Color enhanced image of fossilized shells drawn from Darwin's "Geological Observations on Volcanic Islands" which describes the geological observations made of South America and its surrounding volcanic islands during his voyage on the H.M.S. Beagle. FULL TITLE: Geological observations on the volcanic islands visited during the voyage of H.M.S. Beagle, together with some brief notices of the geology of Australia and the Cape of Good Hope. Being the second part of the geology of the voyage of the Beagle, under the command of Capt. Fitzroy, R.N. during the years 1832 to 1836.