No. 422.] NOTES AND LITERATURE. 
[n 
Cn 
“I 
ZOOLOGY. 
Biogeographical Regions. — A valuable contribution to biogeog- 
raphy has recently been published by Jacobi. The author has 
accepted the modern views on geographical distribution, and espe- 
cially the fundamental idea that the present distribution does not cor- 
respond, in many cases, to the present conditions of life, but has 
often its origin in the past, and indicates conditions prevailing in 
former geological periods. He points out that the best zodgeo- 
graphical divisions proposed by previous authors have not covered 
all cases, and cannot do so, because the past conditions were often 
directly the opposite to the present ones. Nevertheless, he tries to 
give a scheme that is intended to unite past and present conditions,” 
and selects Lydekker’s division in three realms (Arktogza, Neogza, 
and Notogza) as the most appropriate, since he believes that it 
accounts best for the distribution of mammals and birds from the begin- 
ning of Tertiary times. 
Aside from the question whether it is necessary at all to have any 
biogeographical realms or regions, we cannot agree with this idea 
that biogeography ought to unite past and present conditions into 
one scheme ; indeed, in many cases it is directly impossible to do so, 
since we do not see any way to reconcile connection and discon- 
nection. And in most cases it would amount just to this, to bring 
under one head certain parts of the earth’s surface which are now 
connected, while they were formerly disconnected, — or vice versa. 
Believing this to be an impossible task, we have always advocated 
another method of investigation, namely, the attempt to establish 
the present conditions of life (not the actual distribution of animals 
or plants) and to divide the earth into regions accordingly. These 
regions refer only to the present time, and by comparing this scheme 
with the actual distribution of animals, those cases which do not 
agree with it are at once revealed. This method calls our attention 
to those facts in distribution which need special investigation and 
explanation, and in most cases we shall be able to account for them 
1 Jacobi, A. Lage und Form biogeographischer Gebiete, Zeitschrift der 
er für Erdkunde zu Berlin, Bd. xxxv, Heft 3 (1900), pp- 147-238. 
2 pls. 
2 The same idea has been advocated by Prof. H. F. Osborn (Science, April 15, 
1900, p. 563), who says: “This, then, is our E to connect i: - 
tribution with distribution in past time and to gie which will be in 
harmony with both sets of facts." 
