FISH-REMAINS OF THE CAEBONIFEROUS ROCKS. 87 



portance of always recording at once the locality from which 

 any fos.sil is obtained. The name is comparatively im- 

 material ; that can be supplied later. But a record of the 

 locality is of essential importance. In view of the interest 

 of this specimen, whether, as we confidently believe, it is 

 local or not, wq have inserted a figure, drawn by Mr. 

 Edwin Wilson, twice the natural size of the tooth. 



This completes the list of Elasmobranch families which 

 ai'c represented by their teeth in the lower carboniferous 

 rocks in the Bristol district. We shall give a table of the 

 genera and species after we have briefly described (1) the 

 minute structure of the teeth and (2) the Ichthyodorulites. 



To examine the minute structure of some of the teeth 

 we have made a series of sections and slices, polishing the 

 former for examination with a hand lens, and mounting the 

 latter for microscopic examination. A polished section of an 

 Orodus tooth exhibits to the naked eye a base somewhat 

 irregularly eroded, surmounted by^the curved crown. The 

 whole of the basal part is stained a deep red with oxide of 

 iron ; but the upper part is a dull white, streaked with red 

 where the vascular canals pass through it towards the sur- 

 face. Examined with a lens, the basal part is seen to have 

 a spongy or net-like structure, the strands of which represent 

 the calcified cartilage, while the hollows were probably 



