

OF TUT. FAMILY OF NAIADES. UT 



2. Unio Rubiginobus. Plate VIII. fur. 10. 



Testn itueqvUaterali, transversa, postice svb-biangvJari, antice rotun- 



data : valrulis sub-crassis ; natibus prominentibus, recurvia, posticfsub- 

 cmgulotis; dente cardinuli magna, latcruli crasso ; margariti Balmonis 

 colore. 



Shell inequilateral, transverse, sub-biangular behind and rounded be- 

 fore; valves somewhat thick; beaks prominent, recurved, rab-angulated 



behind; cardinal tooth large; lateral touth thick; nacre salmon co- 

 loured. 



Hab. Ohio. 



My Cabinet. 



Cabinet of T. G. Lea. 



Cabinet of Prof. Vanuxem. 



Cabinet of the Academy of Natural Sciences. 



Diam. 1-2, Length 2-1, Breadth 2-fi inches. 



Shell somewhat ventricose ; substance of the shell some- 

 what thick: umbones slightly elevated: beaks recurved, sel- 

 dom decorticated, almost touching, whitish, possessing several 

 concentric undulations, which are lost along the umbonial 

 slope, which is carinate: a small curved elevated line passes 

 from the point of the beaks to the margin above the posterior 

 margin; ligament rather large passing from the points of the 

 beak-: dorsal margin oblique ; posterior dorsal margin cari- 

 nate and slightly emarginate; posterior margin angular; pos- 

 terior basal margin very slightly curved: basal, anterior and 

 anterior dorsal and basal mar gins rounded: epidermis colour 

 of rust, Bometimes salmon yellow, slightly wrinkled and show- 

 ing the marks of growth; rays in young specimens percepti- 

 ble; cardinal tooth sulcate, broad and nol elevated, often 

 single in both valves; the tooth in the lefl yalve closing in a 

 cavity which sinks almost into the cavity of the beaks of the 

 righl yalve; lateral teeth rather thick, elevated, straight, ge- 

 nerally double in both valves; in the left valve the upper 

 division is le-s elevated and shorter; anterior and posterior 

 cicatrices both distinct : the smaller posterior cicatrix is situ- 

 \ in,, in. — 5 q 



