42 
and Laurillard figure it. But Coues* names as supinator longus the 
muscle which Brooks regards as extensor carpi radialis longior. 
Coues’ view is certainly erroneous. 
Mivart describes a supinator longus in Echidna,+ though he inserts 
a query to the name; and the same muscle is also described and 
figured by Westling} as fused at its origin with the brachialis anticus, 
and as supplied by the median nerve along with the latter muscle. 
In dissections by Dr. McKay I find no separation of supinator 
longus from brachialis anticus (in fact no satisfactory indication of a 
supinator longus at all) in Ornithorhynchus, while in Echidna there is 
a very well marked segmentation of a supinator longus parallel with 
and close to the brachialis anticus. 
In Chlamydophorus and Tatusia$ the muscle is absent, as also in — 
Dasypus||; but in most Edentata it appears to be present. 
It is absent in all Jnsectivora and Rodentia,{ but generally present in 
Carnwora. It is absent, e.g., in Hyena striata and Proteles.** 
M. extensor carpi radialis (figs. 6, 7, 9, 10, 12, and 17 e.c.7.) 
arises from the ectocondylar ridge and from the septa between it 
and the adjacent muscles. 
It is a large fleshy muscle (indivisible into segments), ending in 
a stout tendon which descends dorsad of the prominent radial 
styloid and passes under cover of the extensor ossis metacarpi 
pollicis which crosses it just below the styloid. Still more dis- 
tally it is crossed (close to its insertion) by the indicial extensor 
tendon. Its insertion is into the dorsal aspect of the base of the 
metacarpal of the third digit. 
There is no trace of a second radial extensor, and the muscle 
present corresponds from its insertion rather to the ext. carpi rad. 
brevior. The entire absence of a portion of muscle or tendon 
representing the long extensor is doubtless correlated with the 
peculiar condition of permanent opposition and partial flexion of 
the metacarpals of both pollex and index in the highly modified 
manus of this animal. 
Cunnigham notes that the fleshy bellies of the radial extensors of 
the carpus are completely amalgamated in Phascogale, though the ten- 
dons were separate. In Cuscus and one specimeni of Thylacinus the same 
author found the muscles quite separate, while another specimen of 
Thylacinus resembled Phascogale in this respect.+ t+ 
MacCormick?{ found in all the specimens of Dasywrus examined by 
him (and of Phalangista ?) that the muscles were fused throughout, the 
single tendon being inserted into the metacarpal of the third digit. 
But in most marsupials its insertion is into the metacarpals of both 
second and third digits. Young found the muscles in Koala$§ fused in 
some cases, separatein others. Macalister|||| mentions one muscle only 
in Macropus bennettvi, Phascolomys sarcophilus, Phalangista, and Macro- 
*lil., page 153. + xxxix., page 386. { lxii., pages 19 and 25. § xxvii., 
page 255. || xiv., page 540. {1 xxvi., page 810. ** Ixxili., page 191. 
tr iv., page 14. f xxxvi., page 123.- §§ lxxii., page 229. |||| xxix., page 
163. 
