196 TESTACEOUS MOLLUSCA. 



rays ; nacre bluish white, anteriorly irridescent : cardinal teeth 

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



U. MuHLFELDiANus. 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. ly\ . . 2-^^. — Tennessee. 

 T U. Cresserus. Lea. on U. 2. (aiid Tr. Am.6.) p. 33. f. 10. 



J\ 28. SubeUiptical, 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 ; naci'e 

 white. l|..2j''o. — Tennessee. 



U. Glaber. Lea. on U. 2. (and Tr. Atn. 6.) 34, i'. j). 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. ^ . . l^. — Tennessee. 



U. HiLDRETHiANus. Lea. Trans. Am. Ph. 5 t. 3. /. 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, -^-q . . 1|'. — Ohio. 



U. Fabalis. Lea. on. U. 1. p. 96. {and Tr. Am. Ph. A.) 

 t. 10. f. 16. — U. Capillus. Say. Transylv. J.our. — 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. — Conr. Mon. U. t. 

 6. y. 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 peai'ly white and 

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

 parallel to the base. ^. . 1^. — Fox River, North Avierica. 



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- 



