310 RAMBLES OF A GEOLOGIST. 



that my scepticism has thoroughly given way ; and that, slow- 

 ly yielding to the force of positive evidence, I have become 

 as assured a believer in the comminuted recent shells of the 

 boulder-clay as in the belemnites of the Oolite and Lias, or 

 the ganoid ichthyolites of the Old Red Sandstone. 



I had marked, when at Wick, on several occasions, a thick 

 boulder-clay deposit occupying the southern side of the har- 

 bour, and forming an elevated platform, on which the higher 

 parts of Pulteneytown are built ; but I had noted little else 

 regarding it than that it bears the average dark-gray colour 

 of the flagstones of the district, and that some of the granitic 

 boulders which protrude from its top and sides are of vast 

 size. On my last visit, however, rather more than two years 

 ago, when sauntering along its base, after a very wet morning, 

 awaiting the Orkney steamer, I was surprised to find, where 

 a small slip had taken place during the rain, that it was mot- 

 tled over with minute fragments of shells. These I examined, 

 and found, so far as, in their extremely broken condition, I 

 dared determine the point, that they belonged in such large 

 proportion to one species, the Cyprina islandica of Dr Fle- 

 ming, that I could detect among them only a single frag- 

 ment of any other shell, the pillar, apparently, of a large 

 specimen of Purpura lapillus. Both shells belong to that 

 class of old existences, long descended, without the pride 

 of ancient descent, which link on the extinct to the recent 

 scenes of being. Cyprina islandica and Purpura lapillus 

 not only exist as living molluscs in the British seas, but they 

 occur also as crag-shells, side by side with the dead races that 

 have no place in the present fauna. At this time, however, 

 I could but think of them simply in their character as recent 

 molluscs ; and as it seemed quite startling enough to find them 

 in a deposit which I had once deemed representative of a 

 period of death, and still continued to regard as obstinately 

 unfossiliferous, I next set myself to determine whether it really 



