CHAP. IV.] ZOOLOGICAL REGIONS. 73 
Ethiopian Region—The limits of this region have been indi- 
cated by the definition of the Paleearctic region. Besides Africa 
south of the tropic of Cancer, and its islands, it comprises the 
southern half of Arabia. 
This region has been said to be identical in the main charac- 
ters of its mammalian fauna with the Oriental region, and has 
therefore been united with it by Mr. A. Murray. Most impor- 
tant differences have however been overlooked, as the following 
summary of the peculiarities of the Ethiopian region will, I 
think, show. 
It possesses 22 peculiar families of vertebrates; 90 peculiar 
genera of mammalia, being two-thirds of its whole number ; 
and 179 peculiar genera of birds, being three-fifths of all it 
possesses. It is further characterized by the absence of several 
families and genera which range over the whole northern 
hemisphere, details of which will be found in the chapter 
treating of the region. There are, it is true, many points 
of resemblance, not to be wondered at between two tropical 
regions in the same hemisphere, and which have evidently been 
at one time more nearly connected, both by intervening lands 
and by a different condition of the lands that even now connect 
them. But these resemblances only render the differences more 
remarkable ; since they show that there has been an ancient and 
long-continued separation of the two regions, developing a dis- 
tinct fauna in each, and establishing marked specialities which 
the temporary intercommunication and immigration has not 
sufficed to remove. The entire absence of such wide-spread 
groups as bears and deer, from a country many parts of which 
are well adapted to them, and in close proximity to regions 
where they abound, would alone mark out the Ethiopian region 
as one of the primary divisions of the earth, even if it possessed 
a less number than it actually does of peculiar family and 
generic groups. 
Sub-divisions of the Ethiopian Region—The African conti- 
nent south of the tropic of Cancer is more homogeneous in its 
prominent and superficial zoological features than most of the 
other regions, but there are nevertheless important and deep- 
VoL. I.—7 
