The TRUE PETRELS (_Procellariæ_) in their general appearance present a certain resemblance to the Sea Gulls, from which, however, they are easily distinguished by their rounder head, high forehead, and smaller wings. The Petrels are powerfully built, short-necked, and large-headed; their beak is shorter than the head, strong, hard, and so deeply furrowed upon the sides that its point seems a mere appendage fastened to it, forming at the extremity of the upper jaw a strongly-bent hook, and upon the under jaw a peculiarly-formed angular termination. The cutting edges of the mandibles overlap each other and are very sharp; the gape opens backwards as far as the eye; the apertures of the nostrils are situated in a horny pipe consisting of two tubes consolidated into one in such a manner that the longitudinal division between them is perceptible; the foot is moderately strong, the tarsus short and compressed laterally, the three front toes are connected together by a well-developed swimming web, but the hinder toe is only represented by a little rudimentary appendage. The wings are very similar to those of Sea Gulls, but are shorter and more pointed, the first quill being invariably longer than the rest. The tail, which consists of twelve or fourteen feathers, is more or less rounded at the extremity. The general plumage is rich, and thicker above than below, indeed, on the under part it is very soft and fur-like. The two sexes are alike in colour, and even the young differ but slightly from the old birds, neither do their colours alter perceptibly with the seasons. [Illustration: THE GIANT PETREL (_Procellaria_ [_Ossifragus_] _gigantea_). ONE-SIXTH NATURAL SIZE.] THE GIANT PETREL. The GIANT PETREL (_Procellaria [Ossifragus] gigantea_) may be regarded as holding a position intermediate between the Albatross and the Storm Petrels. In this bird the plumage is deep chocolate-brown. The eye is blackish brown; beak horn-grey, with red tip. The young bird is more lightly coloured, and has a silvery white eye. The length of this species is about two feet eight inches, and the spread of the wings from four feet and a half to five feet. The habitat of the Giant Petrel extends over the temperate and antarctic zones of the southern hemisphere.