ORTMANN: monograph of the naiades of PENNSYLVANIA. 123 



of variation is not very great, and chiefly lies in the color of the epidermis. One 

 peculiar local phase, however, deserves special mention. In Conococheague Creek 

 at Greencastle, Franklin Co., this species is represented by rather large specimens, 

 which have an unusually heavy shell', with the nacre more frequently of a clear 

 salmon color, and the beaks in a beautiful state of preservation, even in large 

 individuals. This creek, at that locality, is so heavily charged with lime (fed by 

 big Umestone springs) , that a deposit of calcareous ooze is formed at the bottom, 

 and there is no doubt, that the peculiar local development is due to these local 

 conditions. Something similar, but not so strongly pronounced, has been observed 

 in Conedoguinet Creek at Carlisle; and in Virginia, in Reed Creek at Wytheville, 

 under the same conditions, a form has been observed, which corresponds entirely 

 to this form from Greencastle. 



Localities in Pennsylvania represented in the Carnegie Museum: 



Delaware-drainage: 



Delaware River, Yardley, Bucks Co.; Shawnee; Monroe Co. 



Schuylkill Canal, Manayunk, Philadelphia Co. 

 Susqueha n n a-dra in age : 



Conedoguinet Creek, Carlisle, Cumberland Co. 



Dunning Creek (J. F. L. Raschen) and Raystown Branch of Juniata River (A. Koenig), Bedford, Bed- 

 ford Co. 



Chest Creek, Patton, Caipbria Co. 



Cush Cushion Creek, Green Township, Indiana Co. (D. A. Atkinson). 



Chemung River, South Waverly, Bradford Co. 

 Potomac-drainage: '* 



Conococheague Creek, Greencastle, Franklin Co. 



Great Tonoloway Creek, Thompson Township, Fulton Co. 



Localities in Pennsylvania rejiresented in the Philadelphia Academy of Natural 

 Sciences: 



" Valley Creek " "' southwest of Coatesville, Chester Co. (C. H. Conner). 

 Pennsylvania Canal, " Chieques,"'" Pennsylvania (S. S. Haldeman). 

 Sinnemahoning Creek, Round Island, Clinton Co. (S. N. Rhoads). 



Other localities represented in the Carnegie Museum: 



Delaware-Raritan Canal, Princeton, Mercer Co., New Jersey. 



South Branch Potomac River, Southbranch and Ronmey, Hampshire Co., West Virginia. 



'* I found this species abundant in Little Antietam Creek, Waynesboro, Franklin Co., but the 

 specimens collected (about a dozen), on .\ug. 10, 1910, were lost during the trip in an unaccountable way. 



" There is no creek of this name on the map, but " Sucker Run " is in the " valley " southwest 

 of Coatesville, tributary to West Branch Brandywine Creek. 



*"■ No doubt " Chickies," near Columbia, Lancaster Co. 



