PHYLOGENETIC 



31 



are arranged on the same general plan as those of the reptile. 

 In so far as the bones of the palate are concerned, this can be 



III. 8. — Skulls of Nestling Penguin (I.) and Emu (II.) to Show the 

 Suture Dividing the Separate Elements of the Cranium 



The quadrate has been displaced in the case of the Penguin to show the 

 base of the skull. These should be compared with that of Sphenodon, III., IV., 

 the most primitive living Reptile. 



Al. = Alisphenoid.' P. = Parietal. F. = Frontal. Sq. = Squamosal. S.o. 

 = Supra-occipital. Q. = Quadrate. Qj. = Quadrato-jugal. Pt. = Pterygoid. 

 Pa. = Palatine. Pm. = Premaxilla. Pt.f. = Post frontal. L. = Lachrymal. 

 N. = Nasal. Jug. = Jugular. Max. = Maxilla. Vo. = Vomer. 



readily demonstrated at all ages in the bird's life-history ; but 

 this is not the case with the cranial bones, that is to say, with 

 the elements which make up the brain case, inasmuch as these 

 rapidly coalesce after birth obliterating all traces of their separate 



