366 KANSAS UNIVBRSITY SCIENCE BULLETIN. 



numerous regular but hardly continuous lines of growth, 

 sometimes possessing a cloth-like texture. Ligament fairly 

 stout and long. 



Interior: Pseudocardinals massive, ragged, double in the 

 left and single in the right, the right pseudocardinal arising 

 from a deep pit ; laterals long, fairly heavy, very slightly 

 curved, oblique, tending to double in the right as well as in 

 the left valve. Interdentum very short, broad. Anterior ad- 

 ductor cicatrix small, cpuadrant-like in outline, very deep. 

 Posterior scars much impressed, distinct, the adductor cica- 

 trix broader behind than before. Pallial line well impressed in 

 its anterior half. Dorsal cicatrices a line on the lower surface 

 of the interdentum and the base of the pseudocardinals ; cav- 

 ity of shell moderate, of the beaks shallow and a little com- 

 pressed ; branchial depression deep but not distinctly outlined ; 

 nacre a warm pink, slightly iridescent posteriorly. 



Leuifth. Height. Breadth. Um. ra. 



60 42 41 0.06 I 



70 54 44 .085 - (Coll. W. C.) 



32 28 08 \ 



(>. pyramidata is found in the Mississippi drainage, north of 

 the states of Mississippi and Louisiana. It has been reported 

 from the Verdigris and Neosho rivers in Kansas. It has 

 only been reported from two localites, and is apparently a 

 rare species. 



There is no species but Q. plena that can be confused with 

 Q. pyramidata. A discussion of the differences between these 

 two closely related species will be found in the notes on Q. 

 plena. 



Quadrula ebenus Lea. Not figured. 



Unio ebenus Lea, Trans. Amer. Phil. Soc, iv, 1831, p. 84, pi. IX, fig. 

 14. 



Shell of moderate size, solid, broadly elliptical in outline. 



Anterior margin Hatly rounded ; ventral margin slightly 



bowed ; posterior margin rounded but sometimes showing a 



tendency to be biangulate ; dorsal margin oblique, straight 



or slightly curved. Umboidal ratio, 0.10 or less. Umbones 



full, of moderate height, incurved, and directed anteriorly. 



Anterior umboidal slope fully curved ; lateral slope rather 



