SCAMMON : THE UNIONID.E OF KANSAS, PART I. 359 



Quadrula rubiginosa Lea. Plate LXXXIV, fig. 2. 



Unio rubiginosus Lea, Trans. Amer. Phil. Soc, ill, 1829, p. 427, pi. 

 vni, fig. 10. 



Shell moderate in size, subinflated, solid, elongate and 

 roundly quadrate. Anterior margin fully rounded ; ventral 

 margin slightly curved anteriorly, straight or a little emar- 

 ginate posteriorly ; posterior margin straight or slightly 

 curved, more or less produced; dorsal margin straight, 

 slightly oblique, meeting the posterior margin at an approxi- 

 mate angle of 130 degrees. Umboidal ratio, 0.15 to 0.25. 

 Umbones full but not much elevated, ornamented with four 

 to eight rough concentric ridges. Anterior margin fully 

 rounded ; posterior position of the lateral slope occupied with 

 a very wide radial furrow ; posterior umboidal ridge gener- 

 ally sharp and well denned almost its entire length ; pos- 

 terior slope fairly abrupt and in most cases a little excavated. 

 Epidermis greenish horn to deep chestnut-brown in color, 

 sometimes possessing a cloth-like texture. Lines of growth 

 at irregular intervals and generally of a darker color than the 

 surrounding epidermis. Lunule rather large, elongate. Liga- 

 ment fairly stout, long or short; color variable. 



Interior : Pseudocardinal fairly large, rough, double in the 

 left, single in the right valve. Anterior left pseudocardinal 

 an erect pyramidal ridge, posterior left roundly pyramidal ; 

 posterior pseudocardinal heavy and erect, high, surrounded 

 by a trench into which the left pseudocardinals fit. Interden- 

 tum very variable in length and breadth. Laterals long, 

 curved or straight oblique. Anterior adductor cicatrix quad- 

 rate in outline, deeply excavated ; posterior scars deeply im- 

 pressed, distinct or confluent. Pallial line impressed for 

 one-half its length. Cavity of the beaks rather large, of the 

 shell small. Nacre white or pinkish, iridescent posteriorly. 



Q. rubiginosa ranges from the St. Lawrence and Nelson 

 rivers, in Canada, to eastern Texas. It is a common species 



