Fig. 16 Frontal section through base of orbito-temporal region. Embryo 

 12 mm. long (H. E. C. Series 403, sect's. 200-207). X ¥-. 



Fig. 17 Median sagittal section through base of cranium. Embryo 12 mm. 

 long (H. E. C. Series 400). X ¥• 



Fig. 18 Median sagittal section through base of cranium. Embryo 15 mm. 

 long (H. E. C. Series 437, sect's. 158, 161, 169). X ¥. 



Fig. 19 Frontal section through occipital and otic regions. (Sect. 246). 

 X ¥. 



Fig. 20 Frontal section through occipital and otic regions. (Sect. 253). 



X -¥. 



Fig. 21 Frontal section through the otic region. (Sect. 256). X -r- 

 Fig. 22 Frontal section through the otic region. (Sect. 273). X V. 

 Fig. 23 Transverse section through the orbito-temporal region. (Sect. 300). 



X ¥-. 



Fig. 24 Transverse section through the orbito-temporal region. (Sect. 339). 

 X ¥• 



Fig. 25 Transverse section through the orbito-temporal and ethmoidal regions. 

 (Sect. 385). X V- 



Fig. 26 The same as in figure 25 but further forward. (Sect. 404). X ¥• 



Fig. 27 Transverse section through the ethmoidal region. (Sect. 457). 



X ¥. 



Fig. 28 Transverse section through the ethmoidal region. (Sect. 489). 

 X ¥• 



Fig. 29 Transverse section through the ethmoidal region. (Sect. 492). 



X V-. 



Fig. 30 Transverse section through the ethmoidal region. (Sect. 513). 

 X Y. 



ABBREVIATIONS 



VI, abducent nerve 



XI, accessory nerve 



Ac.fis., acustic fissure 



VIII, acustic nerve 



Al. orb., alsi orbitalis 



Al.temp., ala temporalis 



Alar., alar element 



Amp. a., ampulla anterior 



Amp. I., ampulla lateralis 



Amp. p., ampulla posterior 



Ant.pl., antorbital plane 



Aq.coc, aquaeductus cochleae 



Pr.at., atlantal process 



At., atlas 



Atrt., atrioturbinale 



Bas.pl., basal plate 



Can.sem,.ant., canalis semicircularis 



anterior 

 Can.sem.lat., canalis semicircularis 



lateralis 



Can. sem. post., canalis semicircularis 



posterior 

 Car. for., carotid foramen 

 Cav.epipt., cavum epiptericum 

 Cav.coc, cavum cochleae 

 Cav.nas., cavum nasi 

 Cav. vest. ant., cavum vestibulare an- 



terius 

 Cav. vest. post., cavum vestibulare pos- 



terius 

 Cent.at., centrum of atlas 

 Cent.ep., centrum of epistropheus 

 Ch.tym., chorda tympani 

 Co.cap., cochlear capsule 

 Co.d., cochlear duct 

 Com. alio., commissura alicochlearis 

 Com.bas., commissura basicochlearis 

 Com.basiv., commissura basivestibu- 



laris 

 Com..el., commissural element 



406 



