This arrangement is not one of convenience only; I attach a certain
ethnographic importance to this classification. There is a distinct
resemblance between the two Atlantic groups, and an equally distinct
contrast between them and the Pacific groups, extending to temperament,
culture and physical traits. Each of the groups has mingled extensively
within its own limits, and but slightly outside of them. Each is subject
to conditions of temperature, altitude and humidity, which are peculiar
to itself, and which have exerted definite influences on the constitution
and the history of its inhabitants. Such a subdivision of the race is
therefore justified by anthropologic considerations.