Sr 
ORTMANN: FAMILIES AND GENERA OF NAJADES. 24 
Fusconaja ebena (Lea). 
Of this species I have examined only very few typical representa- 
tives, found by myself in the Ohio River at Portsmouth, Scioto 
County, Ohio (Sept., 1910). 
The soft parts of a gravid female have been figured by Lefevre and 
Curtis (1910, pl. 1, fig. 4). Although this figure is correct, the struc- 
ture of the gills is not well represented, and the septa are not visible. 
I was inclined to regard this form as only a variety of F. subrotunda, 
but Dr. Sterki differs from me in this, and he calls my attention to the 
fact that the color of the gonads in F. ebena is not crimson, as in sub- 
rotunda, but distinctly purple. I have been able to verify this.  Al- 
though I had before me not more than half a dozen F. ebena, and 
although I found the gonads white in some, the others had them more 
or less (lighter or darker) purple, differing distinctly in hue from speci- 
mens of subrotunda, which I had at hand simultaneously. This 
matter, however, should be further investigated. 
In other respects F. ebena agrees with F. subrotunda, and also has 
the two types of color of the soft parts, whitish and orange. I have 
never seen gravid females, but Lefevre and Curtis (1910, p. 97, fig. 1) 
have figured the glochidium, which is identical with that of F. sub- 
rotunda, and has practically the same dimensions (length 0.14; 
height 0.15). 
Fusconaja kirtlandiana (Lea). 
Numerous specimens, chiefly from the Beaver drainage in western 
Pennsylvania have been investigated, among them only one gravid 
female with glochidia (found in the beginning of August). 
This agrees in every detail with F. subrotunda. The only difference 
is that the orange type of color of the soft parts israther infrequent, 
while the whitish prevails. The only gravid female was of the orange 
type, and had crimson gills. Glochidia identical. Length 0.13; 
height 0.15 mm. (see Ortmann, 19110, pl. 89, fig. 1). 
I am very much inclined to consider this as being only a variety of 
F. subrotunda. 
Genus CRENODONTA Schlueter. 1836. 
Simpson, 1900), p. 766 (as section). 
Shell rounded, ovate, subquadrate, or trapezoidal, with more or less 
elevated beaks, well developed hinge-teeth, and rather deep beak- 
