1890.] 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 Phri/nosoma 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 meta- 

 carpal 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 poUex 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 

 Hofl^mann, 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 /. per/orans digitorum, and it is found to 

 be 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 meta- 

 carpal, 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. l68), while the muscle I here describe as the 

 Adductor quinti digiti may be his Abductor quarti digiti (loc. cit. 

 p. 169) ; but even in that event they are essentially very diS"erent, 

 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 u ell-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 poUex metacarpal, upon its inner aspect. 



53. Lumhricales. — The auxiliary muscular slips which I described 

 above when speaking of the flexor j^^rforatus and perforans digi- 

 torum muscles undoubtedly represent the lumbrical muscles in this 



13* 



