Atlantic Coleoptera. 211 
pheric propulsion; whereas over an unbroken region 
positive hurricanes would not be necessary for our pur- 
pose —the general tendency of the insect fauna (includ- 
ing the wingless tribes) being manifestly to follow the 
course of the most prevalent winds.* And that the 
winds in even remote times have blown from the same 
quarter as they do now is proved to a demonstration by 
the fact, that nearly every extinct crater which I have 
hitherto inspected throughout the three archipelagos 
(and in the Canarian Group there are scores of them) are 
more or less broken into, or open, on the north-eastern 
side ; thus evidently showing in which direction it was 
that the breeze was most persistent. 
Into the geological difficulties of the problem I do 
not profess to enter ; they may, or may not, be insuper- 
able. But any experienced observer, who has examined 
critically the various phenomena in situ, could scarcely 
fail, I think, to arrive at the conclusion that at all 
events the several islands themselves which compose 
each of the individual groups, and many of which are now 
separated from each other by wide oceanic channels of 
twenty, thirty, and even forty miles in breadth, were 
once united so as to form a comparatively extensive 
land ; for if there is one thing more unmistakable than 
another, throughout every portion of these sub-African 
Groups, it may be expressed in a single word—depaupera- 
tion. ‘Taking this therefore as sufficiently proved, it 
seems to follow inevitably that (despite the uniformita- 
rian opinions of the day) ‘‘ catastrophes,” properly so 
called, must have had a significant place in the geologi- 
cal record; and if this be true, who shall venture to limit 
their magnitude ? 
My own opinion is (as indeed was sufficiently expressed 
in the Preliminary Remarks both of the ‘ Coleoptera 
* TI say “the insect fauna,’ because if a certain proportion are 
compelled to migrate (however gradually) in the manner in which I 
have suggested, others which (like the hunting races) prey upon them 
would of their own accord inevitably follow: and so, in the course of 
time, the general tendency would be in a uniform direction,—even whilst 
occasional storms and tornados, at rare intervals, might pueceed in con- 
veying elsewhere a few of the characteristic types. 
