ANODONTITES 1455 



ridge ends and above which it is somewhat obliquely truncated ; 

 beaks not high ; epidermis green to olive ; nacre brilliant, bluish 

 or purplish, iridescent, rayed with very fine, indistinct ridges ; 

 posterior end with a slight sinus. 

 Type, Anodo}i eiisifonnis Spix. 



Anodontitks ENSii^ORMis (Spix). 



Shell very greatly elongated, subsolid, convex, inequilateral, 

 wider in front, drawn out to a slender point behind, more or 

 less arcuate when adult : beaks but little elevated ; posterior 

 ridge well developed, sometimes pinched up into a rather nar- 

 row, rounded ridge, ending at the base of the shell in a de- 

 cided point ; anterior end evenly rounded ; hinge line lightly 

 arched, joining the long oblique dorsal slope at a low angle; 

 surface with strong, irregular growth lines and inconspicuous, 

 radial threads; epidermis dark, greenish-brown, scarcely shin- 

 ing; nacre brilliant, bluish, bordered and tinted with green, 

 richly iridescent ; anterior scars well marked ; posterior scars- 

 shallow. 



Length to6. height 2~, diam. 15 mm. 



Length 97, height 25, diam. 15 mm. 



Tropical South America. 

 Anodon ensiformis Spix, Test. Fluv. Bras., 1827, p. 31, pi. 



XXIV, figs. I, 2. — SowcRBY. Conch. Icon., XVII, 1867, pi. 



XI, fig. 31. 

 Iridina ensiformis Lka. Syn., 1836, p. 57. 

 Anodonta ensiformis d'ORBiGXY, Voy. Am. Mer., 1843, P- 618, 



pi. Lxxix, fig. 10. — KusTER, Conch. Cab. Ano., 1853, p. 8, 



pi. II, fig. 12. — PChknu, Man., 1859, II, p. 146, fig. 721. 

 Margarita (Anodonta) ensiformis Lea, Syn., 1838, p. 32. 

 Margaron (Anodonta) ensiformis hv,\, Syn., 1852, p. 51 ; 1870, 



p. 82. 

 Glaharis ensiformis Simpson, Syn., 1900, p. 932. 



An excessively elongated and peculiar species, with daz- 

 zlingly brilliant, iridescent nacre. 



