scammon : the unionid.e of kansas, part i. 285 



Genus LAMPSILIS Rafinesque, 1820. 



"Shell oval to elliptical, smooth or slightly concentrically 

 sculptured, usually without a posterior ridge ; epidermis gen- 

 erally smooth and shining, often brilliantly rayed ; beak 

 sculpture, for the most part, consisting of fine, parallel 

 ridges, which show a tendency to fall into an anterior and a 

 posterior loop ; hinge with one or two pseudocardinals and 

 one lateral in the right valve, and two pseudocardinals and 

 two laterals in the left ; female shell having a moderate and 

 gradual inflation in the post-ventral region opposite the mar- 

 supium. Animal with the inner gills attached nearly or 

 quite through entire length to the abdominal sac ; marsupium 

 occupying the hinder part of the outer gills ; ovisacs distinct, 

 separated by sulci, rounded below, having a fold near their 

 bases, the whole projecting below the inner gills ; mantle 

 edge doubled and thickened, often swollen behind in a sort of 

 flap in the female." (Simpson ) 



Lampsilis ventricosa Barnes. Plate LXIII, fig. 2. 



Unio ventricosus Barnes. Amer. Jour. Sci. and Arts, No. iv, 1832, pi. 

 xxxn. 



Unto occidens Lea. Trans. Amer. Phil. Soc, iii, 1829, p. 435, pi. x, 



fig. 16. 

 Unio subovatus Lea. Trans. Amer. Phil. Soc, iv, 1831, p. 118, pi. 



XVIII, fig. 46. 



Unio canadensis Lea. Proc. Acad. Nat. Sci. Phila., I, 1857, p. 85. 



Shell large, of moderate thickness, subelliptical in females, 

 elliptical in males; females much inflated, males less so. 

 Anterior margin decidedly rounded ; ventral margin nearly 

 straight in female, bowed in male ; posterior margin often 

 slightly emarginate in the female, roundly pointed in the 

 male ; dorsal margin somewhat curved or straight. Umboi- 

 dal ratio approximately one-third. Umbones large and full, 

 marked with a few coarse ridges. Anterior umboidal slope 

 rounded short ; posterior slope long and flat in males, rather 

 short and high in females. Shell generally smooth except 

 in old specimens ; lines of growth dark, continuous, imbri- 

 cated. Epidermis from straw-yellow to dark brown, with a 

 few posteriorly placed dark-green rays in some specimens. 

 Ligament short, stout, black. 



Interior : Pseudocardinals high, serrate, directed anteriorly, 



