594 Dr. Daubeny on a certain Kind of 



the genial temperature and mineral constitution of the water that 

 flows over it, than to understand the production oi AlgcB 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 Linnaeus ;|.. He notices, as a remarkable circumstance, that 

 this Bysms 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. fills ramosis, tenuissimis, rigidiusculis, niveis ; ramis in verticillo confertis, 

 articulis diametrum longitudine superantibus. — Dillmyn's Conferva, p. 54. 

 t Willan On Sulphureous Waters, p. 10. 

 % I found it myself this autumn growing in great abundance at the old spring of Croft. 



Mr. 



