TRIBE NAYADES. 215. 
H. Corrueata. Lam. 2.—E. t. 247. f. 2.—Reeve. t. 90. f. 2. 
—Mya Ancutata. W.S. t. 1. f. 12. Triangular, posteriorly 
narrower and obliquely rounded, the beaks with longitudinal 
wrinkles, which anteriorly become coarser and subdivided, with 
transverse groove-like striee; the ears short, the anterior one obtuse. 
—Variety. Sow. G. f. 2. The anterior ear sinuous at the base and 
somewhat plaited : cuticledark brown. 33.—Guiana. 
H. Brownrana.—Unrio B. Lea. on U. 2. p. 108. t. 24. ff. 
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.—%. Amazon. 
ANODONTA. 
Equivalve, inequilateral and transverse; hinge linear, without 
teeth ; dorsal edge glabrous, adnate and anteriorly either trun- 
cated or forming a sinus ; two lateral, remote, twin, muscular 
impressions ; ligament linear, external, sunk in a cleft at the 
anterior extremity. 
* No distinct angle at the pesterior extremity of the 
hinge margin. 
SYMPHONOTE. 
A..WautamaTeEnsis. Lea. on U. 2. p. 78. t. 20. f. 64. 
Obtusely triangular, winged, 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. 
14..23.—Near the Rocky Mountains. 
A. Maenirica. Lea.—Sympnonota M. Lea. Am. Ph. 
Tr. 1837. p. 43. t. 5. f. 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. 2,3,..32.— 
Canton. 
A. Woon1ana. Lea.—Sympnonota W. Lea. Am. Ph. 
Tr. 1837. f. 42. t. 5. f. 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 
