218 TESTACEOUS MOLLUSCA. 
A. Epentuta. Lea.—Arasmoponta E. Say.—Awn. AREO- 
Latus. Swain. Zool, ll. 2d series. Transversely-oval, inequi- 
lateral, sides rounded both above and below, convex, ventral edge 
arcuated, ligamental edge direct; umbones small, bent, not touch- 
ing; with a short undulated projection of the hinge margin in one 
valve and a corresponding concavity in the other, both placed 
beneath the umbones ; cuticle dark olive, smooth. 2.—N. America. 
A. Pavonia. Lea. on U. 2. p. 78. t. 21. f. 65. Elliptical, in- 
flated, inequilateral, thin: beaks somewhat prominent and with 
rather large undulations at the tip: ligament rather short and thin : 
cuticle smooth shining, with numerous dark green rays which 
diverge to the whole margin: nacre bluish. 13..3.—Ohio. 
A. Limnorca. D’Orbig. in Mag. de Z. 1835. Oblong, sub- 
inflated, rather smooth, thin, green, short and rounded posteriorly, 
elongated broad, almost angulated, yellowish, anteriorly ; nacre pink. 
14..2.—S. America. 
A.Tricona. Spix. Test. Braz.t. 22.f.2. Ovate-triangular 
inequilateral, compressed solid, transversely grooved, with a longi- 
tudinal gibbous elevation in the middle; anteriorly somewhat 
beaked and acuminated, posteriorly rounded, ventral edge anteriorly 
incurved ; dorsal edge straight anteriorly angulated and winged : 
beaks depressed and decorticated, umbones flattened. 1..13.— 
Brazil. 
A. Purpurea. Valen. Zool. to Humb. voy. t. 48. bis. f. 3. 
Transverse, elliptic, rich brown, transversely striated; dorsal edge 
nearly straight ; anterior side compressed, the edge obtusely angu- 
lated, the slope not ridged ; ventral edge incurved in the middle : 
beaks decorticated ; inside purple. 14..21.—Philippines. 
A. Ferussacciana. Lea. Am. Ph. Tr. 1837. t. 6. f. 15. p. 
45. Oblong-subcylindraceous, thin, inequilateral, inflated, ventral 
and ligamental edges nearly straight and subparallel (the former 
very slightly incurved,) dorsal margin curved immediately under the 
point of the beak; posteriorly rounded shorter and narrower, an- 
teriorly somewhat angulated: cuticle dark olive, shining, with 
obsolete rays ; beaks somewhat prominent, very slightly undulated ; 
nacre bluish white and irridescent : scars perceptible. 14..33.— 
Ohio. 
A. Satmonia. Lea. on U. 2. p. 45.t. 14. f. 41. Elliptical, 
transverse, inflated, very inequilateral, within salmon colour, and 
usually very rough ; thin, ventral edge subincurved; beaks some- 
what prominent and slightly undulated at the tip, the ligament 
rather short ; cuticle dark brown, sometimes with yellow bands. 
12..2,7,.— Ohio. 
A. Incerta. Lea. Am. Ph. Tr. 1837. t. 6. f. 16.—Impr- 
citutis? Say. Elongated-elliptic, very thin, inflated, posteriorly 
shorter and rounded, anteriorly subangulated ; dorsal line nearly 
