1867.] MYOLOGY OF IGUANA TUBERCULATA. 783 



appear to go mainly to the ulna. Thus its insertion has much re- 

 semblance to that of the same muscle in the Echidna. 



The brachialis anticus (figs. 1 , 2, 6, 8 & 10, fi. A.), which may 

 be, as Meckel appears to think*, a humeral head of the biceps, 

 springs from the front of the shaft of the humeru;!, immediately below 

 the insertions of the deltoid, epicoraco- humeral, and pectoralis major. 

 It soon fuses with the biceps, and is inserted in common with it into 

 the upper ends of the flexor surfaces of both radius and ulna. The 

 fibres of this muscle, however, appear to be connected mainly, if not 

 exclusively, with the radius. 



Supinator longus. This muscle (figs. 1, (i, 10 & 1 1) is exceed- 

 ingly large, and, as Meckel observes t, arises by two heads, which 

 do not unite till far down the forearm (fig. 1, ^S. L.). Indeed I find 

 that that head vihich has the more posterior (lower) origin may be 

 again divisible at and near its origin into two portions, of which the 

 anterior (upper) one is much the smaller ; all these parts, however, 

 arise from the external condyle, and have a common insertion into 

 the radial margin of the radius for almost its whole length, and 

 therefore side by side with the pronator teres as far as the latter 

 extends. The head, which has the more posterior (lower) origin, is 

 intimately connected with the radial extensor. 



The extensor carpi radialis, which appears to answer to both the 

 longior and brevior of mammals, arises by tendinous fibres from the 

 outer and posterior surface of the external condyle, immediately super- 

 ficial to the posterior (lower) part of the origin of the supinator 

 longus, with which, for some distance, it is very intimately connected. 

 Passing downwards (fig. 1, E. B.) it divides into three parts, which 

 are inserted, each by a tendon, into the proximal ends of the dorsal 

 surfaces of the second, third, and fourth metacarpals. 



Extensor communis digitorum. As Meckel observes^};, this muscle 

 has, as it were, '■'■ descendu a la mai7i" (fig. 11, E. C). It is small, 

 arises from the carpus, and is inserted into the bases of the digits. 

 It is much subdivided, there being more or less distinct fleshy bun- 

 dles for the several digits. 



The extensor carpi u/naris (fig. 1, E. U., and fig. 11, ^. C JJ.) is 

 rather indistinct. It arises indeed by tendinous fibres from the 

 posterior surface of the external condyle ; but its insertion is into 

 the adjacent border of another muscle, the flexor carpi ulnaris. 



Extensor ossis metacarpi pollicis. This is a rather thick muscle 

 which arises from the posterior surface of rather less than the distal 

 half of the ulna. It is inserted into the metacarpal of the poUex 

 (fig. \\,E.M.P.). 



Pronator teres (figs. 6 & 12, P. T.). The origin of this muscle 

 is by a very strong tendon attached to the summit of the internal 

 condyle. Its fibres spread out, and are inserted into the lower two- 

 thirds of the radial margin of the radius. 



The fiexor carpi radialis (figs. 6, 9,F.R., and fig. 12, F. C. R.) 

 arises from the internal condyle immediately below the origin of the 



* Loc. cif. p. ,362. t Loc. vi(. p. ;j{)7. 



+ Loc. cif. p. 391. 



