CHAP. X.] THE PALZZARCTIC REGION. 213 
islands and also occurs in South Europe, but is always apterous. 
It is however closely allied to another genus, Cryptorhynchus, 
which is apterous in some species, winged in others. We may 
therefore well suppose that the ancestors of Acalles were once in 
the same condition, and that some of the winged forms reached 
Madeira, the genus having since become wholly apterous. 
We may look at this curious subject in another way. The 
Coleoptera of Madeira may be divided into those which are 
found also in Europe or the other islands, and those which are 
peculiar to it. On the theory of introduction by accidental 
immigration across the sea, the latter must be the more ancient, 
since they have had time to become modified ; while the former 
are comparatively recent, and their introduction may be supposed 
to be now going on. The peculiar influence of Madeira in 
aborting the wings should. therefore, have acted on the ancient 
and changed forms much more powerfully than on the recent 
and unchanged forms. On carefully comparing the two sets of 
insects (omitting those which have almost certainly been 
introduced by man) we find, that out of 263 species which 
have a wide range, only 14 are apterous; while the other class, 
consisting of 393 species, has no less than 178 apterous; or 
about 5 per cent in the one case, and 45 per cent in the other.! 
On the theory of a land connection as the main agent in intro- 
ducing the fauna, both groups must have been introduced at or 
about the same time, and why one set should have lost their 
wings and the other not, is quite inexplicable. 
Taking all these singular facts, in connection with the total 
absence of all truly indigenous terrestrial mammalia and reptiles 
from these islands—even from the extensive group of the Cana- 
ries so comparatively near to the continent, we are forced to 
reject the theory of a land connection as quite untenable; and 
this view becomes almost demonstrated by the case of the 
Azores, which being so much further off, and surrounded by 
such a vast expanse of deep ocean, could only have been con- 
1 The facts on which these statements rest, will be found more fully 
detailed in the Author’s Presidential Address to the Entomological Society 
of London for the year 1871. 
