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).^ 



List No. I. 



1. Fusconaia suhrotunda (Lea) 



2. Fusconaia undata trig ana (Lea) 



3. Fusconaia undata rnbiginosa (Lea) 



4. Crenodonta plicata nndidata (Barn.) 



5. Qnadnila 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. Hemilastena ambigua (Say) 



22. Anodonta grandis Say 



23. Alasmidonta marginata (Say) 



24. Strophitus edentulus (Say) 



25. Ptychobranchus phaseolus (Hildr.) 



26. Obliquaria reflexa Raf. 



27. Cy progenia irrorata (Lea) 



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

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

 Anodonta imbecillis Say, Anodontoides ferussacianus (Lea), Carunculina 

 pan>a (Barnes). 



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

 found in the uppermost Allegheny. 



