by William Swainson, Zoological Illustrations Series II… (1829)
“ They appear to us, taken collectively, to form one group, in which every species exhibits a peculiar modification of structure, assimilating either to the Vultures or the Falcons. Allied both in structure and manners to both these families, each bird may be considered as a strongly marked link of connexion. They present, in short, that interchange of characters, generally confined to individual species, which Nature invariably exhibits at the union of her more comprehensive groups. ”
