326 KANSAS UNIVERSITY SCIENCE BULLETIN. 



Louisiana (Simpson). It is generally a rare species, but 

 sometimes abundant locally (Call). It has been reported 

 from only two localities in the state, the Neosho river in the 

 southern drainage (Call), and Silver Lake, Shawnee county, 

 in the Kansas drainage. Its habitat is the muddy beds of 

 slow streams and ponds. 



This is the largest anodon found in the state. The largest 

 specimen I have seen from the state measured 176 mm. in 

 length. It is in the Quintard collection of the Kansas Acad- 

 emy of Science, at Topeka. There is but little variation. 

 The juvenile shells are much more rayed than are the adult, 

 and the dorsal posterior angle grows less acute as the shell 

 increases in size and age. 



Anodonta grandis Say. Plate LXXIV, fig. 3. 



Anodonta grandis Say, New Harm. Diss., ll, 1829, p. 341, 



Anodonta ovata Lea, Trans. Amer. Phil. Soc, VI, 1838, p. 2, pi. II, fig. 2. 



Anodonta salmonia Lea, Trans. Amer. Phil. Soc, vi, 1838, p. 45, pi. 

 XIV, fig. 41. 



Anodonta lewisii Lea, Proc. Acad. Nat. Sci. Phila., I, 1857, p. 84. 



Shell large, moderately thin, inflated, wide elliptical. An- 

 terior margin rounded ; ventral margin generally gently bowed 

 but sometimes almost straight ; posterior margin bluntly an- 

 gulate or rounded ; dorsal margin straight or slightly curved 

 and extremely variable in its length, the dorsal posterior 

 angle quite variable. Umboidal ratio quite constant, at 

 approximately one third. Umbones more or less inflated and 

 marked with three or four coarse double-looped ridges. Um- 

 boidal slopes rounded, the posterior and anterior slope flat- 

 tened near their margins. Epidermis smooth, shining, variable 

 in color, generally green over the disk and brownish gray 

 on the umbones, and the posterior slope almost black, the 

 color often arranged in concentric bands of different shades ; 

 large old specimens are often black, young specimens ob- 

 scurely rayed. Ligament moderately long, stout, very dark 

 brown. Posterior hinge line slightly curved and well defined. 

 Muscle cicatrices large, rather faintly outlined. Pallial line 

 not visible in some specimens and never impressed. Dorsal 

 muscle scars occasionally impressed, but often faint, located 

 in the wall of the tip of the umbone cavity. Umboidal cavity 

 small, cavity of shell large. 



