ORTMANN: THE CRAWFISHES OF THE STATE OF PENNSYLVANIA 433 
2. Cambarus propinquus, Cambarus propinquus sanborni and Cambarus obscurus. 
a. Summary of Facts. (See pp. 362-363 ; 368-369 ; 372-373.) 
If we desire to arrive at a proper understanding of the distribution of C. propin- 
quus, C. propinquus sanborni, and C. obscurus, they must be discussed together. 
The area occupied by these three forms (see Pl. XLII, Fig. 3) includes eastern 
Iowa, southern Wisconsin, northern Illinois, Indiana, Michigan, Ohio, northeastern 
Kentucky, northern West Virginia, western Pennsylvania, western New York, and 
parts of Canada (Ontario and Quebec).. In the western and northern part of this 
range C. propinquus is found; OC. propinquus sanborni occupies the larger part of 
Ohio and parts of Kentucky and West Virginia; while C. obscwrus has its chief 
domain in western Pennsylvania, passing southward into West Virginia and north- 
ward into New York. Thus it is apparent that the three forms occupy different 
sections of the general area of the group, propinquus being western (and northern), 
sanborni central, and obscwrus eastern. As far as observations go all three forms are 
rather |sharply separated geographically, although they come into contact at the 
edges of their ranges. This is especially true, as we have seen, in our state and the 
adjacent portions of Ohio and West Virginia, while in western Ohio and in Indiana 
nothing is known of the boundaries of the forms represented there. 
In Pennsylvania only two of these forms are found (Pl. XLII, Fig. 2). C propin- 
quus is restricted to Lake Erie and its drainage; C obscwrus belongs to the Ohio sys- 
tem, and is found everywhere in the western section of the state, in the Ohio, Mo- 
nongahela, and Alleghany Rivers and their tributaries. The boundary toward the 
east is formed by the divide between the Alleghany and Susquehanna systems, and 
farther south generally by the Chestnut Ridge (with exceptions to be discussed 
below). Northward this species crosses over into the Genessee drainage, and extends 
into New York. It also crosses over into the Lake Erie drainage in Pennsylvania. 
Along the western border of the state it passes beyond the state line into Ohio, 
the drainage belonging in the northern part to the Beaver River. Furthermore it 
goes down the Ohio and is found in all creeks running from Pennsylvania through 
the Panhandle of West Virginia as far south as Fish Creek in Greene County, 
Pennsylvania, and Marshall County, West Virginia. Fish Creek falls into the Ohio 
a little below Moundsville, West Virginia, and contains only the typical form of 
C. obscwrus. 
Going further down the Ohio conditions suddenly change. In Fishing Creek, 
Wetzel County, West Virginia, which empties into the Ohio near New Martinsville, 
about thirteen miles below the mouth of Fish Creek, C. propinquus sanborni appears. 
But the form here found is not typical. As we have seen above, it inclines some- 
