414 



ZOOLOGY 



SECT. 



The skull of Birds is generally remarkable for its huge orbits 

 separated by a thin inter-orbital septum, and for the comparatively 

 small size of the ethmoid bone and its turbinals. The most striking 

 exception is afforded by the Kiwi (Apteryx), in which the orbits 

 (Fig. 1075) are small and indistinct, while the olfactory chambers 

 (Ec. Eth.} extend backwards between the eyes ; the orbits being 

 therefore separated from one another by the whole width of the 

 organ of smell. The same thing occurs, to a less degree, in the 

 Moas. 



In its essential features the skull is remarkably uniform through- 



Nvff.OT.IV 

 S.Orb.F 



JVv.VJl 



FIG. 1075. Apteryx mantelli. Skull of a young specimen, side view. The cartilaginous 

 parts are dotted. AL Sph. alisphenoid ; Anij. angular ; Cn. 1, en. 2, condyle of quadrate ; Dent. 

 dentary ; d. pr., d. pr. descending processes of nasal and frontal ; EC. Eth. ectoethmoid 

 Ex. col. extra-columella ; Ex. Oc. ex-occipital ; Fr. frontal ; Ju. jugal ; Lac. lacrymal ; lac. 

 for. lacrymal foramen ; Na. nasal ; na. ap. nasal aperture ; Nv. II, III, IV, optic foramen,^ 

 transmitting also the 3rd and 4th nerves ; Nv. V, foramen for orbito-nasal nerve ; Nv. VII, ' 

 for facial ; Pa. parietal ; Pal. palatine ; pa. oc. pr. par-occipital process ; Pmx. pre- 

 maxilla ; Pr. ot. pro-otic ; Qu. Ju. quadrato-jugal ; Qu. (orb. pr.) orbital process of quad- 

 rate ; S. Orb. F. supra-orbital foramen ; Sq. squamosal. (After T. J. Parker.) 



out the class. The rounded form of the brain-case, more or less 

 concealed externally by ridges for the attachment of muscles ; the 

 upper beak, composed mainly of great triradiate premaxillse ; the 

 single, small, rounded occipital condyle ; the slender maxillo- jugal 

 arch ; the large parasphenoidal rostrum ; the freely articulated 

 quadrate, with its otic, orbital, and articular processes ; the absence 

 of the reptilian post-frontals ; and the early ankylosis of the bones 

 all these characters are universal among Birds. There are, however, 

 endless differences in detail, some of which, connected with the 

 bones of the palate, are of importance in classification. 



In the Ratitae and the Tinamous (Crypturi) there are large basi- 

 pterygoid processes (Fig. 1076, B, ptg. pr) springing, as in Lizards, 

 from the basi-sphenoid, and articulating with the pterygoids near 

 their posterior ends. The vomer (Vo) is large and broad, and is 

 usually connected posteriorly with the palatines (Pal), which do 

 not articulate with the rostrum. The maxillo-palatine 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 drom.cBognathous. 



