I9I3-] ORTMANN— THE ALLEGHENIAN DIVIDE. 291 



Ohio, Allegheny, Monongahela Rivers, and their tributaries, exclud- 

 ing those found only in the Beaver or French Creek systems (Gla- 

 cial Drift streams). 2 



List No. i. 



i. Fusconaia subrotunda (Lea) 



2. Fusconaia undata trigona (Lea) 



3. Fusconaia undata rubiginosa (Lea) 



4. Crenodonta plicata undulata (Barn.) 



5. Quadrula pustulosa (Lea) 



6. Quadrula lachrymosa (Lea) 



7. Quadrula tuberculata (Barn.) 



8. Quadrula metanevra (Raf.) 



9. Quadrula cylindrica (Say) 



10. Rotundaria tuberculata (Raf.) 



11. Plethobasus cooperianus (Lea) 



12. Plethobasus cyphus (Raf.) 



13. Pleurobema obliquum (Lamarck) 



14. Pleurobema obliquum pyramidatum (Lea) 



15. Pleurobema obliquum coccineum (Conr.) 



16. Pleurobema clava (Lam.) 



17. Elliptio crassidens (Lam.) 



18. Elliptio dilatatus (Raf.) 



19. Symphynota compressa Lea. 



20. Symphynota costata (Raf.) 



21. H emilast ena ambigua (Say) 



22. Anodonta grandis Say 



22,. Alasmidonta marginata (Say) 



24. Strophitus edentulus (Say) 



25. Ptychobranchus phase olus (Hildr.) 



26. Obliquaria reflexa Raf. 

 2 7- Cyprogenia irr or ata (Lea) 



2 Forms peculiar to Beaver or French Creek (or both) are: 

 Fusconaia subrotunda kirtlandiana (Lea), Symphynota complanata (Barnes), 

 Anodonta imbecillis Say, Anodontoides ferussacianus (Lea), Carunculina 

 parva (Barnes). 



Symphynota compressa Lea probably also falls in this category, but is also 

 found in the uppermost Allegheny. 



