ORTMANN: THE CRAWFISHES OF THE STATE OF PENNSYLVANIA 365 
that in no case is there a spine on the carpopodite at the lower articulation with the 
hand, but only a tubercle; in other respects they are typical, with a spine and 
anterior tubercle on the inner margin of the carpopodite, a low tubercle at the 
anterior margin of the lower side of the carpopodite, and only two spines on the 
lower margin of the meropodite. 
In the shape of the sexual organs of the male there is much uniformity in their 
length and the shape of the tips. However, there is a tendency in the Pennsy]l- 
vanian specimens toward the development of a slight notch on the anterior margin 
in the place where C. obscwrus has a shoulder. I have only twelve males of the first 
form from Temple Creek, Albion, four from Walnut Creek, and two from Elk 
Creek. Of these, six from Temple Creek and one from Walnut Creek show a notch, 
while all the rest (eleven) have no trace of it. The notch never assumes the shape 
of the “shoulder” of C. obscwrus, and the sexual organs differ in other respects 
from the later species, chiefly in that the tip of the inner part is never blunt or 
dilated. 
The female annulus is rather constant, as has been said above; only slight differ- 
ences due to age are noticeable. 
We may sum up the variations of C. propinquus in the state of Pennsylvania by 
saying that there is a distinct inclination toward C. obscwrus, indicated by the tend- 
ency of the rostral keel to disappear, of the chelipeds to increase in spinosity, and of 
the male copulatory organs to develop a notch at the anterior margin. Nevertheless 
there are numerous specimens which represent the typical C. propinquus. This fact 
is to be borne in mind, and we shall learn more about it when we come to discuss 
the geographical distribution of this and the related forms. 
I introduce here the systematic account of a variety of this species, which is 
extralimital to the state of Pennsylvania. I have, however, decided to treat of it 
more fully, since its relation to the representative Pennsylvania form is highly inter- 
esting, and since we shall have to refer to it repeatedly in the chapter on distribution. 
2a. CAMBARUS (FAXONIUS) PROPINQUUS SANBORNI (Faxon). 
Cambarus sanborni Faxon, 1884b, p. 128. 
Cambarus propinquus sanborni Faxon, 1885a, p. 91, Pl. 5, f. 3, Pl. 9, f. 10; Underwood, 1886, p. 372 ; Osburn & William- 
son, 1898, p. 21 ; Williamson, 1899, p. 20, 48; Hay, 1899, p. 960, 964 ; Ortmann, 1905, p. 132. 
According to Faxon, this variety differs from the typical C. propimqwus in the 
following characters: 1) The two parts of the male sexual organs are less deeply 
separated, and the tips are closer together. 2) The rostrum is not carinate. 3) The 
hands are finely pubescent. 4) The inferior median anterior spine of the carpopodite 
is evident. 
