466 



The first group, the Dromoeognathous birds, contained only the 

 single genus Tinamus "which has a completely struthious palate". In 

 using the term in a descriptive sense as is done in the table below, the 

 dromoeognathous birds therefore comprise not only the tinamous but 

 also the struthious birds. 



The second group, the Schizognathous birds, were divided into six 

 sub-groups but the term applies equally well to them all and, as used 

 here, includes the whole six sub-groups. 



The third group, the Desmognathous birds, were divided into seven 

 sub-groups and the term is employed below to include these seven sub- 

 groups. 



At the end of this group an exceptional sub-group the Celeomor- 

 phae, of doubtfull position, was discussed and it was concluded that, 

 although possessing some points in common with the last sub-group of 

 the desmognathous birds, on the whole the Celeomorphae were best re- 

 garded "as an aberrant group of the Aegithognathae" (Huxley, loc. 

 cit. p. 468). Parker in 1872 (4) pointed out the importance of this 

 isolated sub-group and proposed to raise them to the rank of a group 

 equal to the others under the name of the "Saurognathae" "a name 

 which shall be a memorial of their Lacertilian facial morphology" 

 (Parker 5, p. 2). In the table given below the term saurognathous is 

 applied to the type of skull met with in this group. 



The fourth group, the Aegithognathous birds, were divided into 

 two further sub-groups and this term as used below comprises only 

 these two sub-groups and not the Celeomorphae. 



It only remains now to define the terms as used in the table. The 

 definitions have been adapted from the works of Huxley (2) and Par- 

 ker (4 and 5) and also Newton (3) and Beddard (1). 



The Dromoeognathous type. The vomer is very broad. At 

 its anterior end it meets the maxillo - palatine plate of the maxilla 

 while at its posterior end it is met by the posterior extremities of the 

 palatines and the anterior ends of the pterygoids 1 . Thus the palatines 

 and pterygoids do not articulate with the basisphenoidal rostrum as in 

 the remaining groups. 



The Schizognathous type. The vomer, which may be large or 

 small, tapers to a point at its anterior end while its posterior end em- 

 braces the basisphenoidal rostrum between the palatines. The palatines 

 and pterygoids articulate directly with one another and with the basi- 



1 This is not the case 'in Stndhio where the vomer is short and is not met by 

 the palatines and pterygoids. These latter however do not articulate with the basi- 

 sphenoidal rostrum so that the skull is truly dromoeognathous. 



