vill INTRODUCTORY REMARKS. 
it is not possible to solve this question with any degree of certainty ; 
nevertheless in a vast number of cases it is: by no means difficult to 
do so; and I am satisfied that local data, if attentively considered, 
will usually enable us to distinguish pretty clearly, at any rate, the 
ultra-indigenous ones (if we may thus express them) from those 
which have been naturalized. Accordingly, in the following Cata- 
logue, I have indicated by a double asterisk (**) those species which 
have been undoubtedly imported ; some of these are indeed well nigh 
cosmopolitan, and are (in Madeira, as elsewhere) liable to be intro- 
duced afresh, by direct human agencies, almost every year. ‘To those 
which there is strong reason to believe have found their way to the 
islands, through various accidental circumstances, during the last 
few centuries (?. ¢. since the Group was first colonized), I have 
affixed a single asterisk (*); whilst those which are left unmarked 
are, in my opinion, indigenous, 
There is still, however, another distinction to be drawn, before we 
can properly attempt to generalize. It is manifest that these cndi- 
genous members of the fauna are made up, in reality, of two kinds ; 
for, though they are all of them ‘“ indigenous” in the common accep- 
tation of that term, it is evident (if there be any truth in the doctrine 
of specific centres of creation) that some must have found their way 
to where they now are, at a very remote epoch, through natural 
causes (perhaps by migration over a land of passage which has been 
since destroyed), operating regularly and during an immense interval 
of time ; whilst others are absolutely endemic, occurring apparently 
in no other country of the world, and being therefore (if we may 
repeat our former expression) “ w/tra-indigenous,’—the very avré- 
x9oves of the soil, called originally into being to satisfy the special 
requirements of the spot, and adapted therefore to the particular 
physical conditions which they were destined, through after-ages, to 
be subservient to. Now it is not always easy to draw the line of 
separation between the creatures which fall under these two opposite 
heads; and therefore in the body of this volume I have not ventured 
to do so, but have simply contented myself by regarding them all as 
indigenous. Still, since a large number of the unasterisked ones are 
eminently characteristic (as it were) of these islands—being not only 
of slow migratory powers, and singularly adjusted to the nature of 
their several “habitats,” but presenting likewise (in a more or less 
evident combination) certain geographical peculiarities which tend to 
affiliate them with what I would emphatically call the Madetran 
types; I have thought it desirable, in the list appended to these in- 
troductory remarks, to indicate such species by putting them in 
italics. 
