Page:Natural History, Birds.djvu/326

Rh Ocean, yet several specimens have been obtained in this country.

Through the Skuas, which have somewhat of the form of beak we have last described, the passage from the Petrels to the Gulls is easy and obvious. These are, for the most part, birds of large size, in which the swimming and diving structure recedes, and the most prominent actions are those of flying and walking. "The whole of the Family," observes Mr. Vigors, who includes in it the Petrels, "is distinctly characterized by the strength and expansiveness of their wings, with the aid of which they traverse immeasurable tracts of the ocean in search of their food, and support their flight at considerable distances from land, seldom having recourse to their powers of swimming. We may thus discern the gradual succession by which the characters peculiar to the Order descend from the typical groups that swim and dive well and frequently, but make little use of their wings for flight, to the present groups, which are accustomed to fly much, but seldom employ their powers of swimming, and never dive." One can scarcely look at a Gull, without being strongly reminded of the Wading-birds, and particularly the Plovers, to which in general form, in attitude, in the long and slender tarsus, with the hind-toe minute and set high up (as in Vanellus), in the naked space above the heel, and