PHYLOGENETIC 45 



exhibited by the Struthious birds and that of the " Carinate " 

 or flying birds, such as is seen in the Fowl, for instance, there 

 appears to be a very wide gap. 



A study of the palate of the nestlings of the ' Carinate " or 

 Neognathine group, however, will show conclusivel)- that this 

 gap is apparent only, and not real. In the skull of the }'Oung 

 Penguin, for example, the palatine and the pterygoid articulate, 

 not by a joint, but by overlapping suture ; the pterygoid termin- 

 ating, moreover, in a spike which just reaches the forked ends 

 of the vomer ; so that, in so far as this contact between vomer 

 and pterygoid is concerned, Carinate and Struthious birds agree. 

 But as growth proceeds the pterygoid segments, at a point 

 corresponding with the level of the hinder end of the palatine, 

 and shortly after this segmentation the spike-like anterior ex- 

 tremity of the pterygoid fuses with the palatine on which it 

 rests, while a true joint is formed between the segmented sur- 

 faces. When this process is complete, all record of the earlier 

 connection between vomer and pterygoid is lost, so that the 

 palate appears to differ fundamentally from that met with in 

 the Struthious birds. In some other species, as for example 

 in the Petrels, the joint formed after the segmentation of the 

 pterygoids is formed between the pterygoid on the one part 

 and the pterygoid and palatine on the other : that is to say, 

 the anterior end of the pterygoid segments at the level of the 

 hinder end of the palatine instead of tail-wards of this point 

 (compare illustrations.) 



These two types of palate have been named by the author 

 the Struthious " Palaeognathine" and the Carinate " Neogna- 

 thine". Concerning the latter more must be said later: for 

 the present it is sufficient to point out the fact that the one has 

 been derived from the other — the Neognathine from the Palaeo- 

 gnathine. 



But this by way of a digression. We must return to the 

 question of the relationship of these Palseognathine forms one 

 to another. Owing to the paucity of material this is a peculiarly 

 difficult problem, and one which, for the present at least, must 

 be regarded as unsolved. That the Emu represents the most 

 primitive member of the group few will doubt. And with the 

 Emus we must reckon the Cassowaries. The Ostrich of Africa 

 is probably nearly related. In the palate it shows degenerate 



