298 KANSAS UNIVERSITY 8CIKNCE BULLETIN. 



Lampsilis parva Barnes. Plate LXVII, fig. 3. 



Unio parvus Barnes, Araer. Jour. Sci. and Arts., VI, 1823, pi. xm, 

 fig. 18. 



Shell small, elliptical, thin, inflated. Anterior margin 

 rounded ; ventral margin gently bowed ; posterior margin 

 rounded ; dorsal margin straight, meeting the posterior at an 

 angle of from 140 to 150 degrees. Umbones placed well for- 

 ward, large and a little inflated, ornamented with five or 

 six coarse concentric ridges. Anterior umboidal slope well 

 rounded, posterior slope less so. Epidermis smooth, gener- 

 ally dull and cloth-like, eradiate, hair brown, with some- 

 times a greenish cast marginally ; umbones often of a lighter 

 shade. Lines of growth numerous, continuous, fine, often 

 darker in color. 



Interior: Pseudocardinals double in the left valve and 

 single or double in the right, fine, triangular, erect, the an- 

 terior right, when present, small and feeble. Laterals long, 

 straight, thin. Anterior adductor scar well impressed, longer 

 than wide. Posterior cicatrices large, lightly outlined, con- 

 fluent. Pallial line impressed anteriorly. Dorsal scars few 

 and placed in the cavity of the umbones. Lines of growth 

 show on the inside of the shell as concentric rounded ridges. 

 Cavity of beaks moderately large, of shell large. Nacre white, 

 iridescent. 



L. parva ranges from western New York and southern Can- 

 ada throughout the Mississippi valley to eastern Texas. It 

 is found in all the Kansas drainage systems, and has been re- 

 ported from as far west as Big creek, at Ellis (Call). It is 

 not an uncommon species in the eastern portion of the Kan- 

 sas area. Its habitat is muddy and sluggish streams. It 

 burrows several inches into the mud. 



This is the smallest species found in Kansas, the average 

 length being about an inch. The females are much more 

 inflated than the males. The small size and heavily undu- 

 lated beaks will serve at once to identify it. A very near 



