PROCEEDINGS OF THE NATIONAL MUSEUM. A411 
8 iad - . . . . 
being rather higher colored, [ think it quite probable that when large 
series of this are compared with U. Forbesianus they will be found to 
be mere variations of one species. 
s 
Unio pusillus Lea. 
(Plate 11, Figs. 2, 6.) 
Unio pusillus Lea, Obs. 1x, p. 19, Pl. xxvit, Fig. 36, Oct.2, 1840. Ogeechee R., 
Ga.; Maj. Le Conte. 
Unio buxeus Lea. (Plate 11, Fig. 3.) Obs. v, p. 17, Pl. xv, Fig. 13, Mar. 5, 1852. 
* Abbeville Dist., 8. C.; J. P. Barrett. 
Unio Anthonyi Lea. (Plate x1, Figs.4,5.) Obs. 1x, p. 19, Pl. xxvur, Fig. 266, 
Feb. 5, 1861. Fla.; Anthony. 
Dr. Lea described U. pusillus from specimens he had long thought 
the young of some other known species. U. bureus was described from 
three shells, only one of which he considered adult. 1 do not see how 
_ it is possible to separate these from the types of pusillus, as they agree 
in size, form, color of epidermis and nacre, and in the teeth, and all 
appear to me to be young shells. His type of U. Anthony, a single 
specimen, probably adult, had been varnished and otherwise injured. 
_Itis a tawny yellowish green, with very faint rays, and is hardly as 
solid a shell as some of the young of buxeus and pusillus. A young 
specimen of U. Anthonyit which Mr. Lea afterwards obtained of Maj. 
Le Conte, from the Ogeechee River, is quite conspicuously rayed, and 
is almost precisely like some of the specimens of the above named spe- 
cies. 
7 Unio dorsatus Lea. 
(Plate 11, Fig. 7, Plate Li, Figs. 1, 2.) 
» Unio dorsatus Lea. Obs. xu, p. 60, Pl. xiv, Fig. 112, June 2, 1868. Type, Cataw- 
ba R., N. C.; C. M. Wheatley. ; 
A very variable and puzzling species. There is much difference in 
the solidity, width, and form of individuals. A specimen is before me 
from the cabinet of Wm. A. Marsh, labeled “ U. Anthonyi Lea, Flor- 
ida,” and another from Mrs. Andrews, collected in Florida, by Rugel, 
without locality, which are, I believe, U. dorsatus. ‘in all the examples 
_I have seen, the epidermis is dull tawny brownish and squamose, the 
substance of the shell rather thin, and the nacre shaded purple. The 
form of the shell, its dorsal ridge, and the slight plications of the pos- 
_ terior slope probably place it here, but if has affinities with the Com- 
 planatus group. 
GROUP OF UNIO COMPLANATUS. 
Unio complanatus, which is one of the most abundant species in the 
United States, may be taken as the type of an extensive group which 
_ is distributed from Canada to northern Florida, and from the Appala- 
- chian Chain to the Atlantic. Mr. Lea recognized the immense varia- 
