ORTMANN: FAMILIES AND GENERA OF NAJADES. 241 
anal, but mantle-connection between them very short, and deciduous, 
often absent. Inner lamina of inner gills free from abdominal sac. 
All four gills marsupial. There is hardly any difference in structure 
between the inner and outer gill, When gravid, the water-tubes 
(ovisacs) do not expand much, and their lumen remains nearly cylin- 
drical. Placentze also subcylindrical, generally red in color, rather 
persistent, and discharged whole. Glochidia rather small, subovate, 
without hooks. 
Type: F. trigona (Lea), which (cf. Walker, 1910b, p. 24) should 
bear the name wndata (Barnes). 
Fusconaja undata (Barnes). 
About a half dozen specimens of the form from Lake Erie have been 
examined, and in July, 1910, I found a few gravid specimens. Mr. 
H. E. Wheeler sent two males, and six females (one of the latter 
gravid) from the Ouachita River, Arkadelphia, Arkansas, collected 
March 25) Lom, 
This form agrees in allessential points with F. rubiginosa. The ova, 
placente, and sexual glands have the same red color. The soft parts 
are less inclined to orange, are paler, and often whitish and cream- 
colored. Simpson (in Baker, 1898, p. 76) gives a rather meager de- 
scription. The glochidia are unknown, all specimens found by myself 
had only eggs. 
The gravid female from Arkadelphia was just beginning to charge 
the gills. This early date (March 21) should be noted. 
Fusconaja rubiginosa (Lea). 
Numerous specimens, in all conditions, have been examined, all 
collected in the smaller creeks of the Ohio drainage in western Penn- 
sylvania. 
This species is typically tachytictic, but the breeding season is 
rather long, from the middle of May to the beginning of August. 
In the case of single individuals it is probably much shorter. 
Descriptions of the soft parts have been given by Lea (Obs., X, 
1863, p. 416) and Simpson (in Baker, 1898, p. 78). 
Edges of the mantle drawn together by the gill-diaphragm, thus 
separating the anal and branchial openings. Anal opening closed 
above by a very short mantle-connection, thus forming a very large 
supra-anal; but this mantle-connection is very inconstant and de- 
