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Show 1879.] ANATOMY OF HY^NA CROCUTA. 99 of ulna to the index finger, there joining the common extensor tendon in the usual manner. Meckel notes an extensor indicis in H. striata, but says it is distributed to the third finger. In the Civet a conjoined extensor secundi et indicis is found. The pronator radii teres, from internal condyle of humerus to junction of upper and middle thirds of radius, is slender; it does not differ from that of H. striata. In the Civet, on the contrary, the muscle is particularly strong, and extends down to the lower end of the radius. In H. crocuta, the smallness and comparative feebleness of the round pronator is compensated by an extensive pronator quadratus, which is attached to the whole length of the bones of forearm. Large also in H. striata, Dog, and Cat, it is limited in Civet to the lower third of the forearm. The flexor carpi radialis arises from the inner condyle, and is inserted into the base of the second metacarpal bone. In the Civet there is an additional inferior attachment to the base of the first metacarpal. Palmaris longus is quite distinct from the inner condyle, and terminates in a strong palmar fascia. Meckel states that in H. striata this muscle is intimately blended with the superficial flexor of the digits. According to Douglas, it is entirely wanting in the Dog. In the Civet, on the other hand, somewhat remarkably, it forms a double muscle from end to end. Flexor carpi ulnaris, from the internal condyle of humerus to the pisiform bone, is prolonged also to the outermost metacarpal. So also in H. striata and Civet; in the latter animal an olecranoid origin likewise exists. Flexores digitorum.-The superficial and the deep form one large irregular muscular mass. This arises from the internal humeral condyle, and also from the bones of forearm-one slip taking origin from the upper extremities of both radius and ulna, while a second comes from the whole length of the posterior border of ulna. Below the middle of the forearm the muscle divides into two parts, a superficial and a deep. The superficial (perforatus) is distributed by means of separate tendons to the four outer toes, each tendon ending at the middle phalanx of its respective digit, and giving passage to the corresponding deep flexor tendon in the usual manner. The deeper part of the muscle (perforans) ends in a single broad tendon which divides into four, and so is distributed to the same four toes as the superficial tendons, perforating these latter, and reaching the terminal phalanges of the digits. This complication of the flexors of the digits appears to be common in the Carnivora. A particularly interesting modification, however, exists in the Civet, in which animal the distribution of the perforatus (i. e. the superficial part of the common flexor mass as in H. crocuta) is limited to the three middle digits, no tendon passing to the outermost. The latter, however, possesses a special little musclel which arises from the 1 Mivart and Murie describe a similar muscle in Hyrax capensis (P. Z. S, 1865, p. 341), and designate it "flexor brevis manus." 7* |