The skeletons of Shetland ponies of the riding type available for study (viz., of Highland Chieftain, Egil, and Eric) also indicate that in a considerable number of cases the dwarfing is uniform. Though in many Shetland ponies the distance between the knees and the fetlocks looks very short, the front cannon-bones may be relatively as long as in thoroughbred race-horses. In Highland Chieftain[F1] (fig. 4) the front cannon-bones (metacarpals) are 136 mm. long and 20 mm. wide at the middle of the shaft; in Persimmon,[F2] the famous thoroughbred 16·2 race-horse (fig. 5), the metacarpals measure 276 mm. by 38 mm. As Highland Chieftain measured 33 inches, and has cannon-bones measuring 136 mm., he was half the height of Persimmon, and has cannon-bones practically half the length. In Highland Chieftain the cannon-bones (fig. 4) are not only relatively as long as in Persimmon (fig. 5), they bear almost exactly the same relation to the bones of the forearm and arm as in Persimmon—the _radius_ (chief forearm bone) being relatively only 8 mm. shorter, the _humerus_ (upper arm bone) relatively only 10 mm. longer. Nevertheless the cannon-bones of Highland Chieftain are relatively shorter than in typical Celtic ponies. In a 33-inch Shetland built on Celtic lines the cannon-bones should measure 142 mm., hence it may be assumed the cannon-bones of Highland Chieftain have been dwarfed to the extent of 6 mm. or one-quarter of an inch. [F1] The skeleton of Highland Chieftain (a 33-inch Shetland pony bred in Scotland) is in the American Museum of Natural History, New York; Egil’s is in the University of Edinburgh. [F2] The skeleton of Persimmon is in the British Museum. The only striking difference between Highland Chieftain and a typical 12-hands Celtic pony is in the face. In modern horses, while the form of the cranium or brain-box is nearly constant, the face varies both in size and in its relation to the cranium. In the wild steppe horse (_Equus przewalskii_) of Mongolia, which during part of the year subsists on hard dry food, the jaws are so long that the length of the face (fig. 8) is twice the width across the orbits, thus giving a frontal index of 50; whereas in a broad-browed Iceland or Highland pony the face may be only 1·6 times the width, which implies a frontal index of 60. In the Celtic race (to which Highland Chieftain mainly belongs) the normal frontal index is 54—_i.e._, the length of the face is 1·8 times the width—but, as in Highland Chieftain, the length of the face is only 1·5 times the width, the frontal index[F3] is as high as 65. Further, in Highland Chieftain the profile instead of being convex as in steppe horses (fig. 8), or nearly straight as in many Exmoor ponies, was decidedly concave or dished (fig. 4). The difference between the profile of a Shetland pony and that of a steppe horse is brought out by figs. 6 and 8.