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Show '890.] HELODERMA SUSPECTUM. 175 is not called upon to use that member, so far as the writer knows, for any particular operation requiring either marked flexibility or suppleness; it simply plods about, and neither runs up trees, grasping the smaller twigs, nor does it especially use its fore feet in feeding. Before closing what I have to say about this muscle I would direct attention to the fact that Professor Mivart, in his ' Elementary Anatomy' (p. 331), has said, that in Iguana "this muscle can hardly be said to be inserted by definite tendons " ; while, again, their mode of insertion in Phrynosoma seems, according to Sanders, to be very simple (P. Z. S. 1874, p. 80). 49. The Abductor quinti digiti arises, fleshy, from the anterior aspect of the pisiform bone, and, its fibres contracting to become tendinous distally, it inserts itself into the shaft of the fifth metacarpal bone, immediately proximad to its head and upon the palmar aspect. 50. The Adductor quinti digiti is here well represented, being a delicate, thin, little band of muscular fibres which arise from the inner side of the proximal end of the pollex metacarpal, and, passing obliquely across the palm of the hand, are inserted into the proximal extremity, on the inner aspect, of the proximal phalanx of the fifth digit. This very distinct and interesting muscle I examined with the greatest care, but it does not seem to be recognized by Hoffmann, nor does it agree with what Sanders found in Liolepis. In Heloderma it is at once brought into view the moment we cut across and turn back the/. perforans digitorum, and it is found to he wider across its middle part than it is either at its origin or its insertion. 51. The Adductor quinti digiti proprius is a thick muscle which arises from the two outer bones of the second row of the carpus, upon the ulnar side, and passing directly forwards and a little outwards, inserts itself, carneous, along the entire length of the fifth metacarpal, upon the inner aspect of its shaft. This may be the Adductor quinti digiti of Sanders as found by him in Liolepis (P. Z. S. 1872, p. 168), while the muscle I here describe as the Adductor quinti digiti may be his Abductor quarti digiti (loc. p. 169) ; but even in that event they are essentially very different, since the Abductor quarti digiti of Sanders, as found by him in Liolepis, is inserted into the ulnar side of the last phalanx of the fourth digit. 52. Abductor metacarpi pollicis is the name I here propose for another very well-developed muscle in the palm of the lizard before us. It arises from the two outer bones of the second row of the carpus upon the radial side, and from the dense aponeurotic fascia of the same region. Passing forwards and a little outwards the muscle is inserted, carneous, along the entire length of the shaft of the pollex metacarpal, upon its inner aspect. 53. Lumbricales.-The auxiliary muscular slips which I described above when speaking of the flexor perforatus and perforans digitorum muscles undoubtedly represent the lumbrical muscles in this 13* |
