398 ROBERT J. TERRY 



tion) the tectum posterius apparently arises as a process. The 

 definitive parietal plate seems to be the result of the fusion of 

 the anterior and posterior elements. 



14. The facial nerve makes its exit from the chondrocranium 

 by the primary facial foramen, at which spot is located the 

 geniculate ganglion and the origin of the great superficial petrosal 

 nerve. The primary facial foramen is to be regarded as com- 

 parable with the foramen faciale of Lacerta. 



15. The floor of the hypophyseal fossa is formed from a single 

 crescentric cartilage arising independently. 



16. In the cat a small space, filled with mesenchyma, existing 

 for a brief period, between the anterior end of the basal plate 

 and the hypophyseal cartilage, is identified as a fenestra 

 basicraniahs posterior. 



17. The dorsum sellae in cat is formed from the crista trans- 

 versa and, in addition, by chondrification of the mesenchyma 

 dorsad of it, probably by a separate center. There is evidence 

 in the literature that the dorsum sellae of the lower mammals is a 

 derivative of the crista transversa alone, while that of the 

 higher mamjaals includes an additional element. 



18. The development of the ala temporalis of the cat, repre- 

 senting the type of discontinuous ala, is comparable with that 

 of mole, representing the type of ala temporalis continuous with 

 the sella turcica. The difference between these forms of ala 

 is an apparent one, resulting from failure of the root of the 

 temporal wing of the cat to form in cartilage. The synchon- 

 drosis between the ala temporahs and alicochlear commissure 

 and the incisura lacera of cat, the foramen or fissure between ala 

 and conamissure in other forms, indicate the plane of junction 

 between these originally independent and different parts. The 

 ala temporahs of cat is comparable with the ala temporahs of 

 Echidna. 



19. A pterygoid element appears in the cat as a condensation 

 of mesenchyma, in which ossification is occiu-ring at the stage of 

 the 23.1 mm., embryo. Cartilage is subsequently developed, in 

 which ossification proceeds. There is evidence of two ossific 

 centers, and from these the medial pterygoid lamella and 

 hamular process are formed. 



