ae 
| MEMOTRS 
OF THE 
CARNEGIE MUSEUM. 
VOL. II. ei ee NO. 10. 
THE CRAWFISHES OF THE STATE OF PENNSYLVANIA. 
By ArnoLtp E. Ortmann, Pu.D. 
I. [yrropuction. 
The present Memoir is a continuation of, and an enlargement upon, the prelimi- 
nary paper published some time ago in the Annals of the Carnegie Museum (Vol. 
III, 1905, p. 387 et seq.) under the title “The Crawfishes of Western Pennsyl- 
vania.”’ The object of these publications is to furnish the student with an account 
of the crawfish-fauna of the state of Pennsylvania as complete as possible, not only 
from the morphological and zoégeographical, but also from the biological, ecolog- 
ical, and economic standpoint. It is now believed that it is possible to present an 
approximately complete report upon this important branch of the fresh-water fauna 
of the state, and in the prosecution of the studies of the author a number of ques- 
tions were raised, the solution of which proved to be highly interesting. 
It may be well at the beginning to give an outline of the work done. At the 
outset the writer resolved to go over the whole state, and to collect specimens in as 
many different localities as possible. Very soon, however, it was discovered that 
the different parts of the state are of unequal interest. Large tracts, located chiefly 
in the central, northern, and northeastern parts of the state, proved to be rather 
uninteresting, only one species of crawfish being present in them, while the western, 
and chiefly the southwestern, and again the southeastern sections offered more 
variety. Thus it became necessary to pay more attention to the latter areas. The 
uninteresting regions were entered only in a few cases, but a good deal of work was 
done around their edges, in order to trace their limits as accurately as possible. 
The location of the writer in Pittsburgh was advantageous, being central within 
that section of the state which offered the greatest number of problems. Most of 
343 
