PRESIDENT’S ADDRESS—SECTION C. 63 
the other, inasmuch as no account is taken of the Mesozoic 
features of its flora. I suggest the term Hunterian System to 
replace Permo-Carboniferous. 
A brief demonstration of the doctrine of homotaxis may be 
graphically expressed as follows :— 
Thus in two separate areas a series of deposits have accumu- 
lated each to each, with identical fossils ; then, on the doctrine of 
contemporaneity, the series in the two areas are not only equal 
in order, but equal in time; thus a = a’, 6 = b’, and so on 
But if, whilst the deposit @ is accumulating, the fauna of it 
migrates towards the other area, and in the interval deposition 
has accrued in each area, then the life-line and the term-line are 
divergent, thus :— 
Te ae eG cre teed see 
RR vatraiautbed Bis wait en 
lines; life-lines by 
dotted lines. 
Hence a and @’ are synchronous, but a and 0b’ is a life-line, 
that is, a and 0’ are homotaxially related. 
My interpretation of the doctrine of homotaxy involves these 
two main contentions : — 
1. That it implies identity of fossil species in distant areas. 
2. That it implies the power of migration of shallow-water 
species across intervening oceanic areas. 
Before proceeding to discuss the two foregoing items, which in 
my opinion constitute the whole crux of the question, I would 
direct attention to the anachronism implied by the doctrine of 
homotaxy, that of two distant areas of deposition one must be 
ahead of the other in point of time. Huxley says:—‘ For anything 
that geology or paleontology are able to show to the contrary, a 
Devonian fauna and flora in the British Islands may have been 
contemporaneous with Silurian life in North America, and with 
a Carboniferous flora and fauna in Africa.” Pushed to an ulti- 
matum, it brings us to the absurd position that Recent Times in 
Australia are not synchronous with Recent Times in Western 
Europe. Moreover, geology is able to show that the Trias of 
Australia and South Africa are contemporaneous. 
In the arguments which follow, I accept the doctrine of the 
permanency of continents, and of the deep oceanic areas which 
separate them. 
Is Lire IDENTICAL AT EAcu oF THE SuCCESSIVE Lirs-Epocus ! 
As selective examples for comparative study, I shall occupy 
myself with the order of life in Australia and Western Europe, 
