TROGON CITREOLUS, Gould. Mas. Trog. vertice, collo, dorso, guttureque ccerulescenti-viridibus ; rectricibus duabus intermediis ad apicem, proximarum duarum utrinque pogonis internis, reliquisque ad basin nigris, his apicem versus albis ; ventre citrino in aurantiacum vergente ; als brunnescenti-nigris, rectri- cum pogoniis externis albo fimbriatis ; rostro ceerulescenti-corneo ; pedibus brunneis. Fem. Capite, gutture, dorsoque saturaté cinereis ; rectricibus sex intermediis brunnescenti-nigris ; an caeteris marz semillima. Male. Crown of the head, neck, back and throat bluish green; tips of the two middle tail- feathers, the internal web of the two next on each side, and the base of the remainder black, the rest of each feather white ; abdomen lemon-yellow passing into orange ; wings brownish black, the outer webs of the primaries fringed with white; bill bluish horn colour; feet brown. Female. Head, throat and back dark grey; six middle tail-feathers brownish ; in other respects the same as in the male. Total length, 10+ inches; bzl/, 1; wing, 5+; tail, 6; tarsi, $. Trogon citreolus, Gould in Proe. of Zool. Soc. Part III. 1835, p. 30. Tuts interesting and very rare Trogon is a native of Mexico, and may be distinguished from all other known species by the delicate lemon-yellow of the under surface, by the greater extent of the white on the lateral tail-feathers, and by the uniform colouring of the central portion of the wing. The birds figured in the accompanying Plate are an immature male, and an adult female. When more fully adult, the male has the whole of the head, neck, chest, and upper surface of an uniform rich green. The specimens from which the above description and the figures are taken form a part of the collection of the Zoological Society, in which are also contained nearly all the species represented in the present Mono- graph.