Before man inhabited India or Africa, some cause must have checked the continued increase of the existing elephant.

A highly capable judge, Dr.

Falconer, believes that it is chiefly insects which, from incessantly harassing and weakening the elephant in India, check its increase; and this was Bruce's conclusion with respect to the African elephant in Abyssinia.

It is certain that insects and blood-sucking bats determine the existence of the larger naturalised quadrupeds in several parts of South America.