ae | PROCEEDINGS OF THE NATIONAL MUSEUM. 433 
GENUS ANODONTA. 
GROUP OF ANODONTA IMBECILLIS. 
Very thin, inflated, smooth, shining anodons, with undulate beaks, 
and having the epidermis brightly painted with shades of yellowish 
and green. The ventral region is well developed, the posterior end is 
rather pointed, the umbonal area is in most cases peculiarly flattened, 
and over it the delicate radiating lines of color are often beautifully 
undulated. The group is widely distributed, the type species being 
found from Rideau Canal, Canada, to Darien, Ga., and from Minne- 
sota to Matamoras, Mexico.* The distinctions between the North 
American forms of anodons are very poor and ill defined. The north- 
ern specimens of A. imbecillis are wider and morecompressed at the 
beaks; in the south they are more inflated, of greater proportional 
length, with the umbonal region less depressed, until they seem to 
almost shade into A. Henryana, A. Dunlapiana, and A. Couperiana. 
Anodonta Couperiana Lea. 
(Plate LxxIv, Fig. 1.) 
Anodonta Couperiana Lea. Obs. 1, p. 65, Pl. xx, Fig. 46, Oct. 2, 1840. Hopeton, 
near Darien, Ga., J. H. Couper. 
Anodonta Dunlapiana Lea. (Plate LXXIVv, Figs. 2, 3.) Obs. 111, p. 86, Pl. XXviI, rig. 
65, Oct. 21, 1842. 8. Carolina; Mrs. Dunlap. 
Dr. Lea claims that A. Dunlapiana is less oblique and more cylindrical 
than A. Couperiuna, but his series of the former shows a gradual 
variation from one to the other. I doubt if A. Henryana from Mexico 
is more than a mere variety. In the younger shells the beaks are much 
compressed; in old specimens they become somewhat inflated. 
EXPLANATION OF PLATES. 
Nore.—The figures are all the natural size of the specimens. 
PLATE XLIX. 
| 
| Fic. 1. Unio infucatus Cour. (U. S. Nat. Mus. register No. 84037); Georgia; light 
| brown; p. 409. 
| 2. The same (84034); Georgia; nearly smooth, black; p. 409. 
3. Unio Forbesianus Lea; Georgia; type (84542); p. 410. 
4, Unio vestitus Lea; Georgia; type (85333); p. 410. 
5. Unio infucatus Cour. (84034); Georgia; smooth, black, inflated; p. 409. 
6. Unio Kleinianus Lea (84081); Florida; brown; p. 409. 
Prarnel: 
. Unio vestitus Lea (85333); Georgia; p. 410. 
. Unio Forbesianus Lea (84542); Georgia; p. 410. 
. The same; Lake Monroe, Florida; p. 410. 
Fig. 
mw to ee 
Proc. N, M, 92 28 
