I MR. SCLATER’S REGIONS 87 
dientia), Viverridae, Horses, or Antelopes, excepting Antilocapra, 
a type of a separate division of Bovidae. But since several of 
these groups have been represented in recent times, no primary 
line of division can be profitably drawn. 
Arctogaea as a whole may be characterised by both negative 
and positive characters. As negative features may be mentioned ; 
—the entire absence of Edentates (Wecrodasypus of Filhol is 
rather doubtful, see p. 164, n.), though a few crept up into the 
Nearctic region from Neogaea during past times ; and of Hapalidae, 
Cebidae, and Marsupials, except an Opossum in North America. 
This realm has, on the other hand, all the Lemurs, all the 
Insectivores with the exception of the West Indian Solenodon, 
all the Proboscidea, Rhinoceroses, Horses, Deer, Antelopes, the last 
group including the Oxen and a variety of other important 
families. It is in fact the headquarters of all the Eutheria with 
the exception of the Edentata and Marsupials. 
The subdivisions of ths realm have been variously effected. 
The classical subdivisions are of course those of Mr. Sclater, who 
would recognise (1) the Nearctic, North America; (2) the Palae- 
arctic, including Eurcpe, Northern Asia, and Japan; (3) the 
Oriental, including Asia south of the Himalayas and the islands 
of the Malay Archipelago as far east as the Australian region ; 
and (4) the Ethiopian, 7.e. tropical Africa and Madagascar. Some 
would alter this by uniting America and the north of the Old 
World into a Holarctic region, separating off the southern parts 
of the North American continent into a Sonoran region. To 
some, the claims of Madagascar to form a separate region are 
convincing, To distinguish the boundaries of the several regions 
is a difficult task; they dovetail into each other on the frontiers 
with the complex curves of a puzzle-map. The difficulty has 
been grappled with by the suggestion of intermediate transitional 
areas ; but this proceeding really doubles the difficulty, for there 
are then two frontiers to delimit in each case instead of 
only one. The animal inhabitants must be expected to mingle 
somewhat at the lines of junction of one region with another. 
The Sonoran region does not appear to us to have great claims 
to recognition. It shows a mingling of southern with northern 
forms exactly as might be expected. An Armadillo and Didelphys 
have, as it is believed, invaded it from the Neogaeic realm; it 
possesses also the South American genera, Dicotyles, Nasua, Cone- 
