Page:The Natural History of Ireland vol1.djvu/10

 Birds; and in Mr. Macgillivray's, the heads, at least, of nearly all the land birds are represented.

With so much already done pictorially and descriptively, on the subject of British ornithology, it may be considered superfluous to treat of the birds of Ireland in a separate work, but, in the author's opinion, every country should possess a Natural History specially appertaining to itself. In the publications referred to, the birds of Ireland have been but briefly indicated,—a species generally dismissed in a single line, and so much appearing only in two works;—those of Sir Wm. Jardine and Mr. Yarrell.

The least reflection will convince any one who appreciates the geographical distribution of species, that the birds of Ireland are in this respect even more interesting than those of Great Britain, as, within its latitude and longitude, Ireland is the "ultima Thule," the extreme western limit to which the European species not found in the Western Hemisphere, resort. The geographical position of the island, also renders it occasionally the first European land on which North American species, after having crossed the Atlantic, alight.

Considerable differences, too, consequent on physical causes, will be found to exist in the economy of the same species in Great Britain and Ireland.

The Physical Geography or natural features of the country compared with those of Great Britain, cannot be said to deprive Ireland of more than one species (the ptarmigan). The relative proportion in the two countries, of land to water, of heaths and bogs to cultivated grounds and plantations, has influence only on the number of individuals.

Nor does the difference in the mineralogical structure of Ireland compared with Great Britain affect the actual presence of any species, although it is the primary cause which influences the