212 Mr. T. Vernon Wollaston on 
Atlantidum’ and the ‘ Coleoptera Hesperidum’) that the 
whole of these island clusters are but the scattered re- 
mains of a once (for the most part) continuous land— 
which, whatever were its northern bounds, had an un- 
doubted north-easterly extension into what is usually 
termed the “ Mediterranean province ;” and it certainly 
appears to me that the particular region which is now 
represented by the Canarian archipelago received the 
first, and most complete, influx of Mediterranean types. 
Apart from every other motive stimulus, the ordinary 
breezes, which seem to have swept well-nigh uninterrupt- 
edly in the same direction formerly as now, would tend 
to keep up a slow, yet steady, migration towards the 
south-west, along that qguondam tract; while occasional 
tornados from the east and south, such as are still ex- 
perienced, might (on the principle suggested by Mr. 
Wallace) account for a slight sub-African element in the 
fauna, and likewise transmit afew genuine Atlantic types, 
as a repayment, to the north. Once fairly colonized, the 
gigantic subsidencies which could alone convert the major 
part of this vast continent into an ocean-bottom, may 
well be supposed to have accomplished what is further 
required,—the isolation of similar species upon areas 
which were respectively larger and smaller, and the 
greater or less depauperation of the areas themselves, 
suggesting innumerable methods for rapidly inaugurating 
distinctly modified races, and reducing the phenomena 
to what we now witness. 
Although I cannot here enter into the minuter details 
of insect-dissemination, I will just call attention to the 
fact that there is a certain small assemblage of anomalous 
beetles attendant upon ants, which would seem, as Mr. 
Wallace has remarked, to have some ewceptional methods 
of dispersion ; for many of them, which possess neither 
wings nor eyes, and are partially even subterraneous in 
their habits, appear to have acquired a wider geographical 
range than is the case with numerous forms whose capa- 
bility for locomotion is developed to the full. We must 
remember, however, that the ants (which tend them with 
the greatest care) are a restless and erratic tribe, and would 
themselves carry their mysterious guests into every fresh 
area which they might succeed in occupying. Moreover, 
in the Atlantic archipelagos, I believe that another, and 
more irregular, principle may unexpectedly have been 
a 
