﻿378 ANODONTA 



in a sharp prodissocuncli, llicir sculptures cunsisliug ut numer- 

 ous rather fine, corrugated, concentric ridges; surface with 

 irregular growth lines ; epidemiis yellowish-green, ashy or 

 lead-color, scarcely shining, seldom having feeble rays ; nacre 

 bluish-white, rather dull, sometimes a little iridescent behind. 



Length 70. height 47, diam. 2'j mm. 



Washington to California ; east to Utah. 



Type locality, Wahlamat River near its junction with the 

 Columbia. 

 Anodonta niittalliana Lea, Tr. Am. Phil. Soc, VL 1838, p. yy, 



pi. x.\, fig. h2 ; ( )bs., II, 1838, p. jj, pi. XX, fig. 62. — CuvSsiN, 



Conch. Cab. Ano., 1874, p. 147, pi. i., figs. i. 2. — Simpson, 



Syn., 1900, p. 629. 

 Margarita (Anodonta) nuttalliana Lk.\. Syn., 1838, p. 29. 

 Margaron (Anodonta) nuttalliana Lka, Syn., 1852, p. 47; 



1870, p. 75. 

 Anodon nuttalliana Cati.ow and Rkeve, Conch. Nom., 1845. 



p. 67. 

 Anodonta triiUigiiUiris Trask, Pr. Cal. Ac. Xat. Sci.. I, 1855, 



p. 29. 

 Anodon triangnUvis SovvivRUV, Conch, icon., X\TL 1870, pi. 



XXIX, fig. 56^. 

 Anodonta cyg)iea impnra (])art). H wxii! \i,. Proc. Mai. Soc. 



London, X, 1912, p. 125. 



This species, if species it may be called, seems to stand about 

 midway between the rude, dark, dull colored A. xcahlametensis 

 and the delicate, shining ./. califoDiicnsis. Dr. R. E. C. 

 Stearns believes that all three of these forms run together and 

 there is much ground for such a position, as there is a good 

 deal of material which cannot be satisfactorily assigned to 

 any of the three. The same thing, however, may be said of 

 most of the closely related forms of Anodontas wherever they 

 are found. A. nuttalliana is more rbom]>oid. is stronger and 

 duller colored than . /. calif ornicnsis. It is less robust than A. 

 ^walikunctcnsis. the wing is not so high, the posterior slope is 

 rarely incurved, the posterior point is not so decided and the 

 color is not as dark. 



