37 



UNIO OCHRACEUS. 



Plate XVII.— Fig. 2. 



DESCRIPTION. 



Shell elliptical, inflated, thin; epidermis smooth 

 and polished, rugose posteriorly, yellowish, with nar- 

 row green unequal rays; anterior side narrowed, and 

 the superior margin elevated and connate; ligament 

 margin not oblique; umbo inflated; posterior extre- 

 mity angular; umbonial slope angular; basal margin 

 profoundly arcuate; within white, rarely pale rose or 

 salmon; cardinal teeth very oblique, much compressed, 

 bifid in the right valve; single or imperfectly divided 

 in the left; lateral teeth arcuate. 



Var. A. Reddish brown; rays obsolete or want- 

 ing; within rosaceous. 



SYNONYMES. 

 U. ochraceus, Say. Nich. Enc. (Amer. ed.) art. Conch, pi. ii. 



Symphynota ochracea, Lea. Trans. Amer. Philos. Soc, new 



series, vol. iii. p. 69. 

 Var. A. Mytilus fluviatilis, Gmel. Lister, tab. 157. fig. 12. 

 Cab. A. N. S. No. 1063. 



OBSERVATIONS. 



Very common in the Schuylkill and Delaware 

 rivers, and inhabits most tide waters north of Savan- 

 nah river. Variety A. is very abundant in James 

 river, Virginia, where I found vast numbers of shells 

 brought ashore by .seines used in the shad fishery in 



