42 ! A Correct Colour Code. [Sess. 
the whole “Transition Tracts” of the Old and New Worlds, 
lying much along the same lines of the parallels of latitude, 
appear to me, with as much justice, to be as definite as the 
Holarctic. 
But as we advance farther south beyond these so-called 
Transition Tracts, the remaining Regional Areas become more 
difficult to define, breaking away from all attempts at amal- 
gamation as a Realm or series of Realms, running out into 
insular and peninsular patches, and their faunas differing 
inter se far more determinedly. Therefore I cannot consider 
that we can for a moment claim any such value as a Realm 
to include South America and South Africa, the Indian Penin- 
sula, or the Australian Continent and its satellites. Leaving 
now Oceana outside our present purpose, we having given 
South America (Neotropical), South Africa (ze, south of the 
Transition Tract, or Ethiopia), India, and Oriental and Austral- 
asian, and others, only regional values: having done this, we 
come to the Circumpolar Antarctic Realm, and I think it 
deserves such a value, so far as our present restricted know- 
ledge of it carries us. And none of the other circumpolar 
divisions should be considered truly deserving of anything 
greater than regional values except the Arctic and the Ant- 
arctic. 
It is evident that differentiation occurs to a greater extent 
towards the far eastern extension of the Holarctic Realm of 
Heilprin, and south thereof into the Oriental and Australasian 
islands and peninsulas,—and still more and more complicated 
and broken up after Wallace’s line is passed, than occurs south 
of the same Realm in the central portions or in the west. 
In other words, far greater stability is found throughout all 
the Northern Hemisphere than after the Transition Tracts are 
crossed, and still less stability is found in the far east than 
in the west, until the Antarctic Realm is reached. 
For these reasons we desire to advocate the following 
Realms, Regions, and Sub-regions, introductory to the more 
immediate purposes of this paper :— 
An Arctic Realm. An Ethiopian Region. 
A Palearctic Region. An Oriental Region. 
A Nearctic Region. An Australasian Region. 
A Neotropical Region. An Antarctic Realm. 
