THE SKULL. 



405 



for articulation with the atlas vertebra; (2) the base of the 

 skull is strengthened by a large membrane-bone, the hasi- 

 temporal ; (3) the orbits are placed almost entirely in front 

 of the cranium, instead of below it, and are separated from 

 each other only by the thin interorbital septum; (4) the 

 lower jaw is connected with the squamosal by a movably 

 articulated bone, the quadrate ; (5) there is only a single 

 auditory'ossicle, the.colnmella ; (6) there are no teeth. 



QJ B Q J 



Fia. 72. — Callus domesticus. The skull from the right side. (a. m. m.) 



A, articular surface of the mandible. AT, anterior tympanic recess, lead- 

 ing to the Eustachian tube. B, pterygoid. C, occipital condyle. D, palatine. 

 E, Tomer. F, mandibular foramen.- "FO, fenestra ovalis. FR, fenestm 

 rotunda. FZ, zygomatic process of frontal bone. Gr, supra^angiilar. H, 

 dentarv. . IS, inter-orbital septum. J, jugal. L, lacrymal. M, maxilla. 

 MP, maxillo-palatine process of maxilla. W", nasal. OF, optic foramen. 

 PM, premaxilla. PT, posterior tympanic recess. Q, quadrate. Q,J, qua- 

 drato-jugal. SF, olfactory foramen. SZ, zygomatic process of squamosal. 

 TF, foramen for fifth nerve. 



The fowl's skull consists of cranial and facial portions 

 which are loosely connected together, and capable of slight 

 movement upon each other. The cranial portion consists of 

 the cranium proper, or brain case, and the auditory capsules : 

 the facial part is formed by the jaws and the olfactory capsules. 



1. The cranial portion of the skull is a somewhat conical 

 box I of bone, the base of the cone forming the hinder 



