Gould determined the species in the collection made by Darwin during the voyage of the 'Beagle,' and drew up the scientific portion of the report on the birds, which forms vol. iii. of the "Zoology" of the voyage. Owing to his departure for Australia the MS. was subsequently completed and edited by G. R. Gray (see DARWIN, C.). HOLMBERG, Dr. E. L. Resultados científicos, especialmente zoológicos y botánicos, de los tres viajes llevados á cabo por el Dr. Holmberg, en 1881, 1882, y 1883 á la Sierra del Tandil. Aves. Act. Ac. Nac. de Ciencias en Córdoba, v. pp. 73-92. [Seventy-nine species of birds are given as occurring in the Sierra of Tandil, south of Buenos Ayres, and slight field-notes are added.] HUDSON, WILLIAM HENRY, C.M.Z.S. My fellow-author of the present work, though English in name and origin and now resident in London, is an Argentine citizen by birth. From his early childhood he was an observer of bird-life in the province of Buenos Ayres, and continued his investigations until he left the country for England a few years ago. Besides the pampas he explored the woods and marshes along the Plata, and the range of the Sierras from Cape Corrientes on the Atlantic to the Azul and Tapalquen, and made an expedition to the Rio Negro in 1871. The following is a list of his scientific papers on this subject, which are mostly incorporated in the present work:-- (1) Letters on the Ornithology of Buenos Ayres. P. Z. S. 1869, p. 432; 1870, pp. 87, 112, 158, 332, 545, 671, 748, 798; 1871, pp. 4, 258, 326. (2) On the Birds of the Rio Negro of Patagonia. With Notes by P. L. Sclater, M.A., Ph.D., F.R.S., &c. P. Z. S. 1872, p. 534. (3) On the Habits of the Swallows of the Genus _Progne_ met with in the Argentine Republic. With Notes by P. L. Sclater, M.A., Ph.D., F.R.S., &c. P. Z. S. 1872, p. 605. (4) Further Observations on the Swallows of Buenos Ayres. P. Z. S. 1872, p. 844. (5) Notes on the Habits of the Churinche (_Pyrocephalus rubineus_). P. Z. S. 1872, p. 808. (6) Notes on the Habits of the Pipit of the Argentine Republic. P. Z. S. 1873, p. 771. (7) Notes on the Procreant Instincts of the three Species of _Molothrus_ found in Buenos Ayres. P. Z. S. 1874, p. 153. (8) On the Habits of the Burrowing-Owl (_Pholeoptynx cunicularia_). P. Z. S. 1874, p. 308. (9) On the Herons of the Argentine Republic, with a Notice of a curious Instinct of _Ardetta involucris_. P. Z. S. 1875, p. 623. (10) Note on the Spoonbill of the Argentine Republic. P. Z. S. 1876, p. 15. (11) Notes on the Rails of the Argentine Republic. P. Z. S. 1876, p. 102. (12) Notes on the Birds of the Genus _Homorus_ observed in the Argentine Republic. Ibis, 1885, p. 283. LEE, WILLIAM BLACKSTONE. Ornithological Notes from the Argentine Republic. Ibis, 1873, p. 129.