594 Dr. DAvBENY on a certain Kind of 
the genial temperature and mineral constitution of the water that 
flows over it, than to understand the production of Alge on the 
abrupt escarpment of a cliff exposed to the waves of the sea. 
It would be natural to inquire, what degree of resemblance 
this product of warm sulphuretted springs may bear to that 
which Mr. Dillwyn has described, under the name of Conferva 
nivea*, as peculiar to the cold sulphureous waters of various 
parts of England and Wales. The latter was first discovered 
by Dr. Willant in the sulphureous water of Croft in Yorkshire, 
where a white hairy mucous matter is seen adhering to the sticks, 
grass, &c., which had been mistaken for sulphur, until Dr. Willan 
proved it to be of a vegetable nature, corresponding with Byssus 
of Linneust. He notices, as a remarkable circumstance, that 
this Byssus should be found below the spring no further than the 
water retains its sensible sulphureous qualities, as if the hepa- 
tic gas were necessary for its production and nourishment. It 
occurs also at Dimsdale in the same county, at Middleton- 
One-Row near Darlington, at Llanwrtyd in Wales,—all springs 
of the same quality. It grows, says Mr. Dillwyn, on roots and 
other substances, which it covers with white filaments two or 
three lines in length, and so extremely slender, that under the 
highest power of my microscope their thickness scarcely ap- 
peared equal to that of a horse-hair. Some of the filaments 
are simple, but most of them are singularly beset towards the 
middle with a whorl-like cluster of very simple branches, re- 
sembling proliferous shoots.  Dissepiments with a high power 
are clearly discernible, and they divide the filaments into joints, 
the length and thickness of which are nearly equal. 
* C. filis ramosis, tenuissimis, rigidiusculis, niveis; ramis in verticillo confertis, 
articulis diametrum longitudine superantibus —Dillwyn’s Conferoe, p. 54. 
+ Willan On Sulphureous Waters, p. 10. 
1 I found it myselfthis autumn growing in great abundance at the old spring of Croft. 
Mr. 
