314 KANSAS UNIVERSITY SCIENCE BULLETIN. 



T. tuberculata is found throughout the Mississippi drainage 

 and in those streams emptying into the Gulf from Alabama 

 to Texas. Its distribution in Kansas is general. Its reported 

 western range in the southern drainage is the Little Arkansas 

 river at Wichita ( Mead) . In the Kansas drainage it has been 

 found as far west as the Smoky Hill river at Salina. It 

 doubtless ranges somewhat further westward. The largest 

 specimens I have seen from Kansas waters were two females 

 from the latter locality. Their measurements are given in 

 the table above (215.1 and 215.2). 



There seems to be no definite habitat for this species. It 

 is found in almost all locations except sandy, shifting river- 

 beds. In the Wakarusa river at Lawrence, where it is a com- 

 mon species, it is found well rooted in the gravel and shingle 

 in a swift current, and again buried to the siphons in the thick 

 black mud, where there is but little current, in company with 

 Symphynota complanata and Strophitus edentulus. I have found 

 specimens in Indian creek, in Johnson county, lying on a hard 

 rock bottom in six inches of rapidly flowing water. 



This is one of the easiest species in which to distinguish 

 the sexes. The males are short, thick, and abruptly truncate 

 posteriorly ; the females long, slender, and provided with 

 the posterior wing. There is great variation in the num- 

 ber and position of the pustules. This is one of the easiest 

 of Kansas Unios to identify. 



MESOGEN.S. 



"Male and female shells alike, short, solid, inflated, em- 

 bryo occupying a few distinct ovisacs in the center of the 

 outer gills." (Simpson.) 



Genus CYPROGENIA Agassiz, 1852. 



•'Shell solid, inflated, rounded triangular, sometimes 

 slightly retuse, generally a little biangulate behind ; posterior 

 ridge unusually well developed, especially in the young shell ; 

 umboidal region flattened parallel with the axis of the shell, 

 sometimes compressed ; beaks turned inward and forward, the 

 sculpture very faint, consisting of slightly doubly looped 

 ridges ; sculpture of the shell nodular, radially wrinkled or 



