THE SKULL. 



331 



mid-ventral plane, where the arches of the two sides meet, a 

 median basibranchial cartilage, BB, is developed. 



In the hinder branchial arches no skeletal elements are 

 formed in the chick. 



b. The Osseous or Bony Skull. 



(i) The cartilage-bones developed in connection with the skull 

 are as follows : 



From the parachordal cartilages are formed the basi-occipital, 

 ex-occipitals, and supra-occipital. 



OF 



MP 



PM 



A QJ G J D 



FIG. 132. The skull of the Fowl, from the right side. (From Marshall and 



Hurst.) 



A, articular surface of the mandible. AT, anterior tympanic recess, leading to 

 Eustachian tube. B, pterygoid. C, occipital condyle. D, palatine. E. rostrum. F, 

 mandibular foramen. FO, feuestra ovalis. FR, "fenestra rotunda. FZ, zygomatic 

 process of frontal bone. GJ-, supra-angular. TT, dentarv. IS, inter-orbital septum. J, 

 jugal. L, lacrymal. M, maxilla. MP, maxillo-palatine process of maxilla. If, nasal. 

 OF, optic foramen. PM, premaxilla. PT, iwsterior tympanic recess. Q,. quadrate. 

 Q,J, quadrato-jugal. SF, olfactory foramen. SZ, zygomatic process of squamosal. 

 TF, foramen for fifth nerve. 



From the periotic capsules are formed the prootics, epiotics, 

 and opisthotics. 



From the trabeculas cranii, the ethmoidal cartilages and the 

 olfactory capsules, are formed the alisphenoids, orbitosphenoids, 

 presphenoid, and mesethmoid. 



In the mandibular arch of each side are formed the quadrate, 

 and the articular e. 



In the hyoid arch are formed the columella, the ceratohyal, 

 and basihyal. 



In the first branchial arch are formed the ceratobranchial, 

 and basibranchial. 



