Ortmann : Unionid^, of Western Pennsylvania. 209 



(Ortmann); Raystown Branch, Everett, Bedford County (P E. 

 Nordgren); Shober's Run, Bedford Springs, Bedford County (A. 

 Koenig); Frankstown Branch of the Juniata River, Huntingdon and 

 Alexandria, Huntingdon County C Atkinson); Frankstown Branch, 

 Hollidaysburg, Blair County (Ortmann); West Branch Mahan tango 

 Creek, Richfield, Juniata County (Atkinson); Middle Creek, P>ee- 

 burg, Snyder County (Atkinson); Canal at Watsontown, Northumber- 

 land County (Atkinson); West branch of the Susquehanna, Williams- 

 port, Lycoming County (Atkinson); Driftwood Branch of the Sinne- 

 mahoning Creek, Driftwood, Cameron County (Ortmann); Beaver 

 Dam Creek, Flinton, Cambria County (Atkinson); Cush-Cushion 

 Creek, Green Township, Indiana County (Atkinson). 

 14. Unio fisherianus Lea. 



White Clay Creek, Chester County (Hartman & Michener); one 

 specimen was found in the Schuylkill at Philadelphia (Gabb). It is 

 a species belonging to the Potomac drainage, but has not yet been re- 

 ported from any place in that drainage in Pennsylvania. 



Not represented from the state in the Carnegie Museum. 



Unio fuUginosus Lea from Cobbs Creek (a branch of Darby Creek, 

 near Essington, Philadelphia County) is quoted twice by Simpson 

 under U. complanatus (p. 723) and under U. icteriniis Conrad (p. 

 727). The latter is a southern form, and it is not very likely that it 

 is found in Pennsylvania. 



The above list at least somewhat extends our knowledge of the dis- 

 tribution of the eastern Unionidse. 



Unio complanatus seems to be as ubiquitous in, and characteristic 

 of, the Atlantic drainage as U. gibbosus is for the Ohio drainage. It 

 goes far up into the headwaters of the Susquehanna drainage. The 

 same is the case with Strophitus undidatus, Symphynota viridis, 

 Alasmidonta undiilata, and Alasviidonta marginata 7'aricosa, yet it 

 seems as if these four species are not so frequent in the larger rivers. 

 According to the present records, Lampsilis cariosa and Lampsilis 

 radiatasQem to prefer the larger rivers, although they ascend also toward 

 the headwaters. The distribution of Lampsilis ochracea remains 

 to be investigated. It is known from the region of tidewater, but 

 not farther up. Lampsilis nasiita so far is restricted to the Delaware 

 drainage, and is absent from that of the Susquehanna and farther 



