cuneiform point ; lower margin straightish. Animal grey, 
yellowish-grey, or reddish-grey. 
Habitat.—Lakes, ponds, canals, and muddy rivers. 
v. radiata (Mull): Shell larger, with yellow rays 
(= Mytilus radiatus, Mull, Verm. hist., ii., p. 209). 
v. incrassata (Shepp.): Shell more swollen and solid, 
olive brown; upper margin slightly curved on its posterior 
side (= Mytilus incrassatus, Shepp. Linn Trans. xii., p. 85, 
pl. 6, f. 4). 
v. Zellensis (Gimel.): Shell yellowish-brown, broader, 
with the upper and lower borders nearly parallel ; posterior 
side much produced (= Mytilus zellensis, Gmel., Syst. Nat., 
1788, i., p. 3262). 
v. pallida (Jeff.): Shell light yellow or fawn-colour ; 
hinge-line rather curved, and raised on the posterior side, 
which is produced to a long wedge-like point; lower margin 
rounded. (B.C., vol.i. p. 42.) 
v. rostrata (Rossm.): Shell oblong-oval ; upper margin 
forming a dorsal crest, which is slightly raised and curved ; 
anterior side rounded; posterior side attenuated, and 
ending in a long curved wedge-like point; lower margin 
nearly straight. B. C., vol. i, p. 42. (=A rostrata 
(Kokeil), Rossmissler, Iconogr., iv., p. 25, f. 284). 
