602 GEOGRAPHICAL DISTRIBUTION 
and North America north of (5); (5) Sonoran—roughly 
corresponding to greater part of United States. 
1. MADAGASCAR REGION, comprising Madagascar, Mau- 
ritius, Bourbon, Rodriguez, Seychelles and Cornova Islands. 
—The mammalian fauna of Madagascar is so remarkable 
that it has strong claims for being placed in a region apart 
from Africa. The most striking feature is the huge quantity 
and variety of lemurs, representing three families and nearly 
forty known species. The allied order of JLusectivora 1s 
represented by a large and unique family, the Cenfecide, in 
addition to a probable immigrant, the musk-shrew, and one 
potamogale. A cat-like carnivore (Crypfoprocta) and a 
number of mongooses represent the Carnivora, all belonging 
to the civet family (Viverride). There are in the case of 
Notogcea about seven species of the cosmopolitan AMuride, 
of the Rodentia, and the list is completed by the bush-pig. 
We may note also the fox-bats (Pferopus) and an extinct 
Lippopotamus. 
Lemurs, insectivores, carnivores and rodents occur on 
the mainland of Africa, but none of the genera found in 
Madagascar. Indeed, the only genera common to the two 
regions are the bush-pig and hippopotamus and the musk- 
shrew. The latter was probably introduced at a later date, 
and the two former probably introduced themselves by swim- 
ming, possibly at a date when the strait was of narrower 
dimensions than now. 
Madagascar has the monopoly of the ‘ollowing families : 
—The Chiromyide (Aye-Aye) and Censetide (Tenrecs), and 
by some authorities the “ Foussa” (C7yptoprocta) is placed 
in a family by itself. 
Almost as strange as these inhabitants is the entire 
absence of all the characteristic African mammals, the large 
Ungulata and Carnivora. 
The usually accepted explanation of these peculiarities is the as- 
sumption that Madagascar has been isolated from the mainland of 
Africa from early Miocene or upper Oligocene. In the Oligocene the 
lemurs flourished in Europe, as also the civets; and a separation effected 
at this period might easily isolate a sample of these two groups, together 
with the primitive Zsectevora, whilst the modern Ungulata and Carnt- 
vora of Africa would not by then have reached that region. Hence the 
history of Madagascar is a more recent repetition on a smaller scale of 
the history of Notogoea. Occurring later, it merely serves to preserve 
