214 



Mr. W. K. Parker on the Structure and [Dec. 19, 



VI. " On the Structure and Development of the Skull in the 

 Lacertilia. Part I. On the Skull of the Common Lizards 

 (Lacerta agilis, L. viridis, and Zootoca vivipara)." By W. 

 K. Parker, F.R.S. Received October 18, 1878. 



(Abstract.) 



The youngest, and therefore the most important, embryos that have 

 been worked out in this present piece of research, were sent me, with 

 those of the snake, by Dr. Max Braun, of Wiirzburg. 



Other valuable specimens were the gifts of Professor T. Rupert 

 Jones, F.R.S. , and Professor Alfred H. Garrod, F.R.S. 



The three species worked out are closely related, and two of them 

 are native to this country : these familiar Sand Lizards are amongst 

 the smallest, and yet the most highly specialized, types, to be found 

 among the Reptilia. 



This type may be taken as a sort of " norma," and by it all the 

 other Lacertilia may be measured, as it were, when their height in the 

 Reptilian scale is to be determined. 



When such forms as Hatter ia and the chamaBleon are compared 

 with a typical Lacertian, then we see how much there is that is gene- 

 ralized in those outlying species. 



Putting together what I have learned as yet of the structure of the 

 skull in the true Reptiles, and comparing what is seen in these cold- 

 blooded Sauropsida with what is seen in the hot-blooded bird, I have 

 come to the conclusion that the common lizard is a culminating type. 



The snake, the tortoise, and the crocodile, notwithstanding their 

 own peculiar specializations, are yet more general in their nature 

 than the nobler and higher kinds of lizards : this is especially shown 

 by the number of characters that are, in the latter, in conformity with 

 those of the bird. 



And, indeed, with the high or Carinate bird ; for the skull of the 

 RatitaB (ostrich and cassowary) does not undergo, in several things, 

 so much metamorphosis as the skull of the typical lizard ; for, as I 

 showed long ago, these birds are not devoid of a Batrachian strain. 



Of all the lizards known to me the chamasleon is the lowest ; in 

 some respects the Chelonians come nearer the higher Lacertilia than 

 that hizarre type does. I have carefully worked out the skull in the 

 adult and the ripe embryo of the common kind, and in the adult of the 

 divarf species. 



In several things the lizard's skull is but little modified from that 

 of the snake ; this is especially seen in the nasal structure, its glands, 

 and the bones of its floor ; so largely illustrated in my last paper. 



These things are not repeated in the Chelonia and crocodiles, nor do 

 they exist in the chamseleon; but in many birds, especially the 



