368 KANSAS UNIVERSITY SCIENCE BULLETIN. 



Key to the Kansas Uniouiclae. 



This key is a purely local and artificial one. It is intended only to supplement the figures 

 and descriptions in the identification of species, 



I. Shell Rodgh. 



A. Shell bearing undulations across the disk. 



a. Undulations confined to the posterior slope, laterals not present. Sym- 

 phynotu costala. 



b. Laterals present. 



1. Umbones high and full. Quadrula plicala. 



2. Umbones fairly high and full; shell decidedly broader behind than 



before ; plications regular. Quadrula psrplicata. 



3. Umbones compressed, 



1*. Umbones smooth except for slight ridges on their tips. Quad- 

 rula undulata, 



2^ Umbones very pustulose. Quadrula heros. 



B. Shell ornamented with coarse concentric folds on the lateral slopes, very heavy; 

 beaks placed far forward, Pleumbema cicairicosum. 



C. Shell with a very pronounced umboidal ridge, which is ornamented with several 

 large, irregular nodules. 



a. Shell decidedly elongate, pseudocardinals small, Quadrula cylitiflrica, 



b. Shell roundly quadrate, pseudocardinals large. Quadrula metanevra, 



D. Shell elongate with strong umboidal ridge, tubercular anterior, generally brokenly 



plicate posteriorly, Tritogonia tubei culaia. 



E. Shell roundly triangular, lateral slopes bearing a single radial row of erect tuber- 



cles 3-5 in number, Obliquaiia rejiexa. 



F. Shell pustulose, 



a. Pustules arranged in two radial rows on either side of a shallow radial furrow. 



1, Pustules confined to the dorsal half of the disk, shell produced posteri- 



orly, Pleurobema a'supus. 



2. Pustules generally extending over the surface of the disk, shell quadrate. 



Group of Quadrula lachrrimosa. 



b. Pustules irregularly scatteredover the disk, shell sometimes almost epustulate. 



Group of Quadrula pustulosu, 



II. Shell Smooth. 



A. Neither laterals nor pseudocardinals present. 



a. Beaks hardly apparent. 



1. Shell small and cylindrical. Anodonta (iracilis. 



2, Shell large and circular in outline, Anodonta suborbiculata. 



b. Beaks of moderate inflation and elevation, 



1, Shell large, hinge line straight in front of the umbones, relation of 



length to breadth as 2 is to 1. Group of Anodonta grandis. 



2. Shell of only moderate size, hinge line slightly incurved in front of the 



beaks; shell drawn out to a point posteriorly. Anodontoides fervs- 

 sacianus, 



c. Shell with extremely high and inflated beaks, Anodonta opaca. 



B, Laterals absent, pseudocardinals present as mere rounded knobs. Steophitus eden- 



tuhis. 



C, Pseudocardinals well developed, laterals indicated only by one low ridge on each 

 valve. Shell often alate, Symj>hynola coviplanata. 



D. Laterals and pseudocardinals present, 



a. Shell alate. 



1. Nacre pinkish in the cavity and over the dentition of the shell, pseudo- 



cardinals small, rounded knobs. Lampsilis gracilis, 



2, Nacre deep purple pink all over the interior of the shell. 



1'. Shell very thin, pseudocardinals extremely lamellar, Lamp- 

 silis la'vissitna. 



2'. Pseudocardinals of moderate size and typical form; shell 

 square posteriorly. I,uinpsili» alala. 



3', Shell only slightly alate, inflated, subsolid, pseudocardinals 

 of typical form, epidermis generally black, Lampsilis pur- 

 purata. 



