SUGGESTIONS.--The domestic pigeon, the =fowl=, and the English sparrow are most commonly within the reach of students. The last bird has become a pest and is almost the only bird whose destruction is desirable. The female is somewhat uniformly mottled with gray and brown in fine markings. The male has a black throat with the other markings of black, brown, and white, in stronger contrast than the marking of the female. As the different species of birds are essentially alike in structural features, the directions and questions may be used with any bird at hand. When studying feathers, one or more should be provided for each pupil in the class. The feet and bills of birds should be kept for study. Does the =body of the bird=, like the toad and turtle, have a head, trunk, tail, and two pairs of limbs? Do the fore and hind limbs differ from each other more or less than the limbs of other backboned animals? Does any other vertebrate use them for purposes as widely different? =Eye.=--Does the _eyeball_ have parts corresponding to the eyeball of a fish or frog; viz., cornea, iris, pupil? Which is more movable, the upper or lower _eyelid_? Are there any lashes? The bird (like what other animal?) has a third eyelid, or nictitating membrane. Compare its thickness with that of the other lids. Is it drawn over the eyeball from the inner or outer corner of the eye? Can you see in the human eye any wrinkle or growth which might be regarded as remains, or vestige, of such a membrane? How many =nostrils=? In which mandible are they located? Are they nearer the tip or the base of the mandible? (Fig. 284.) What is their shape? Do the nasal passages go directly down through the mandible or do they go backward? Is the inner nasal opening into the mouth or into the throat? The beak or =bill= consists of the upper and lower mandibles. The outside of the beak seems to be of what kind of material? Examine the decapitated head of a fowl or of a dissected bird, and find if there is a covering on the bill which can be cut or scraped off. Is the mass of the bill of bony or horny material? With what part of the human head are the mandibles homologous? (Fig. 284.) [Illustration: FIG. 284.--SKULL OF DOMESTIC FOWL. _q_, quadrate (“four-sided”) bone by which lower jaw is attached to skull (wanting in beasts, present in reptiles; see Fig. 277).] =Ears.=--Do birds have external ears? Is there an _external opening_ leading to the ear? In searching for it, blow or push forward the feathers. If found, notice its location, size, shape, and what surrounds the opening. There is an owl spoken of as the long-eared owl. Are its ears long?