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ISLAND LIFE. 
[part II. 
Ancient continental islands differ greatly from the preceding 
in many respects. They are not united to the adjacent continent 
by a shallow bank, but are usually separated from it by a depth 
of sea of a thousand fathoms or upwards. In geological structure 
they agree generally with the more recent islands; like them 
they possess mammalia and amphibia, usually in considerable 
abundance, as well as all other classes of animals ; but these are 
highly peculiar, almost all being distinct species, and many form- 
ing distinct and peculiar genera or families. They are also well 
characterised by the fragmentary nature of their fauna, many of 
the most characteristic continental orders or families being quite 
unrepresented, while some of their animals are allied, not to 
such forms as inhabit the adjacent continent, but to others found 
only in remote parts of the world. This very remarkable set of 
characters marks off the islands which exhibit them as a 
distinct class, which often present the greatest anomalies and 
most difficult problems to the student of distribution. 
Oceanic Islands . — The total absence of warm-blooded terrestrial 
animals in an island otherwise well suited to maintain them, is 
held to prove that such island is no mere fragment of any ex- 
isting or submerged continent, but one that has been actually 
produced in mid-ocean. It is true that if a continental island 
were to be completely submerged for a single day and then again 
elevated, its higher terrestrial animals would be all destroyed > 
and if it were situated at a considerable distance from land it 
would be reduced to the same zoological condition as an oceanic 
island. But such a complete submergence and re-elevation 
appears never to have taken place, for there is no single island 
on the globe which has the physical and geological features of a 
continental, combined with the zoological features of an oceanic 
island. It is true that some of the coral-islands may be formed 
upon submerged lands of a continental character, but we have no 
proof of this ; and even if it were so, the existing islands are to all 
intents and purposes oceanic. 
We will now pass on to a consideration of some of the more 
interesting examples of these three classes, beginning with 
oceanic islands. 
All the animals which now inhabit such oceanic islands must 
