Having previously embarked on a collecting expedition to the Pyrenees, backed by Sir William Hooker and George Bentham, the botanist Richard Spruce (1817-93) travelled in 1849 to South America, where he carried out unprecedented exploration among the diverse flora across the northern part of the continent. After his death, Spruce's writings on fifteen fruitful years of discovery were edited as a labour of love by fellow naturalist Alfred Russel Wallace (1823-1913), whom Spruce had met in Santarém. This two-volume work, first published in 1908, includes many of the author's exquisite illustrations. Showing the determination to reach plants in almost inaccessible areas, Spruce collected hundreds of species, many with medicinal properties, notably the quinine-yielding cinchona tree, as well as the datura and coca plants. Volume 1 contains Wallace's biographical introduction and a list of Spruce's published works. The narrative includes discussion of Pará, Santarém, and the Negro and Orinoco rivers.

Discusses travellers such as Sir Joseph Banks, Heinrich Barth, Henry Walter Bates, George Bentham, Margaret Brooke, Hugh Clapperton, Captain James Cook, Charles Darwin, General Sir Rufane Donkin, Francis Galton, Sir Joseph Hooker, Sir William Hooker, Alexander von Humboldt, Thomas Henry Huxley, Sir Harry Johnston, Mary Kingsley, John Lander, Richard Lander, Sir Charles Lyell, Marianne North, Richard Owen, Mungo Park, Captain James Ross, Richard Spruce, Alfred Russel Wallace, Charles Waterton, and others.

The text presents a descriptive list of the hepaticae and anthocerotes of California. The author obtained specimens in various stages of development, fixed them with chromic acid and preserved them in alcohol in order to retain the natural outlines and faciliate an accurate study of the internal structures through the use of microtome sections.

Vol. 25: The distribution of Hepaticæ in Scotland, by S.M. Macvicar.