THE SKILL, 



32f> 



In front of the notochord, the parachordals are continued for- 

 wards as a pair of short and rather slender rods, the trabecule 

 cranii: these lie at the sides of the pituitary body, and unite in 

 front of this to form the ethmoidal plate, which underlies and 

 supports the fore-brain. 



By the eighth day (Figs. 131 and 116) important changes 



SF P° 0M 



A *- QJ 3B SR 



Fig. 131.— The skull of a Chick Embryo at the end of the eighth day of incu- 

 bation; seen from the right side. The head and eye are represented in 



outline. 



10. 



AN", angulare. AE, articular portion of mandibular bar. BB, basi-branchial 

 cartilage. BK, cerato-branchial cartilage. CL, columella. EH, external or hori- 

 zontal semicircular canal. EP, posterior vertical semicircular canal. ET. mesethmoid 

 cartilage. FE, fenestra ovalis. HE, ceratoliyal cartilage. MC, Meckel's cartilage. 

 OC, occipital condyle. OK, slit-like aperture of olfactory capsule. OL, outline of 

 lens. ON, outline of eyeball. PG, pterygoid. Q, quadrate cartilage. QJ,quadrato- 

 jugal. RL, trabecula cranii. SE, pre-'splienoidal region. SE, ali-sphenoidal region. 

 SL, supra-occipital region. SR. supra-angular. 



ha 



: 



have occurred in the skull, mainly associated with the growth 



rwarcls of the beak. 

 At the hinder end of the skull the two parachordal cartilages 



ig. 116, rc) have united, above and below the notochord, to form 

 the basilar plate ; and the sides of the basilar plate, including the 

 auditory capsules which are fused with them, have grown up- 



