MOLLUSCA. 151 



LIST OF THE HABITATS. 



Aquatic Habitats. 



I. Habitats of Saginaw Bay. 



1. Deep littoral, 16-24 feet. • 



2. Shallow littoral, rocky, unprotected. 



3. Rock pools. 



4. Shallow littoral, rocky, protected. 



5. Shallow littoral, sandy, unprotected. 



6. Sand pools. 



7. Shallow littoral, sandy, protected. 



8. Cove, almost cut off from Bay. 



II. Habitats of the Sand Dune Lakes. 



9. Shallow lakes, north side of Sand Point. 



10. Deep lakes, south side of Sand Point. 



III. Habitats of Rush Lake. 



11. Mucky bottom. 



12. Floating sedge-marshes. 

 1.3. Marly bottom. 



14. Raymond's Point. 



15. Dune Point. 



16. Fourth Point. 



17. County ch'ain. 



IV. Habitats of the Swamps. 



18. Annual swamps. 



19. Perennial swamps. 



20. Swamp in old stone quarry. 



V. Habitats of the Pigeon River. 



21. River portion. 



22. Bayou off of the Pigeon River. 



23. Creek portion. 



24. Dead waters. 



Land Habitats. 



I. Habitats of the Sand Dunes. 



25. Sand beach. 



26. Borders of lakes and swamp. 



27. Under rock ledge, Hat Point. 



28. Outer sand dunes. 



29. Inner sand dunes. 



II. Habitats of North and Stony Islands. 



30. Swampy woods. 



31. High woods. 



