195 ANNALS OF THE CARNEGIE MUSEUM. 
agree with typical eastern specimens, and generally, in the mountain 
streams (Cheat, Youghiogheny, Loyalhanna, Quemahoning) this 
species remains as small as the eastern form. On the other hand I 
have eastern specimens, which are larger than any western specimens 
(see below). Several series containing specimens of all sizes, from 
various localities, both in the eastern and western drainage, show that 
there actually is no difference whatever between the two supposed 
species, and | challenge anyone to identify them, when the locality is 
not known. 
25. Anodonta imbecillis Say. 
Not reported previously from the state. I found it only in Erie 
County, in Conneauttee Lake, and in the outlet of Lake Leboeuf. 
26. Anodonta grandis Say. 
This species occurs in none of the older lists, but there is a specimen 
in the Carnegie Museum collected in 1897 by Clapp in an artificial 
pond at Edgeworth, Allegheny County. 
The typical form (rather heavy-shelled, elongate, dark-colored) is 
not rare over the western part of the state, and prefers the smaller 
streams, where it is sometimes found in abundance in quiet pools. It 
goes eastward as far as Westmoreland, Indiana, and Warren Counties. 
In the larger rivers it is generally absent, although single specimens 
(chiefly young ones) turn up here and there. In stagnant ponds a 
large, thin shelled, higher, and beautifully colored form (var. gzgantea 
Lea) is encountered. ‘Ihis form is quite abundant in a pond (aban- 
doned ox-bow of the Allegheny) at Harmarville, Allegheny County. 
A similar form, but with a peculiar green color (similar to var. dene- 
dictensis Lea!) occurs in Conneaut Lake, together with a very thin- 
shelled, light green, elongate form. A similar form to the latter, but 
of a darker color, is found in the black muck of Conneauttee Lake in 
Erie County. The var. sa/monia Lea, which has been regarded as 
a pathological form, is rather frequent in the northwestern section of 
the state, and, as is quite remarkable, at certain places is found to the 
exclusion of the typical form. 
27. Anodontoides ferussacianus (Lea). 
Not reported previously. It is found in the northwestern corner of 
the state, in Mercer and Crawford Counties, in the drainage of She- 
nango River and French Creek. It is most abundant in the Upper 
Shenango at Linesville, Crawford County, and in Conneaut Lake and 
Conneaut Outlet. At the latter localities, the specimens very closely 
resemble in shape the var. swbcy/indraceus (Lea). 
