12 ELEMENTARY SKETCH OF THE OSTEOLOGY OF BIRDS. 



Characters of the sTcull in different groups. — As the inferior 

 aspect of the skull has been taken by Professor Huxley as 

 affording characters for the classification of birds, it will be 

 necessary to go somewhat more fully into this portion. For 

 this purpose views of the inferior surface of the skull of four 

 birds have been given on plate II. These views exhibit the chief 

 types of modification to which the bones on this surface are 

 liable. 



Batitce. — In the division of birds known as the Ratitse (corres- 

 ponding to the old order or tribe Cursores., pi. II. fig. 5) the 

 vomer (vo.) is broad and cleft posteriorly, and usually supports the 

 posterior extremities of the palatines (pi.), and the anterior extre- 

 mities of the pterygoids (pt.), thus preventing either of these bones 

 from articulating with the sphenoidal rostrum. Strong processes, 

 carrying articular facets, and known as hasi-pterygoid processes 

 (b. pt.)j which arise from the body of the basi-sphenoid, and 

 not from the sphenoidal rostrum, articulate with facets, which 

 are placed near the postero-internal angles of the pterygoids 

 (pt.) The figured skull, which is taken as an example of 

 the Ratitian modification of palate, is that of the Emeu 

 {Dromceus nova-hollandits), 



Carinatoe. — In the other great division of living birds, known 

 as Carinatse, which comprehends all living birds which are 

 not Ratitse, four groups have been made from the characters 

 afforded by the palatal aspect of the skull, namely, (I.) Dromao- 

 gnathee; (II.) Schizognathce ; (III.) Desmognatkce ; and (IV.) 

 ^githognath<E. 



(I.) The group Dromasognathse* comprehends only the Tina- 

 mous {Tinamidce). The structure of the palate in these birds 

 is the same as that which occurs in the Ratitas, and therefore 

 needs no further notice here. 



(II.) The group Schizognathsef which comprehends most of 

 the old Cuvierian orders, Columbse, Gallinse (except TinamidceX) 

 GrallsB and Natatores is exemplified by the skull of the common 

 fowl, (pi. II., fig. ] ). The characteristic points of the palate of 

 this group are that the vomer (vo.), which may be either 

 large or small, is always pointed anteriorly, while posteriorly 

 it embraces the sphenoidal rostrum between the palatines (pi.) 

 The maxillo-palatine processes (mxp.) are usually elongated or 

 lamellar, and pass inwards over the anterior processes of the pala- 

 tines, (pi.), with which they unite, and then bending inwards along 



* From ^pofxaioS, the scientific name of the Emeu and yyadas, a jaw. 

 t From ffX'^*^ I cleave, and yvado?, a jaw. 

 % Turnix is said to be ^githoguathous. 



