TRIBE NAYADES. 215 



H. CoRRUGATA. Lam. 2.—E. t 247./. 2.— Reeve, t. 90./. 2. 

 — Mya Angulata. W. S. t. 1./. 12. Triangular, posteriorly 

 narrower and obliquely rounded, the beaks with longitudinal 

 "wrinkles, which anteriorly become coarser and subdivided, with 

 transverse groove-like striae; the ears short, the anterior one obtuse. 

 — Variety. Sow. G.f. 2. The anterior ear sinuous at the base and 

 somewhat plaited : cuticle dark brown. 3|. — Guiana. 



H. Browniana.— Unio B. Lea. on U. 2. /). 108. t. 24. f. 

 116. Triangular, inflated very inequilateral, winged anteriorly, 

 thick ; beaks prominent ; epidermis striated, dark brown, nacre 

 white ; cardinal teeth rather large and striated, lateral long and 

 nearly straight. 1 . . 2. — R. Amazon. 



ANODONTA. 



Equivalve, inequilateral and transverse; hinge linear, without 

 teeth ; dorsal edge glabrous, adnate and anteriorly either trun- 

 cated or forming a simis ; two lateral, r-emote, twin, muscular 

 impressions ; ligament linear, external, sunk in a cleft at the 

 anterior extremity. 



* No distinct angle at the posterior extremity of the 

 hinge margin. 



Symphonote. 



A. Wahlamatensis. Lea. on U. 2. p. 78. t 20. /. 64. 

 Obtusely triangular, w^inged, somewhat inflated, thin, inequilateral, 

 connate over the ligament ; beaks rather compressed, yellowish and 

 undulated at the tip, cuticle rather smooth and shining, having a 

 small dark band at the line of growth near the margin : nacre white. 

 ]| . . 2^. — Near the Rocky Mountains. 



A. Magnifica. Lea. — Symphonota M. Lea. Am. Ph. 

 Tr. 1837. p. 43. t. 5. /. 14. Rounded-ovate, inequilateral, thin, 

 very inflated near the beaks, the dorsal edge almost straight and 

 sharply angulated at the extremities, the anterior edge obliquely 

 sloping, the ventral simply but strongly arcuated ; beaks inflated 

 and near the tips undulated ; cuticle smooth, yellow, with numerous 

 green rays, nacre pearly and highly irridescent (sometimes tinged 

 -with salmon and pink) ; scars scarcely perceptible. 2J_ . . 32^ — 

 Canton. 



A. Woodiana. Lea. — Symphonota W. Lea. Am.. Ph. 

 Tr, 1837./ 42. t. 5. /. 13. Transversely-ovate-subpentangular, 

 thin, turned over the umbones, posteriorly very short, narrower and 

 obtuse, anterior edge almost forming a right angle with the sinuated 

 ventral which curves outwards near the middle ; anterior slope cari- 

 nate ; ligamental edge nearly straight and direct : cuticle dark 



