ANODONTA. 159 



its basal edge more frequently subretuse. The beaks 

 seem rarely eroded in this form, but commonly so in the 

 preceding. 



When in this species the hinder contour is broad and 

 subrhomboidal, the dorsal line manifestly rising behind, so 

 as somewhat to alate or render winged the upper posterior 

 corner, and the ventral edge obliquely ascending in front atte- 

 nuates below the anterior extremity, whilst sweeping up- 

 ward behind it rounds off the subtruncated tip of the hinder 

 termination, the shell is usually known by the name anati- 

 nus, (Grande Moule des etangs, Geoff. Coq. Paris, pi. S. — 

 Mytilus anatinus^ Da Costa, Brit. Conch, p. 215, pi. 15, 

 f. 2. — Mont. Test. Brit. p. 171. — Chemn. Conch. Cab. 

 vol. viii. pi. 86, f. 763. — Dillw. Eecent Shells, vol. 1, 

 p. 817. — Anod. anatina. Lam. Anim. s. Vert. (ed. Desh.) 

 vol. vi. p. 565. — Flem. Brit. Anim. p. 415. — Sowerby, 

 Genera Shells. — Reeve, Conch. Systemat. vol. i. pi. 91. — 

 RossMASL.Iconog. Land und Siissw. Moll. pt. 6. pi. 80, f.4l7, 

 420. — Hanl. Recent Shells, vol. i. p. 216. — Mytilus ma- 

 cula, Sheppard, Trans. Linn. Soc. vol. xiii. p. 5, f. 6. — 

 Anodon cygneus var. Brown, 111. Conch. G. B. pi. 29, f. 1). 

 In this variety the epidermis is generally of a clear lustrous 

 yellowish-green, for the most part faintly radiated with 

 darker green lines, and the umbonal folds are usually more 

 wavy than usual. The surface, which in the adult is 

 smooth, is rather coarsely wrinkled in the fry, where (as 

 is the case with most Anodons) the elevation of the dorsal 

 margin is pre-eminently remarkable. 



The variety rostrata {Anod. rostrata, Ziegl. in Ross- 

 masl. Iconog. pt. 4, pi. 20, f. 284, and pt. 11, pi. 54, 

 f. 787. — A. cygnea, var. rostrata. Brown, 111. Conch. G. B. 

 p. 81), is not very common, and may easily be recognized 

 by its strongly marked characters. It is elongated, more or 



