15 
inasmuch as many persons would hesitate to include in our lists such 
species as have from time to time strayed over from America, or others 
which we may reasonably suppose to have escaped from confine- 
ment. With these difficulties in view I have restricted the additions 
to our list of native birds, with only a few exceptions, to those 
species pertaining to the fauna of the Old World which, without con- 
stantly residing in our islands, have from time to time appeared 
therein, and whose visits oft repeated may ultimately entitle them 
to a permanent place in our lists. I may state with tolerable accu- 
racy that the total number of our species is about three hundred 
and fifty. 
If the supposed number) of birds inhabiting the globe be about 
10,000, it must be admitted that the British Islands have their due 
proportion of them; of course it would be quite out of place to in- 
stitute a comparison between our country, or even the whole temperate 
region of either hemisphere, and the tropics, where bird-life is so re- 
dundant, in accordance with the profusion of fruits and insects upon 
which they mainly subsist. 
It must be conceded by every one who has paid attention to general 
ornithology, that very considerable difficulties exist in the formation 
of a perfect scientific arrangement of the Birds of the British Islands, 
since these are but an appendage of a vast tract embracing the 
two continents of Europe and Asia, sections of the world assimilating 
in their bird-life, not only as regards genera, but in many instances 
also with respect to species. Hence in our own lists there will be 
occasionally breaks, as it were, that would be filled up by forms 
which, while found not far distant from us, still have never been 
actually killed in our islands. Far wider gaps will of necessity occur 
through the absence of such genera as are peculiar to Australia— 
the Bower-, Lyre-, and Mound-raising birds, or of those which are 
confined exclusively to the New World—Toucans, Trogons, Humming- 
birds, &e. 
Man has frequently been induced to try his hand at the in- 
troduction of certain species the acquisition of which he has 
considered desirable; such attempts have generally proved futile ; 
Nature having adapted each for a certain locality, the climate 
and the condition of the country must be altered and rendered 
fit for the reception of either bird or quadruped before there 
is the slightest chance of their successful naturalization. Many 
persons have been desirous of establishing the North-American 
Prairie-hen (Cupidonia cupido) on our moors, and the Ortya 
virgumanus or American Partridge in our fields and coverts; but 
what good would be effected thereby? The Prairie-hen would 
but displace a better bird, the common Grouse; and the little Par- 
tridge would be no improvement upon our familiar species. There 
is no fear, however, that this will ever be accomplished ; and the 
sooner such fallacies are ended the better. It would be far wiser 
were the efforts of our well-meaning patrons of acclimatization di- 
rected rather to that interchange of blood among the same species 
which is essential to the maintenance of a healthy stock. I am sure 
