THEACIA. 231 



wall ; and Mr. Aider has taken some odd valves upon the 

 coast of Northumberland. 



In Ireland it has been taken alive by Mr. Warren on 

 the Dublin coast (Thompson), and has likewise been 

 met with in Cork harbour (Humphrey), in Strangford 

 Lough, and near Belfast (Thompson), and in Bantry bay 

 (M'Andrew). 



Some single valves have also been found at Arran (Alder), 

 It occurs fossil in pleistocene clays at Belfast. An account 

 of the animal of this remarkable shell is much to be desired. 



T. DISTORT A, Montagu. 



Small, variously-shaped, almost always indented at the mar- 

 gin, shorter in front ; umbones not prominent ; cardinal plate 

 rounded and projecting. 



Plate XVII. fig. 1, 2, 3, 8, and (animal) Plate H, fig. 5. 



Afi/a distorta, Mont. Test. Brit. p. 42, pi. 1, f. 1. — Linn. Trans, vol. viii. p. 37. 

 — TuRT. Conch. Diction, p. 101. — Wood, General Conch, p. 

 98. — DiLLW. Recent Shells, vol. i. p. 45. — Index Testae, pi. 2, 

 Mya, f. 15. 



Anatina , Turt. Dithyra Brit. p. 48, pi. 4, f. 5. — Brit. Marine Conch. 



p. 43.— Hanl. Recent Shells, p. 23. 

 Amj)Mdesma disioiium, Flem. Brit. Anira. p. 432. 

 Thracia distorta. Brown, 111. Conch. G. B. p. 110, pi. 44, f. 7. — Loven, Index 



Moll. Scand. p. 47. 

 Anatina riipicola, Lam. Anim. s. Vert. (ed. Desh.) vol. vi. p. 80. — Delessert, 

 Rec. Coquil. pi. 3, f. 4. 

 „ truncatu, (variety,) Turt. Dithyr. Brit. p. 46, pi. 4, f. 6. — Brit. Ma- 

 rine Conch, p. 41. — Hanl. Recent Shells, vol. i. p. 48. 

 Ampliidesma truncatiim, Flem. Brit. Anim. p. 431, 

 Thracia truncaia, Brown 111 Conch. G. B. p. 110, pi. 42, f. 28. 



From the nature of its habitat, and the various distor- 

 tions assumed for the purpose of accommodating itself to 

 the cavity in which it may be lying, this shell, like other 

 rock-dwelling species, is extremely variable in contour. 

 Hence it has happened, that examples in which the growth 



