JDH hopes Asa Gray continues his U.S. EXPLORING EXPEDITION publication. JDH is studying the flora of Fiji, Tahiti & the Sandwich Islands [Hawaii] & working on a preliminary essay to FLORA TASMANIAE. He is trying to trace the extent of Australian flora in the Pacific: it goes as far as New Zealand, Norfolk Islands, New Caledonia & the New Hebrides [Vanuatu] but no further, the flora of Fiji is more Indian. Possibly the explanation lies in differing geology. He thinks that an ancient Southern Continent must be the origin of the Australian flora & explanation for there being South African types in South West Australia & Polynesian species on the East coast of the continent. Discusses evidence of type persistence in Australia: Miocene era Banksia ericifolia preserved in lava beds in Victoria, & fossil Casuarina cones from Bass Straits. However, he also has an Araucaria excelsa cone from oolite in England. He concludes that geographical ranges have changed & the old theory of absolute creation is disproved & he will work to more modern hypotheses [Darwin's natural selection] without accepting them as doctrine. It must be accepted that the formation of land & sea has changed as agents of migration such as animals, wind & currents cannot account for current species distribution. He lists his five starting hypotheses to explain distribution of species, including the evolution of new species by selection & effects of land movement. Also, enumerates how this agrees with the expected fact of evolution of species from an aboriginal condition, including the existence of greater numbers of distinct species on remote islands & the great biodiversity of the southern temperate zone considering there is so little land compared to the North. JDH wrote these thoughts at Lord Wrottesley's, he has now returned to Kew & paid Thomson's[?] debt to [William Henry?] Harvey. JDH is shocked by Alphonse de Candolle begging to be made a Foreign Fellow of the Royal Society. [Letter incomplete]