218 TESTACKOUS MOLLUSCA. 



A. Edentula. Lea. — Alasmodonta E. Say. — An. Areo- 

 LATUS. Stvain. ZooL III. 2cl 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./. 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. 1^ . . 3. — Ohio. 



A. LiMNOiCA. 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, 

 li . . 2. — S. America. 



A. Trigona. 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 . . If. — 

 Brazil. 



A. Purpurea. Valen. Zool. to Humb. voy. t. 48. his. 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. 1^ . . 2^. — Philippines. 



A. Ferussacciana. Lea. Am. Ph. Tr. 1837. t. 6. /. 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. 1^ . . 3^. — 

 Ohio. 



A. Salmonia. Lea. on U. 2. p. Ab.t. 14. f. 41. Elhptical, 

 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. 

 l|..2Jo.— 0/«o. 



A. Incerta. Lea. Am. Ph. Tr. 1837. t. 6./. 16.— Imbe- 

 ciLLis ? Say. Elongated-elliptic, very thin, inflated, posteriorly 

 shorter and rounded, anteriorly subangulated ; dorsal line nearly 



