THE SKULL 299 



The most remarkable feature of this change is the fact that it 

 was effected without functional discontinuity. There was 

 never a time when, the quadrate and articular having been 

 drawn away into the service of the ear, the lower jaw had no 

 articulation with the upper, because, before this happened, the 

 dentary had already established connexion with the squamosal. 

 This new squamoso-dentary method of articulation, which is 

 peculiar to mammals, was in working order before the quadrate 

 and articular underwent their modification. 



Literature 



Gaupp, E. Die Entwicklung des Kopfskelettes. Hertwig's Handbuch 

 der Verg. und Exp. Entwickelungslehre der Wirbeltiere. Part 3. 

 Fischer, Jena, 1906. 



Goodrich, E. S. Vertebrata Craniata. Cyclostomes and Fishes. Black, 

 London, 1909. 



Gregory, W. K. Present Status of the Problem of the Origin of the 



Tetrapoda. Annals of the New York Academy of Sciences. Vol. 26. 



1915. 

 Huxley, T. H. Contributions to Morphology. Ichthyopsida. On 



Ceratodus forsteri. Proceedings of the Zoological Society of London, 



1876. 



Williston, S. R. The Osteology of the Reptiles. Harvard University 

 Press, 1925. 



