1907.] TO THE OSTEOLOG'S OF BIRDS. 359 



Artamia is scroll-shaped, and attached to the floor of the chamber 

 and to the hoi'n of the bifurcate vomer. 



In Artcmius the chamber is much larger, and, as in Artamia, is 

 open behind. The septum nasi is perforate, placing the right and 

 left chambers in communication, in the dried skull. The concha 

 media is large, conch-shaped, and attached by its posterior end, 

 caudad of the tip of the vomer, to the extreme hinder end of the 

 vertical outer wall of the vestibule ; so that this turbinal lies above 

 the vomer, and is bounded mesially — at its posterior end — by an 

 upward, vei-tical, flange developed by the palatine. Corvinella 

 resembles Artamia in this matter ; and the same is true of 

 Gyimnorhina, but the concha media of each side is here attached 

 to the tips of the bifurcate vomer, while its wall is cribriform. 



The floor of the olfactory chamber, in the forms now under 

 discussion, demands a more detailed notice than is usually the 

 case with this region of the skull. 



In all save the Artamidse, Prionopidje, and Gymnorhidfe, this 

 floor is cartilaginous, so that, in the dried skull, there is a large 

 palatal foramen which is divided by a median partition — the 

 septum nasi. This, generally, has its free edge broadened by a 

 flange along each side, thereby reducing the size of the foramen. 

 In the exceptional cases this floor becomes completed by the 

 ossification of the nasal capsule in connection with the septum, 

 converting the palate into one of the desmognathous type. That 

 this desmognathism is caused by the ossification and fusion of the 

 inturned capsular wall of the vestibule with the inferior border of 

 the nasal septum, and not by the fusion of the maxillo-palatines 

 with the septum, is clear from a study of the palate of say Vireo- 

 lanitcs (text-fig. 102 e, p. 362), where this ossified capsule extends 

 backwards above the maxillo-jDalalines, or of the Prionopidte (e. g. 

 Prionops), where a narrow chink is left on each side of the septum 

 immediately in front of the vomer. In Paradisea the septum 

 descends as it were, so as to close up a median chink, left between 

 the right and left portions of the vestibular floor, while both floor 

 and septum are sharply truncated posteriorly, so as to impinge on 

 the maxillo-palatine process and the vomer (text-fig. 103 b). In the 

 Gymnorhidfe the vestibular floor meets beneath the nasal septum, 

 but it has not blended with the palatal surface of the premaxilla, 

 which presents a sharply defined posterior border into which the 

 ends of the palatines are thrust. 



The Premaxilla and N'asal. 



These bones present no characteristics sufficiently remarkable 

 to dwell upon here. Suflice it to say, that the palatal surface of 

 the premaxilla is often apparently increased by fusion with the 

 ossified nasal capsule, while the nasals are always holorhinal ; and 

 in some cases, as has already been pointed out, the form of the 

 nasal aperture has been altered by a similar ossification of this 

 capsule. 



In the Pittidfe and in Terpsiphone among the Muscicapse there 

 is a fairly well-developed nasal hinge. 



