212 TESTACEOUS MOLLUSCA. 
subcuneiform, posteriorly rounded, ligamental edge straight, ventral 
incurved in the middle; inflated, thin, beaks small, ligament shortish, 
umbonal slope large and rounded ; cuticle brown with rays ante- 
riorly, nacre bluish white: cardinal teeth small, rather compressed. 
115. -2,4-—LV. Carolina. 
U. Raprara.—Atasmoponta R. Conr. in Sil. J. 25. t. 1. fe 
10. Elongated-ovate, transverse, ventricose, posteriorly narrow and 
obtusely angulated, anteriorly produced and pointed at the end, 
ventral edge entire and rounded at the sides: beaks prominent and 
pointed at the apex which has two or three profound undulations, 
cuticle light olive with beautiful dark green rays, nacre waxen 
yellowish : .cardinal teeth elongated, in one valve distant, close 
under the beak in the other. 22.—S. Alabama. 
U. Catceora. Lea.on U.1.p.7.t. 3. f. 1.—ALASMODONTA. 
Truncata. Conr. Transverse, suboval, inequilateral, ventricose, 
subcylindrical, thin, posteriorly rounded, anteriorly obtusely angu- 
lated both above and below, ventral edge not incurved, dorsal 
straightish and anteriorly ascending : beaks slightly undulated and 
touching, not decorticated : cuticle dark green, lighter towards the 
beaks, with indistinct rays, nacre white and silvery : cardinal tooth 
prominent. +..14.—Ohio. 
U. BoneLiii.—ALasmoponta B. Ferussac.—Derressa. Pfeif. 
t.8. f. 3, 4.—Rosm. f. 134. Oblong, compressed, thin, posteriorly 
attenuated, rounded and very short, anteriorly produced and dilated, 
ventral edge simple and scarcely arcuated ; cardinal teeth coarse, a 
single one in each valve, no lamellar ones : ligamental sinus ovate. 
23 __S. Ger MANY. 
“U. Paracuayana.—Monoconpyiea P. D’Orbig. Am. t. 
70. f. 5, 6, 7. Ovate-subquadrilateral, inflated, thick, strigillated, 
posteriorly rounded short and narrow, anteriorly dilated, with an 
elevated sulcus radiating from the beaks and angulating at its extre- 
mity the arcuated ventral edge: beaks prominent, rounded, the 
cuticle thick, greenish brown: nacre greenish white, the tooth thick, 
elevated and obtuse. iS. America. 
U. Parcuarriu. Zea.—Monoconpytea P. D’Orbig. S. 
Am. t. 68. f. 1, 2, 3. Ovate-oblong, compressed, striated, an- 
teriorly dilated, posteriorly short and rounded, ligamental edge 
straight, ventral entire and little arched; beaks eroded and not pro- 
maine an indication of a lunule ; the cuticle greenish brown ; 
inside rosy, the tooth prominent thick rounded and obtuse. 
14..14.—S. America, 
U. Corrtentesinsis.—Monoconpytea C. DD’ Orbig. S. 
Am. t. 68. f. 8, 9,10. Rounded-ovate, compressed, strigillated, 
greenish, posteriorly narrow short and rounded, anteriorly dilated 
rounded and with one or two green lines ; ventral edge strongly 
arcuated, beaks not prominent, no lunule, inside bluish white: tooth 
thick, broad, and prominent. . 13..14.—S. America. 
