yet markedly discontinuous. The Tragulidae are small
deer-like animals, known as chevrotains or mouse-deer, abundant in India
and the larger Malay islands and forming the genus Tragulus; while another
genus, Hyomoschus, is confined to West Africa. The other family is the
Simiidae or anthropoid apes, in which we have the gorilla and chimpanzee
confined to West and Central Africa, while the allied orangs are found only
in the islands of Sumatra and Borneo, the two groups being separated by a
greater space than the Echimyidae and other rodents of Africa and South
America.

Among birds and reptiles we have several families, which, from being found
only within the tropics of Asia, Africa, and America, have been termed
tropicopolitan groups. The Megalaemidae or barbets are gaily coloured {28}
fruit-eating birds, almost equally abundant in tropical Asia and Africa,
but less plentiful in America, where they probably suffer from the
competition of the larger sized toucans. The genera of each country are
distinct, but all are closely allied, the family being a very natural one.
The trogons form a family of very gorgeously coloured and remarkable
insect-eating birds very abundant in tropical America, less so in Asia, and
with a single genus of two species in Africa.

Among reptiles we have two families of snakes--the Dendrophidae or
tree-snakes, and the Dryiophidae or green whip-snakes--which are also found
in the three tropical regions of Asia, Africa, and America, but in these
cases even some of the genera are common to Asia and Africa, or to Africa
and America. The lizards forming the family Amphisbaenidae are divided
between tropical Africa and America, a few species only occurring in the
southern portion of the adjacent temperate regions; while even the
peculiarly American family of the iguanas is represented by two genera in
Madagascar, and one in the Fiji and Friendly Islands. Passing on to the
Amphibians the worm-like Caeciliadae are tropicopolitan, as are also the
toads of the family Engystomatidae. Insects also furnish some analogous
cases, three genera of Cicindelidae, (Pogonostoma, Ctenostoma, and
Peridexia) showing a decided connection between this family in South
America and Madagascar; while the beautiful family of diurnal moths,
Uraniidae, is confined to the same two countries. A somewhat similar but
better known illustration is afforded by the two genera of ostriches, one
confined to Africa and Arabia, the other