VIII.J THE SENSE CAPSULES. 241 



iutemasal septum, continuous behind with the inter- 

 orbital septum, grows up (Fig. 78); while the lateral 



Fig. 78. 



tlln 



7n^ 



Side view of the cartilaginous cranium of a Fowl on the 

 SEVENTH DAT OF INCUBATION. (After Parker.) 



pn. prenasal cartilage, aln. alinasal cartilage, ale. aliethmoid ; 

 immediately below this is the ahseptal cartilage, eth. eth- 

 moid, pp. para plana, ps. presphenoid or inter-orbital. 

 pa. palatine, pg. pterygoid, z. optic nerve, as. aHsphenoid. 

 q. quadrate, st. stapes, fr. fenestra rotunda, hso. horizon- 

 tal semicircular canal, psc. posterior vertical semicircular 

 canal : both the anterior and the posterior semicircular 

 canals are seen ' shining through the cartilage, so. supra- 

 occipital, eo. exoccipital. oc. occipital condyle, na. noto- 

 chord. mh. Meckel's cartilage, ch. cerato-hyaL hh. basi- 

 hyal. chr. and ehr. cerato-branchial. hhr. basibranchial. 



part is known, as the lateral ethmoid region, which 

 is always perforated for the passage of the olfactory 

 nerve. 



The sense capsules. The most important of these 



is the auditory capsule, which, as we have seen, fuses 



intimately with the lateral walls of the skull. In front 



there is usually a cleft separating it from the alisphe- 



F. & B. 16 



