232 AMERICAN MIDLAND NATURALIST 
GENUS ANODONTA, BRUGUIERE 1792. 
. grandis Say, 1829. 
The nacre of the species, which is normally bluish 
white, is often excessively roughened and salmon 
colored, a pathologic condition brought about by 
the work of a parasitic trematode. Other species of 
Anodonta, as well as Symphynota costata have been 
observed as similarly affected. Lea's A. salmonia 
is merely A. grandis thus diseased. This species is 
common to all streams of Iowa. 
. corpulenta Cooper, 1834. 
ommon in the Wapsipinicon and Turkey, usually 
in company with the preceding species. 
. imbecillis Say, 1829. 
Collected only in the Wapsipinicon at Independence, 
where it is common in the slough near the Second 
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GENUS ANODON TOIDES SIMPSON, 1898. 
19. Ano. ferussacianus (Lea, 1834) Baker, 1898. 
Occurs in all the rivers of northeastern Iowa. 
GENUS SYMPHYNOTA LEA, 1829. E 
20. S. complanata (Barnes, 1823) Lea, 1830. a 
ery common in the Wapsipinicon and Turkey riv- Pr 
ers. In the former stream, the species attains a D | 
diameter of from six to eight inches. -F 
21. S. compressa Lea, 1829. 
Dead shells referable to this species are found quite 2*3 
abundantly along the Volga at Fayette, but thus far — 
lowing locality: “A few specimens taken in the 
Des Moines River at Des Moines: very rare." 
22. S. costata (Rafinesque, 1820) Simpson, 1900. EU: 
Abundant: Wapsipinicon, Volga, and Turkey 
Rivers. í E 
GENUS ALASMIDONTA SAY, 1818. 
23. Alas. calceola (Lea, 1830) Simpson, 1900. E 
3 pos quite abundantly in the Volga at Fayette and = 
24 Alas. truncata B. H. Wright, 1898. AR A 
o apsipinieon, abundant; Volga, at Fayette, a few 
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