182 TESTACEOUS MOLLUSCA. 
ing almost the whole disc, nacre milk white : cardinal teeth rather 
small, the lateral long and straightish. 1,9, .. 23.—Ohio.1 
U. Granosus. Brug. Journ. H. N. 1.t. 6. f. 3, 4.—Lam. 
37.—E. t. 249. f. 2. Obovate, convex-depressed, reddish brown, 
anteriorly broader and rounded ; with oblique granular strie, the 
granules crowded : nacre bluish white. 12.— Guiana. 
U. Tusercutatus. Barnes. in Sil. J. 6. t.7. f. 8.—Laton. 
—Hildr. in Sil. J. 14. Ovate-oblong, thick and rugged, anteriorly 
produced compressed attenuated and rounded at the tip, posteriorly 
short rounded and obtuse; beaks flat and lower than the ligament : 
cuticle dark brown with longitudinally elongated tubercles, anterior 
slope bordered by a ridge from whence proceed deep and irregular 
nodulous undulations ; nacre white, cardinal teeth crenated, the 
lateral long and striated. 22..43.—N. America. 
U. Novw Houtanoiz. Gray. Z. P. 1834. Oblong-elon- 
gated, slender, solid: posteriorly subcompressed, smooth rounded ; 
anteriorly subventricose, produced, with large unequal tubercles 
disposed in curved radiating rows: the disc silvery and spotted 
with purple, the ventral margin posteriorly very thick: posterior 
cardinal tooth small, little elevated, bituberculated ; anterior teeth 
small and placed under the anterior edge of the cartilage: cuticle 
thick and black. River Maequarrie, New Holland. 
U. Cyuinpricus. Say. in Ene. Am. Nich. Conch. t. 4. f. 
3.—-Laton.—Hildr.—U. Navirormis. Lam.—Reeve. t. 89. 
Transversely oblong, straight, posteriorly very short and rounded, 
ligamental edge very long and straight, ventral edge incurved in 
the middle; anteriorly angulated above and below and emarginate 
at the tip : beaks not prominent and as well as the anterior slope 
(which is bounded by a broad flattened umbonal ridge) undulated : 
cuticle yellow speckled with angular black marks, nacre pearly 
white, teeth crested. 14..3—Ohio. 
* * * Spinous. 
U. Sprnosus. Lea. on U. 2. p. 57. t. 16. f. 50.—Jay. Cat. 
ed. 3. pl. 5. Subtriangular, inflated, inequilateral, acutely angular 
anteriorly, thickish, beaks scarcely prominent, cuticle dark brown 
and shining, armed with a few long and thick spines: cardinal 
teeth inclining downwards, the lateral rather large and curved : 
nacre purple. 14..3-3,.— Georgia in America. 
* * * & Smooth. + Triangular. 
U. Arca#rormis. Lica. on U. 1. p. 126. t. 17. f. 44.— 
Nexus. Say. Am. C. t. 51.  Subtriangular, very ventricose, 

1 Add likewise the U. Lenat of Gray. 
