CONCHYLIA— D/rifyE^. 55. 243 



Da Costa, p. 225, tab. 15, fig. 3. 



Donovan, British Shells, iii. tab. 73. 



Montagu, Test. Brit. p. 33. 



Linn. Trans, viii. p. 40. 



Turton, British Fauna, p. 146. 



Wood, Conch, p. 107. tab. 23. fig. 1-3. 



Dillwyn, Descript. Catal. p. 52. 



Turton, Conch. Diet. p. 106. 

 Musculus niger. Lister, Conch, tab. 149, fig. 4. 

 Mus. nost. In most rapid rivers. 



Shell two inches or more long, and four or five broad, covered 

 with a black wrinkled skin which fringes the margin ; inside black- 

 ish-white mixed with green, with a blackish border round the edge : 

 the front margin a little contracted in the middle, giving a some- 

 what curved outline to its figure. 



Young shells have the interior marginal edge, under the ligament, 

 raised into a kind of laminar process; but the teeth distinguish it 

 from the last family, and the terminal cavity from the next. 



5.5. MYSGA— TURTON. 



Test transversa, tsquivalvis, inaequilateralis, laterihus sub- 

 hiantibus ; umbonibus corrugato - verrucosis. Cardo dente 



2i2 



