38 
equatorial zone an almost impassable barrier to the greater number 
of animals inhabiting the extra-tropical regions, you will observe by 
looking at the map before you, that any one zone of latitude may 
be divided by such banders, as seas or lofty mountain ranges, into 
different districts, which are wholly inaccessible, one from the other, 
to the animals of each ; and this again produces a multiplicity of 
“ representative species," each fitted to live in a number of similar 
localities, which it could only reach by the agency of man, who may 
as an aceliuiatiser bring all of them into each of the localities to 
which nature had only given one, with the certainty of their thriving. 
I have placed on the table a few examples to show the curious imi¬ 
tations which the representative species are of each other, and many 
more may be found in the National Museum where the classification 
I have adopted brings the law of representative forms strongly before 
the eye. As representatives from similar climates in opposite hemi¬ 
spheres, I may show you the barn-owl, and the kestril-hawk of 
Europe, each distinguished from all the other birds of prey of their 
native country by delicate colouring of most peculiar and unusual 
hues ; yet, in the corresponding latitudes in Victoria, yon see they 
are exactly represented by birds of almost exactly the same size, 
shape, habits, markings, and even the peculiar hues of the unusual 
delicate buff and white of the owl, and reddish cinnamon colour of 
the hawk is reproduced. If you cast your eye to the lino on the 
map marking the region in Africa inhabited by the genus Camelo¬ 
pardalis, or the giraffes, extending from 20 deg. N. to 30 deg. S. 
of the equator, you find an interesting case from the proximity of 
the representative centres ; the cameleopard or Giraffe of Abyssinia, 
and the portion of the district north of the equator, being a distinct 
species from that of the corresponding latitudes in South Africa, yet 
the two are so nearly alike, that they have usually been confounded, 
and thrive equally under precisely similar circumstances. From the 
same country I have on the table the sacred crocodile of Egypt, 
and the rivers north of the line, and a specimen of its “ representa¬ 
tive ” species from the rivers of the like latitudes in South Africa, 
which you see almost exactly resembles it in appearance, OB it does 
in habits. Then of representative specific centres in the same zone 
we find the magpie of Europe represented almost exactly, as 
you see by the specimens, by another kind in the same latitudes in 
North America. If you glance at the region marked on the 
map as that inhabited by the true genus Camelus or the camels, 
you find one portion of it cut off from the rest by the lofty chains 
of the Himalaya mountains and the Taurus. The portion N.E. of 
