^{page 316 note 1} See a similar case described by Mr. Rofe, Geol. Mag., Vol. VII., p. 5.

^{page 317 note 1} For example, during a brief visit to Cheddar last July, I did not come upon quite the right kind of rock, and only found two or three burrows—and these in a boulder—that satisfied me. It will not, however, surprise me if they are found there; for I had other matters in hand, and was too hurried to look carefully for them. Mr. Main, Lecturer in Chemistry at St. John's College, Cambridge, has kindly analyzed for me a fragment of the limestone from Derbyshire. He finds only 3·5 per cent of foreign matter, the rest, 96·5, being carbonate of lime.