156 UNIONIDiR. 



Schroter, Fliissconch. p. 160, pi. i. f. 2, 3 ; Einleit. Conch, 

 vol. iii. p. 442. — Index Testaceolog. pi. 12, Myt. f. 33. 

 MytUtis stagnate, Sowerby, Brit. Miscellany, pi. 16. — Turt. Conch. Diction. 

 p. 115. — Dillw. Recent Shells, vol. i. p. 316. 

 „ </e//tu//ix, Turt. Conch. Diction, p. 115. 

 Anodonta (and Anodon) cygnea, Draparn. Moll. Terr, et Flu v. France, p. 134, 

 pi. 11, f. 6, and pi. 12, f. 1.— Turt. Dithyra Brit. p. 239 ; 

 Manual Land and F. W. Shells, p. 17. — Flem. Brit. Anim. 

 p. 415.— Gray, Manual Land and F.W. Shells, p. 289.— 

 Thompson, Ann. Nat. Hist. vol. vi. p. 197. — Brown, 111. 

 Conch. G. B. p. 179, pi. 28, 28* ; 29, f. 1, 2, 3 ; pi. 30, 

 f. 1 to 8. — Lamarck, Anim. s. Vert. (ed. Desh.) vol. vi. 

 p. 564. — Kickx, Moll. Brab. Austr. p. 80. — Blainv. 

 Manuel Malacolog. pi. 66, f. 1. — Hanl. Recent Shells, 

 vol. i. p. 216.— Gras, Moll. T. et Fl. France, p. 70. 

 ,, intermedia, Lam. Anim. s. Vert. (ed. Desh.) vol. vi. p. 568. — Kenyon 

 Mag. Nat. Hist. vol. i, f. 1 85, at p. 428.— Nilsson, Moll. 

 Sueciae Terr, et Fl. p. 1 1 7. 

 „ anatina, Drap. Moll. Terr, et Fl. France, p. 133. — Turt. Dithyra 

 Brit. p. 240. — Macgilliv. Moll. Aberd. p. 241. — Lam. 

 Anim. s. Vert. (ed. Desh.) vol. vi. p. 565. — Nilsson, 

 Moll. Sueciae Terr, et Fl. p. 114. — Phiuppi, Moll. Sicil. 

 vol. i. p. 67, vol. ii. p. 49. 

 „ ventricosa, Kickx, Moll. Brab. Austral, p. 80. 

 „ paludosa, Turt. Dithyra Brit. p. 240, pi. 15, f. 5. 

 „ piscinalis, Nilsson, Moll. Suecire Terr, et Fluv. p. 116. — Rossmasl. 

 Iconog. Land und Siissw. Moll. pt. 4, p. 23, pi. 19, f. 281 ; 

 pt. vi. pi. 30, f. 417. 

 Symphonota eygiwa, Lea, Obs. on Unio, vol. i. p. 70. 



We may aptly preface our account of this ubiquitous 

 shell, with a paragraph from Mr. Gray's excellent " Manual 

 of the Land and Fresh- water Shells of the British Islands. 11 

 It is truly, indeed, " a most variable species which appears 

 to assume different appearances under every circumstance ; 

 as for example, the depth, the stillness or motion, and the 

 purity or impurity, or peculiar impregnation of the water 

 in which it happens to be located.*' 1 After a wearisome 

 examination of a multitude of forms, both native and 

 foreign, not only must we dissent to the division of this 

 polymorphous bivalve into those numerous species into 

 which it has been separated by the continental writers, 



