Portion of a toothbrush

FIG. 1 is a perspective view of a portion of a toothbrush as seen from the top, front and right sides, wherein the broken line disclosure is for environmental purposes only and does not form a part of the claimed design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a right side elevational thereof, the left side elevational view being a mirror image;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is an enlarged top plan view thereof; and,

FIG. 6 is an enlarged bottom plan view thereof.