350 KANSAS UNIVERSITY SCIENCE BULLETIN. 



cardinals; posterior scars large, lightly impressed, often 

 fused, and sometimes roughened. Pallial line impressed an- 

 teriorly, sometimes throughout its length. Dorsal scars on 

 the base of the interdentum. Cavity of the shell moderate, 

 of the beaks deep. Nacre pure white. 



(Coll. K. S. A. C.) 



Q. metanevra occurs throughout the northern portion of the 

 Mississippi valley. In Kansas it is confined to the clear- 

 water rivers of the southern drainage, being found as far up 

 the Neosho as its juncture with the Cottonwood river. Gravel- 

 bars are its favorite habitat. Although well distributed it 

 is never (in the author's experience) very common. The 

 largest specimen I have ever seen from this state came from 

 Fall river, a tributary of the Neosho. It is in the Popenoe 

 collection of the State Agricultural College and its dimen- 

 sions are given above. 



It will be impossible to confuse this Unio with any other 

 found in Kansas. The umboidal ridge, semicircular in out- 

 line, will alone serve to distinguish it. There is much varia- 

 tion in the character of the nodules found on the umboidal 

 ridge. The Kansas representatives are all less nodulous in this 

 region than are those of a series which I have examined from 

 the Cumberland river of Tennessee. 



Quadrula aspera Lea. Not figured. 



Unio asper Lea, Trans. Amer. Phil. Soc, iv, 1831, p. 85, pi. xix, fig. 15. 



"Shell subtriangular, angular behind and rounded before, 

 covered with small, rough tubercles, except in a furrow which 

 passes from the beak obliquely to the basal margin, which is 

 there arcuate ; the tubercles on the posterior slope arrange 

 themselves into a series of undulations as far as the beaks ; 

 substance of the shell thick ; beaks slightly prominent, liga- 

 ment short and thick ; epidermis brown and wrinkled ; car- 

 dinal tooth rather large, slightly elevated, and widely cleft in 

 the left valve, single emerging from a pit in the right ; lateral 

 teeth small, slightly curved in a direction over the cardinal 



