Figures to illustrate Structure of Palate. 



Pmx. 



Under view of the skull of Charadrius plu- 

 vialis, to illustrate the schizognathous type 

 of palate. 



Under view of the skull of Cuculus canorus, 

 to illustrate the desmognathous type of 

 palate. 



These two figures are copied by permission from the late Prof. Huxley's paper on the 

 Classification of Birds (P. Z. S. 1867, pp. 427, 444). Pmx, the preuiaxilla; MX, the maxilla; 

 Mxp, its maxillo-palatine process ; PI, the palatine bone ; Vo, the vomer ; Pt, the pterygoid ; 

 Qu, the quadrate bone ; X the basipterygoid process ; * the prefrontal process . 



" In the large assemblage of birds belonging to the Ouvierian orders Gallinae, Grallae, and 

 Natatores, which may be termed Schizognathous, the vomer, sometimes large and sometimes 

 very small, always tapers to a point anteriorly; while posteriorly it embraces the basi- 

 sphenoidal rostrum, between the palatines. 



" The maxillo-palatines are usually elongated and lamellar; they pass inwards over the 

 anterior processes of the palatine bones, with which they become united, and then bending 

 backwards, along the inner edge of the palatines, leave a broader or a narrower fissure 

 between themselves and the vomer and do not unite with it or with one another." 

 HUXLEY, P. Z. S. 1867, p. 426. 



" In Desmognathoiis birds the vomer is often either abortive, or so small that it dis- 

 appears from the skeleton. When it exists it is always slender and tapers to a point anteriorly . 



" The maxillo-palatines are united across the middle line, either directly or by the inter- 

 mediation of ossifications in the nasal septum. 



" The posterior ends of the palatines and the anterior ends of the pterygoids articulate 

 directly with the rostrum, as in the preceding division" [and not with the diverging posterior 

 ends of the vomer as in Dromaeognathous birds and generally in Ratitae]. HUXLEY, /. c. p. 435. 



In the JZgithognathous type of palate (figured Vol. I. of the present work, p. 4), " the 

 vomer is a broad bone, abruptly truncated in front, and deeply deft behind, embracing the 

 rostrum of the sphenoid between its forks. The palatines have produced postero-external 

 angles. The maxillo-palatines are slender at their origin, and extend inwards and backwards 

 obliquely over the palatines, ending beneath the vomer in expanded extremities, which do not 

 become united by bone, either with one another or with the vomer." HUXLEY, 1. c. p. 450. 



