I9I3-] ORTMANN— THE ALLEGHENIAN DIVIDE. 313 



B. ATLANTIC SIDE. 



Besides the writer's own investigations, the following publica- 

 tions have been used for compilation of the f aunistic lists : 



For Delaware, Susquehanna, and Potomac rivers : Gabb, 1861 ; 

 Hartman and Michener, 1874; Pilsbry, 1894; Schick, 1895; CafTrey, 

 1911. 



For James River : Conrad, 1846. 



Since the Atlantic side does not form a single drainage system, 

 but consists of a number of rivers running independently to the sea, 

 we must discuss these rivers separately. 



I. The Fauna of the Delaware River. 



This is the most northern system in the region discussed here. 

 The following Na jades are known to exist here: 



List No. 17. 



1. Margaritana margaritifera (L.) 



2. Elliptio complanatus (Dillw.) 



3. Elliptio fisherianus (Lea) 



4. Symphynota tappaniana (Lea) 



5. Anodonta Cataracta Say 



6. Anodonta implicata Say 



7. Alasmidonta heterodon (Lea) 



8. Alasmidonta undulata (Say) 



9. Alasmidonta varicosa (Lam.) 



10. Strophitus undulatus (Say) 



11. Strophitus edentulus (Say) 



12. Eurynia nasuta (Say) 



13. Lampsilis radiata (Gmel.) 



14. Lampsilis cariosa (Say) 



15. Lampsilis ochracea (Say) 



It is to be remarked that no. 3, no. 10 and no. 15 are found ex- 

 clusively in the tidewater region of the lower Delaware and Schuyl- 

 kill, and that no. 3 is at the best extremely rare (only once reported), 

 and that no. 10 is altogether a doubtful form. No. 1 is very local 

 (uppermost Schuylkill). 



