14 V. E. SHELFORD. 



ward only to the Mississippi and Illinois rivers. Dr. Cowles, 

 whose work is still unpublished, has studied the forest of the 

 eastern United States and has come to the conclusion that with 

 the base leveling of the eastern plateau the beech and maple 

 forest would, man eliminated, succeed the less mesophytic types 

 and come to completely cover the territory extending to the 

 western limit of its climatic range. This forest would then come 

 to occupy the entire territory east of the Mississippi and Illinois 

 rivers. This means the driving out of C. sexgnttata which is 

 now abundant in the forest of this region. Not at once, to be 

 sure, but irregularly and gradually, first giving irregular and 

 finally discontinuous distribution with a constant narrowing of 

 the range of the isolated habitats. For immense ages habitats 

 would no doubt continue to exist, but since the differences 

 between the different elevations and brook and river margins on 

 the one hand and the climax forest on the other become less and 

 less as the development of the climax stage proceeds, the chances 

 for the maintenance of habitats of C. scxgnttata indefinitely, 

 seem small. 



The general effect of the development of these conditions on 

 the distribution, would be as follows : C. sexguttata would be 

 left only in that portion of its present range, west of the climatic 

 conditions suitable for the development of the beech and maple 

 forest, with possible remnants in the eastern plateau which might 

 by a process of isolation, be caused to take on new habitats and 

 new characters. 



The general principles here set forth apply to the Cicindelas 

 associated with the development of rivers and the erosion of up- 

 lands. Observations now under way go to show that they apply 

 to the fauna in general. Strikingly different faunas are to be 

 found in the different forest stages herein mentioned. Plant suc- 

 cession is then a factor which we cannot afford to neglect in con- 

 sidering distribution and evolution. 



LITERATURE CITED. 

 Cowles, H. C. 



'01 The Plant Societies of Chicago and Vicinity, Geographical Society of Chicago, 

 Bull. No. 2. 1901. 

 Clements, F E. 

 '05 Research Methods in Ecology, Lincoln, Neb. 1905. 



