238 
POPULAR SCIENCE REVIEW. 
The groups to which the vampires belong — the Phyllosto- 
midce — is strictly confined to the Neotropical and Nearctic 
regions ; and the Neotropical region is not only distinguished 
as the head-quarters of the Phyllostomidoe , but also by being 
altogether destitute of the flying foxes and Rhinolophidce. 
Such being the relation of bats to space — their geographical 
distribution — what are their relations to time — their geological 
distribution ? 
I assume that my readers are acquainted with the funda- 
mental facts and laws of geology, and know that the successive 
layers, of which the superficial crust of the earth is in very 
various degrees composed, are classifiable into three sets : (1) 
The Primary or Palaeozoic rocks, (2) the Secondary or Mesozoic 
rocks (from the Trias to the Chalk inclusively), and lastly (3) 
the Tertiary or Cainozoic rocks, extending upwards from the 
Chalk to the present day. 
Eemains of beasts more or less closely resembling some of 
those existing now in Australia are found low down in the 
secondary rocks, namely in the Triassic and Oolitic formations. 
Generally speaking, however, beasts such as those which now 
exist are not found deeper than the Tertiary strata, and this is 
the case with bats. 
The oldest fossil bat yet known is represented by a few teeth 
found in Eocene deposits in Suffolk. The oldest perfect fossil 
bat is the Vespertilio parisiensis of the gypsum beds of Mont- 
martre, near Paris. 
Some forms of existing beasts, however, which are now dis- 
tinct enough, such as the ox and the pig, or the tapir and the 
horse, were preceded in early Tertiary times by others which 
were more or less intermediate in structure. This is not the 
case as regards bats. Bats, as soon as they appear at all, 
appear as thoroughly and as perfectly organised bats as are 
those living amongst us now. 
This leads us to speculate upon questions of origin ; but, 
before so doing, let us see that we have a clear idea of what a 
bat is, and can give a good definition of it. 
In order that we may have this clear idea, we must consider 
for a few moments zoological classification. 
The whole group of animals is fancifully termed the animal 
kingdom, in contradistinction to the world of plants — the 
vegetable kingdom. 
This vast mass of animals is subdivided into a number of 
very large groups, each of which is called a subkingdom. Thus 
we have the subkingdom to which we ourselves belong — the 
vertebrate subkingdom ; the subkingdom of insects, &c. ; that 
of snails, cuttle-fishes, &c., and so on. 
Each of these various subkingdoms is again divided into 
