90 MEMOIRS NATIONAL ACADEMY OF SCIENCES. [vol.xii. 



Walker, B. 



1909. Annotated list of the moUusca of Isle Royale, Michigan. Ann. Rep. Mich. Geol. 

 Surv. for 1908, pp. 281-298. 

 Wetherby, a. G. 



1876. Remarks on the variation in form of the family Strepomatidse, with descriptions of 



new species. Proc. Cincinnati Soc. Nat. Hist., no. 1, pp. 1-12. 

 1881. On the geographical distribution of certain fresh-water molluscs of North America, 

 and the probable causes of their variation. Journ. Cincinnati Soc. Nat. Hist,, 

 vol. 3, pp. 317-324; vol. 4, pp. 156-166. 

 White, C. A. 



1883. A review of the non-marine fossil mollusca of North America. 3rd Ann. Rep. 



U. S. Geol. Surv., 1881-82. pp. 403-550. 

 1905. The ancestral origin of the North American Unionidae, or fresh-water mussels. 

 Smithsonian Misc. CoU., vol. 48, pp. 75-88. 

 Williamson, E. B. 



1901. The crayfish of Allegheny County, Pennsylvania. Ann. Carnegie Mus., vol. 1, pp. 

 8-13. 



2. THE ENVIRONMENT, ITS DESCRIPTION AND EVOLUTION. 



Adams, Charles C. 



1901. Base- leveling and its faunal significance, with illustrations from southeastern United 

 States. Amer. Nat., vol. 35, pp. 839-851. 

 Ayers, H. B., and Ashe, W. W. 



1905. The southern Appalachian Forests. Prof. Paper, no. 37, U. S. Geol. Surv. 

 Campbell, M. R. 



1893. Geology of the Big Stone Gap Coal Field of Virginia and Kentucky. Bull. Ill, 



U. S. Geol. Surv. 



1894. Tertiary changes in the drainage of southwestern Virginia. Amer. Journ. Sci., vol. 



48, pp. 21-29. 



1894. EstUlville folio. U. S. Geol. Surv. 



1896. Drainage modifications and their interpretation. Journ. Geol., vol. 4, pp. 567- 

 581; 657-678. 

 Campbell, M. R., and W. C. Mendenhall. 



1896. Geologic section along the New and Kanawha Rivers in West Virginia. 17th Ann. 

 Rep. U. S. Geol. Surv. 1895-96. Pt. 11, pp. 1-39. 

 Chamberlin, T. C, and R. D. Salisbury. 



1906. Geology. New York. 

 Davis, W. M. 



1891. The geological dates of origin of certain topographic forms on the Atlantic Slope of 

 the United States. Bull. Geol. Soc. Amer., vol. 2, pp. 545-586. 

 Glenn, L. C. 



1911. Denudation and erosion in the southern Appalachian Region and the Monongahela 

 Basin. Prof. Paper, no. 72, U. S. Geol. Surv. 

 Harris, J. A. 



1903. An ecological catalogue of the crayfishes belonging to the genus Cambarus. Kans. 

 Univ. Sci. Bull., vol. 2, pp. 170-180. Includes many references to descriptions 

 of streams, and particularly valuable to the student of river faunas. 

 Hayes, C. W. 



1895. The southern Appalachians. Nat. Geogr. Monographs, vol. 1, pp. 305-336. 



1899. Physiography of the Chattanooga District in Tennessee, Georgia, and Alabama. 



19th Ann. Rep. U. S. Geol. Surv., 1897-98, pt. 2, pp. 1-58. 

 Hayes, C. W., and M. R. Cambell. 



1894. Geomorphology of the southern Appalachians. Nat. Geog. Mag., vol. 6, pp. 63-126. 



1900. The relation of biology to physiography. Science, n. s., vol. 12, pp. 131-133. 



