1893. CLASSIFICATION OF ISLANDS. 193 
existence of continents in what are now oceanic areas; and when all the 
facts are considered it is seen that they are opposed to the extreme 
views regarding the permanence of oceans and continents which have 
been accepted and maintained by Dr. Wallace in his ‘“ Island Life.” 
It would appear, therefore, that if the division into continental 
and oceanic islands be retained, a fourth class must be admitted into 
the classification; not only must continental islands be divided into 
ancient and modern, but oceanic islands must be defined geographi- 
cally and then divided into those which are the remnants of sunken 
continents and those which are of recent origin. It will, however, 
be very difficult to distinguish islands of recent formation from 
mountain peaks which have been submerged and again elevated 
above the ocean level, for lofty mountain peaks so often consist of 
volcanic rocks. 
I am convinced that the attempt to exclude islands in which 
stratified rocks occur from the category of oceanic islands will only 
lead to confusion and misconception, and that it is a mistake to infer 
from ‘the absence of warm-blooded terrestrial animals in an island 
otherwise suited to maintain them,” that the island is of recent forma- 
tion. The characters of an island fauna may, perhaps, be relied on 
to show whether the island has been colonised by former connection 
with a continent or not, but beyond this it will be no guide to the 
geological history of the region. The biological evidence must simply 
be taken for what it is worth, and the geological history of the island 
must be read from its geological structure, without the bias given by 
any preconceived theoretical ideas about the permanence of oceans 
and continents. There is, in fact, no hard and fast line to be drawn 
between oceanic and continental islands. 
A. J. JUKES-BROWNE. 
I l¢ 
NOTE ON MR. JUKES-BROWNE’S PAPER. 
The Editor having kindly sent me a proof of Mr. Jukes-Browne’s 
paper, [ beg to make a few remarks thereon. 
I cannot but think that Mr. Jukes-Browne’s criticism of the 
Darwinian classification of islands, which I have adopted and more 
fully developed, is rather one of words and definitions than of realities. 
The very terms of the classification—‘* Oceanic” and “ Continental ” 
—show that it is a broad and wide-reaching one; and its main impli- 
cation, the permanence of oceanic and continental areas, is equally 
broad and fundamental. That there should be islands situated upon 
the ever-fluctuating margin of these two areas which are difficult to 
class, or which may, at different geological periods, have possessed 
the characteristics of ‘‘ oceanic” or of ‘‘ continental” islands, is what 
might certainly be expected ; the’wonder is that there are so very few 
of them. Barbados is, technically, an oceanic island; but it is 
O 
