334 ANNALS OF THE CARNEGIE MUSEUM. 
Proptera purpurata (Lamarck). 
One male, and two sterile females from Bayou Pierre, De Soto 
Parish, Louisiana, have been sent by L. S. Frierson, and three males 
from Ouachita River, Arkadelphia, Clark Co., Arkansas, by H. E. 
Wheeler. 
Description of soft parts given by Lea (Obs., X, 1863, p. 436). 
This species is closely allied to the foregoing, and is its representative 
form in the south. The close relationship is borne out by the soft 
parts, which are absolutely identical. I have not seen the glochidia, 
but they have been described and figured by Lea (Obs., XIII, 1874, 
p. 73, pl. 21, fig. 13). They much resemble those of P. alata, but since 
Lea does not give the proportions, a closer comparison is impossible. 
Proptera levissima (Lea). 
I myself found a young male in the Ohio River, Portsmouth, Scioto 
Co., Ohio, and received, from R. L. Moodie, four males, and three 
gravid females from the Kansas River, Lawrence, Douglas Co., 
Kansas. 
Soft parts described by Lea (Obs., X, 1863, p. 425). 
Simpson places this species near L. gracilis, but the shape of the 
glochidia (see Plate XX, fig. 2) shows that it belongs to Proptera, 
and is related to P. alata. The soft parts, although similar in the 
genera Proptera and Paraptera, are more like Proptera, because of the 
shorter mantle-connection between the anal and the supra-anal. 
The glochidia are of the Proptera-type, but they differ distinctly from 
those of P. alata in being considerably smaller, and in having the 
ventral margin broader and more curved. The difference in shape is 
well expressed in Lea’s figure (Obs., VI, 1858, pl. 5, fig. 24; see also 
Coker and Surber, 1911, pl. 1, fig. 1) while that of size is not. 
Length 0.12; height 0.18 mm. (Coker and Surber give length 0.095 
mm.; height 0.15 mm.). 
Genus MEDIONIDUS Simpson. (1900.) 
(Simpson, 1900), p. 588.) 
Shell elongated. Posterior slope plicately or nodulously wrinkled. 
Beak-sculpture of the double-looped type, indistinct. Epidermis 
yellowish green, with green rays and blotches. Shell of the female 
different from that of the male, somewhat swollen just behind the 
middle of the base. 
