Atlantic Coleoptera. 209 
termined ‘ almost wholly by such exceptional causes as 
storms and hurricanes, which still continue to bring 
immigrants from the nearest lands.” 
Without recapitulating the various arguments and evi- 
dence for these two opposite modes of colonization, I feel 
bound to add that my own views (as elsewhere, and 
oftentimes, expressed) are more in accordance with those 
propounded by Mr. Murray than with the theory of 
exceptional, atmospheric dissemination which is so ably 
advocated by Mr. Wallace. That storms and hurricanes 
may have played a decided part, at rare intervals, in the 
accidental transportation of living organisms into many 
a remote island I would not for an instant wish to dis- 
pute; but, nevertheless, after much consideration in situ, 
and with no other desire (through many years) than to 
arrive simply at the truth, 1 cannot convince myself that 
any such abnormal methods of dispersion have done much 
towards bringing about the phenomena in the Atlantic 
archipelagos which we now witness, and which appear 
to me to be dependant rather upon causes which geologi- 
cally perhaps might (whether correctly so or not) be de- 
fined as “ exceptional,” and of which an ‘ overwhelming 
catastrophe,” involving its legitimate results, whether 
from upheaval or depression, may be selected as an intel- 
ligible example. 
Judging simply from the Coleopterous statistics, from 
the exact phenomena which present themselves on the 
various portions of these scattered archipelagos, and from 
the unmistakable manner in which the most characteristic 
forms permeate the entire province (in nearly every in- 
stance increasing steadily, both as regards species and 
individual numbers, up to some central nucleus, and then 
gradually diminishing as we proceed towards the south), 
I feel more and more convinced that nothing but a land 
of passage between at any rate the consecutive Groups, 
destined to be broken up at some later period by a gigan- 
tic convulsion, will satisfy the requirements of the Atlantic 
problem, and harmonize its otherwise discordant parts. 
Yet, although I can see (or, rather, think that I can see) 
a nearly equal necessity for a north-easterly extension of 
that guondam tract, I should imagine (from the much 
greater preponderance of significant European types in 
