164 Prof. A. Macalister on the Myology of 



This possibly may be the muscle described by Professor Owen 

 in Perameles as supinator longus, which " is inserted by one 

 of its divisions into the base of one of the metacarpal bones of 

 the index finger, and by the other into the adjoining metacarpal 

 bone," as this is similar to the arrangement of the extensor 

 carpi radialis in M. Bennettii, to which a separate supinator is 

 superadded. 



The extensor digitorum communis arises from the outer 

 condyle, and is inserted into the second, third, fourth, and fifth 

 toes in the Wombat, Sarcojyhilus, Opossum, Phalanyista, Wal- 

 laby, and Giant Kangaroo. 



The extensor digitorum secundus (extensor minimi digiti 

 of anthropotomy) is normal in origin and supplies tendons to 

 the fourth and fifth toes in the Wcnnbat, to the third, fourth, 

 and fifth in Sarcoj)Iulus {and of these the latter two are double), 

 to the third, fourth, and fifth in Bennett's and the Giant 

 Kangaroo, to the fourth and fifth in the Opossum and Pha- 

 langer. 



The extensor carpi ulnaris has a double origin, from the 

 ulna and outer condyle, and is inserted into the fifth meta- 

 carpal, in the Wombat ; it has no ulnar origin in the Tasmanian 

 Devil, Opossum, or Phalanger, but has one in Bennett's and 

 the Giant Kangaroos, as well as in Perameles. 



The anconeus externus of the Wombat is distinct and fan- 

 shaped, and separate from the triceps. In the Devil it is 

 united to the triceps, and extends down from the upper fifth 

 of the ulna. It is distinct in the Opossum, Phalanger, Giant 

 Kangaroo, and Macro^us Bennettii. 



The anconeus internus is round and more distinct than the 

 externus in all the marsupials, and, in all, crosses over the 

 ulnar nerve. This muscle is even more distinct in the majo- 

 rity of animals than the last. 



The extensor ossis metacarpi pollicis is large in all, and 

 runs from the whole of the back of the ulna and interosseous 

 membrane to the trapezium and metacarpal bone of the thumb ; 

 it crosses the extensor carpi radialis tendon ; and in the Opos- 

 sum and Phalanger it extends over the supinator longus tendon 

 also. 



The extensor primi internodii is absent in all. The extensor 

 secundi internodii in Sarcophilus and the Wombat passes from 

 the lower third of the ulna to the last phalanx of the pollex ; 

 it is present and similar in all the other marsupials, and also 

 in the Monotremes Echidna hystrix and Orniihorhynchus 

 paradoxus^ in both of which the extensor ossis metacarpi 

 pollicis and primi internodii pollicis are both absent. 



The extensor indicis is absent in the Wombat, but in 



