VIII.] 



THE SENSE CAPSULES. 



241 



internasal septum, continuous behind with the inter- 

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



FIG. 78. 



bb r 



SlDE VIEW OF THE CARTILAGINOUS CRANIUM OF A FOWL ON THE 



SEVENTH DAY OF INCUBATION. (After Parker.) 



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

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

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

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

 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. nc. noto- 

 chord. mJc. Meckel s cartilage, ch. cerato-hyal. bh. basi- 

 hyal. cbr. and ebr. cerato-branchial. bbr. 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 



