SCAMMON : THE UNIONID/E OF KANSAS, PART I. 363 



with the posterior margin. Umboidal ratio, from 0.15 to 0.20. 

 Umbones large, full, high, bluntly incurved, directed for- 

 ward, very slightly ornamented with a few coarse, con- 

 centric ridges. Anterior umboidal slope very abruptly curved, 

 in some cases almost straight dorsally ; lateral slope fully 

 rounded, bearing a very faint, broad groove extending from 

 the posterior portion of the ventral margin about one-half 

 the distance up the slope ; posterior umboidal slope rather 

 abrupt and sometimes slightly excavated. Epidermis smooth 

 in young and rough in old specimens, honey color to black ; 

 young specimens ornamented over the umbones with dark 

 green, narrow rays. Lines of growth coarse, crowded, and 

 imbricated. Lunule very large. Ligament long, thick, dark 

 brown. 



Interior : Pseudocardinals very heavy, large, erect, ragged, 

 double in the left and single (with sometimes an anterior and 

 a posterior auxiliary) in the right valve ; the left pseudo- 

 cardinals light, running to an edge, arranged in the form of 

 a V or U ; the right pseudocardinal broad and truncated and 

 surrounded by a deep v -shaped trench. Interdentum broad, 

 flat, and long. Laterals short, thick, straight or curved, very 

 oblique. Anterior adductor cicatrix elongate, small, deeply 

 pitted, the left one communicating with the trench about the 

 left pseudocardinal. Posterior scars large, deeply impressed, 

 distinct. Dorsal muscle scars arranged in a long row on the 

 lower surface of the pseudocardinals. Pallial line impressed 

 almost its entire length. Cavity of the shell slight, of the 

 beaks deep but compressed. Branchial outline well marked 

 dorsally. Nacre satin-white. 



Solida is distributed throughout Mississippi drainage. Lo- 

 cally it is found in the Neosho, the Verdigris and the Walnut 

 rivers, of the southern drainage. It is to be found on gravel- 

 bars and is not a rare species. 



Q. solida possesses the most massive shell of any Kansas 

 Unio. It is closely related to Q. coccinea and Q. plena, but it 



