at Pounceford, in Sussex. 607 



The shells found in such abundance in these strata belong, 

 for the most part, for the genus Cyclas (Cyclas membranacea 

 and media forming entire beds). In some specimens of ' rag- 

 ged bole ' I collected from some heaps of rubbish on the road- 

 side, near Burwash Wheel, I found several individuals of a 

 beautiful little species of the spiral genus Melanopsis or 

 Melania. Mantell mentions (Geol. South-East of England, 

 p. 227.) having collected with Mr. Lyell on the quarries at 

 Swife's Farm, just about a mile to the right of Pounceford, spe- 

 cimens of the genus ikfytilus from the shale : undescribed 

 species of Corbula and Zellina also occasionally occur. — 

 These two last, as well as the ikfytilus, are, I believe, con- 

 sidered marine ; the existing species of these genera in- 

 habiting the sea-coast. The presence of a few marine shells, 

 however, will not, as De La Beche most justly observes # , 

 invalidate the general testimony in favour of a lake, river, or 

 estuary; "for not only may these shells have been intro- 

 duced accidentally, but the animals inhabiting them may also 

 have been gradually accustomed to live in fresh or estuary 

 waters, as is the case, in the present day, with the species of 

 some genera usually considered marine." {Manual of Geology, 

 p. 305.) 



Among other instances of this interesting fact, I may cite, 

 from my own observation, that noble sheet of water, the 

 Albufuera, near Alcudia, in the beautiful island of Majorca, 

 separated from the sea by a shingle bank, through the pebbles 

 of which the salt water percolates, the water of which I tasted, 

 and found extremely brackish and unpleasant, — where a great 

 variety of freshwater fish are, I was told, found. In a stream 

 communicating with the Albufuera, about four miles up the 

 country, several eels, natives of that lake, were caught in my 

 presence, which I and my guide afterwards cooked and had for 

 supper : we found them most delicious eating. 



There are three workmen employed on this quarry, who 

 are paid by the day : they work ten hours, and extract daily 

 four square yards of limestone, containing about a hundred 

 bushels of lime. A kiln, containing eight hundred bushels of 

 lime, takes thirty-four hours in burning; and two hundred 

 fagots are consumed in each kiln ; a bushel of lime costs six- 



* The experiments of M. Beudant have shown that, if freshwater Mol- 

 lusca be suddenly introduced into sea water, they die in a very short time ; 

 but, if the fresh water be gradually impregnated with salt, they will live in it 

 when of the strength of sea water, withoutany injury : the same experiments 

 repeated on fresh water Moll u sea gave similar results. See Annals de Chim. 

 et de Physique, t. 2. p. 32. 



u u 4 



