196 TESTACEOUS MOLLUSCA. 



rays ; nacre bluish white, anteriorly irridescent : cardinal teeth 

 direct, prominent, pyramidal. 2. — R. Alabama. 



U. Muhleeldianus. Lea. Tr. Am. 6.f. 36. p. 41. Elliptical, 

 rather compressed, transverse, inequilateral, thickish, rounded at 

 both ends, ventral and anterior dorsal edge straightish : beaks rather 

 prominent, finely undulated : cuticle yellowish with dark green rays 

 anteriorly, nacre white and irridescent ; cardinal teeth rather small 

 and erect, lateral long and erect. l-f$ . . 2 t 3 q. — Tennessee. 



U. Cresserus. Lea. on U. 2. (and Tr. Am. 6.) p. 33. t. 10. 

 f. 28. Subelliptical, very transverse, very inequilateral, thickish, 

 ventral edge little rounded and rather sinuated, anterior dorsal 

 edge straightish, anterior edge incurved ; beaks rather prominent 

 and undulated at the tip, retuse : cuticle dark green, obscurely 

 rayed : cardinal teeth small and elevated, the lateral obscure ; nacre 

 white. If ..2^. — Tennessee. 



U. Glaber. Lea. on U. 2. (and Tr. Am. 6.) 34. t. p. 10. f. 

 29. Elliptical, transverse, compressed, smooth and shining, inequi- 

 lateral, thin ; beaks somewhat prominent, with fine nearly parallel 

 undulations at the tip ; ligament short: cuticle smooth yellow with 

 numerous fine rays over nearly the whole disc : cardinal teeth small 

 and elevated, the lateral long. | . . 1 J. — Tennessee. 



U. Htldrethianus. Lea. Trans. Am. Ph. 5. t. 3. f. 8. — 

 U. Ambigua ? Say. Narrow elliptical, subcylindraceous, very 

 transverse, thin, rounded at both ends, ventral edge little arcuated, 

 incurved, subparallel to the dorsal, cuticle dark brown, nacre above 

 brown, below white ; ligament long and thin ; cardinal teeth single 

 in each valve, no lateral, xo •• If* — Ohio. 



U. Fabalis. Lea. on. U. 1. p. 96. (and Tr. Am. Ph. 4.) 

 t. 10. f. 16. — U. Capillus. Say. Transyh. Jour. — Lapillus. 

 Say. Am. Conch, t. 41. Subelliptical, transverse, inequilateral, 

 thick, rounded at both ends ; ventral margin incurved in the middle ; 

 ligament short ; beaks slightly prominent ; cuticle dark, with green 

 hair- like undulating rays (especially anteriorly) ; nacre pearly white 

 and irridescent ; cardinal teeth small, the lateral short thick and 

 enlarged anteriorly, i . . 1. — Ohio. 



U. Parvus. Barnes. Sil. J. 6. — Eaton. — Con?'. Mon. U. t. 

 6. /. 1. Oblong-ovate, convex, rounded at the sides, thinnish ; 

 beaks slightly elevated and placed at one-fourth the distance from 

 the posterior end ; ligament very narrow, and slope distinct and 

 obsoletely ribbed ; ventral edge little rounded ; cuticle brownish, 

 an obtuse slightly elevated anterior ridge ; nacre pearly white and 

 irridescent ; the lateral tooth rectilinear, rounded at the end and 

 parallel to the base. J- . . 1^. — Fox River, North America. 



U. Glans. Lea. on U. 1. p. 92. (and Tr. Am. Ph. 4.) t. 8. 



f. 12. Ovate elliptical, transverse, inequilateral, inflated, rather 



thick, rounded at both ends ; ventral edge rounded ; beaks some- 



