rorum, Pluk, Almath. p. 63, quam meolim in ipfius Herbario ficco vidifle meminij 

 & cujus fpecimen etiam habeo, non differt a vulgari hac." 



I mult allow that there are alio two fpecimens of the prefent plant in the 

 Herbarium, under the name of C. paluftris bombycina, to which fubfequcnt 

 authors have referred as their C. bullofa ; but neither Dillenius's figure or 

 defcription of that fpecies agree at all with this plant, and this inaccuracy is by 

 no means furprifing when we refleft that Dillenius did not ufe a microfcope, and 

 that his C. paluftris bombvcina contains all thofe Conferva:, which generate and 

 retain among their filaments a fufficiency of air to raife them up, and enable 

 them to float on the furface of the water, as is frequently the cafe with the 

 prefent fpecies. 



C. rivularis grows in very compact filky (lender raafles, of a dark green color, 

 frequently carried out to the length of two or three feet, and twifted by the 

 action of the ftream. The filaments are fimple and (lender, of a uniform color, 

 and divided into fhort joints, which fometimes appear filled with granules, that 

 moft probably are the fructification of the plant, no other having been difcovered. 



In very fhady clear dreams I have feveral times found a plant approaching the 

 prefent fpecies in many particulars, but difFering in being furniihed with numerous 

 fhort fpine-like branches, three or four of which moftly iilue from the fame 

 diflepiment, and fome being ere£t, and fome reflected, prefent a curious appear- 

 ance. Dr. Roth, and Profeflbr Mertens, in a letter to my friend Dawfon Turner, 

 cxprefs their opinion that it is but a variety of this fpecies ; but the above-men- 

 tioned, and fome other more trifling differences, are fo ftriking, that with great 

 deference to their experience in this tribe, I conceive that publifhing them as 

 diftincvt will be the moft certain way to avoid all future confufion. 



The ancients attributed to it the power of uniting fractured bones, by binding 

 it on the fracture, and keeping it conftantly moiftened with water. See Plin. 

 Hift.Nat. Book 27 Chap. 9. 



It adheres firmly to either glafs or paper. 



A. C. rivularis, natural fize. 



B. Ditto, magnified i. 



