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Show 78 MR. A. SANDERS ON THE [Jan. 6, fenestra, and is inserted into the ventral surface of the humerus for about half its length, commencing at the head. _ Triceps (figs. 1 & 3, Tr. e.) in this species has four origins. The outer head arises from the external surface of the humerus for nearly its whole length, commencing immediately within the insertion of the infraspinatus. The long head (figs. 2 & 3, Tr. I.) arises from the posterior border of the scapula just above the glenoid cavity, and gives a tendon which passes across the teres minor in the usual manner to be inserted into the humerus close behind the anterior level of the insertion of the infraspinatus. The inner head (fig. 2, Tr. i.) is divided into two distinct portions : one part arises by muscular fibres from nearly the whole length of the inner surface of the humerus ; at about the junction of the distal with the middle third it joins the other portion, which arises by a narrow tendon from a ligamentous band, which goes from the external angle of the sternum to the inner surface of the scapula, dorsad of its point of junction with the coracoid; at the point of insertion the tendon spreads out into a broad expansion, one end of which is attached to the above-mentioned ligament, while the other end is connected to the posterior angle of the coracoid close to the origin of the coraco-brachialis longus. All four heads join together, and developing a sesamoid bone in the substance of their common tendon are inserted into the proximal end of the ulna. The arrangement of this muscle iu this species is just opposite to that found in P. japonicum, in which lizard the outer head, and not the inner head, is the one which is divided into two parts*. Extensor carpi ulnaris (fig. 3, E. C. U.) arises by two heads-one by a flat tendon from the outer condyle of the humerus, the other fleshy from the proximal end of the ulna ; it is inserted by a narrow tendon into the base of the metacarpal bone of the fifth digit. Supinator longus (figs. 1 & 3, S.L.) arises from the external condyle of the humerus, and is inserted into the whole length of the radius. Extensor longus digitorum (fig. 3, E.L.) arises from the outer condyle close to the last; half of it goes to join that muscle at about the distal third of the radius ; the remainder develops three short tendons, which are inserted into the base of the 2nd, 3rd, and 4th metacarpal bones ; the tendon for the fourth digit is given off higher up than the other two. Extensor ossis metacarpi pollicis (fig. 3, E.M.) seems very constant ; in this species it is a triangular muscle precisely resembling that of L. belli. Extensor brevis digitorum (fig. 3, E.B.) consists of five short muscular slips which arise from the dorsal surface of the carpus ; each of these slips ends in a tendon which is inserted into the terminal phalanx of its respective digit. There are two muscles which have the attachment of pronators of the forearm. The first may be called * Loc. cit. p. 416. |