758 B. W. KUNKEL 



22. The septum interorbitale is imperforate and is quite evi- 

 dently of double origin since in younger stages than that mod- 

 elled it is seen in cross section to have a distinct Y-form, the two 

 limbs of the Y being parallel to each other and then suddenly 

 diverging to form the planum supraseptale. 



23. The fenestra optica is large and is situated in front of the 

 foramen ophthahnicmn through which the arteria ophthalmica 

 passes into the region of the orbit of the eye. The two foramina 

 ophthalmica are separated from each other by the subiculum 

 infundibuh. 



24. The septum interorbitale passes without interruption for- 

 ward into the septimi nasi which divides the ethmoidal region 

 into two symmetrical halves. 



25. The olfactory capsule is of compact form and is composed 

 of continuous plates of cartilage not separated by extensive fora- 

 mina. 



26. The capsule is bent somewhat ventrally as is indicated 

 by the plane of the fenestra olfactoria which is not horizontal, 

 as in Lacerta, but inchnes downward in front; and also by the 

 fact that the fenestra basalis is situated below the level of the 

 ventral margin of the septum interorbitale. 



27. The olfactory capsule is connected with the septum pos- 

 teriorly only by the slender commissurae spheno-ethmoidales 

 wliich bound the fenestrae olfactoriae laterally and separate 

 them from the fissurae orbitonasal es. 



28. The fissura orbitonasaUs extends the entire length of the 

 posterior cupula of the capsule, as in the Lacertiha, the planum 

 antorbitale being entirely separated from the septum. 



29. The nervus ethmoidahs passes into the capsule from the 

 orbit thi-ough the fissiu-a orbitonasalis. 



30. The plane of the fenestra narina is transverse so that the 

 fenestra faces directly anteriorly. 



31. The lamina transversalis anterior is represented by the 

 portion of the floor of the capsule in front of the foraman prae- 

 palatinum. 



32. The shortness of the cartilago paraseptalis of the stage 

 modelled is a secondarj^ condition, since in earUer stages the fora- 



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