SCAMMON : THE UNIONID.E OF KANSAS, PART I. 353 



Quadrula fragosa Conrad. Plate LXXXII, fig. 1. 



Unio fragosus Conrad, Mon. Fresh-water Shells, II, 1836, p. 12, pi. VI, 

 fig. 2. 



Shell of moderate size, fairly thick, thickest anteriorly, 

 quadrate in outline. Anterior margin and the first half of 

 the ventral margin a full curve ; posterior half of the ventral 

 margin slightly incurved ; posterior margin almost straight 

 and at right angles to the posterior half of the ventral margin ; 

 dorsal margin straight or slightly curved, slightly oblique. 

 Umboidal ratio variable, from 0.20 to 0.30. Umbones of 

 moderate height and inflation, incurved, tuberculate. An- 

 terior umboidal slope smoothly rounded ; lateral slope marked 

 posteriorly by a wide radial furrow, along each side of which 

 is a row of erect, prominent tubercles, which run from the 

 umbones to the margin ; minor tubercles are scattered among 

 the major ones, particularly those of the anterior series ; poste- 

 rior umboidal slope somewhat excavated and covered with a 

 series of small, irregular plications, which are gently bowed 

 ventrally. Lines of growth fairly continuous and prominent. 

 Epidermis horn color to seal-brown. Ligament short, of 

 moderate thickness, light brown in color. Lunule small. 



Interior: Pseudocardinals large, erect, serrate, double in 

 the left and single in the right valve. Interdentum broad 

 and short, quite oblique. Anterior adductor scar placed in 

 front of the pseudocardinals, set slightly under the anterior 

 leftpseudocardinal, small, quite deeply excavated, with a level 

 floor. Posterior scars of moderate size, impressed, distinct. 

 Pallial line impressed for the greater part of its length 

 Dorsal muscle scars few but well marked, placed on the lower 

 surface of the pseudocardinals. Cavity of the shell moder- 

 ately large, of the beaks large. Nacre silvery white, irides- 

 cent on the posterior half. 



This species is found in the Ohio, Cumberland and Ten- 

 nessee river drainage systems and ranges west into Kansas, 

 Nebraska, and Minnesota. In Kansas it is confined to the 

 southern drainage system. It has also been reported from 



