FIG. 1 is a perspective view of a book bag of the present invention;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a side elevational view thereof;

FIG. 5 is a side elevational view thereof opposite that shown in FIG. 4;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken lines in all views indicate stitching and form part of the claimed design.