Width between the sides or branches of the lower jaw is another distinctive feature of the horse of pure descent. ([Fig. 3.]) A wide furrow or channel between the points mentioned is necessary for speed, in order to allow room for free respiration when the animal is in rapid motion. The coarser breeds have very small, narrow channels ([Fig. 4]), and very rapid motion soon distresses them.
Fig. 4.—Width of lower jaw in the low-bred.
The mouth of the well-bred horse is large, allowing ample room for the bit, and giving him a determined and energetic, but at the same time pleasant, amiable expression. The mouth of the low-bred horse is small and covered with coarse hair, and gives the animal a sulky, dejected appearance.
Fig. 5.—Oblique shoulder.
The angle at the joint being about 45°.
The light, elegant head of the Arabian is well set on his neck; a slight convexity at the upper part of the throat gives freedom to the functions of this organ, as well as elasticity to the movements of the head and neck; and the encolure, or crest of the neck, is arched with a graceful curve. But it is especially in the shape of the shoulders that this horse excels all others, and this is the secret of those easy movements which make him so desirable for the saddle. These shoulders are deep, and placed obliquely at an angle of about 45°; they act like the springs of a well-made carriage, diminishing the shock or jar of his movements. They are always accompanied by a deep chest, high withers, and fore-legs set well forward, qualities which make the horse much safer for riding. ([Fig. 5.])