CHANGE OF HABITS IN ANIMALS 



415 



have been removed in 1912 from a quarter of a mile of water 

 main, conducting unfiltered water, at Hampton-on-Thames. 

 There the solid growths of the shell-fish on the inner surface 

 of the pipe had reduced the diameter from thirty-six inches 

 to nine inches. From various supplies in Scotland, I have 

 seen odd samples of Hair Worms (Gordiidae), Freshwater 

 Shrimps, and Water-fleas, while tangled masses ofPaludicella 

 articiilata, some pieces of Freshwater Sponge (Spongilla 



Fig. 68. Zebra Mussels from a mass of some 90 tons removed from a water-main 

 at Hampton-on-Thames. Almost natural size. 



lacustris), a few young specimens of a Freshwater Snail 

 (Lwm&a peregra), and some larvae of Gnats (Chironomus) 

 were received by Dr S. F. Harmer from Aberdeen water- 

 works in March 1913. 



THE FAUNA OF A COAL PIT 



Coalpits are as artificial in their origin as are waterworks, 

 yet they also have become tenanted by a fauna of their own, 

 whose members live and multiply and die at great depths, 



