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Show 1 9 0 5 . ] ANATOMY OF THE LEATHERY TURTLE. 3 0 7 covers the flexor surface of the wrist and partly from the outer side of metacarpal I. Insertion : upon the penultimate phalanges of digits II., III., IV., and upon the flexor surface of the pisiform and of metacarpal V. The parts of the muscle proper to digits II., III., IV. are perforated by the tendons of the deep flexor. Ulna-digiti I.-V. ( Plexor digitorumprofundus) (text-fig. 64. 67). -Origin : from the whole length of the flexor surface of the ulna and from that of the ulnar half of the carpus exclusive of the pisiform. Insertion; by four round tendons to the terminal phalanges of digits I.-IV. Intrinsic muscles of the hand (text-fig. 64, Y).-These are seven in number. They take origin from the distal parts of the flexor surface of carpus and are inserted upon the metacarpo-phalangeal joints. There are two in connection with the thumb, very much matted together and partly fused with the tendon of the deep flexor; one to the second digit, having a common origin with the outer one of the two to the thumb ; two to the third digit; and one each to the outer side of digits IV., V. Abdominal Muscles. Rectus abdominis (text-figs. 57, 65, 66. 75).-a. Anterior part. Origin : from the plastron about 4 cm. behind the pectoralis by a backwardly concave semilunar attachment. Insertion : into the anterior margin of the lateral born of the pubis. The insertion encroaches somewhat upon both dorsal and ventral surfaces of the pubis. b. Inner posterior part. Origin : from the hinder edge of the plastron close to the mid-line. Insertion : upon the anterior end of the epipubis. c. Outer posterior part. Origin : from the hinder edge of the plastron to the outer side of the origin of " b." Insertion : upon the ventral surface of the lateral horn of the pubis posterior to the insertion of " a." The anterior part is a large fan-shaped muscle, the outer parts of which are lost in the loose skin of the groin. The two posterior parts are ribbon-shaped and fairly stout. The part " b " does not tally with any part of the rectus abdominis described by Gadow*, but I think it must be regarded as forming part of this muscle-sheet. Obliquus abdominis interims (text-figs. 57 & 67. 73).-Origin : from the plastron close outside the lateral part of the origin of the anterior rectus abdominis, and from the loose skin of the groin. Its fibres run inwards and forwards dorsal to the thigh and are inserted upon the dorsal posterior border of the lateral horn of the pubis. Transversus abdominis (74).-A very small muscle-sheet lying between tlie lateral parts of tlie obliquus internus and the perito* Gadow : " Untersuchungen iiber die Bauchmuskeln der Krokodile, Eideclisen und Schildkroten," Morph. Jalirb. Bd. vii. (1882) p. 57. |
