FOSSIL TEETH. 



641 



characters frequently enables the Microscopist to determine the 

 nature of even the most fragmentary specimens, with a positive- 

 ness which must appear altogether misplaced to such as have 

 not studied the evidence. 



452. It was in regard to Teeth, that the possibility of such de- 

 terminations was first made clear by the laborious researches of 

 Prof. Owen ;* and the following may be given as examples of 

 their value : A rock formation extends over many parts ot 

 Russia, whose mineral characters might justify its being likened 

 either to the Old or to the New Red Sandstone of this country, 

 and whose position relatively to other strata is such, that there is 

 great difficulty in obtaining evidence from the usual sources, as 

 to its place in the series. Hence the only hope of settling this 

 question (which was one of great practical importance, since, if 

 the formation were new red, Coal might be expected to underlie 

 it, whilst if old red, no reasonable hope of coal could be enter- 

 tained) lay in the determination of the Organic remains which 

 this stratum might yield ; but unfortunately these were few and 

 fragmentary, consisting chiefly of teeth, which are seldom per- 

 fectly preserved. From the gigantic size of these teeth, together 

 with their form, it was at first inferred that they belonged to 

 Saurian Reptiles, in which case the sandstone must have been 

 considered as New Red ; but microscopic examination of their 

 intimate structure unmistakably proved them to belong to a 

 genus of Fishes (Dendrodus) which is exclusively Palaeozoic, and 

 thus decided that the formation must be Old Red. So again, the 

 microscopic examination of certain fragments of teeth found in 

 a Sandstone of Warwickshire, disclosed a most remarkable type 

 of tooth-structure (shown in Fig. 344), which was also ascertained 

 to exist in certain teeth 



that had been discovered Fl - 344. 



in the " keuper-sandstein" 

 of Wirtemberg; and the 

 identity or close resem- 

 blance of the animals to 

 which these teeth belonged 

 having been thus establish- 

 ed, it became almost cer- 

 tain that the Warwickshire 

 and Wirtemberg sand- 

 stones were equivalent for- 

 mations, a point of much 

 geological importance. 

 The next question arising 

 out of this discovery, was 

 the nature of the animal 

 (provisionally termed La- 

 byrinthodon, a name expressive of the most peculiar feature in its 



of Tooth of Labyrinthodon. 



1 See his magnificent u Odontography." 

 41 



