52 



ANATOMY OF VERTEBRATES. 



is a single bone, expands from before backAvard, and divides into 

 a superior and medial nasal process, ib. 22', and a pair of infero- 

 lateral maxillary processes, ib. 22 ; the interval between the nasal 

 and maxillary processes being the fore part of the outer bony 

 nostril. The nasal process indicates by a median slit or groove the 

 typical duality of the bone in the Gallince and a few other birds : 

 the maxillary process usually sends oif a ' palatal ' plate, fig. 32, 22. 



Skull of Emeu (Bromahis). 



The maxillary, figs. 27-32, 21, is a small and usually slender 

 bone, anteriorly expanded and engrained into the notch be- 

 tween the maxillary and palatal processes of the premaxillary : 

 usually imiting also with the nasal, and in some birds with the 

 lacrymal, 73, and vomer, 13 ; it then bifurcates posteriorly on the 

 horizontal plane to join the malar, 26, and the palatine, 20. The 

 palatine process sometimes developes from its upper surface a 

 turbinal structure. In the Rhea the palatine plate of the maxil- 

 lary is perforated : in the Emeu, Ostrich, Apteryx, and in most 

 birds, it is entire : it is of great breadth in the Night-jars ( Capri- 

 mulgus, Podargus), and is both long and broad in the Ajpteryx, 

 In Striithio and Rhea the maxillary sends upward a process to- 

 wards the nasal, the descending maxillary process of which is 

 wanting. 



The palatines, fig. 32, 20, articulate by a longitudinally grooved 

 mesial surface to the vomer, 13 {Emeit), more commonly to both 

 this bone and the presphenoid, or to the latter only : they give at- 

 tachment posteriorly to the pterygoids, 24 : they diverge as they 

 extend forward, developing a ' meatal ' plate mesially, which par- 

 tially bounds the posterior nostril, and a "^ muscular ' plate externally 

 for the attachment of the entopterygoideus ; they then extend for- 

 Avard, parallel or converging, to join the maxillaries, and some- 

 times also the vomer, and there complete the roof of the mouth. 

 In the StruthionidcB the ' palatal ' part is short aud broad ; arti- 



