﻿360 ANODONTA 



sal wing', wliicli. lunvcvcr. never rises to a great height; there is 

 an angle at the posterior end of the wing and from this point 

 the shell is obliquely truncate, the ujiper outline of the posterior 

 slope being often slightly incurved. Posterior ridge generally 

 low. more or less double, and. when double, it ends in a bian- 

 gulation at some distance above the base line ; base line curved, 

 or rarely straight ; growth lines irregular, sometimes forming 

 low ridges; epidermis more or less shining, yellowish-green, 

 ash-colored or olive, very often having wide, faint bands of 

 darker color, and occasionally feebly rayed ; hinge line widen- 

 ed a little behind the beaks, narrow at or in front of them,, 

 edentulous ; escutcheon small ; nacre whitish, sometimes tinted 

 dull purplish in the cavities ; beak cavities shallow, showing a 

 few irregular dorsal scars ; muscle scars large, superficial. 



Length 180, height 86. diam. 50 mm. 



Length 138, height 76. diam. 44 mm. 



Length 135, height 86. diam. 47 mm. 



Europe generally : Siberia ; southward, perhaps, into Asia 

 Minor. It has been reported from the Amoor River drainage, 

 but I presume that the specimens from that region belong to 

 the group of A. zvoodiana. 

 MytHus cygneus Linn^us, Syst. Nat., loth ed., 1758, I, p. 



706, No. 1 158.— Da Costa, Hist. Nat. Test. Brit., 1778, p. 



214, pi. XV, fig. 2. — ScHROTER, Flussconch., 1779, p. 162, pi. 



in, fig. I. — Donovan, Brit. Shells, 11, 1800, pi. lv.— Maton 



and Rackett, Tr. Linn. Soc. Lond., VIII, 1807, p. 109, pi. 



Ill, figs. 2. 3. — Sheppard. Tr. Linn. Soc. Lond., XIII. 1820, 



p. 84. pi. V. fig. 3.— Wood. Ind. Test.. 1825. p. 58. pi. xii. 



fig. 32/; Ind. Test. Rev.. 1856, p. 69, pi. xii, fig. 32/. 

 Anodontes cygneus Cuvier, Regne An.. II. 1817, p. 472. 

 Anodon cygneus Turton, Conch. Ins. Brit., 1822, p. 239; Man. 



L. and F. W. Shells, 1831. p. 17, fig. 8. — P)Rown, Land and 



F. W. Conch., 1836. p. 99, pi. XI, figs. 1-3^; 111. Rec. Conch., 



1844, p. 79. pi. xxvin. etc. — Turton. Man. L. and V. \\ . 



Shells, 1857, p. 271. fig. 65 ; pi. t. fig. 8.— Tate, L. and F. W. 



Moll. Brit.. t866. pi. 1.— v^owerby, Conch. Icon., XVII. 1870,. 



pi. I. fig. 2. 



