On the minute structure and movements of voluntary muscle - King's College London. (Printed by R. and J. E. Taylor, 1840)

On the outskirts of empire in Asia - Zetland, Lawrence John Lumley Dundas, Marquis of, 1876 -1961 (W. Blackwood, 1904)

On the plains, and among the peaks, or, How Mrs. Maxwell made her natural history collection - Ridgway, Robert, 1850 -1929 (Claxton, Remsen & Haffelfinger, 1879)

On the power, wisdom and goodness of God, as manifested in the creation of animals, and in their history, habits and instincts - Kirby, William, 1759 -1850 (Carey, Lea & Blanchard, 1836)

On the reproduction and growth of the snow sheep (Ovis nivicola Esch) - Cherni͡avskiĭ, F. B. (Feliks Borisovich) (1962)

Onomasticon zoicon, plerorumque animalium differentias & nomina propria pluribus linguis exponens : cui accedunt Mantissa anatomica, et quaedam De variis fossilium generibus - Charleton, Walter, 1619 -1707 (Apud Jacobum Allestry ..., 1668)

Die Ontogenie der Primatenzähne - Bolk, L. (Louis), 1866 -1930 (G. Fischer, 1913)

Die Ontogenie der Primatenzähne : versuch einer Lösung der Gebissprobleme - Bolk, L. (Louis), 1866 -1930 (Verlag von Gustav Fischer, 1913)

Opinions and declarations rendered by the International Commission on Zoological Nomenclature - International Commission on Zoological Nomenclature (Printed by order of the International Trust for Zoological Nomenclature, 1947)

Opinions and declarations rendered by the International Commission on Zoological Nomenclature - International Commission on Zoological Nomenclature (Printed by order of the International Trust for Zoological Nomenclature, 1958)

Opinions and declarations rendered by the International Commission on Zoological Nomenclature - International Commission on Zoological Nomenclature (Printed by order of the International Trust for Zoological Nomenclature, 1955)

Opinions and declarations rendered by the International Commission on Zoological Nomenclature - International Commission on Zoological Nomenclature (Printed by order of the International Trust for Zoological Nomenclature, 1954)

Opuscula medica, quae reperiri potuere omnia, nunc primo simul edita - Drelincourt, Charles, 1633 -1697 (Apud Alberts & van der Kloot, 1727)

Opuscula subseciva, observationes miscellaneas de animalculis et plantis quibusdam marinis, eorumque ovariis et seminibus continentia - Baster, Job, 1711 -1775 (apud J. Bosch, 1762)

Orang-outang, sive homo sylvestris: or, The anatomy of a pygmie compared with that of a monkey, an ape, and a man. To which is added, A philological essay concerning the pygmies, the cynocephali, the satyrs, and sphinges of the ancients. Wherein it will appear that they are all either apes or monkeys, and not men, as formerly pretended - Tyson, Edward, 1650 -1708 (Printed for T. Bennett and D. Brown, and are to be had of Mr. Hunt, 1699)

The Orchid review (Orchid Review ltd.], 1909)

The orders of mammals - Gregory, William K. (William King), 1876 -1970 (The Trustees, 1910)

The Oregon naturalist (Naturalist Pub. Co, 1896)

Organic remains of a former world. An examination of the mineralized remains of the vegetables and animals of the antediluvian world; generally termed extraneous fossils - Parkinson, James, 1755 -1824 (Sherwood, Neely and Jones, etc, 1811)

The origin and relationship of the large mammals of North America - Grant, Madison. (Reprinted from the eighth annual report of the New York Zoological Society, 1904)

The origin and relationship of the large mammals of North America - New York Zoological Society. (1904)

Ornithologia methodice digesta, atque iconibus aeneis ad vivum illuminatis ornata - Lorenzi, Lorenzo. (In Aedibus Mouchianis, 1769)

Ornithologia methodice digesta, atque iconibus aeneis ad vivum illuminatis ornata - Lorenzi, Lorenzo. (In Aedibus Mouchianis, 1773)

Ornithologie Nordost-Afrika's : der Nilquellen- und Küsten Gebiete des Rothen Meeres und des nördlichen Somal-Landes - Heuglin, Theodor von, 1824 -1876 (T. Fischer, 1869)

Ornithologische Monatsschrift - Deutscher Verein zum Schutze der Vogelwelt. (Kommissions-Verlag der Creutschen Verlagsbuchhandlung, 1895)

Ornithologische Monatsschrift - Deutscher Verein zum Schutze der Vogelwelt. (Kommissions-Verlag der Creutschen Verlagsbuchhandlung, 1913)

Ornithologisches Centralblatt (L.A. Kittler, 1879)

Ornithologisches Centralblatt (L.A. Kittler, 1878)

The ornithologist's guide to the islands of Orkney and Shetland - Hullmandel, Charles Joseph, 1789 -1850 (Printed by Richard Taylor, Red Lion Court, Fleet Street, and published by the author, 31, George Street, Hull, 1837)

Ostéographie, ou, Description iconographique comparée du squelette et du système dentaire des Mammifères récents et fossiles : pour servir de base à la zoologie et à la géologie - Blainville, H.-M. Ducrotay de (Henri-Marie Ducrotay), 1777 -1850 (J.B. Baillière et fils, 1839)

