The relation of the mammals of North America to the similar animals now inhabiting other portions of the earth may be briefly shown by indicating the distribution of the orders into which the mammalia are divided. It will be remembered that in general each order is subdivided into families, these again into genera, the genera into species, and a species may contain several varieties. The classification here adopted is the one used by Lydekker in his Manual of Palaeontology. An order when represented in the fauna of a continent is indicated in the following table by a plus, and when absent by a minus sign. CLASS--MAMMALIA +-------+-------------+--------------------+--------------------------+ | | | | DISTRIBUTION | | Sub- | | +---+---+----+------+------+ |Classes| Orders | Examples | N.| S.|Eur-| |Aus- | | | | |Am.|Am.|asia|Africa|tralia| +-------+-------------+--------------------+---+---+----+------+------+ | {|1. Primates |Man, lemurs, | + | + | + | + |(Man) | | {| |apes, monkeys. | | | | | | | {|2. Chiroptera|Bats. | + | + | + | + | + | | {|3. Insecti- |Moles, shrews, | + | + | + | + | - | | {| vora |hedgehogs. | | | | | | | {|4. Carnivora |Lions, tigers, cats,| + | + | + | + | - | | {| |dogs, seals, etc. | | | | | | | {|5. Rodentia |Beavers, rats, | + | + | + | + | + | | {| |mice, squirrels, | | | | | | | {| |rabbits. | | | | | | |Eu- {|6. Ungulata |Ox, horse, elephant,| + | + | + | + | - | |theria{| |tapir, etc. | | | | | | | {|7. Sirenia |Dugong and | + | + | + | + | + | | {| |manatee. | | | | | | | {|8. Cetacea |Whales, dolphins, | + | + | + | + | + | | {| |narwhals. | | | | | | | {|9. Edentata |Sloths, armadillos, | + | + | + | + | - | | | |ant-eaters. | | | | | | +-------+-------------+--------------------+---+---+----+------+------+ |Meta- |10. Marsu- |Kangaroos, opossums,| + | + | - | - | + | |theria | pialia |etc. | | | | | | +-------+-------------+--------------------+---+---+----+------+------+ |Proto- |11. Monotre- |Ornithorhynchus, | - | - | - | - | + | |theria | mata |echidna | | | | | | +-------+-------------+--------------------+---+---+----+------+------+