THE MICROSCOPE IN GEOLOGY. 121 



bones, the dermal skeleton of vertebrate animals, will 

 enable the microscopist to name the animal to which 

 the parts belonged. You are, of course, aware that 

 the different strata are more or less characterised by 

 the organic remains which they contain. In some 

 cases the strata may be so similar in composition, that 

 it is impossible to determine its position on the geo- 

 logical chart in the absence of organic remains. Many 

 thousand pounds would have been saved to the 

 pockets of certain land proprietors had they con- 

 sulted the geologist or microscopist before they sank 

 shafts for coal in beds which could not possibly con- 

 tain any. Extending over many parts of Russia, there 

 occurs a certain rock formation, whose mineral cha- 

 racters might justify its being likened either to the 

 Old or 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. The nature of 

 this formation could be determined by the organic 

 remains which it might yield, but in this case they 

 were few and fragmentary, and consisted chiefly of 

 teeth which were seldom found entire. It was at first 

 supposed from the great size of these teeth, that they 

 belonged to Saurian reptiles ; hence the formation 

 must have been considered New Red. External form 

 may be deceptive ; so recourse was had to a micro- 

 scopic section of the tooth, the result of which was to 

 show that it belonged to an undoubted fish, called, 

 from the dendritic disposition of the tissues, by the 

 name of Dendrodus. This decided the all-important 

 point, for as the genus Dendrodus is exclusively 

 Palaeozoic, the rock in question belonged not to the 

 New, but to the Old Red formation ; therefore there 

 would be no possibility of finding coal in it. 



You will be interested in another similar case. The 



