ORTMANN: THE CUAWFISHES OF THE STATE OF PENNSYLVANIA 365 



that in no case is there a spine on the carpopodite at the lower articuhition 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 tlie lower side of the carpopodite, and oidy two spines on the 

 lower margin of the meropodite. 



Ill tlie shape of the sexual organs of the male there is much uniformity in their 

 length and llic shape of the tips. However, there is a tendency in the Pennsyl- 

 vanian specimens toward the development of a slight notch on the anterior margin 

 in the place where C. obscwus has a shoulder. I have only twelve males of the first 

 fcjrm 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. obscunis, 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. j)ropinquus in the state of Pennsylvania by 

 saying that there is a distinct inclination toward C. obsmrui^, indicated by the tend- 

 ency of the rostral keel to disappear, of the chelipeds to increase in spinosit}', and of 

 the male copulatory organs to develop a notch at the anterior margin. Nevertheless 

 there are numerous specimens which represent the typical C. propinqiius. This fact 

 is to l>e borne in mind, and we .shall learn more abovit it when we come to discuss 

 the geographical distribution of this and the related forms. 



1 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 Penn.sylvania form is highly inter- 

 esting, and since we shall have to refer to it repeatedly in the chapter on distrii)Ution. 



2a. Cambarus (Faxonius) propinquus sanborni (Faxon). 



Cnmbanis sanbomi Faxon, 1884i, p. 128. 



CnmbnruH propinquus sn/ihorni Fa.xoii, ]885«, p. 91, Pi. .5, f. 3, PI. 9, f. 10 ; Underwood, 188(i, p. 372 ; Oshnrn iS: William- 

 son, 1898, p. 21 ; Williamson, 1899, p. 20, 18 ; Hay, 1899, p. 9G0, 961 ; Ortmann, 190.Vj, p. 132. 



According to Faxon, this variety differs from the typical ('. propiiKimi.t in the 

 following characters: 1) The two parts of the male sexual organs are less deeph' 

 separated, and the tij)s are closer together. 2) The rostrum is not oarinate. 3) The 

 hands are finely pubescent. 4) The inferior median anterior spine of the carpopodite 

 is evident. 



