THE SKELETON AND ANATOMY OF BIEDS. 



339 



cavities are more 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 (B-G), the first four being anchylosed together (7), so as to 

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



%%?^- OP 105 

 / I 1 : 



oc- 



Fro. 176. — Skull of Fowl. 



PAf, Prcmaxillary ; Jf, maxilla ; P, palatine ; Jf, nasal ; Z, lachrymal ; 705, inter- 

 orbital septum ; OF, interorbital foramen ; ZP, zygomatic process of frontal ; ZP2, 

 same of squamosal ; OC, occipital condyle ; TC, tympanic recess ; FO, foramen ovale ; 

 ATC^ anterior tympanic recess ; FJV, foramen of fifth nerve ; G. quadrate ; QJ, quadrato 

 jugal; Pt, 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 vertebrae {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 " 



