The true Game-birds, the Grouse, Fowls, Peacocks, Pheasants, Turkeys, Partridges, Quails, and Guinea-fowls, with Megapodes, Curassows, and Guans, form a well-defined and easily recognizable order. They have a stout bill, strong legs and feet, suited for progress on the ground, a plump body and rounded wings, in which the 5th secondary is present, and there are 10 primaries. There is frequently a spur, sometimes more than one, on the tarsus in males, and, in a few genera, in females also. The hallux is always present; the nails are short, blunt, and but slightly curved. An aftershaft is always developed to the body-feathers. The spinal feather-tract is well defined on the neck and not forked on the back. Oil-gland present, except in the genus Argusianus.
The deep plantar tendons are joined by a fibrous vinculum, but their distribution is normal, the flexor perforans digitorum supplying the three anterior digits, whilst flexor longus hallucis passes to the hallux or posterior digit alone (see Vol. I, p. 3). The ambiens muscle is present, as are also the accessory femoro-caudal, the semitendinosus, the accessory semitendinosus, and, except in Peafowl and Turkeys, the femoro-caudal, so that in general all the thigh-muscles are developed (see Vol. III, p. viii). Caeca of the intestines are large. Both carotids are present, except in Megapodius, which has only the left one.
The palate is schizognathous ; the nasals holorhinal. True basipterygoid processes are wanting, but there are sessile facets situated far forward on the sphenoidal rostrum. Cervical vertebras 16. The sternum has two deep incisions in the posterior border on each side of the keel; the inner xiphoid process between the two is shorter than the outer, which is bent over the hinder ribs and expanded at the end. The episternal process of the rostrum is completely perforated to receive the inner ends of the coracoids.
All members of the order nest on the ground (the nidification of the Megapodiidae is peculiar) and lay numerous eggs. The young are hatched covered with down, usually coloured with a pattern, and are able to run very soon after leaving the egg.
Gallinae are generally distributed, but are divided into two suborders, one of which is essentially northern, the other southern, being almost confined to the Australian and Neotropical regions (see Huxley, P. Z. S. 1808, p. 294). The former is well represented in India; of the latter a single species is found in the Nicobar Islands. The suborders are thus distinguished :—
Hallux raised above the level of the other toes………………………ALECTOROPODES.
Hallux on a level with the other toes………………………PERISTEROPODES