310 ANNALS OF THE CARNEGIE MUSEUM. 
marsupium to a few ovisacs, compensating for the reduction in their 
number, by an increase in their length. The tendency to move the 
marsupium backward toward the branchial opening is but slightly 
indicated. 
Obliquaria reflexa Rafinesque. 
Three males and one sterile female from the Ohio in Beaver Co., 
Pennsylvania, and another sterile female taken at Portsmouth, Scioto 
Co., Ohio, have been collected by myself. I received a sterile female 
from the Ouachita River, Arkadelphia, Clark Co., Arkansas, collected 
by H. E. Wheeler, February 6, 1911; and two males and four gravid 
females from Bayou Pierre, De Soto Parish, Louisiana, collected by 
L. S. Frierson, August 6, 1910. 
Soft parts described by Lea (Obs., X, 1863, p. 429) and figured by 
Lefevre and Curtis (1910, pl. 1, fig. 3). 
Branchial, anal, and supra-anal 
as usual, mantle connection be- 
tween the two latter moderately 
long, but shorter than the small 
anal. Branchial with papilla, anal 
crenulated. Toward the front the 
papilla of the branchial disappear 
suddenly, and the edge of the 
mantle is smooth, with a few indis- 
tinct crenulations just in front of 
the branchial. Palpi normal, their 
Fic. 16. Obliquaria reflexa Rafin- 
esque. Gravid female, from Bayou 
Pierre, De Soto Parish, La. (Carn. 
Mus., No. 61, 4,755.) at base. 
Gills short and broad, the inner 
posterior margins connected only 
wider anteriorly. Diaphragm normal; inner lamina of inner gills free 
from abdominal sac except at anterior end, where a portion less than 
half the length of the abdominal sac is connected. Anterior ends of 
gills normal. 
Septa and water-tubes of both gills of the usual structure in the 
male. In the female, the marsupium is formed by a part of the outer 
gill lying just behind the middle of the gill, and not extending to the 
posterior end of it. The most characteristic feature is that the mar- 
supium consists only of a small number (four to six in my specimens, 
but reported up to eight) of ovisacs, which, when empty, are hardly 
