Of the genus Certhia were obtained two species, of one of which no description has been found, though Dr. Cabot was under the impression that he had seen specimens of it in some of the cabinets of Europe. It is three inches and seven eighths long; top of head, neck, and back, dark brown, each feather having a light, buff-coloured, pear-shaped mark in the centre; chin light buff colour; breast and belly light brown, each feather having also a light buff-coloured mark down the centre; primaries, secondaries, tertiaries, and tail dun-coloured; bill one inch and three eighths along the ridge, and one inch and five eighths along the gap, bent in its whole length, and horn-coloured. They were not numerous. The other species is the yellow-bellied nectarinia (Nectarinia Flaveola. Vieill., Ois. Dor. Certh., plate 51, p. 102). They were quite numerous at Cozumel, where two specimens were procured. They were not seen in any other part of the country. Of the genus Trochilus were procured two or three species, one of which is undescribed; another is probably the young of the same, and one is described. The undescribed, male, is four inches long; bill six eighths of an inch, yellowish, tipped with black; upper parts of head and back dull green; throat and upper part of breast bright emerald green in scales, with metallic lustre; lower part of breast, belly, and tail dun or bay colour; the feathers of the tail fringed and tipped with black; primaries dark brown, with some purplish reflections. The four middle tail feathers have greenish reflections on them. The female is rather less, and wants the bright emerald throat, the whole under parts being bay-coloured; the male had some white about the thighs. The known species is the Ourissia humming-bird (Trochilus Maugeri. Lesson.). Of the genus Turdus were procured two species, thought to be new. One agrees very nearly with Le Merle de Paraguai, or Calandra, as described in Vieillot, but it wants the white on the wings. The other is a good deal like the Turdus Plumbeus, as described by the same author. The first is quite common throughout Yucatan, but the second is rather rare.