SCAMMON : THE UNIONID^ OP KANSAS, PART I. 323 



of umboues shallow. Nacre variable, sometimes silver-white ; 

 cavity of the shell often salmon-yellow, varying to salmon- 

 rose ; posterior and lower margins of the shell iridescent. 



This species is found throughout the Mississippi and St. 

 Lawrence drainage areas and in eastern Texas. In Kansas 

 it is common to all the drainage basins. It has been re- 

 ported as far west as Reno county (Mead) in the southern 

 drainage, and as the Smoky Hill river at Salina in the west- 

 ern drainage. In the streams and small rivers of the east 

 central part of the state it is quite abundant. Although pre- 

 ferring a muddy bottom and quiet water, it is able, by anchor- 

 ing itself in the silt with its muscular foot, to withstand a 

 strong current. It is a rapid burrower and quite tenacious 

 of life. 



There is but little variation in this form while it remains 

 in quiet, muddy streams, but rapid flowing and rocky streams 

 produce a variety of forms and colors in the shell, any of 

 which would be sufficient to characterize a species were they 

 constant. 



The peculiar rudiments of pseudocardinals will serve to 

 separate this species from any other in the state. 



HOMOGEN^. 



"Male and female shells alike, oval to elongate ; beak sculp- 

 ture coarse ; embryos filling the entire gills in the form of 

 thick, smooth pads; the ovisacs not separated by sulci." 

 (Simpson.) 



Genus ANODONTA Lamarck, 1799. 



"Shell elliptical, thin, inflated, often slightly winged pos- 

 teriorly ; beak sculpture consisting of rather numerous more 

 or less parallel ridges, usually somewhat doubly looped, and 

 becoming slightly nodulous on the loops ; surface generally 

 smooth, shining; hinge edentulous, reduced to a mere line, 

 regularly curved ; muscle scars rather faint ; nacre dull. 



