The Kerguelen Islands, known also as the Desolation Islands, lie in the extreme south of the Indian Ocean. By the late nineteenth century they were still relatively unexplored, but they represented a fascinating puzzle: although the Islands were four thousand miles away from South America, they shared the same species of flora. Rodrigues, an island off the coast of Madagascar, was also a point of increasing interest among naturalists. While most archipelagic islands then discovered were volcanic, explorers noted that the caves of Rodrigues were formed of limestone, and that most local species were not indigenous. Like the Kerguelen Islands, they provided some of the first clear evidence that modern sea-levels were much altered from those of prehistory. Naturalists visited both locations as part of the expeditions to study the transit of Venus in 1874. Originally published in 1879, this collection of essays is a comprehensive catalogue of their findings.