Sir John Graham Kerr (1869–1957) was a Scottish zoologist and politician, well known for his work in relation to the embryology of lungfishes. Originally published in 1950, this book provides an account of Kerr's travels and discoveries within the Gran Chaco region of South America. The text is divided into two main parts: the first discusses the Pilcomayo Expedition of 1889–91, providing detailed information on the 'Natokoi or Toba Indians', together with their natural environment; the second gives an account of the 1896–7 Lepidosiren Expedition, mainly focusing on Kerr's observations of the South American lungfish. Numerous illustrative figures are also incorporated, including photographs, drawings and maps. This book will be of value to anyone with an interest in the Gran Chaco region, anthropology, zoology and the history of science.