i893. CLASSIFICATION OF ISLANDS. 193 



existence of continents in wiiat 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. 



II. 

 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 



