Miscellaneous. 417 
the range and distribution of the animals themselves. However, by 
the very attempt to place side by side, in a methodical order, all the 
representatives of adjoining faune, I have gradually been led to de- 
fine more accurately the natural limits of the faune themselves. It 
is surprising to me that the principle by which faunze may be defined 
has not yet been stated, although it is very simple. It may thus be 
expressed: the geographical range of representative species occupy- 
ing adjoining regions marks the natural boundaries of their respective 
fauna. 
Since in our days it is no longer possible to study the animal king- 
dom without including in the investigation the remains of past geolo- 
gical ages, the question has naturally arisen, what disposition to make 
of the fossils. After mature consideration, I have come to the con- 
clusion, that for their most suitable arrangement it was indispensable 
to make also two kinds of collections of the fossil remains. In one 
of them, which corresponds to the systematic collection of the living 
animals, they are arranged systematically, according to the natural 
affinities of the different representatives of each geological period, in 
such a manner that the zoological character of these epochs is shown 
as distinctly to the eye of the student as the character of the present 
creation, by the study of the systematic collection of the living ani- 
mals. With the aid of these collections, special zoological treatises 
of each period may be compiled without difficulty ; and I have 
already satisfied myself that a comparison of those collections fur- 
nishes much information respecting the true affinities of animals. 
The second kind of collections of fossils is arranged in a way which 
corresponds to the faunal collections of living animals,—that is to say, 
according to their geographical distribution during each successive 
geological epoch. This arrangement has enabled me to display by 
themselves the more extensive collections of fossils, obtained from 
particular localities, in their characteristic mode of association, with- 
out crowding them upon the attention of the beginner, or giving them, 
by their larger number, an undue preponderance in the collection of 
the epoch to which they belong. But there is another advantage in 
making special faunal collections of fossils: they suggest comparisons 
with the faunze of the present time, which could not otherwise be 
made so effectively. Thus far geologists, in identifying the horizons 
of the successive deposits forming the stratified crust of our globe, 
have started from the universally accepted assumption that animals 
of the same geological age are either identical or closely allied over 
the most extensive areas. Nothing can be further from the truth 
than such a view ; and we need only to compare the faune of the pre- 
sent period in remote continents, to see how widely these differ. If 
the remains of past ages, belonging to the same geological periods, 
have generally appeared to be identical or closely allied, it is chiefly 
owing to the fact that they have been collected in the same geogra- 
phical zones ; and at present we find a similar agreement between the 
living animals of the temperate zone of Europe, Asia, and North 
America. But when we pass to other zones, the scene is entirely 
changed ; and so it was in former ages, as we already know from the 
