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. 

 1 t l . . 2 1 1 q.— iV". Carolina. 



U. Radiata. — Alasmodonta R. Conr. in Sil. J. 25. t. 1. f. 

 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. 2\. — S. Alabama. 



U. Calceola. Lea. on U. I. 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. A..1J. — Ohio. 



U. Bonellii. — Alasmodonta B. Fernssac. — Depressa. Pfeif. 

 t.8.f. 3, 4. — Posm. 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. 

 2J. — S. Germany. 



U. Paraguayana. — Monocondylea P. jyOrbig. 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 angulatingatits extre- 

 mity the arcuated ventral edge : beaks prominent, rounded, the 

 cuticle thick, greenish brown : nacre greenish white, the tooth thick, 

 elevated and obtuse. S. America. 



U. Parchappii. Lea. — Monocondylea 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- 

 minent, an indication of a lunule ; the cuticle greenish brown ; 

 inside rosy, the tooth prominent thick rounded and obtuse. 

 H • • !■&• — &• America. 



U. Corrientesinsis. — Monocondylea C. D'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. 1| . . 1|. — S. America. 



