174 
ON THE GEOGRAPHICAL DISTRIBUTION OF BIRDS. 
fact a variety of surprising instances were detailed. It was on this principle, he 
stated, that colonies are sometimes formed, the posterity of an accidentally 
straggling pair remaining in or regularly returning to a neighbourhood, occasionally 
insulated, and remote from other haunts of the species; an exemplification of 
which he adduced from personal observation, and suggested that the limited and 
peculiar range of the Pied Flycatcher in England was in all probability thus 
explicable. He considered that the operation of the mysterious and remarkable 
instinct, which he had been dilating on, had been a great deal too much over¬ 
looked by those who have written on the subject of the dispersion of animals; 
although decidedly the most influential of the many causes which tend to 
circumscribe their geographical range. Mr. Blyth was heard throughout his 
discourse with the greatest attention, and received considerable applause at its 
termination. 
N. A. Vigors, Esq., M.P., then rose, and having stated that he hoped this 
highly interesting and important subject would be followed into its subdivisions at 
ensuing meetings of the Society, proceeded to make a few remarks upon some 
of its more striking points—such as the correspondency, or geographical representa¬ 
tion, of groups and of species inhabiting different localities; as, for example, the 
Ostrich, of the African deserts, which is represented in Asia and its islands by the 
Cassowary, in Australia by the Emeu, in the Pampas of South America by the 
Rhea, and in Europe, as he conceived, by the Great Bustard. It was his opinion, 
that every prominent group has thus an analogue, or representative, in each of 
the principal divisions of the world ; or that, if in any case such representative 
be wanting, the deficiency is invariably occasioned by some adequate and equally 
harmonious cause. As an example, the Starling family was represented as inhabit¬ 
ing all parts of the world except Australia; the explanation of which exception 
is, that they seek their food principally on the backs of cattle, and in Australia 
there are no indigenous ruminant quadrupeds. It was thus that, in numerous 
instances, the diffusion of animals is regulated by that of their prey—this, again, 
by that of particular vegetables, which, in its turn, is dependent on the soil. — 
Before Mr. Vigors concluded, he expressed a hope that, at the next meeting, 
there would be laid on the table a greater number of specimens to illustrate the 
subject of discussion. 
Mr. Chester stated, that if the gentlemen who proposed to favour the Society 
with any scientific observations at future meetings, would apprise the Council of 
the specimens which would be desirable for illustration, every possible exertion 
should be used to obtain them. 
