348 PROF. W. K. PAEKEE ON ^GITHOGNATHOUS BIRDS. 



" ascending process," which is due to bifurcation of the pedicle itself ; it is rather ana- 

 logous than homologous. 



In birds the pterygoid is single. In the Eatitse it approximates in character to 

 the lower Chelonian bone, being a large fibrous slab ; in the Carinatse, especially the 

 higher aerial types, it is most like the lacertian columella ; but the true homologue of 

 that bone is the ascending or epipterygoid process. This corresponds to the " hamular 

 process of the internal pterygoid plate " of Man and the other Mammalia, and is the 

 apex of the secondary pterygo-palatine arch. 



In the Lizard the pedicle of the suspensorium is quite lost in the adult, the facet or 

 facets for the quadrate with the outstretched ear-sacs being formed on the " otic pro- 

 cess." In the Chelonia the otic process, instead of being solid as in the bird, is 

 hollowed out to form the large drum-cavity, the roof of which is largely formed by the 

 " tegmen tympani " and its bony roof-tile (the squamosal). 



The most instructive series of types for these comparisons would be found in this 

 order, namely Menobranchus, Dactylethra, Clielone, Dromceus, Tinamus, Tumix, Pipra, 

 Coccothrausfes. 



Such a comparison would yield much more than a view of the procession of the forms 

 of the palatine and mandibular regions ; the relations of the rest of the skull would 

 force themselves upon the mind of the observer. 



DESCRIPTION OF THE PLATES. 



PLATE LIV. 



Tumix rostrata (young). 



Fig. 1. Lower view of palate, x 4 diameters. 



Fig. 2. Upper view of face, X 4 diam. 



Fig. 3. First section of face, X 10 diam. 



Fig. 4. Second ditto, X 10 diam. 



Fig. 5. Third ditto, X 10 diam. 



Fig. 6. Fourth ditto, X 10 diam. 



Fig. 7. Fifth ditto, X 10 diam. 



Fig. 8. Vomer and cartilages, lower view, X 10 diam. 



Hemipodius varius. 



Fig. 9. Lower view of palate, X 4 diam. 



Fig. 10. Upper view of face, X 4 diam. 



Fig. 11. Side view of ditto, X 4 diam. 



Fig. 12. Tympanies and quadrate, X 4 diam. 



Fig. 13. Pterygoid and mesopterygoid of young, X 14 diam. 



