OSSEOUS SYSTEM OF AVES. 53 



culates laterally with the maxillary, and, as it retrogrades, ex- 

 pands, mesiad, to abut upon the presphenoid {Struthio) or hind 

 part of the vomer (^Dromaius, fig. 32, is), and to articulate with 

 the pterygoids : the palatines nowhere meet in the median line, 

 and the meatal process is wanting. In the Apteri/x the palatines 

 coalesce anteriorly with the maxillaries, posteriorly with the pte- 

 rygoids, have a straight outer and a concave inner border, from 

 wliich, posteriorly, is continued the ^ meatal ' plate curving inward 



Skull of Emeu iDroviaiiis). 



and forward, obliquely, about the hind part of the meatus, and 

 applying itself mesiad to the vomer and presphenoid. In Nata- 

 tores, and most Grallatores, the palatines meet each other poste- 

 riorly, for a short extent, before diverging as they advance to 

 bound posteriorly the palatine nostril. In the PelecanidcE the 

 mesial union is extensive beneath the 2:)resphenoid and vomer. 

 In Tinamus the palatines join behind; they there touch each 

 other for a shorter extent in ColumhidcB ; but in most Gallinacea 

 they are kept apart by the presphenoid. In Podargus and some 

 other Fissirostrals the palatines are short and broad, and exten- 

 sively joined together behind the small palatal nostril. In Rap^- 

 tores the palatines meet behind beneath the presphenoid and 

 vomer : the meatal plate developes a ridge, descending, to increase 

 the concavity of the entopterygoideal surface, the outer border of 

 which also descends ; and these carinal boundaries of that surface 

 are found in many birds. The extent of the palatine plate varies 

 in diiFerent birds ; it is largest in StruthionidcB, large in Raptores, 

 and least in the Gallin(E : in the Tinamous and Pigeons it is of 

 moderate size. In the Emeu it has a large vacuity ; ^ it is per- 

 forate in Tinamus, and in some Grallatores. 



The pterygoids, figs. 27, 32, 24, articulate with the outer 

 and hinder angles of the palatines by a squamous overlapping 



' XTi-. vol. iii. pi. 39, fig. 2, 20. 



