THE SKELETON AND ANATOMY OF BIRDS. 



339 



cavities are nwre or less connected with the air, and the bones 

 are spoken of as " pneumatic " bones. 



The vertebrae of the neck (fig. 175, A-B) allow the bird con- 

 siderable powers of movement in that region ; they vary from 

 eight to as many as twenty-three. The dorsal vary from six to 

 ten (5-C), the first four Ijeing anohylosed together (7), so as to 

 give support to the powerful fore-limbs or wings. We cannot 



z%?'7- OP 10$ 

 I I 



Fig. 17(5, — Skull ok Fowl. 



FM, Premaxillary ; Hr, maxilla ; P, palatini ; N, nasal ; L, lachrymal ; JOS, intf-r- 

 orbiUil septuiu ; OF, interorbital foranien; Zl', zygomatic process of frnntal ; ZP2, 

 same of squamosal ; DC, occipital condyle; TC, tym]ianic recess; FO, foramen ovale; 

 ATC, anterior tympanic recess ; FI^, foramen of fifth nerve ; Q, quadrate ; QJ, quadrate 

 jugal ; Ft, pterygoid ; SA, supra-angular ; D, dentary ; MF, mandibular foramen. 



distinguish any lumbars. The bones between the dorsal and the 

 caudal are all united, forming the sacrum much as in mammals ; 

 but to this sacrum the ilia (S) are joined completely : thus the 

 spine in this region and the pelvis (fig. 178) are incapable of 

 movement. The tail vertebras (D-E) also vary in number, 

 usually eight to ten, and are movable. The last joint of the 

 tail is long and slender, and forms the curious " ploughshare " 



