VIII.] 



THE MUSCLES. 



335 



muscle's special destination to the fifth digit is a human but 

 not a Mammalian character. Very often, even in man's own 

 order, this muscle may send tendons to the third and fourth 

 digits also 



The extensor carpi itlnaris, normal in man, may be much 

 increased in size, as e.g. in the Two-toed Ant-eater. It may 

 be diminished not arising from the humerus as in some 

 Birds. It may, as in Iguana, be united in one with the 

 flexor carpi ulnaris. 



FIG. 303. DEEPER MUSCLES OF EXTENSOR ASPECT OF RIGHT FORE-ARM OF 



PARSON'S CHAMELEON, the extensores radiales longior and brevior being cut 



and reflected. 

 B, biceps ; E* E^, extensores metacarporum : ERB, extensor radialis brevior ; 



ERL, extensor radialis longior: EU, extensor ulnaris; FU, flexor ulnaris; 



MP, extensor ossis metacarpi pollicis : PQ, pronator quadratus ; SL, supi- 



nator longus ; T, triceps. 



Extensor ossis metacarpi pollicis. This muscle of man ex- 

 emplifies a very constant condition, since it exists in animals 

 in which the pollex is entirely absent, as e.g. in the Horse. 



