by William Swainson, Zoological Illustrations Series II… (1829)
“ It seems subject to much variation in point of colour, but we have strong suspicions that some of the varieties are distinct species. The richness of the black resembles Genoa velvet, while that of the yellow may be compared to glossy satin. All the larger species of the group are Oriental, but we suspect America is not without typical examples, although they are of a much smaller size. The species however, even with these additions, are so few, that the sub-types of the group cannot be accurately made out. ”
