by William Swainson, Zoological Illustrations — Vol I. Pl… (1820)
“ Bill from the upper base to the tip one inch one line, and from the gape one inch four-tenths; the colour blueish-black; the upper mandible above sharply carinated and slightly curved; orbits (in the dead bird) yellowish-white; the whole of the head and nape, sides of the neck, rump and tail-covers, and all the under plumage pure white, with a tinge of yellow down the middle of the belly: a narrow black line commences at the ears, and is carried down on each side, joining the black of the upper neck; the wings and remaining upper plumage are of a uniform dark sooty black ”
