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Show 1903.] THE MUSCLES OF THE UNGULATA. 277 Extensor proprius hallucis.-This muscle is often described in Ungulates, but, we think, without any real reason. As the hallux and often the fibula are suppressed, the muscle called extensor proprius hallucis is a slip of the extensor longus digitorum passing to the index or medius digit. Unless the authors who use the name have good grounds for thinking that this is really a displaced muscle of the hallux, it seems a needless complication to retain the name in the Ungulata. Extensor longus digitorum.-In the Hippopotamiclae (1, 3) and Suiclse (4, 7, 10, 11, 12, 13, 14) this muscle is inserted into all four toes, and its origin is from the front of the external condyle of the femur with the tibialis anticus. Meckel (VII.) denies that it has a femoral origin in the Pig, but his was clearly an exceptional case. In the other Artioclactyla the origin is always femoral and the insertion into both toes. An interesting point about this muscle in the Ox (40), Sheep (46), Duiker-bok (54), Harnessed Antelope (55), Chevrotain (20), and Camel (17) is that there is an insertion into the middle phalanx of the medius digit as well as into the terminal of the medius and annularis. A more careful examination of the muscle in the other Artio-dactyles would possibly show that this is a constant arrangement, In the Tapiridae (59, 61, 62) and Rhinocerotidas the origin is femoral and the insertion into all three toes. In the Equidee (63, 65) the origin is also femoral and the insertion into the middle and terminal phalanges of the single digit (medius). Among the Subungulata the origin is femoral in Hyrax (74, 75), though Meckel (VII.) says that it is tibial; its insertion is into all the digits. In the Elephant (81, 84, 85) the origin is certainly tibial and the insertion into the 2nd, 3rd, 4th and 5th digits. Both Paterson and D u n (85) and Miall and Greenwood (81) notice that insertions are given to some of the proximal as well as the distal phalanges, though which digits have slips to these phalanges varies in different individuals as well as on opposite sides of the same individual. The nerve-supply is the anterior crural. Summing up, it m ay be said that the origin of this muscle in the Ungulata is always femoral except in the Elephant. Extensor brevis digitorum.--This muscle is always present and has the usual origin from the front of the upper surface of the calcaneum. In the Hippopotamus (1, 3) it is inserted into the index, medius, and annularis digits. In the Suidae (4, 5, 10, 11, 14) it usually goes to the medius and annularis only, but it may send a slip which joins the tendon of the extensor longus digitorum on the dorsum of the foot. In the Tapiridse (61, 62) the muscle is very large and is inserted into all three toes. Murie (XVII.) notices that the slip to the medius is inserted into the proximal phalanx. In the Equidae (63, 65) there is only one insertion into the extensor longus as in the Ruminants. In the Rhinoceros, Haughton (XXI.) only found a tendon for the medius toe. Among the Subungulata, Hyrax may have three tendons for the proximal phalanges |