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Show 1903.] THE MUSCLES OF T H E UNGULATA. 267 believe that these two muscles are always present in Ungulates, and that the line of separation can be determined, if carefully looked for, by the branch from the superior gluteal nerve to the tensor fasciae femoris passing through it. The origin is from the ventral part of the gluteal surface of the ilium near that portion of the bone usually described by veterinary anatomists as the neck, while its insertion is into the front and outer side of the great trochanter. In the Horse, Lesbres (V.) says that the ento-and meso-glutei can only be distinguished from one another at their insertions. The nerve-supply seems always to be the superior gluteal. Gluteus ventralis {Gluteus quartus ; Scansorius).-This muscle, when it is distinct, as it generally is in the families of Camelidaa, Giraffidse, and Bovidaa, rises from the ventral border of the ilium and is concealed by the overlapping entogluteus, and is inserted into the anterior surface of the great trochanter. In Ungulates belonging to other families than those just mentioned, it is often difficult to separate the muscle from the entogluteus unless the nerve to the tensor fasciae femoris is looked for. The nerve-supply is the superior gluteal. Gluteus profundus {Gluteus quintus ; Ilio-capsular is).-It is quite certain that this is not a constant and well-defined muscle in Ungulates, though it is occasionally found. Lesbres (V.) describes the " abductor trochitereen" in the Horse as very distinct, and says that it lies over the superior surface of the capsule of the hip, rises from the supracotyloid crest, and is inserted into the anterior part of the internal surface of the great trochanter which is known to veterinary anatomists as the convexity of the trochanter. He regards it as the serial homologue of the infraspinatus secundus (see Part I. of this paper, P. Z. S. 1901, vol. ii. p. 687), but it answers very well to our idea of the gluteus profundus. In addition to this, he describes another muscle in the Horse, rising from the ilium close to the origin of the rectus and inserted into the anterior surface of the femur close to the head ; this he considers is the homologue of the ilio-capsularis of the Carnivora. For practical purposes it does not seem to us that these two muscles require separate names ; they are probably two slips of the deepest delamination of the gluteal mass lying in contact with the capsule of the hip. In the Harnessed Antelope (55) we found a gluteus profundus, and Kinberg (X.) describes it in the Chevrotain under the name of M. tenuis femoris. In the other Ungulates the muscle is not as a rule delaminated from the entogluteal sheet. The nerve-supply in the Harnessed Antelope is from the sacral plexus just below the origin of the superior gluteal nerve. Pyriformis.-We have already stated that the mesogluteus is usually fused more or less completely with the pyriformis, but in some cases, e. g. the Duiker-bok (54) and Harnessed Antelope (55), the entogluteus is more closely blended with it than is the mesogluteus ; it must, however, be remembered that in the Ungulates |