180 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. 1| .. 1|. — JV. America. 



U. Pustulosus. Lea. on U. 1. p. 86. t. 7 . f. /• 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. Turgidus. Lea. on U. 2. p. 11. t. b.f. 11. — U. Mortoni. 

 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. 

 IX . . lj?. — 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. 2| . . 3 1. — Ohio. 



U. Verrucosus. Barnes, in Sil. J. 6. t. 5.f. 6. — U. Tubercu- 

 losa. Valen. in Humbs. voy. t. 53. f. 2. — Tuberculatus. 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 sulcated : nacre brownish red with a 

 tinge of blue or light chocolate (rarely pearly white,) slightly irri- 

 descent anteriorly, posterior scar deep and rough. l^J . . 1 t 9 q. 



U. Graniferus. Lea. on U. 2. p. C9. 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^..2j.— Ohio. 



U. Nodulosus. Lea.— Mya N. Wood. G. C. t. 22. /. 1, 2, 



