No. 498] THE CAUDATE AMPHIBIA 367 



bones paired in the median line: the premaxillae, the 

 nasals, the frontals, the parietals, and on the posterior 

 end of the skull occur the exoccipitals. In this series it 

 is clear that the supraoccipital elements have disap- 

 peared. Lateral to the median paired row there are the 

 maxilla, the prefrontal, the squamosal, and in allied forms 

 the jugal, quadratojugal and quadrate. The epiotic is 

 wanting in all skulls of modern amphibians except some 

 coccidians and the elements are not so firmly united as 

 in the skull of the Branehiosauria. The skull of the 

 Caudata exhibits a weaker, more degenerate condition, 

 than is found among the early forms. The lower sur- 

 face of the skull is practically the same in the two groups, 

 especially in the possession of a large parasphenoid. Teeth 

 on the palate bones are lacking, for the most part, in the 

 modern form-, which is another evidence of degeneracy. 



If the structure of the vertebra 1 is now examined it will 

 be seen that in this particular there is close affinity 

 between the modern Caudata and the Paleozoic Branehi- 

 osauria. The vertebra 1 of the modern Caudata are 

 amphiccrlous and opisthocnplous, with the notochord rarely 

 persistent and with the transverse processes springing 

 off boldly from the body of the centrum. Similar condi- 

 tions are observed in the Branehiosauria where the ver- 

 tebra?, so far as they are known, are arnphiccelous and the 

 transverse process is unusually strong with the notochord 

 probably persistent. The transverse processes give sup- 

 port to the short, heavy, stout ribs which lay in the flesh 

 and made acute angles posteriorly with the vertebral 

 column. The ribs in the Branehiosauria and in the later 

 Caudata are indistinguishable so far as form is con- 

 cerned. The point of difference is that in the modern 

 forms the ribs are usually weaker posteriorly and are, 

 for the most part, confined to the presacral region of the 



