UNIO VENTRICOSUS. 



SPECIFIC CHARACTEI?. 



Shell large, thick, triangularly'ovate, convex ; iimbonch 

 large, round, prominent ; beaks recurved ; cavity capa^ 

 cious. 



SYNONYMS. 



U. VENTRICOSUS, Bcimes, SiUiman's Journal, Vol. fi, 

 No. 2, p. 267, pi. 13, fig. 14, a, b, c, 



U. ovATUs, Far. b. Lam. Anim. Sans. Verfcbr. Vol. G. 

 p. 75. 



U. occiDENs? Lea. Dans. Jimer. Philos. Soc. New 

 Series, foh 3. 



DESCRIPTION. 



"•Shell with the anterior side very broad, sub-truncate ; 

 posterior side rapidly narrowed, sub-angulated ; disks very 

 convex ; umbones large, round, elevated ; beaks recurved 

 over the ligament ; ligament large and prominent, passing 

 under the beaks ; anterior lunule depressed at the margin, 

 fuscous, broad-heart-shaped, longitudinally waved ; hinge 

 margin depressed between the beaks ; posterior slope cari- 

 nate ; epidermis yellowish-olive, becoming chesnut-brown 

 on the umbones; rayed with green, more conspicuous in 

 young specimens; in old ones the dark chesnut brown 

 covers the whole and conceals the rays ; surface smooth 



PI. 32. 



