34 
CENTEAL HALL. 
cell-layer (epidermis) of an organ takes part ; and Emergences, 
in which tissues beneath the epidermis are also concerned. At 
the back of the bay is a large transverse section of the Karri tree 
{Eucalyptus cliversicolor) of Western Australia, which grows to 
a heioiit of 400 feet. The tree., of which this is a section, was 
about 200 years old when cut down. 
The Introductory Collection of Minerals will be found in the 
gallery devoted to that department of the collection (see p. 54). 
Gallery of 
British 
Zoology. 
Gallery of Beitish Zoology. 
At the north end of the Central Hall, with entrances on either 
side of the great staircase, is a large room containing a collection 
of animals of all classes, which are, or have been in recent times, 
found in the British Isles, either as permanent residents, or as 
regular migrants or occasional visitors. The animal inhabitants 
of any country or district are collectively termed its "fauna." 
Our country in this respect belongs to the great zoographical 
region- called Palsearctic, embracing all Europe, the north of 
Africa, and the western and northern portions of Asia. As in 
the case of all islands, the species belonging to groups whose 
powers of locomotion are limited to the land or fresh water, 
are not numerous compared with those inhabiting large con- 
tinental tracks. Their numbers can only increase under very 
exceptional circumstances, but, on the contrary, have a 
tendency to diminish, as the growth of human population and 
increase of the area of cultivated land gradually circumscribe 
their native haunts. In this way, the Brown Bear, the Wolf, the 
Beaver and the Wild Boar have all disappeared from Britain 
within the historic period, and others, as the Badger, Marten 
and Wild-cat, with difficulty maintain a somewhat precarious 
existence. These have all been originally derived from the main- 
land of Europe, probably before the formation of the channel 
which now makes our country an island. The wider and older 
channel which separates Ireland from Great Britain has proved 
a greater barrier to the emigration of animal life than that 
between the latter and the Continent, many species (as the 
I'olecat, Wild-cat, Mole, Squirrel, Dormouse, Harvest-mouse, 
