1898.] osTBOLoax of the impbkm-bs. 975 



slowly brought into relation with the parasphenoidal rostrum. 1£ 

 the palatine be carefully removed, however, the spine-like anterior 

 end of the pterygoid will be found to run along the superior 

 border of the posterior limb of the vomer, though for a short 

 distance only. The condition of things which obtains here between 

 the pterygoid and vomer permanently is represented, more or less 

 perfectly, for a short time in the life-history of many, if not all, 

 Carinatse. 



But to return to the palatines. In Carinatse more or less 

 of the anterior region of the internal border of each palatine 

 articulates with the vomer — which, though still paired, is generally 

 more or less blade-shaped, and not, as in the Eatitae, depressed 

 and laterally expanded ; the remainder, meeting its fellow of the 

 opposite side below the parasphenoidal rostrum, runs back to 

 articulate with the pterygoid. Thus, in a ventral view of the 

 skull, the vomer lies wedged in between the palatines and appears 

 to be far removed from the pterygoids, having apparently been 

 thrust forwards by the approximation of the palatine toward 

 the middle line. Seen dorsally, however, in the young skull, the 

 internal palatine border is found to be still in part connected 

 with the vomer and in part with the pterygoid, as in Bhea — the 

 connection being made by means of the hemipterygoid. If this 

 connection is now in a vanishing quantity, it still undeniably 

 exists. 



The Mandible. — All the elements which take part in the formation 

 of the lower jaw are present (PI. LXI. figs. 1 & 3). The relations 

 between the coronoid and splenial most nearly resemble those of 

 the Crocodilia amongst the Eeptiles, the coronoid lying behind 

 the splenial. In its elongated form and superior size, however, 

 the coronoid differs from all the Reptilia, and resembles the rest 

 of the Aves. Within the Class, the form and relations of these 

 two bones one to another and to the neighbouring parts vary 

 slightly, and may prove to be characters of some value in systematic 

 work. In a young Gatarrhactes chrysocome, as shown in PI. LXI. 

 fig. 1, the coronoid extends from beldnd forwards as far as the 

 middle of the ramus. Its posterior end is expanded and closely 

 applied to the articular, from which, however, it can be clearly 

 distinguished. The splenial is a large lozenge-shaped lamina 

 lying in front of, and below, the anterior end of the coronoid. 

 The greater part of its superior border is overlapped by the 

 dentary. The articular is wedged in between the posterior ends of 

 the coronoid, on the inside, and the supra-angular and angular, on 

 the outside. The supra-angular runs forwards to join the dentary 

 at about the middle of the ramus. It is perforated, rather behind 

 its middle, by the posterior lateral vacuity. The angular underhes 

 the supra-angular, and forms the inferior border of the jaw from 

 the dentary backwards ; it appears on the inside, where it overlaps 

 the coronoid for some considerable distance. Its extreme anterior 

 end is concealed on the inside by the splenial, on the outside by 



