XXXIV. { Aglaia striata, _in place of_ { Tanagra Darwinii. XXXV. Pipilo personata. XXXVI. Geospiza magnirostris. XXXVII. —— strenua. XXXVIII. —— fortis. XXXIX. —— parvula. XL. Camarhynchus psittaculus. XLI. —— crassirostris. XLII. Cactornis scandens. XLIII. —— assimilis. XLIV. Certhidea olivacea. XLV. Xanthornus flaviceps. XLVI. Zenaida Galapagoensis. XLVII. Rhea Darwinii. XLVIII. Zapornia notata. XLIX. —— spilonota. L. Anser melanopterus. ADVERTISEMENT. When I presented my collection of Birds to the Zoological Society, Mr. Gould kindly undertook to furnish me with descriptions of the new species and names of those already known. This he has performed, but owing to the hurry, consequent on his departure for Australia,—an expedition from which the science of Ornithology will derive such great advantages,—he was compelled to leave some part of his manuscript so far incomplete, that without the possibility of personal communication with him, I was left in doubt on some essential points. Mr. George Robert Gray, the ornithological assistant in the Zoological department of the British Museum, has in the most obliging manner undertaken to obviate this difficulty, by furnishing me with information with respect to some parts of the general arrangement, and likewise on that most intricate subject,—the knowledge of what species have already been described, and the use of proper generic terms. I shall endeavour in every part of the text to refer to Mr. G. R. Gray’s assistance, where I have used it. As some of Mr. Gould’s descriptions appeared to me brief, I have enlarged them, but have always endeavoured to retain his specific character; so that, by this means, I trust I shall not throw any obscurity on what he considers the essential character in each case; but at the same time, I hope, that these additional remarks may render the work more complete.