It looks like an ink blotch starting at the s in reserve, through the u in united then into the oval frame surrounding president Grant. Four blotches also appear between 3 and 4 o'clock in the oval frame. One small then three smaller ink spots appear in the field south of the left (facing) ear running in a slight downward diagonal toward the beard. The color appears to be the same as used in the border and in the words The United States of America. Are these printing errors? Do they add value over face? The ink in the lower right margin looks like a different shade and I assume to be post print damage. Please forgive my limited knowledge of currency. Sharing of knowledge would be greatly appreciated.
more than likely its from a tellers stamp, bundles of notes are wrapped with a paper band and stamped by bank tellers, they dont always hit the center of the bands...
My thoughts too. More than likely the ink bled through the band. If you connect the dots they show to be a right angle, exactly as a stamp would look.