There are 58 such beautiful images including these within the 4 volume set by WL Bailey, executed from nature between 1855 - 1858, but never published. They are displayed on the (non-Firefox compatible, at all) website of the Academy of Natural Sciences.
Bailey published several books on nature but these watercolours, in which he pioneered the depiction of plumage iridescence, were his most notable achievements.
These volumes are but a small part of the Ewell Sale Stewart Library natural sciences display, which I shall have further cause to explore in the future. (This inventory of available works is viewable in Firefox)
May 2011 - note to self : fix this! Working link = http://www.ansp.org/library/getty_findaid/Baily11.xml
Serves me right for hotlinking back in the dim dark ages!