INDEX. 
147 
Page. 
Van Ingen, Gilbert, acknowledgments to. . 9 
work done by 8 
Variation of specific forms, conditions influ- 
encing 35-3(5 
definition of 17 
Verrill, A. E., cited on adjustment of faunas 
to local conditions 106 
Wagner, Moritz, extract from letter from 
Charles Darwin to 33 
Walcott, C. D., aid rendered by 8 
work in geologic correlation done by . . 10 
Walther, J., names for biologic aggregates 
adopted by 11 
Waverly fauna, geologic place of 47, 122 
Waverly group, fauna of 48 
stratigraphic equivalents of 122 
■ Weller, Stuart, aid by 9, 49 
cited on fauna of Hamilton formation 
of Illinois 66 
work done by 8 
Page. 
White, C. A., work in geologic correlation 
done by 10 
Whiteaves, J. F., cited on fauna of Hamil- 
ton formation of Ontario, Canada 60, 64 
Williams, H. S., cited 8, 12, 
27, 30, 39, 42, 43, 44, 45, 47, 69, 70, 79, 80 
work in geologic correlation done by . . 10 
Willis, Bailey, cited 38 
Wisconsin, Hamilton fauna of 65-66 
Williams, S. G., aid by 49 
Wolf Creek conglomerate, fauna of 48 
Y. 
Yak- University, work done by students of. 8, 9, 43 
Z. 
Zones, fossiliferous, features of 20-23 
subdivisions of 21 
transgression of 23 
Zoological classification, principles of 15-16 
o 
