Two illustrations from the book Colouration in Animals and Plants by Alfred Tylor, 1886From Memoirs of the Carnegie Museum, 1902From The Proceedings of the Zoological Society of London, 1907Two illustrations from the book Mammals of Eastern Asia by GHH Tate, 1947From the book Notes on the natural history of common British animals and some of their foreign relations by Kate M. Hall, 1913From the book Mostly Mammals: zoological essays by Richard Lydekker, 1903Vaquita skull by Giorgia Louise JacquesTeeth of the seven gilled shark from the book Natural History of Victoria by Frederick McCoy, 1885From the book The Royal Natural History by Richard Lydekker, 1893From the book The Breeding of Animals by Frederick Blackmar Mumford, 1917Illustration by Etta Piotti from The Placentation of the Manatee (Trichechus latirostris) by George B. Wislocki, 1935
