426 MEMOIRS OF THE CARNEGIE MUSEUM 



Mr. W. Ti. ]Mc('onnell mentions (in his n(;tes) the absence of crawfish in the Dela- 

 ware at Porthmd, Northanijiton County. 



It is found, liowever, 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 ( 'reek) in ]^)erks 

 ( 'ounty, 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 Brand3'wine 

 Creek in ( 'h ester County. 



It is known from a number of places in the drainage of the Sus(),uehanna, Init 

 they are ail in the region of the Gi'eat Alleghany Valley or the Alleghany ]\Ioun- 

 tains. I was unable to find it in the Susquehanna in Lancaster and York Coun- 

 ties, (Pequea and Yoi'k Furnace), and I do not tiiink that it is present there on 

 account of the roughness of the rivei', which tlows over a I'ock}' bed in a channel 

 cut deep into strata, cliiefly 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 tliese 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 HoUidaysburg, 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. l!tno.'<iiH is often 

 found in canals. First reported by Faxon from near ("uniberland, Maryland, I 

 have found it in considcralile numbers in the Sciiuylkill and Delaware and Uaritan 

 ( 'anals. It is quite possible that the Susquehanna and Pennsylvania ( anals afforded 

 this species the means of reaching the Susquehanna River in the region of the < ireat 

 Alleghany \'^alley south of Ilarrisburg. Its further distribution up stream is then 

 not strange, after the rough portion of the lower vSusquelianna had been overcome, 

 or avoide<l. 



The same may be true of the Schuylkill Uivei-. Although certainly originally 

 present in the lower ])ai-t, it was the Schuylkill canal (once connected with the Penn- 

 sylvania, canal) which possibly alfoi'dcd an o])])ortunity for '' '. IInio^^ks to go up the 

 river as far as it does now, since the Schuylkill above Philadelphia is rather rough. 



" The maiu line of the canal was completed in 18:54, the Susijnehanna Canal from Columbia to Havre cle (iiace in 

 1840 ; see Jenkins, 1903, jip. 27.5, 277, 2S2 and Klein, 1900, p. LXXIX ; see also Hoyt & Anderson, 1905, p. 24. In 

 the latter paper line views of the scenery of the lower Susquehanna are published (PI. 1, B, PI. 8), which couvey a good 

 idea of the roughness of the water of the liver. 



