16 ZOOLOGICAL EXERCISES. 
back to a period anterior to the origin of existing species, 
and when the physical geography of the earth was some- 
what different to what it is now, and when therefore the 
barriers were not all in their present positions, and we must 
take this into account when dividing the earth into zoo- 
geographical districts. Professor Huxley, divides the world 
into the following four regions :— | 
1. The Arctogeal Region, including North America, 
Europe, Africa, and Asia as far south as Java and 
Borneo. It is characterised by the presence of 
catarrhine monkeys, lemurs in the tropical portions 
of the old world, by the elephant and camel, either 
living or fossil, and by the presence of insectivora, 
oxen, and ganoid fishes, and also by the absence 
of marsupials, except two species of opessum in 
North America. It is divided into four sub-regions ; 
(1) the Nearctic, comprising North America, charac- 
terised by the prong-buck, musk-rat, tree porcupine, 
turkey ; (2) Palwarctic, containing Europe, Northern 
Asia, and North Africa to the Sahara, characterised 
by the sheep, goat, and pheasant ; (3) the Oriental, 
comprising India, China, and the Indian Archipelago 
to Java and Borneo inclusive, characterised by the 
musk-deer, cattle, hornbills, peacock, and jungle-fow!; 
and (4) the Ethiopian, comprising the remainder of 
Africa, and Arabia. It is characterised by the 
giraffe and hyrax; and by the absence of bears, 
camels, deer, goats, and sheep. 
2, The Austro-columbian Region, comprising all the 
American Continent south of Mexico. It is charac- 
terised by the presence of platyrrhine monkeys and 
marmozets, llamas, peccaries, cavies, sloth, ant-eater, 
todies, trogons, humming birds, and curassows : also 
