ORTMANN: FAMILIES AND GENERA OF NAJADES. 267 
There were only three gravid females among them, which were found 
on June 22, 1909. 
Anatomy normal: margin of the mantle, siphons, gill-structure, and 
marsupium typically Unionine. In a few cases the rather short 
Fic. 10. Elliptio crassidens (Lamarck). Male, from Allegheny River, Kelly, 
Armstrong Co., Pa. (Carn. Mus., No. 61, 3,777.) Coll. July 3, 1908. 
Fic. 10a. Left gills of a sterile female, from same locality. (Carn. Mus., No. 61, 
3,055.) Coll. Sept. 5, 1907. 
mantle-connection between the anal and supra-anal was found to be 
absent. Anal with small, but quite distinct, papilla. Palpi with the 
posterior margins connected for a short distance. 
