428 



ZOOLOGY 



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 drommogna- 

 ihous. 



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. 

 Tlie maxillo-palatines do not 

 unite with one another. 

 These peculiarities charac- 

 terise the schiwgnatJwtis 

 arrangement. In the Pas- 

 seres a similar arrangement 

 obtains, but the vomer is 

 broad and truncated instead 

 of pointed in front. This 

 gives the mgithognathous ar- 

 rangement. Lastly in the 

 Storks, Birds of Prey, Ducks 

 and Geese, &c., the maxillo- 

 palatines (Fig. 1066, ma;. ^) 

 fuse witJi one another in 

 tlie middle line, often giving 

 ]ise to a flat, spongy palate 

 and producing the desmo- 

 gnatlious arrangement. 



The most specialised form 



of skull is found in the 



Parrots (Fig. 1067). 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 



S.Oc 



Fig. 1005.— Apteryx mantelli. Skull of young 

 specimen, from below. The cartilaginous parts 

 are dotted. S. Oc. busioccipital ; H. ptg. pr. 

 basi-pterygoid process ; B. Tmp. basiteroporal ; 

 Mr. Etk. ccto-ethmoid ; Bus. T. Eustachinn tube ; 

 Ej-.. Col. extra-columella ; Ex. oc. exoccipital ; 

 Int. car. carotid'forameu ; Mx. maxilla ; Nv. VII, 

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

 geal and vagus ; Nv. XII, for hj'poglossal ; Oc. en. 

 occipital condyle; Oc.for. foramen magnum; 

 TaU palatine ; 'pa. oc. pr. p.ar-occipital process ; 

 P)ax. premaxilla ; Ptrj. pterygoid ; Qu. {orb. pr.) 

 orbital process of quadrate; Qu.{ot.pY.) otic 

 pi-ocess ; Host, rostrum ; S. Oc. (supraoccipital) ; 

 ti. Orb. F. supra-orbital foramen ; Sq. squamosal ; 

 Vo. vomer. (After T. J. Parkei-.) 



