426 MEMOIRS OF THE CARNEGIE MUSEUM 
Mr. W. R. McConnell mentions (in his notes) the absence of crawfish in the Dela- 
ware at Portland, Northampton County. 
It is found, however, in small tributaries of the Delaware in the southeastern 
half of Bucks County (Neshaminy Creek). In the Schuylkill River it goes up to 
Reading (Girard and also McConnell), and slightly beyond (Maiden Creek) in Berks 
County, but I have not been able to find it in the Schuylkill, where it comes out of 
the Blue Mountain, (Shoemakersville). It has been reported from Brandywine 
Creek in Chester County. 
It is known from a number of places in the drainage of the Susquehanna, but 
they are all in the region of the Great Alleghany Valley or the Alleghany Moun- 
tains. I was unable to find it in the Susquehanna in Lancaster and York Coun- 
ties, (Pequea and York Furnace), and I do not think that it is present there on 
account of the roughness of the river, which flows over a rocky bed in a channel 
cut deep into strata, chiefly of the archaic age, belonging to the Piedmont Plateau, 
from York Haven to the Maryland state-line and beyond. Such conditions are de- 
cidedly unfavorable for this species, and it is rather strange that it should be found 
at all above this rough part of the Susquehanna, which is about thirty to forty 
miles long. I think that this species immigrated into these parts in very recent 
times by way of the Susquehanna and Pennsylvania canals, which closely followed 
the river from its mouth in Maryland to the New York state-line and the Juniata 
up to Hollidaysburg, and connected it with the Schuylkill. These canals were 
maintained and in use a long time, beginning as early as 1834, were abandoned 
about 1890," and at present only remnants of them are seen. C. limosus is often 
found in canals. First reported by Faxon from near Cumberland, Maryland, I 
have found it in considerable numbers in the Schuylkill and Delaware and Raritan 
Canals. It is quite possible that the Susquehanna and Pennsylvania Canals afforded 
this species the means of reaching the Susquehanna River in the region of the Great 
Alleghany Valley south of Harrisburg. Its further distribution up stream is then 
not strange, after the rough portion of the lower Susquehanna had been overcome, 
or avoided. 
The same may be true of the Schuylkill River. Although certainly originally 
present in the lower part, it was the Schuylkill canal (once connected with the Penn- 
sylvania canal) which possibly afforded an opportunity for C. limosus to go up the 
river as far as it does now, since the Schuylkill above Philadelphia is rather rough. 
“The main line of the canal was completed in 1834, the Susquehanna Canal from Columbia to Havre de Grace in 
1340; see Jenkins, 1903, pp. 275, 277, 282 and Klein, 1900, p. LXXIX; see also Hoyt & Anderson, 1905, p. 24. In 
the latter paper fine views of the scenery of the lower Susquehanna are published (Pl. 1, B, Pl. 8), which convey a good 
idea of the roughness of the water of the river. 
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