The observing eye; or, Letters to children on the three lowest divisions of animal life: the radiated, articulated, & molluscous - Wright, Anne (Jarrold, 1860)

Occasional papers - Boston Society of Natural History. (1904)

Occasional papers of the Boston Society of Natural History - Boston Society of Natural History. (Boston Society of Natural History, 1905)

Occasional papers of the California Academy of Sciences - California Academy of Sciences (California Academy of Sciences, 1893)

Occasional papers of the California Academy of Sciences - California Academy of Sciences (California Academy of Sciences, 1985)

Occasional papers of the California Academy of Sciences - California Academy of Sciences (California Academy of Sciences, 2010)

Occasional papers of the California Academy of Sciences - California Academy of Sciences (California Academy of Sciences, 2013)

Occasional papers on mollusks - Harvard University. Museum of Comparative Zoology. Department of Mollusks. (Dept. of Mollusks, 1947)

Ocean life - Sommerville, James M. (Barnard & Jones, 1859)

Öfversigt af Finska vetenskaps-societetens förhandlingar - Suomen Tiedeseura (s.n.], 1838)

Öfversigt af Kongl. Vetenskaps-akademiens forhandlingar - Kungl. Svenska vetenskapsakademien. (P. A. Norstedt & Söner, 1865)

Öfversigt af Kongl. Vetenskaps-akademiens forhandlingar - Kungl. Svenska vetenskapsakademien. (P. A. Norstedt & Söner, 1867)

Ohio fossils - La Rocque, Aurèle, 1909 -1990 (Ohio Dept. of Natural Resources, Division of Geological Survey, 1955)

Old bones : or, Notes for young naturalists - Brooks, Vincent, 1815? -1885 (Robert Hardwicke, 1861)

Old bones : or, Notes for young naturalists, on vertbebrate animals, their fossil predecessors and allies - Symonds, W. S. 1818 -1887 (Robert Hardwicke, 1864)

Om Galapagos-hoarnes vegetation - Andersson, N. J. (Nils Johan), 1821 -1880 (Norstedt, 1857)

On animal and vegetable parasites of the human body a manual of their natural history, diagnosis, and treatment - Lankester, Edwin, 1814 -1874 (Printed for the Sydenham Society, 1857)

On animal and vegetable parasites of the human body, a manual of their natural history, diagnosis, and treatment - Küchenmeister, Friedrich, 1821 -1890 (Printed for the Sydenham society, 1857)

On animal and vegetable parasites of the human body, a manual of their natural history, diagnosis, and treatment - Küchenmeister, Friedrich, 1821 -1890 (Printed for the Sydenham Society, 1857)

On germinal selection as a source of definite variation - Weismann, August, 1834 -1914 (Open Court Pub. Co, 1902)

On germinal selection as a source of definite variation - Weismann, August, 1834 -1914 (The Open court publishing company, 1902)

On morphology and teleology, especially in the limbs of Mammalia - Wilder, Burt G. (Burt Green), 1841 -1925 (Riverside Press, 1865)

On morphology and teleology, especially in the limbs of Mammalia - Wilder, Burt G. (Burt Green), 1841 -1925 (Riverside press, 1865)

On morphology and teleology, especially in the limbs of mammalia - Wilder, Burt G. (Burt Green), 1841 -1925 (Printed at the Riverside Press, 1865)

On some remarkable forms of animal life from the great deeps off the Norwegian coast... - Sars, G. O. (Georg Ossian), 1837 -1927 (Printed by Brøgger & Christie [etc.], 1875)

On some remarkable forms of animal life from the great deeps off the Norwegian coast... - Sars, G. O. (Georg Ossian), 1837 -1927 (Printed by Brøgger & Christie [etc.], 1872)

On some remarkable mimetic analogies among African butterflies - Trimen, Roland, 1840 -1916 (Linnean Society of London, 1868)

On the archetype and homologies of the vertebrate skeleton - Owen, Richard, 1804 -1892 (John Van Voorst, 1848)

On the domesticated animals of the British islands - Low, David. (Longman, Brown, Green & Longmans, 1845)

On the domesticated animals of the British islands : comprehending the natural and economical history of species and varieties; the description of the properties of external form; and observations on the principles and practice of breeding - Low, David, 1786 -1859 (Longman, Brown, Green & Longmans, 1845)

On the domesticated animals of the British islands: comprehending the natural and economical history of species and varieties; the description of the properties of external form; and observations on the principles and practice of breeding - Low, David, 1786 -1859 (Longman, Brown, Green, & Longmans, 1846)

