LABYRINTHODONTIA. 



209 



longer than those of the Cmcilia, by a fossil reptile combining 

 therewith all the essential batrachian characters of the skull, 

 would not be sufficient ground for pronouncing such reptile to 

 be a lizard or crocodile. Much less could its saurian nature be 

 pronounced from the cir- 

 cumstance of its possessing 

 large conical striated teeth : 

 the ordinary characters of 

 size, form, number, and even 

 of presence or absence of 

 teeth, vary much in existing 

 Batrachians ; and the loca- 

 tion of teeth on the vomer- 

 ine bones is the only dental 

 character in which they 

 differ from all other orders 

 of reptiles. 



The writer's acquaintance 

 with the remarkable fossils 

 under consideration was be- 

 gun by the examination, in 

 1840, of portions of teeth 

 from the new red sandstone 

 of Cotton End quarry, War- 

 wickshire. The external 

 characters of these teeth 

 corresponded with those (fig. 

 86) which had previously -pig. 86. 



been discovered by ProfeS- Canine tooth of the Labyrinthodon Jayaeri 



sor Jaeger in the German ^ nat * slze '' 



Keuper formation in Wirtemberg, and on which the genus 



Mastodonsaurus had been founded. 



The results of a microscopic examination of the teeth of the 

 Mastodonsaurus from the German Keuper, and of those from 



