416 



ZOOLOGY 



SECT. 



and the palatines are articulated 

 in front with the premaxilla, and 

 together push it upwards ; in 

 this way depression of the lower 

 produces an automatic raising of 

 the upper jaw. The great size 

 and strength of both premaxilla 

 and mandible are remarkable, as 

 also is the fact that the orbit is 

 completely surrounded by bone, 

 a backward process of the lacry- 

 mal being joined beneath it by a 

 forward process of the frontal. 



The mandible contains in the 

 young Bird the six bones on each 

 side characteristic of Reptiles ; 

 the coronary is, however, often 

 absent. As a rule the head of 

 the quadrate articulates with the 

 roof of the tympanic cavity by 

 a single facet in Ratitae, by a 

 double facet in Carinatae. The 

 FIG. 1077. Anas boBchas (Duck). Ventral hyoid always agrees in essential 



view of Skull, a. p. f. anterior palatine rt **-nt*n+* w ;fh fTiat nf HIP Pio-Pnn 



foramen ; b. o. basi-occipital ; b. pg. basi- respects Wltn tnat OI tne rigeon , 



pterygoid process ; 6. 8. basi-sphenoid ; b. t. m the "Woodpecker the posterior 

 basi-temporal ; e. o. ex-occipital ; eu. aper- 



ture of Eustachian tube ; /. m. foramen COHlUa are CUTVed round the 



nSSi m ; : if' " T^.'TaS: head and attached to the skull in 

 SS5r;. : . e ^? t iS!f^ &* neighbourhood of the right 



premaxilla; q. quadrate; qj. quadrato- nostril, a Very flexible and Pro- 



jugal ; v. vomer ; IX, X, loramen for , ., ,' J , . r -. 



ninth and tenth nerves ; XII, for twelfth trUSlble tongue being produced. 

 nerve. (From Wiedersheim's Vertebrata.) ^ strilc ture of^the shoulder- 



girdle furnishes one of the most fundamental distinctive characters 



between Ratitae and 



Carinatae, but, as 



with the sternum, 



the differences are 



adaptive and not of 



phylogenetic signifi- 



cance. In most Cari- 



natae both coracoid 



and scapula are large 



and united with one 



another by ligament ; 



the coracoid has an 



acrocoracoid and the 



scapula an acromion 



process ; the coraco- 



ria ' 1 78 - sk < 



<From * Ph0t 8rap " " y 



