IV 
INTRODUCTION. 
of wilful misstatement, it is often impossible to give 
the habitat, except in the most general terms. 
Those specimens which have been presented to the 
Museum have the name of the donor marked imme- 
diately after the habitat. When there is no such indica- 
tion, the specimens have been either purchased or pro- 
cured in exchange ; and in this case, whenever the place 
or person from whom they have been received gives au- 
thenticity to the specimens, or adds any thing of moment 
to their history, they are noted as being from such or 
such a collection. 
The system followed may be regarded as a modifica- 
tion of those of Ray and Linnaeus, adapted to the pre- 
sent state of zoological science. In its main features it 
agrees with that which I published in the “ Annals of Phi- 
losophy ” for 1826, when the exotic Mammalia in the 
Museum were first arranged for exhibition, and wdiich 
was soon afterwards commented on by Mr. W. S. Mac- 
Leay, in the “ Linnean Transactions.” Some parts of 
this system have undergone a more careful revision, as, 
for example, the genera of Bats, which are arranged in 
conformity with my paper on the subject in the second 
volume of the “ Magazine of Zoology and Botany,” 
and the Seals, Kangaroos, &c., according to my paper on 
the new species of Mammalia in the British Museum, in 
the “ Magazine of Natural History.” A short exposition 
of the entire system, together with the more prominent 
characters of the orders, families, and minor groups, and 
of most of the genera, is given in the 44th edition of the 
“ Synopsis of the Contents of the British Museum,” pub- 
lished in 1842. 
In the adoption of generic and specific names, it has 
been thought right to use, whenever it was possible, that 
which was first applied to the species. As far as regards 
