242 ME. W. P. PYCRAFT ON THE MORPHOLOGY AND 



In Apteryx the usual flexors and extensors of the forearm are present, and, as the 

 late Prof. T. J. Parker points out, a rather unusually large development of muscles 

 acting as pronators and supinators for so small and vestigial an organ. 



The biceps of Apteryx is single-headed, arising only from the coracoid ; it is inserted 

 only on to the radius. Apteryx differs only from the other genera in the possession of 

 the Gallinaceous and Tinamine entepicondylo-ulnaris and an accessory brachialis 

 anticus. 



In Casuarius and Dromceus the wing seems to have reached its most vestigial 

 condition. 



The biceps in Casuarius arises only from the coracoid, and is inserted by a single 

 tendon both upon the radius and ulna. In Dromceus, according to Beddard, the biceps 

 has the same peculiar origin to that of Rhea (p. 241). 



" All the Struthious birds," writes Beddard [7], " except Apteryx, have lost the 

 serratus metapatagialis, the latissimus dorsi metapatagialis , and the pectoralis 

 abdominalis. 



" On the other hand, Apteryx has lost what the other Struthious birds have retained, 

 the latissimus dorsi anterior and the rhomboideus profundus ; the latter muscle, 

 however, is not distinguishable in the Cassowary. 



" It must be admitted, therefore, that Apteryx, so far as concerns the anterior 

 extremity, has diverged from the hypothetical ancestral condition in slightly different 

 lines from other Struthiones." 



The rhomboideus superficialis in Rhea and Struthio arises as in Neognathce. In 

 Rhea it is inserted on to both the coracoid and scapula, in Struthio on to the scapula 

 only. 



In Apteryx, Casuarius, and Dromceus it arises from the ribs. 



The rhomboideus profundus in Casuarius and Dromceus arises from the ribs. In 

 Casuarius it is with difficulty distinguishable from the serratus profundus, and on this 

 account Furbringer [22] inclines to disallow its existence as a separate muscle. 



The serratus superficialis of Apteryx retains the pars metapagialis, which is wanting 

 in the other Palwognathw. 



The coraco-brachialis intermts of Casuarius is entirely tendinous ; in Rhea largely so. 

 Furthermore, in this last genus it extends on to the sternum. In Struthio it is larger 

 than in any other Palosognathce. 



Thigh- and Leg-muscles. 



Struthio and Apteryx only have the leg-muscles complete, which make up the 

 formula AB . XY +. 



In the Struthiones generally the accessory femoro-caudal (pars iliaca m. caud-ilio- 

 femoralis) calls for special comment. In all save Apteryx it is characterized by its 



