There are many birds which have stripes of variously coloured feathers situated above, before, and behind the eye; while others sometimes occur at the base of the lower mandible. To all these distinct names have been appropriated. A _superciliary_ stripe is situated _above_ the eye, occupying a position analogous to that of the human eyebrow. An ordinary eye-stripe is either _anterior_, _posterior_, or _entire_. It is called _anterior_ when it only occupies the space between the eye and the bill; _posterior_ when it commences behind the eye, and advances towards or unites with the ear-feathers; and _entire_ when it is both posterior and anterior. A _maxillary_ stripe commences at the base of the under mandible, and descends on the sides of the neck. [Illustration: Fig. 14.--CHICKEN IN THE EGG, NEARLY ARRIVED AT MATURITY, Showing the little Hammer or "Bill-scale" on the end of its beak, wherewith it is enabled to break through the egg-shell.] Such is the by no means very long list of names of parts used by the ornithologist in his description, and which in the course of the present volume will necessarily be of very frequent occurrence. The oil with which birds preen their feathers, and the glands that supply it, constitute a remarkable provision peculiar to the feathered creation. Embedded among the feathers at the root of the tail, there is on each side a small nipple, yielding upon pressure a butter-like substance, which the bird extracts by squeezing the orifice with its bill. By means of the oil, or rather ointment, thus procured, it dresses its feathers, either for the purpose of increasing their brilliancy, or, as in the case of the swimming birds, to make them impenetrable to wet. The pairing of birds is a feature in their history which draws a broad line of distinction between the feathered tribes and the generality of quadrupeds. Among mammiferous quadrupeds the young derive their nutriment during the earlier period of their existence entirely from the maternal breast, the male parent contributing nothing towards its support; but in the winged races the callow brood derive their supply of food from the industry of both parents, whose united exertions are not more than is requisite to procure the needful supply. In this circumstance we may see a reason for the faithful love of the feathered mate as contrasted with the vagrant disposition of the quadruped. The parental fondness of birds towards their young has escaped no observer; no historian of nature is silent upon this subject. "How well they caress them," says Derham, "with their affectionate notes, lull and quiet them with their voice, put food into their mouths, cherish and keep them warm, teach them to peck and eat, and gather food for themselves, and, in a word, perform the part of so many nurses deputed by the Sovereign Lord and preserver of the world to help such young and shiftless creatures."