Though correspondence has never ebbed so low, CD is constantly in his thoughts.

Observations on cheetahs used as domesticated hunting animals.

Finds geographical barriers sometimes separate species, but also finds species that remain separate where there are no barriers to migration.

Colour "individuates" isolated animal species.

Plains and alpine animal distribution show altitude not strictly analogous to latitude.

Impact of timber cutting on climate has led to extinction of crocodiles.

Will discuss coal formation in letter to Edward Forbes.

CD often asked whether isolated mountains in southern latitudes had closely allied representatives of Arctic and north temperate plants; JDH has found a representative barberry.

Making for Darjeeling via Calcutta.

At Madras [Chennai] JDH asked about cheetahs. Conveys observations on their domestication & hunting. Describes hawking practices & birds used. Observes that natural features separate species but this is only one factor, e.g. different antelopes found on either side of River Soane which should not be a barrier to migration. The different types of Indian elephant also an example of races in districts. Discusses kinds of wild & domesticated dogs & cattle. The native Bison is extinct. Sciurus maximus: Peninsular Squirrel, is example of locality-specific colouring. From behaviour of alpine & plain species observes animals are more able to adapt to heat than cold, altitude a factor. JDH wants a specimen of an alligator from Zillah Shahabad. Deforestation changing climate & killing crocodiles. Observes Sand Martins nests colonised by Phalangium spiders & comments on diurnal migration of Neilgherry Ghaats [Nilgiri Ghats] swallows. Plains are alluvial deposits with interesting mineralogy. Will send Forbes a letter re. coal formation. Re. botany, as Darwin is interested in vegetation of isolated mountains, JDH comments on flora of one he climbed incl. barberry. Has found new species of Vallisneria. 4 Mar: JDH left Williams' geological survey to go to Mirzapore, Calcutta [Kolkata] & Darjeeling in Sikkim Himalaya. JDH's address is botanic garden Calcutta, care of Falconer. Recounts passage out to India. Has stayed with Sir L. Peel, Mr Colvile nephew of Lord Auckland, & at Government House. JDH hopes to join the Geographical Survey of Kamaon by naturalists, covering Sewalik hills to Tibet & Simla to Nepal. Thomson is in Yarkand studying geology & botanical geography, Cunningham in Cashmere [Kashmir] & Strachey in Chinese Tibet. Mentions Equus hermionus, an Auroch horn, his health & plan to go to Cherra Poonjee in Sylhet. Mar 8: en route to Bhagulpore down Ganges. Feb 16: will look for cirripedia for Darwin in Borneo, sends regards to Lyells & recommends Griffith's Journals.