On the fossil foot-marks in the red sandstone of Pottsville, Pennsylvania / by Isaac Lea - American Philosophical Society. (Printed for the author, 1852)

On the fossil foot-marks in the red sandstone of Pottsville, Pennsylvania - American Philosophical Society. (Printed for the author, 1852)

On the genus Actinometra, Müll., with a morphological account of a new species (A.) polymorpha from the Philippine Islands. Part I - Carpenter, P. Herbert (Philip Herbert), 1852 -1891 (1879)

On the geology and natural history of the upper Missouri :Being the substance of a report made to Lieut. G.K. Warren, T.E. U.S.A - Hayden, F. V. (Ferdinand Vandeveer), 1829 -1887 (Printed by C. Sherman & son, 1862)

On the history and natural arrangement of insects - Shuckard, William Edward, 1802 -1868 (Printed for Longman, Brown, Green & Longman's Paternoster Row, 1840)

On the history and natural arrangement of insects - Shuckard, William Edward, 1802 -1868 (Printed for Longman, Orme, Brown, Green, & Longmans [etc.], 1840)

On the impregnation of the ovum in the Amphibia ... (First series ... second series, rev.) And on the direct agency of the spermatozoon - Newport, George 1803 -1854 (1851)

On the origin & metamorphosis of insects - Lubbock, John, Sir, 1834 -1913 (Macmillan, 1890)

On the origin and metamorphoses of insects - Lubbock, John, Sir, 1834 -1913 (Macmillan, 1874)

On the origin and metamorphoses of insects - Lubbock, John, Sir, 1834 -1913 (Macmillan, 1890)

On the origin and metamorphoses of insects - Lubbock, John, Sir, 1834 -1913 (Macmillan and co, 1874)

On the origin of species - Darwin, Charles, 1809 -1882 (D. Appleton and Co, 1871)

On the origin of species by means of natural selection, or, The preservation of favoured races in the struggle for life - Darwin, Charles, 1809 -1882 (Henry Frowde, 1907)

On the origin of species by means of natural selection; or, The preservation of favoured races in the struggle for life - Darwin, Charles, 1809 -1882 (D. Appleton and Co, 1860)

On the origin of species by means of natural selection, or, The preservation of favoured races in the struggle for life - Darwin, Charles, 1809 -1882 (John Murray, Albemarle Street, 1859)

On the origin of species by means of natural selection, or, The preservation of favoured races in the struggle for life - Darwin, Charles, 1809 -1882 (John Murray, 1860)

On the origin of species by means of natural selection, or, The preservation of favoured races in the struggle for life - Darwin, Charles, 1809 -1882 (John Murray, 1859)

On the origin of species by the means of natural selection, or, The preservation of favoured races in the struggle for life - Darwin, Charles, 1809 -1882 (Odhams Press, 1872)

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 principles of classification in the animal kingdom - Agassiz, Louis, 1807 -1873 (Steam-Power Press of Walker and James, 1850)

On the senses, instincts, and intelligence of animals, with special reference to insects - Lubbock, John, Sir, 1834 -1913 (K. Paul, Trench, 1889)

On the senses, instincts, and intelligence of animals : with special reference to insects - Lubbock, John, Sir, 1834 -1913 (Kegan Paul, Trench & Co, 1889)

On the senses, instincts, and intelligence of animals, with special reference to insects - Lubbock, John, Sir, 1834 -1913 (D. Appleton and Company, 1888)

On the senses, instincts, and intelligence of animals : with special reference to insects - Lubbock, John, Sir, 1834 -1913 (Kegan Paul, Trench, 1888)

On the systematic position of the Brachiopoda - Morse, Edward Sylvester, 1838 -1925 (Press of A.A. Kingman, 1873)

On the systematic position of the Brachiopoda; by E.S. Morse (book review) - Verrill, A. E. (Addison Emery), 1839 -1926 (S. Converse, 1874)

On the unity of structure in the animal kingdom - Royal College of Physicians of Edinburgh. ([s.n.], 1837)

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, 1956)

Opisthobranch newsletter - Long, Steven J. (S.J. Long, 1969)

Orchard and farm (Calkins Newspaper Syndicate, 1898)

The orders, sub-orders and genera of insects - Couper, William, 1886 (s.n, 1864)

Organic evolution considered - Fairhurst, Alfred, 1843 -1921 (Christian publishing, 1897)

The organization of Trilobites, deduced from their living affinities. With a systematic review of the species hitherto described - Bell, Thomas, 1792 -1880 (Printed for the Ray Society, 1846)