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Show 1866.] ON THE ANATOMY OF THE CRESTED AGOUTI. 403 Guinea-pig dissected, an old fleshy male, there was a good-sized fleshy belly to the muscle above the tendon, which latter ended in the thick palmar fascia. The flexor sublimis digitorum is quite a small muscle; it arises fleshy from the internal condyle along with the flexor profundus digitorum, lying rather to the ulnar side of this last. At the wrist it divides on the right limb into three rather delicate tendons, which form the perforated tendons of the second, third, and fourth digits; on the left limb it sends a division to the fifth digit (fig. 2, F. s. d.). In the Hare we find it to have three tendons, going to the same digits as in the right limb of Dasyprocta ; while in the Guinea-pig there are four, as in the left limb of D. cristata. The Rabbit, as Prof. Huxley has observed, is peculiar in having the flexor sublimis dividing into three tendons, with an extra muscle and fleshy belly to the ulnar side of these tendons, which itself sends a tendon to supply the fifth digit. Flexor profundus digitorum and flexor longus pollicis (fig. 2, F.p. d. and F. I.p. 1, 2, 3, 4). These are represented by a complex muscle consisting of four parts: the first, and much the larger part, arises from the internal condyle ; the second, outer part arises from the shaft of the ulna, its middle three-fourths; the third part, the smallest, arises in common with the first head, but rather deeper; the fourth part (which we take to represent the flexor longus pollicis?) arises from the middle three-fourths of the shaft of the radius. The first, large portion is fleshy down close to the wrist, and so are the second and fourth portions ; but the smallest portion becomes tendinous as far up as the middle of the forearm. The whole of these tendons form an extraordinarily strong, hard, flat, single tendon, filling the entire interspace between the pisiform and scaphoid bones. In the palm of the hand this mass divides into four very bioad tendons, inserted respectively into the second, third, fourth, and fifth digits; but no tendon goes to the pollex. The component parts and distribution of the tendons of this muscle are the same in the Guinea-pig; but in the Hare and Rabbit there is an additional tendon to the thumb; in them also the fourth division, and not the third, is the smallest one. Lumbricales (fig. 2, L.). These seem to be three in number. The first (radial) one arises from the radial side of the conjoined mass of tendon of the flexor profundus and longus pollicis, and also in part from the index tendon; it is inserted into the proximal end of the first phalanx of the second digit. The second (middle) one comes from the superficies of the same large conjoined tendon, and partly from the tendons of the index and third digits ; it goes to the radial side of the third digit. The third (ulnar) one has a similar superficial origin from the conjoined tendon and those of the third and fourth digits; it is inserted into the ulnar side of the proximal phalanx of the third digit. In the Rabbit, Hare, and Guinea-pig there are likewise three lumbrical muscles. Eacii of these is given off from, and attached to, the radial sides of the third, fourth, and fifth digits. |
