400 



ZOOLOGY 



SECT. 



processes are comparatively small, and do not unite with .one 



another or with the vomer. This arrangement of the bones of the 



- palate is called dromceogna- 



thous. 



In many Carinatse, e.g. 

 the Pigeon and the Fowl, 

 the basi-pterygoid processes 

 are either absent or spring 

 from the base of the rostrum. 

 The vomer is small and 

 pointed, or may be absent, 

 and the palatines articulate 

 posteriorly with the rostrum. 

 The maxillo-palatines do not 

 unite with one another. 

 These peculiarities charac- 

 terise the schizognathous 

 arrangement. In the Pas- 

 seres a similar arrangement 

 obtains, but the vomer is 

 broad and truncated instead 

 of pointed in front. This 

 gives the oegithognathdus 

 arrangement. Lastly in the 

 Storks, Birds of Prey, Ducks- 

 and Geese, &c., the maxillo- 

 palatines (Fig. 1005, mx.p\ 

 fuse with one another in 

 the middle line, often giving 

 rise to a flat, spongy palate 

 and producing the desmo- 

 gnathous arrangement. 



The most specialised form 

 of skull is found in the 

 Parrots (Fig. 1005 bis). In 

 many Birds the nasals and 

 the ascending process of the 

 premaxilla are very thin 

 and elastic where they join 

 the skull, and there is an 

 unossified space in the 

 mesethmoid, so that the 

 upper beak is capable of 

 a considerable amount of 

 movement in the vertical plane. In Parrots there is a true 

 joint between the upper beak and the skull, allowing of that 

 movement of the former which is so striking in the living- 



Oc.Cn. 



S.Oc 



FIG. 1004. Apteryx mantelli. Skull of young 

 , from below. The cartilaginous parts 



specimen, 

 are dotted. 



B. Oc. basi-occipital ; B. ptg. pr. 



basi-pterygoid process ; B. Tmp. basi-temporal ; 

 EC. Etli. ecto-ethmoid ; Eus. T. Eustachian tube ; 

 Ex. Col. extra-columella ; Ex. oc. ex-occipital ; 

 Int. car. carotid foramen ; MX. maxilla ; Nv. VII, 

 foramen for facial ; Nv. IX, X, for glossopharyn- 

 geal and vagus ; Nv XII, for hypoglossal ; Oc. en. 

 occipital condyle ; Oc. for. foramen magnum ; 

 Pal. palatine ; pa. oc. pr. par-occipital process ; 

 Pmx. pre-maxilla ; Ptg. pterygoid ; Qu. (orb. pr.) 

 orbital process of quadrate ; Qu. (of. pr.) otic 

 process ; Rost. rostrum ; S. Oc. (supra-occipital) ; 

 S. orb. F. supra-orbital foramen ; Sq. squamosal ; 

 Vo. vomer. (After T. J. Parker.) 



