240 



AVES. 



and humerus, and between the humerus and forearm. The posterior 

 of these folds is of importance in connecting the wing with the body ; 

 the anterior has a relation to the mechanism by which the wing is 

 unfolded, inasmuch as it contains an elastic band which extends 

 along its outer edge from the humerus to the articulation of the 

 hand, and which, when the forearm is extended, exercises a traction 

 on the thumb side of the carpal joint, and so causes the simultaneous 

 extension of the hand. 



FIG. 651. Pteryloe and apteria of Gallus BanJciva (after Nitzsch-). a, ventral side ; 

 b, dorsal side. 



The large wing- feathers (remiges) are attached along the lower 

 edge of the hand and forearm. Those which are attached to the 

 hand, from the extremity of the wing to the carpal joint, are known 

 as primary remiges (fig. 652, HS), while those attached to the fore- 

 arm as far as the elbow joint are called secondary remiges (A S). 

 There are usually ten primaries, and a greater but variable number 

 of smaller secondaries. 



A number of feathers (coverts) attached to the upper end of the 

 humerus are called scapulars (parapterum), and some feathers fas- 



