380 
GEOGRAPHICAL ZOOLOGY. 
[part iv. 
other. About this same time (but perhaps not contempo- 
raneously) Madagascar must have been connected with some 
portion of Southern Africa, and the whole of the country would 
possess no other Primates but Lemuroidea. , After the Mada- 
gascar territory (very much larger than the existing island) 
had been separated, a connection appears' to have been long 
maintained (probably by a northerly route) between the more 
equatorial portions of Asia and Africa ; till those higher forms 
had become developed, which were afterwards differentiated into 
Simia, Presbytes, and CynopitJmm , on the one hand, and into 
Troglodytes , Colohus, and Cynocephalus, on the other. In ac- 
cordance with the principle of competition so well expounded 
by Mr. Darwin, we can understand how, in the vast Asiatic and 
African area north of the Equator, with a great variety of 
physical conditions and the influence of a host of competing 
forms of life, higher. types were developed than in the less 
extensive and long-isolated countries south of the Equator, 
In Madagascar, where these less complex conditions prevailed 
in a considerable land-area, the lowly organised Lemuroids have 
diverged into many specialized forms of their own peculiar type ; 
while on the continents they have, to a great extent, become 
exterminated, or have maintained their existence in a few cases, 
in islands or in mountain ranges. In Africa the nocturnal and 
arboreal Qalagos are adapted to a special mode of life, in which 
they probably have few competitors. 
How and when the ancestors of the Cebidrn and Hapalidm 
entered the South American continent, it is less easy to conceiye. 
The only rays of light we yet have on the subject are, the 
supposed affinities of the fossil Coenopithecus of the Swiss, and 
the Lemuravidae of the North American Eocene, with both 
Cebidse and Lemuroids, and the fact that in Miocene or Eocene 
times a mild climate prevailed up to the Arctic circle. The dis- 
covery of an undoubted Lemuroid in the Eocene of Europe, 
indicates that the great Northern Continent was probably the 
birthplace of this low type of mammal, and the source whence 
Africa and Southern Asia were peopled with them, as it was, 
at a later period, with the higher forms of monkeys and apes. 
