THE SKELETON AND ANATO^FY OF BIRDS. 



369 



cavities are Jiiore or less connected with the air, and the hones 

 are spoken of as " pneumatic " hones. 



The -^-ertebrae of the neck (fig. 208, A-B) allow thr, bird con- 

 siderable powers of movement in that region ; they vary from 

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

 ten (B-C), the first four being anchylosed together (7), so as to 

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



/ I ; 1 



0C-- 



Fro. 20il.— Skul'. or Fowl. 



PM, Preinaxillary ; 3/", maxilla ; P, palatini ; N, nasal ; L, lachrymal ; JOS, inter- 

 orbital septum ; (JF, interortital foramen ; ZP, zygomatic process of frontal ; ZF2, 

 same of squamosal ; 00, occipital condyle; TO, tympanic recess; FO, foramen ovale; 

 ATC, anterior tympanic recess ; FN, foramen of fifth nerve ; Q, quadrate ; QJ, quadrato 

 jngal; 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. 212) are incapable of 

 movement. The tail vertebrse (D-E) also vary in nitmber, 

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

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



2 A 



