28 
CENTRAL HALL. 
Water and Land Vole, Common Hare, Eoedeer, as well as 
Snakes and Toads) never having crossed it, unless by aid of 
human agency. 
On the other hand, those species that have the power of 
travelling through the air or traversing the ocean are far less 
fixed in their habitat, and thus the list of so-called " British 
birds" receives accessions from time to time from stragglers 
which find their way from the European continent or even across 
the Atlantic, and doubts as to the authenticity of some of the 
recorded occurrences make the list rather a vague and uncertain 
one. The constitution of the marine fauna in the same vray is 
continually liable to undergo fluctuations. 
Slight but permanent variations from the continental type can 
be recognised in a few of our indigenous species, but the only 
vertebrated animals undoubtedly peculiar to the British Isles are 
the common Eed Grouse (Lagojjiis scoticus), and several species 
of fresh- water fishes (fifteen are enumerated by Dr. Giinther), 
mostly belonging to the genus Salmo. Some of these have an 
extremely local distribution, being only found in some small 
groups of mountain lakes. Many species, or at all events, 
well-marked varieties of insects, and a few land and fresh- water 
molluscs, have at present been only found within the limits of 
our islands. 
Staibcase. 
statue of On the first landing of the great staircase, facing the centre of 
Darwin.. ^j^^ YiqII^ is placed the seated marble statue of Charles Darwix 
(b. 1809, d. 1882), to whose labours the study of natural history 
owes so vast an impulse. The statue was executed by Mr. J. E. 
Boehm, E.A., as part of the " Darwin Memorial " raised by public 
subscription. It was unveiled and placed under the care of the 
Trustees of the Museum on the 9th of June, 1885, when an 
address was delivered on behalf of the Memorial Committee, by 
the Chairman, Professor Huxley, P.K.S., to which His Eoyal 
Highness the Prince of Wales, as representing the Trustees, 
reiilied. 
Above the first landing the staircase divides into two flights, 
each leading to one of the corridors which flank the west and 
