i80 TESTACEOUS MOLLUSCA. 
Conr. Mon. t. 4. f. 1. Rounded-triangular, anteriorly angulated, 
posteriorly rounded and. shorter, ventral edge well rounded, beaks 
somewhat elevated, with the ligament passing between them; 
anterior slope compressed, bounded by a roundish elevated ridge, 
marked by small transverse subnodulous wrinkles and obsolete 
longitudinal grooves: surface waved, a longitudinal row of large 
distant elevated transversely compressed tubercles divides the shell 
into two subequal parts: nacre pearly white and irridescent : 
cardinal teeth sulcated. 13..14.—N. America. 
U. Pusrutosus. Lea. on U. 1. p. 86.t. 7. f. 7. Quadrate, 
as long as broad, equilateral, inflated, anteriorly with large irregular 
long tubercles, thick ; beaks elevated and granular at the tip: liga- 
ment short and thick, epidermis bright brown with a single broad 
interrupted ray in the middle, nacre pearly white and irridescent : 
cardinal teeth rather large, lateral short thick and straight.— Ohio. 
U. Turcripus. JLea.on U.2.. 11. t. 5. f. 1i.—U. Mortont. 
Conr. Mon. U. t. 6. f. 1. Subrotund, inflated, subequilateral, 
thick, subangular anteriorly, tubercles small crowded on the um- 
bones and scattered near the margin; beaks elevated, ligament 
short and thick : cuticle dark brown, nacre white and irridescent : 
cardinal teeth large and compressed, lateral short and nearly straight. 
13,..13.—New Orleans. 
U. Cooperianus. Lea. Trans. Am. Ph. 5. t. 8. f. 21. Sub- 
orbicular, transverse, oblique, thick, anteriorly much longer and 
irregularly tuberculated ; beaks thick and elevated ; ligament rather 
short and thick : cuticle wrinkled, dark rusty brown, rays scarcely 
visible, nacre flesh coloured and white ; cardinal teeth rather large, 
lateral rather short, thick and straight. 24..3!.—Ohio. 
U. Verrucosus. Barnes. in Sil. J. 6. t. 5. f. 6.—U. TuBERcu- 
Losa. Valen.in Humbs. voy. t. 53. f. 2.—TusBercuiatus. Conr. 
Mon. t. 22. Very inequilateral, thick, rounded posteriorly, biangu- 
lated and subtruncated anteriorly ; ligament deeply inserted between 
the valves ; hinge margin nearly straight, compressed, alated, heel- 
shaped, making an obtuse angle with the anterior ; ventral edge 
arcuated ; cuticle light green (usually tinged with reddish brown), 
studded anteriorly with irregular transversely compressed tubercles : 
cardinal teeth crenated or suleated : nacre brownish red with a 
tinge of blue or light chocolate (rarely pearly white,) slightly irri- 
descent anteriorly, posterior scar deep and rough. 147..1,%. 
U. Granirerus. Lea. on U. 2. p. 69. t. 19. f. 60. Subrotund, 
longer than broad, inflated, ponderous, sulcated on the anterior 
slope, tubercles not numerous rather small disposed to be erect and 
transverse ; beaks very prominent ; cuticle dark brown, nacre 
chocolate coloured ; cardinal teeth large, lateral short and straightish. 
1,7, ..2!.—Ohio. 
U. Noputosus. Zea.--Mya N. Wood. G. C. t. 22. f. 1, 2, 
