878 



SKULL 



fuse with the Prsemaxillary, Nasals, Palatines and Jugals, frequently 

 also with the Vomer and Lacrymals. Each Maxillary is usually 

 pyramidal in shape, having an outer, inner and ventral surface, the 

 anterior corner of which joins the Praemaxilla, the posterior the Jugal. 

 and the dorsal the descending process of the Nasal. It varies much 

 in size : very small in the Gallinse, it is in the Ardex next to the 

 Prsemaxilla the most conspicuous bone of the Skull. Inwardly 

 each Maxilla sends out a more or less horizontal transverse process, 

 the proc. 7iiaxillo-palatinus, of which more presently. 



The so-called Palatines are long, and for the most part flat 

 and horizontally-placed bones, always fused at their anterior end 

 with the Prsemaxilla, and frequently with the ventral surface of 

 Maxillse and their maxillo-palatine process, just mentioned, while 

 posteriorly they rest movably on the Prsesphenoid rostrum, articu- 

 lating also, in most Birds, with the anterior end of the Pterygoids. 

 The Palatines form the greater portion of the palatal roof of the 

 mouth, and border the CHOAN^ (p. 87) or inner narial openings. 



The Vomer, a median bone, rests on the Praesphenoidal rostrum, 

 and to the ventral view appears between the Palatines. It is very 

 variable in shape and size, being wholly absent or reduced to a 

 mere trace in the Gallinse, Pterodidse, Columhse, Fsittaci, Musophagidse, 

 Alcedinidss, Todidm, Coliidss, Upupidse and Bucerotidse, while it is 

 small in the Coraciidai and Meropidx. In Pici it is secondarily re- 

 solved into a right and left half, which in Galhulidse and Bucconidx 

 are very much reduced in size.^ 



^ On the various bones of the palate, Prof. Huxley based his classification of 

 CARINAT.E, published in 1867 (see Introduction), dividing them into four 

 sub-orders — DROM^OGNATHiE, Schizognath^, Desmognath^ and J2githo- 

 GNATH^. As details of the cranial structure have become better known, many 

 additions to and corrections of the original scheme have been rendered necessary, 

 chiefly through the labours of Parker, Garrod and Forbes, Profs. Magnus and 

 Fiirbringer and Dr. Shufeldt. Doubtless the most primitive formation is the 

 Schizognathous, whence has arisen the Desmognathous — either by direct 

 approach of the Palatines in the middle line, or by the help of the Ethmoid 

 and internasal septum. Desmognathism therefore does not necessarily imply 

 blood-relationship, but has been reached independently in various groups, while 

 a like consideration applies to the jEgithoguathous feature, which is also derived 

 from earlier Schizognathous conditions. Thinocorys and 7'urnix, for instance, 

 are incompletely iEgithognathous, and the same may be said of Ilenura, while 

 the hulicatorldai and the Cypselidae, are as completely .ffigithognathous as the 

 true Passeres, exclusive of the Schizognathous Furnariinm. Among certain 

 Fasseres, such as Gymnorhina, Faraxlisea, Artamus, De7id7-ocolaptes, Thamno- 

 phihis and Fhytotoma, what may be called compound iEgithognathism prevails, 

 in that fusion of the Palatines with each other at their anterior end and with 

 the internasal septum leads to a sort of Desmognathous condition. 



According to our jiresent knowledge, the following forms and groups are 

 Schizognathous : — Struthio, Aptcryx, Cryp>iuri, Sphenisci, Tuhinares, Colymhi, 

 Fodicipedidas, Alcidee, Laridm, Limicolaa (excl. ThiTwcorys above named), Ptero- 



