Four uniformly bound works. New York and London: D. Appleton and Company, 1900-1909. 12mo (7 3/4in.). Half calf and marbled paper; gilt and red leather labels to spines; marbled endpapers, top edges gilt. "Authorized Editions." Condition: Fair-Good; all with wear/losses to spines (including partial/missing labels); considerable edge and corner wear; rubbing; light toning; all with owner's inscription; other issues noted by volume. 1. The Descent of Man and Selection in Relation to Sex. 1904. Second revised and augmented edition. In-text illustrations. Front board/spine detached from text block. 2. The Formation of Vegetable Mould Through the Action of Worms, with Observations of Their Habits. 1900. In-text illustrations. Edge tear p. 21. 3. Geological Observations, On the Volcanic Islands and Parts of South America Visited During the Voyage of H.M.S. 'Beagle.' 1900. Third Edition, with in-text illustrations, 2 fold-out maps, 1 fold-out chart, and 4 fold-out shell illustrations. 4. Journal of Researches into the Natural History and Geology of the Countries Visited During the Voyage of H.M.S. Beagle Round the World, Under the Command of Capt. Fitz Roy, R.N. 1909. New Edition. The front and back boards/spine are nearly detached from text block.