Geology.
By Thomas C. Chamberlin and Rollin D. Salisbury, Professors in the University of Chicago.
Physiography.
By Rollin D. Salisbury, Professor in the University of Chicago.
General Biology.
By William T. Sedgwick, Professor in the Mass. Institute, and Edmund B. Wilson, Professor in Columbia University.
Botany.
By Charles E. Bessey, Professor in the University of Nebraska.
Zoology.
By A. S. Packard, Professor in Brown University.