Osteological assessment of Pleistocene Camelops hesternus (Camelidae, Camelinae, Camelini) from Alaska and Yukon - MacPhee, R. D. E. (American Museum of Natural History, 2016)

The Ottawa naturalist - Ottawa Field-Naturalists' Club (Ottawa Field-Naturalists' Club, 1893)

The Ottawa naturalist - Ottawa Field-Naturalists' Club (Ottawa Field-Naturalists' Club, 1892)

The Ottawa naturalist - Ottawa Field-Naturalists' Club (Ottawa Field-Naturalists' Club, 1895)

The Ottawa naturalist - Ottawa Field-Naturalists' Club (Ottawa Field-Naturalists' Club, 1896)

The Ottawa naturalist - Ottawa Field-Naturalists' Club (Ottawa Field-Naturalists' Club, 1907)

Our domestic animals in health and disease - Gamgee, John, 1831 -1894 (Maclachlan & Stewart, 1871)

Our domestic animals in health and disease - Gamgee, John, 1831 -1894 (Thomas C. Jack, 1861)

Our living resources : a report to the nation on the distribution, abundance, and health of U.S. plants, animals, and ecosystems - United States. National Biological Service. (U.S. Dept. of the Interior, National Biological Service, 1995)

Our living world; an artistic edition of the Rev. J. G. Wood's Natural history of animate creation - Wood, J. G. (John George), 1827 -1889 (S. Hess, 1885)

Our native birds; how to protect them and attract them to our homes - Lange, D. (Dietrich), 1863 -1940 (The Macmillan company, 1915)

Ouresiphoitēs Helveticus, sive, Itinera per Helvetiae Alpinas regiones facta annis MDCCII, MDCCIII, MDCCIV, MDCCV, MDCCVI, MDCCVII, MDCCIX, MDCCX, MDCCXI : plurimis tabulis aeneis illustrata - Scheuchzer, Johann Jakob, 1672 -1733 (Typis ac sumptibus Petri Vander Aa, 1723)

Outlines of clinical diagnostics of the internal diseases of domestic animals - Malkmus, Bernhard, 1859 -1925 (A. Eger, 1908)

Outlines of comparative anatomy and medical zoology - Allen, Harrison, 1841 -1897 (Lippincott, 1874)

Outlines of comparative anatomy and medical zoology - Allen, Harrison, 1841 -1897 (J.B. Lippincott & co, 1869)

Outlines of comparative anatomy intended principally for the use of students - Fyfe, Andrew, 1754 -1824 (Printed by J. Pillans & Sons for Adam Black ... [etc.], 1818)

Outlines of comparative physiology touching the structure and development of the races of animals, living and extinct : for the use of schools and colleges - Agassiz, Louis, 1807 -1873 (Bell & Daldy, 1870)

Outlines of general zoology - Baird, Spencer Fullerton, 1823 -1887 (Rudolph Garrigue, 1851)

Outlines of lectures on materia medica and botany :delivered in Jefferson Medical College, Philadelphia - Barton, William P. C. (William Paul Crillon), 1786 -1856 (Joseph G. Auner, 1827)

Outlines of the natural history of Great Britain and Ireland, containing a systematic arrangement and concise description of all the animals, vegetables and fossiles which have hitherto been discovered in these kingdoms - Berkenhout, John, 1730 -1791 (Printed for P. Elmsly (Successor to Mr. Vaillant), 1769)

The outlines of the veterinary art; or, The principles of medicine : as applied to the structure, functions, and economy, of the horse, and to more scientific and successful manner of treating his various diseases : comprehending, also, a concise view of those of neat cattle and sheep... - Blaine, Delabere P. (Delabere Pritchett), 1770 -1845 (Printed for Boosey & Sons, 1826)

The outlines of the veterinary art, or, The principles of medicine as applied to the structure, functions, and oeconomy, of the horse, and to a more scientific and successful manner of treating his various diseases : comprehending, also, a concise view of those of neat cattle and sheep - University of Glasgow. Library. (1816)

Outlines of zoology - Thomson, J. Arthur (John Arthur), 1861 -1933 (Young J. Pentland, 1895)

Outlines of zoology - Thomson, J. Arthur (John Arthur), 1861 -1933 (Young J. Pentland, 1892)

Outlines of zoology - Thomson, J. Arthur (John Arthur), 1861 -1933 (D. Appleton & Co, 1892)

Outlines of zoology - Thomson, J. Arthur (John Arthur), 1861 -1933 (H. Frowde and Hodder & Stoughton, 1899)

Outlines of zoology - Thomson, J. Arthur (John Arthur), 1861 -1933 (Pentland, 1899)

Outlines of zoology - Thomson, J. Arthur (John Arthur), 1861 -1933 (D. Appleton & Co, 1895)

Outlines of zoology - Thomson, J. Arthur (John Arthur), 1861 -1933 (Appleton, 1916)

Outlines of zoology - Thomson, J. Arthur (John Arthur), 1861 -1933 (H. Frowde and Hodder & Stoughton, 1921)

Outlines of zoology - Thomson, J. Arthur (John Arthur), 1861 -1933 (Humphrey Milford, Oxford University Press, 1929)

Outlines of zoology - Thomson, J. Arthur (John Arthur), 1861 -1933 (D. Appleton, 1906)