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Show 1903.] THE MUSCLES OF THE UNGULATA. 279 on Elephant's muscles, is into the bases of all the metatarsal bones from the fifth to the first. The nerve-supply is from the external popliteal in the Duiker-bok, Chevrotain, Sheep, and Elephant. Peroneus brevis.-In animals such as the Lemur and many of the Rodents, where a complete set of peroneals is found, the peroneus brevis runs from the fibula to the base of the fifth metatarsal bone, while the peronei quarti et quinti digitorum pass on to the dorsum of the phalanges. Judging by this standard, we have no hesitation in saying that we have as yet seen no reason to believe that a peroneus brevis is ever present in Ungulates, except, perhaps, in the Elephant. It is described by a great many authors, but in every case we have found that what they call peroneus brevis is continued on to the dorsum of the fourth (annularis) digit, and does not even end in the fourth metatarsal bone. W h e n one realises how commonly the fibula and the fifth metatarsal are suppressed in this order, one is prepared to expect a similar suppression of the peroneus brevis. In Paterson and Dun's Elephant a muscle was found which they call peroneus minimus, which rose from the fibula and was inserted into the calcaneum and base of the fifth metatarsal; this we believe is a peroneus brevis, and the only example of it found in the Ungulata. The authors call it peroneus minimus because they have fallen into the common mistake of calling the peroneus quarti digiti the peroneus brevis. Peroneus quarti digiti.-This muscle is always present in Ungulates. When the fibula is well developed, as in Hyrax and the Elephant, it rises from the middle third of that bone, but when, as in most Ungulates, there is only the head of the bone present, the muscle rises from that and often from the adjacent part of the tibia. The tendon usually runs in a groove on the outer side of, not behind, the external malleolus, and is inserted into the extensor longus digitorum tendon of the annularis. In the Horse, however, with the suppression of the annularis, the peroneus quarti digiti, which is the only peroneal present, shifts its insertion on to the dorsum of the medius. W e have records of the peroneus quarti digiti under various names in the following representative series of animals:-Hippopotamus (1, 3), Pig (4, 6, 7, 11), Peccary (13, 14), Camel (17), Chevrotain (20, 22, 24), Deer (25, 26, 27, 29), Elk (30), Musk-Deer (31), O x (35, 36, 38, 40) (in the last-named animal, 40, the tendon was inserted into the middle phalanx of the annularis toe), Sheep (41, 42, 43, 47, 48), Goat (50, 51), Antelope (54, 55), Tapir (58, 62), Horse (63, 64, 65), Rhinoceros (71), Hyrax (74, 75), and Elephant (81, 85). The nerve-supply is always the musculo-cutaneous. Peroneus quinti digiti.-This muscle is present in the Hippopotamus (1, 3) and sometimes in the Pig (4), Musk-Deer (31), and Elephant (81, 85). It rises from the upper part of the fibula and is inserted into the extensor tendon of the fifth digit. Its nerve-supply is the musculo-cutaneous. |