Ortmann: Families and Genera oi Najai 



255 



than in the male. The "inside flap" can onlj be the inner edge of the 

 mantle, which is present, however, in the male also. The true position 

 of tlii> species was first indicated bj 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 



mp 



Fig. 6. Quadrula metanevra (Rafinesque). Male, from Allegheny River, Kelly, 

 Armstrong Co., Pa. (Cam. Mus., No. 61, 4,549.) Coll. May 20, 1910. 



held, 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- 

 pilla', anal practically smooth, 

 or only with mere traces of ir- 



regular crenulations. Palpi with tin' posterior margins connected for 

 about one-fourth to one-third of their length. 



(■ills short and wide, their anterior attachment as usual. Dia- 



mp 



Fig. 6a. Left gills of a sterile female, 

 fiom same locality. 



