of Wirtemberg and Warwickshire. 



511 



base and less obtuse at the apex, resembling more the ordinary simple form of a 

 laniary tooth. The external surface of the Warwick sandstone tooth is similarly 

 impressed with fine longitudinal striae, continued with a very slight degree of con- 

 vergence towards the apex of the tooth, where the longest striae terminate. 



The interspaces of the striae are more prominent and convex than in the Laby- 

 rinthodon Jesgeri. The apex of the tooth, though rather obtuse, and worn by attrition 

 obliquely down one side, does not present the depression and central eminence 

 which Professor Jaeger describes as the chief characteristic of the larger tooth of his 

 salamandroid Labyrinthodon. This appearance in the tooth of that species may, 

 however, be due to the mode in which it has been worn down ; and we have just 

 seen that the tooth of the Labyrinthodon possesses a distinctive character of a very 

 different and much more important kind. 



It was in relation to this structural modification that I felt most anxious to exa- 

 mine the teeth from the Warwick sandstone. I could perceive indications at the 

 fractured basis of the larger tooth of fissures leading from the external striae into 

 the substance of the tooth, and the question was, were thpse fissures continued to 

 the same extent, and in the same convoluted course which they had presented in 

 the tooth of the Labyrinthodon of the German Keuper ? This I was unable to de- 

 termine by inspection of the fractured surfaces of the dense and opake tooth from 

 the Warwick sandstone, either by unaided vision or the use of the microscope with 

 reflected light. 



I solicited, therefore, and obtained permission from Dr. Lloyd, to have the re- 

 quisite sections made, selecting such a portion of the larger tooth as least inter- 

 fered with the exposition of its external form and characters. 



The subjoined cut (fig. 2.) faithfully exhibits the ap- Fig. 2. 



pearance which a portion of one of the transverse 

 sections presented, as seen by transmitted light ; the 

 complication of the structure of the tooth is as great 

 and its plan is the same as in the Labyrinthodon Jageri ; 

 all the peculiarities indeed of this most extraordinary 

 type of tooth are so clearly preserved in the specimens 

 from the Warwick sandstone, that I conclude it to 

 have belonged to a reptile of the same genus as that 

 which characterises the Keuper of Wirtemberg. 



The differences which remain to be noticed in the 

 tooth of the Warwick Labyrinthodon are of a compara- 

 tively slight and probably only of a specific nature. 



At the upper part of the tooth a thin layer of 

 enamel*', besides a coating of cement, is inflected at 



* I have subsequently ascertained that this is not true enamel 



3 u 2 



