Chap. IX.] 



SKULL OF BIRDS. 



which they are connected with the frontal and with the 

 palatines are very important factors in the attachment * 

 of the beak to the cranium ; especially is this the case 

 in those skulls in which ossification of the ethmoidal 

 region is incomplete. 



In the wood-peckers, where the head is " employed 



Fig. 143.-Side view of a Dissected Head 

 of a common Wood-pecker. (Half iiat. 

 size.) 



u i, Upper and lower jaws ; t, barbed tip of 

 tongue ; thh, thyrobyal of right side, with 

 its muscle and sheath ; o, right orbit ; n. 

 right nostril; sgr, salivary gland; m, m, 

 muscles of neck ; o, oesophagus ; tr, trachea ; 

 rm, retractor muscles of tongue. (.After 

 Macgillivray.) 



as a powerful hammer or axe, whose strokes can be 

 heard at a considerable distance " (Garrod), the bones 

 of the skull are thicker and stronger than in most 

 birds, and the upper jaw has its power of vertical 

 movement considerably limited. The articulation of 

 the palatine with the basisphenoid disappears, in 

 consequence of the feeble development of the hinder 



