This is the geographical division followed by Lichtenstein, Swainson, Erichson, and Richardson.

The section from Vera Cruz to Acapulco, given by Humboldt in the "Polit.

Essay on Kingdom of N.Spain" will show how immense a barrier the Mexican table-land forms.

Dr.Richardson, in his admirable "Report on the Zoology of N.America" read before the British Association 1836 page 157, talking of the identification of a Mexican animal with the Synetheres prehensilis, says, "We do not know with what propriety, but if correct, it is, if not a solitary instance, at least very nearly so, of a rodent animal being common to North and South America.") Some few species alone have passed the barrier, and may be considered as wanderers from the south, such as the puma, opossum, kinkajou, and peccari.

South America is characterised by possessing many peculiar gnawers, a family of monkeys, the llama, peccari, tapir, opossums, and, especially, several genera of Edentata, the order which includes the sloths, ant-eaters, and armadilloes.