DEVELOPMENT OF THE SKULL OF EMYS 739 



and ventrallj' from each foramen the capsular wall is produced 

 in an anterior direction into a short process, the dorsal one of 

 which is shghtly stronger than the ventral. Laterally the margin 

 of the foramen is incised to accommodate the duct of the glan- 

 dula nasaUs externa which passes medially to open into the nasal 

 sac. The fenestra narina lies in the ventral half of the capsule 

 so that the entire front wall of the pars respiratoria is lacking. 

 The septum nasi ends freely in front on a level with the lateral 

 margins of the fenestra so that the two fenestrae are completely 

 separated from each other. 



A small fenestra epiphaniale in the antero-dorsal portion of the 

 paries nasi, near the point at which the latter passes over into the 

 tectum nasi, is the only perforation of the paries nasi in the stage 

 modelled. Through this fenestra the ner\'Tis lateraUs nasi of 

 the ophthalmic branch of the trigeminus passes to the exterior 

 of the capsule. 



The foramen praepalatinum is an elongated slit separating 

 the solum nasi from the septum nasi for a space posterior to the 

 lamina transversalis anterior. It is divided by a projection of its 

 lateral margin into a smaller anterior and larger posterior lobe. 

 The indentation of its lateral margin is produced by the posterior 

 end of the pila supraglandularis wliich is attached at this point 

 to the solum nasi as already described. 



The fenestra olfactoria {f.oL, fig. 24) as already mentioned, 

 slopes ventrally in front from the antero-ventral margin of the 

 planum supraseptale to the tectum nasi. It is a long oval, 

 bounded medially by the free margin of the septum nasi and 

 laterally by the commissura spheno-ethmoidalis. The planes of 

 the two fenestrae are slightly inclined toward each other because 

 the septum does not extend dorsally as far as the level of the com- 

 missurae spheno-ethmoidales. 



The fissura orbitonasalis is continuous ventrally and ante- 

 riorly with the sinus paraseptahs. Dorsally it is separated from 

 the fenestra olfactoria by only the slender commissura spheno- 

 ethmoidaUs. The nervus ethmoidalis rami ophthalmici trigemini 

 gains access to the nasal capsule from the orbit through it. 



