Geographical Distribution, 231 
of the isolated species, and the degree in which their 
nearest allies on the mainland are there confined 
to narrow ranges, and therefore less likely to keep 
up any biological communication with the islands. 
St. Helena.—A small volcanic island, ten miles long 
by eight wide, situated in mid-ocean, 1100 miles from 
Africa, and 1800 from South America. It is very 
mountainous and rugged, bounded for the most part 
by precipices, rising from ocean depths of 17 000 feet, 
to a height above the sea-level of nearly 3,000. 
When first discovered it was richly clothed with 
forests; but these were all destroyed by human 
agency during the 16th, 17th and 18th centuries. 
The records of civilization present no more lament- 
able instance of this kind of destruction. From a 
merely pecuniary point of view the abolition of 
these primeval forests has proved an irreparable 
loss; but from a scientific point of view the loss 
is incalculable. These forests served to harbour 
countless forms of life, which extended at least from 
the Miocene age, and which, having found there an 
ocean refuge, survived as the last remnants of a remote 
geological epoch. In those days, as Mr. Wallace 
observes, St. Helena must have formed a kind of 
natural museum or vivarium of archaic species of all 
classes, the interest of which we can now only surmise 
from the few remnants of those remnants, which are 
still left among the more inaccessible portions of the 
mountain peaks and crater edges. These remnants 
of remnants are as follows. 
There is a total absence of all indigenous mam- 
mals, reptiles, fresh-water fish, and true land-birds. 
There is, however, a species of plover, allied to one 
