28 University of Michigan 
mannsen, 47, p. 436 (type, U. dilatata Raf.) ; Agassiz, ’52, p. 45 (type, 
U. recta Lam.). 
Cunicula Swainson, ’40, p. 378 (no type named); Herrmannsen, ’47, 
Pp. 335 (type, U. purpurascens Lam.). 
The type of Eurynia has been designated by Herrmannsen 
as U. dilatata Raf., a species congeneric with the type of Ellip- 
tio. Thus, Elliptio and Eurynia are equivalent and have the 
same date of publication. Our preference given to Elliptio 
is justified by Art. 28 of the Code and the recommendation 
(c) as to page precedence. Agassiz’s designation of recta as 
the type of Eurynia-thus becomes invalid. 
Herrmannsen’s type of Cunicula being congeneric with the 
type of Elliptio, that genus also becomes a synonym of Elliptio. 
ELLIPTIO CRASSIDENS (Lamarck), 1919 
Type locality: Lake Erie (erroneous). 
Umo crassidens var. b. Lamarck, 19, p. 71. 
Unto nigra Rafinesque, ’20, p. 291, pl. 80, f. 1-4. 
Unio cuneatus Barnes, ’23, p. 263. 
U. crassidens, var. b. Lam.=U. cuneatus Bar., Lea, ’34, p. 87 (type 
examined). 
U. niger Raf. =U. cuneatus Bar., Conrad, ’34, p. 70 
U. niger Raf. =U. crassidens var. b. Lam.=U. cuneatus Bar., 
Ferussac, ’35, p. 27; Conrad, ’36, p. 40, pl. 26. 
Unio crassidens Lam. Simpson, ’14, p. 606. 
U. nigra Raf.=U. crassidens Lam. (of Simpson), Vanatta, ’15, p. 
555 (‘type” examined). 
Elliptio niger (Raf.), Utterback, ’16, p. 88; Ortmann, 718, p. 555. 
Unio crassidens Lam. = U. nigra Raf., Walker, ’18¢, p. 174 (if iden- 
tifiable). 
“Lamarck proposed this species to include several long, solid 
forms which we now know belonged to three species, still 
another being included by him in the citation of a figure from 
Lister. One of these species is now known, from examination 
of his specimens, to be a plicate shell; the others are smooth. 
There is some difference of opinion as to whether he intended 
to describe crassidens as plicate, but as he included two 
