ORTMANN: FAMILIES AND GENERA OF NAJADES. 255 
than in the male. The ‘‘inside flap’’ can only be the inner edge of the 
mantle, which is present, however, in the male also. The true position 
of ‘this species was first indicated by Sterki (1907, p. 48). 
Quadrula metanevra (Rafinesque). 
Thirteen specimens of either sex, one a gravid female, were exam- 
ined in the laboratory, all from the Allegheny and Ohio Rivers in 
western Pennsylvania; ‘additional specimens were examined in the 
Fic. 6. Quadrula metanevra (Rafinesque). Male, from Allegheny River, Kelly, 
Armstrong Co., Pa. (Carn. Mus., No. 61, 4,549.) Coll. May 20, 1910. 
field, in the Ohio River in West Virginia and Ohio, and two (male 
and female) were received from the Ouachita River in Arkansas (H. E. 
Wheeler). 
The gravid female was found 
on June 22, 1909, and had only 
eggs, 
Margins of the mantle con- 
nected so as to separate anal 
and supra-anal openings; this 
connection is short, but in no 
case was found to be absent. 
Supra-anal very large. Bran- 
chial with well developed pa- 
Fic. 6a. Left gills of a sterile female, 
from same locality. 
pille, anal practically smooth, 
or only with mere traces of ir- 
regular crenulations. Palpi with the posterior margins connected for 
about one-fourth to one-third of their length. 
Gills short and wide, their anterior attachment as usual. Dia- 
