100 THE CHICAGO ACADEMY OF SCIENCES. 
Distribution: Ottawa River, Canada, to Minnesota, Iowa 
and Kansas, and south to Central Alabama and Texas. (Call. ) 
Geological distribution: Pleistocene. 
Habitat; Found in rivers and sloughs where there is a 
muddy bottom and not much current. 
Remarks: This is a distinct shell and is quite readily iden- 
tified. Its peculiar yellow surface, with green rays (sometimes 
pure yellow, without rays), its depressed umbones and its alate 
postero-dorsal margin will at once distinguish it. It may be 
distinguished from Z. a/atus by its yellowish color, weak teeth 
and thinner shell. Very old specimens lose the alate character 
and become broadly elliptical in outline, and some specimens 
have the posterior end very much produced. The very weak 
hinge teeth allies this species to the members of the genus 
Alasmodonta, and under very favorable conditions it might be- 
come, by living in a quiet, muddy pond, an Anodonta by the 
atrophy of the teeth. In some individuals the cardinal teeth 
are so small that they appear as simple nodules. The posi- 
tion of the protractor pedis muscle scar is quite peculiar. The 
species does not appear to be very common, but is rather widely 
distributed. A specimen from Thorn Creek weighed one pound 
and one ounce when alive. ( Vide Jensen.) 
Section EURYMA Rafinesque, 1820. 
GROUP OF LAMPSILIS ANODONTOIDES. 
30. Lampsilis anodontoides Lea, pl. x., figs. 1, 2, 3. 
Unio anodontoides Lka, Trans. Amer. Phil. Soc., Vol. IV., pp. 81, 89, pl. 
viii., fig. 11, 1830. 
Unio teres RAFINESQUE, vide Conrad's monograph, pl. xxviii. 
Unio floridensis Lea, Trans. Amer. Phil. Soc., Vol. X, p. 274, pl. xxi., 
fig. 31, 1852. 
Shell: Solid, very long, somewhat inflated, rounded before 
and acutely pointed behind, the female much swollen and pro- 
duced in this region; dorsal and ventral margins about straight; 
surface smooth and shining, frequently highly polished; um- 
bones placed anteriorly, prominent but not much elevated, 
marked by from five to seven scarcely elevated wrinkles arranged 
in along double loop; ligament elevated, strong, wide, dark chest- 
nut color; epidermis varying from plain yellow without rays to 
light green with dark green rays; in some specimens the pos- 
terior umbonal slope is painted with dark green; anterior 
umbonal slope rounded, short; posterior slope long, slightly ex- 
cavated; cardinal teeth double in both valves, elevated, long 
