The number at top left of each double elephant is a group number. There were 87 such groups consisting of 5 prints each. The number at top right is the individual plate number, from 1 to 435. These plate numbers were usually in Roman numerals. Interestingly, plate numbers ending with a 1 or 6 will be a larger bird or composition. Why? Audubon released prints to subscribers in groups of five, with the first print in each group generally being a large bird or a full page composition. Smaller numbers appearing next to birds within the image correspond to the type, sex or maturity of each bird as noted in the bottom script.