SCAMMON : THE UNIONIDiE OF KANSAS, PART I. 313 



Tritogonia tuberculata Barnes. Plate LXX, fig. 4. 



Unw tuberculatus Barnes, Amer. Jour. Sci. and Arts, VI, 1823, p. 



125, pi. vil, figs. 8a, 86. 

 Unio verricosus Say, Amer. Conch., VI, 1834. 



Shell large, solid, elongate, and irregularly trapezoidal. 

 Anterior margin and front third of the ventral margin a gen- 

 tle curve, middle third of the ventral margin incurved, pos- 

 terior third of the ventral margin straight or curved somewhat 

 upward; posterior margin somewhat oblique and rounded, 

 straight in males and greatly produced in females ; dorsal 

 margin straight or slightly curved and meeting posterior 

 margin at a variable a.ngle. Umboidal ratio variable, from 

 0.15 to 0.25 Umbones sharp, low, incurved, marked with 

 a number of acute tubercles, which posteriorly form fine 

 lines in some cases. Anterior umboidal slope flatly rounded, 

 lateral slope slightly excavated, both thickly studded with 

 small, low tubercles, which often arrange themselves into 

 diagonal rows. Posterior umboidal ridge very prominent, 

 slightly curved posteriorly ; in the males numerous side 

 ridges are given off which run to the posterior margin ; this 

 character not well developed in females ; posterior slope of 

 male short and truncate, of female developed ventrally into 

 a long, smooth wing. Epidermis from rusty chestnut brown 

 to dark horn color, with sometimes a greenish tinge. Lines 

 of growth coarse, but not continuous. Ligament long, dark 

 brown. Lunule large, black. 



Interior : Pseudocardinals large, pyramidal, ragged, double 

 in the left, single and sometimes double in the right. Later- 

 als long, straight, rather heavy. Anterior adductor cicatrix 

 deep, and sometimes set slightly under the anterior pseudo- 

 cardinal ; retractor cicatrix small and well impressed. Pos- 

 terior scars well marked, of moderate size, fused. Dorsal 

 cicatrices small. Pallial line impressed and crenulate an- 

 teriorly. Cavity of beaks deep, of the shell moderate. Nacre 

 milk-white, iridescent posteriorly. 



