428 



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 Carinata3, 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 schizo gnathous 

 arrangement. In the Pas- 

 seres a similar arrangement 

 obtains, but the vomer is 

 broad and truncated instead 

 of pointed in front. This 

 gives the wgitho gnathous ar- 

 rangement. Lastly in the 

 Storks, Birds of Prey, Ducks 

 and Geese, &c., the maxillo- 

 palatines (Fig. 1066, mx.p) 

 fuse with one another in 

 the middle line, often giving 

 rise to a flat, spongy palate 

 and producing the desmo- 

 gnathoiLS 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 



process; Host. .rostrum ; _*. Oc. (^praoccipital) ; rnese thmoid, 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 



&o 



FIG. 1065. Apteryx mantelli. Skull of young 

 specimen, from below. The cartilaginous parts 

 are dotted. B. Oc. basioccipital ; B. ptg. pr. 

 basi-pterygoid process ; B. Tmp. basitemporal ; 

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

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

 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. premaxilla ; Ptg. pterygoid ; Qu. (orb. pr.) 

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

 (supraoccipital) ; 

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

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



