SCAMMON : THE UNIONID^ OF KANSAS, PART I. 343 



Quadrula perplicata Conrad. Not figured. 



Unio perplicatus Conrad, Proc. Acad. Nat. Sci. Phila., i, 1841, p. 19. 

 Unio atrocostatus Lea, Trans. Amer. Phil. Soc, x, 1847, p. 70, pi. ll, 

 fiR. 5. 



Shell large, quite thick, somewhat inflated, quadrate, wider 

 before than behind. Anterior margin flatly rounded ; ven- 

 tral margin regularly and gently bowed ; posterior margin 

 flatly rounded, inclined to be biangulate ; dorsal margin 

 straight, directed somewhat upward. Umboidal ratio, about 

 0.25. Umbones fairly inflated, but not very high. Anterior 

 umboidal slope rather abruptly rounded ; lateral slope fully 

 rounded ; posterior slope wide, flattened, inclined to be 

 slightly excavate. Lateral slope ornamented with a series 

 of more or less regular folds, four to seven in number, di- 

 rected obliquely across the disk from the umbones to the 

 ventro-posterior margin ; the posterior slope bearing a con- 

 tinuation of the series of folds, which in this region are 

 smaller, arranged more transversely, and bowed dorsally at 

 either end. Epidermis glossy chestnut brown, with imbri- 

 cated lines of growth marginally. Lunule small. Ligament 

 short and stout. 



Interior : Pseudocardinals of moderate size and height, 

 roundly pyramidal, double in the left, and single, with some- 

 times one or two auxilaries, in the right valve. Interdentum 

 broad, smooth, rather long. Laterals short, straight, a little 

 oblique. Anterior adductor cicatrix evenly and shallowly ex- 

 cavated, with a roughened floor, uniform in outline ; pos- 

 terior scars broader than long, lightly impressed, confluent; 

 dorsal muscle scars on the lower surface of the interdentum 

 and pseudocardinals. Pallial line impressed and crenulate 

 the first two-thirds. Cavity of beaks and shell fairly large. 

 Nacre a beautiful silver-white, iridescent posteriorly. 



Length, Height. Breadth. Um. ra. 



87 50 44 0.23 (470.1) 



Q. perplicata is a Southern species, found in the Alabama 

 drainage and the streams flowing into the Gulf of Mexico, as 

 far west as central Texas and north to Kansas. The only 

 specimens from Kansas of which I have personal knowledge 

 are two received from Doctor Newlon, from the Neosho river 



