These are absent in the Cetacea alone.
There are no large mammals in all this extensive region except the Cetacea and a species of the Phocidae of southern waters.
Orders: Insectivora, Chiroptera, Dermoptera, Edentata (Sub-orders: Xenarthra, Pholidota, Tubulidentata), Rodentia (Sub-orders: Duplicidentata, Simplicidentata), Tillodontia, Carnivora (Sub-orders: Fissipedia, Pinnipedia, Creodonta), Cetacea (Sub orders: Archaeoceti, Odontoceti, Mystacoceti), Sirenia, Ungulata (Sub-orders: Proboscidea, Hyracoidea, Barypoda, Toxodontia, Amblypoda, Litopterna, Ancylopoda, Condylarthra, Perissodactyla, Artiodactyla), Primates (Sub-orders: Prosimiae, Anthropoidea).
The cetacea and a few rodents are also without it.
It is not my intention, were it in my power, to enter into the inquiry as to the true method of dividing the cetacea into groups and families....
Of the marine orders of Sirenia and Cetacea the Dugong, Halicore, is exclusively found in the Indian Ocean; and a dolphin, Platanista, peculiar to the Ganges, ascends that river to a great distance from the sea.