Muscles and Nerves 



193 



wa\y cross-lines, or striations, on those which are moved 

 voluntarily, such as the muscles of the neck or wing; 

 but those which are moved involuntarily, as the gizzard, 

 are smooth and without the cross-lines. 



Fig. 142. — Amazon Parrot in sleeping position, hanging by its toes; illustrating 

 the wonderful strength of the tendons. 



Among birds new muscles have appeared, or old ones 

 have split up or so changed in position that it is all but 

 impossible to compare them, muscle for muscle, with other 



