206 LABYRINTHODONTS. 



With the kind permission of Dr. Lloyd, 1 took a thin transparent 

 transverse section from the middle of the tooth, corresponding with 

 the place of the section from the German tooth above described : 

 at PI. 64 B, fig. 2, is shown the structure of the tooth of the British 

 Labyrinthodon as seen by transmitted light in one half of the 

 transverse section : the complication of the interblended laminae of 

 dentine and cement is as remarkable, and its plan is the same as in 

 the tooth of the great Labyrinthodon of the German Keuper. 

 All the peculiarities, indeed, of this most extraordinary tj'pe of 

 dental structure are so closely preserved in the specimen from the 

 Warwick sandstone, that generic identity, at least, may be predicated 

 of the fossils from both localities. 



The differences which require to be noticed are such as might 

 be expected in distinct species of the same genus. The inflected folds 

 of cement in the Warwick tooth are continued for a greater relative 

 extent before the lateral sinuosities commence, than in the German 

 reptile, and the inflections or anfractuosities are rather fewer in 

 number ; some of the inflected converging folds in the Warwick 

 tooth, having nearly reached the central pulp-cavity, are reflected 

 backwards for a short distance before they terminate. 



The modifications of the complex diverging plates of dentine 

 correspond with those of the tooth of the Labyrinthodon Jaegeri ; but 

 their terminal quadrilateral lobes, as seen in the transverse section, 

 are relatively longer. 



The number of the inflected folds of cement is equal to that 

 in the Lab. Jaegeri and varies in the same degree at diflerent 

 parts of the tooth ; thus the folds which reach longitudinally to 

 near the apex of the tooth extend inwards to near its centre in 

 the section figured, and the shorter folds are inflected to a less 

 extent proportionate to their diminished length. 



The dentine is composed of calcigerous tubes of the same 

 relative size and disposition as in the Labyrinthodon Jaegeri. The 

 base of the tooth appeared to have been similarly anchylosed to the 

 osseous substance of the jaw. 



After having adduced this evidence of the affinity of the fos- 

 sils of the German and British sandstones, I concluded by stating 



