MESOPTERYGOID IN CERTAIN REPTILIAN SKULLS. 



459 



process. If Gaupp's observation be confirmed, the ossifications 

 must be regarded, I think, as the paired centres of the true 

 basisphenoid. In fact, if one looks at the basisphenoid of an 

 embryo lizard with its huge median fontanelle (cf. text-fig. 5), 

 it is difficult to see how it could be ossified except by lateral 

 ossifications if it is not completely ossified by invasion from the 

 pai-asphenoid. 



The other suggestion made by Watson, that the meniscus 

 pterygoideus found in Sphenodon by Howes and Swinnerton and 

 previously figured by Parker in the lizard is the homologue of 

 the little bones in '•'■ Seymouria^^ seems to me manifestly the 

 correct one. 



The bony element which forms the cranial base is regarded by 



Text-fiffure 7. 



The palate of the Rhipidistian Pish, Eustlienopteron foordi. After Biyant. 



The palate of the primitive Tetvapod Conodectes favosus Co-pe= Seiymouria 

 baylorensis Broili. After Watson. In the opinion of Watson, Williston, and 

 others this is a very primitive reptile : the writer favours the view that it is a 

 highly developed Embolomerous Amphibian. 



Watson as made up of parasphenoid in front and basisphenoid 

 behind. Though I have not seen the specimens, I incline to 

 think it probable that the whole will prove to be parasphenoid 

 or vomer. But, in any case, there seems to me no doubt that the 

 little intercalated element is the homologue of the little one 

 we have in the lizard and Sphenodon. 



When we go further down in the scale we have hitherto had 

 difficulties, as no good palate was known of any of the Rhipidistian 



