51 



horn color, not radiated ; flattened and fuscous on the anterior mai- 

 gin ; beaks decorticated, placed nearer central ; umbo prominent ; 

 within parlaceous ; cavity of the beaks capacious; primary teeth 

 very oblique, almost parallel to the posterior margin and much 

 compressed. Length, three inches; breadth, four inches. 



Inhabits the Ohio river and its tributary streams. 



Eiicyc. Method, vol. 63, tab. 24:S, Jig. 5. Plate 2, fig. 7. 



Unio cariosus. — Shell moderately thick, much longer before, 

 and shorter behind the beaks ; olive green, sometimes radiate with 

 green, and with fine interrupted wrinkles placed in longitudinal 

 rows, but usually the green radii are wanting, or only visible in the 

 anterior margin, and the wrinkled radii indistinct ; in older shells 

 the naiddle of the base is a little shortened ; beaks somewhat promi- 

 nent, rather distant, carious, exposing a wax-yellow surface ; con- 

 cavity bluish-white, teeth resembling those of the preceding species, 

 but the primary ones are not so much compressed or oblique ; they 

 are often sub-conic and crenate. Length one inch and a half : 

 breadth, two and a quarter. Plate 3, fig. 2. 



Muscvlus latioVj sub/uscus, Cseruleis lineis Radiatus. Lister, 

 Conch, tab. \b2,fig. 7. 



Martini's figure of U. jiictorum resembles this shell in outline. 

 Vol. 6. 



Vei-y common in the Delaware and Schuylkill rivers. 



Gmelin, Ed. Syst. Nat. p. 3220, refers to Lister's figure as a 

 variety of Mya radiata, a native of Malabar : but we have ventured 

 to consider it a distinct species ; the largest we have seen was 

 brought from Wilkesbarre by Mr. Lard. Vanuxem, in length two 

 and one-fourth, breadth three and three-fourths inches. The animal 

 rarely infested by a parasite. See the article Ht/drachne. 



Unio ochraceus. — Shell thin, fragile, translucent, subovate, 

 hinge margin somewhat rectilinear, color from a pale reddish orange 

 to a pale olive ; generally radiate with dull green and with minute 

 wrinkled radii; anterior margin very finely wrinkled; beaks de- 

 corticated and approximate, with two or three small concentric un- 

 dulations ; within bluish-white or ochraceous, tinged with red near 

 the base ; teeth very oblique and much compressed. Length one 

 inch and a quarter : breath, one and three-quarters. Plate 2, 

 fig. 8. • 



This shell; in many respects, resembles the preceding, with which 



