Conrad Martens was the official artist on board the Beagle. During the expedition of Charles Darwin to South America from 1833 to 1835, Martens registered in his notebooks the landscapes they saw. His pencil drawings and watercolors have been digitized and are available for free in the Digital Library of the University of Cambridge. His work can also be checked in this video:
The The writings on Brazil by Robert FitzRoy, the captain of HMS Beagle during Charles Darwin’s expedition were analyzed by Gabriel Passetti in the article “Brazil in the travel journal by Captain Robert FitzRoy of the HMS Beagle, 1828-1839“.
For other related articles, see:
Carvalho, Andre Luis de Lima. Das intermináveis incursões de Darwin pelo Brasil, pela América Latina e pelo mundo. Hist. cienc. saude-Manguinhos, Nov 2013, vol.20, suppl.1, p.1421-1426. ISSN 0104-5970
Caponi, Gustavo. Darwin: entre Paley y Demócrito. Hist. cienc. saude-Manguinhos, Dic 2003, vol.10, no.3, p.993-1023. ISSN 0104-5970
See the full edition of HCS- Manguinhos “Oceans and Seas: History, Science, Policy”