LIMESTONES OF SOUTH DEVON. 389 



dolomites were not typical dolomites — that was to say, there were 

 only isolated aggregations and crystals of that mineral in the 

 limestone. As to the origin of the micro-crystals of quartz, there 

 could be no doubt that those in the Devonian Limestone had 

 originated from the decomposition of silicates. 



In reply to Dr. Hicks, the Author suggested that he should 

 examine his slides in which the tubular structures occurred, and he 

 thought that the evidence would be such that Dr. Hicks would 

 agree that the tubules were organic. 



He was much obliged to Prof. Eupert Jones and Mr. Etheridge 

 for the references to which thej^ had called his attention. 



