151 



thickness throughout the field, they represent a quantity of more 

 than one hundred and sixty-nine million tons, or, deducting 50 per 

 cent, for working, a yield of 900,000 tons per annum for ninety- 

 four years. 



The cost of working, including royalties, would be about six 

 shillings and sixpence per ton, the selling price seven shillings and 

 three pence at the pit's mouth. 



I am indebted to ^r. P. S. Tleid for much of the information 

 contained in this part of my lecture, and to Mr. F. Brady for the 

 report of the Dover boring. 



History repeats itself. The long expired furnaces of the 

 Weald may glow once more, not witli the fuel of its forests, but 

 with that of the carboniferovis period, now proved to exist 2,000 

 feet beneath East Kent, so that Dover may rival Newcastle, and 

 Canterbury Birmingham. 



XXXV. 



NOTES ON THE FRESH WATER POLYZOA OF 

 THE DISTRICT. 



BY 



GEORGE DOWKER, F.G.S. 



The past season has been favourable for the fresh water 

 Polyzoa, and I have met with the following species in the Isle of 

 Thanet and the ilinster Marshes and neighbourhood of the Stour. 



Cristatella mucedo was found abundantly and in large 

 colonies in the Minster Stream in the Autumn of 1894 and again 

 in 1895 ; in most cases they were attached to Potamogcton tiatans, 

 in a slow moving stream or sewer. In the same place Fredericella 

 mltana was met with but not in so great abundance. Alcyonella 

 fungosa frequents the Reed Ponds, near Richborough, and large 

 masses are met with surrounding the reeds. 



Plumatella repens was found in great abundance in the small 

 ponds on the higher ground in the Isle of Thanet, and in similar 

 localities, Plumatella coralloides, and perhaps other species. 



Lophopns chrijstallinus we have not found here, but a few 

 years ago it was met with in great abundance in running water 



