RIVULAKIA. 263 



^^ Fronds a line in diameter, scattered or confluent, of a dark 

 green colour and fleshy firmness. Filaments radiating from 

 the base, dichotomously branched and alternate, the apices 

 free." — Carm. I have no hesitation in referring all the 

 British specimens which I have seen of this species to Rivu- 

 laria botri/oides, and these again to R. granulifera, which spe- 

 cies I consider R. Pisum to be in the earliest period of its 

 developement, and Rivularia hotryoides that species in the 

 middle period of its growth. 



The following is Carmichael's description of R, hotryoides^ 

 which, like the preceding, is found attached to stones, &c., in 

 streamlets. 



" Fronds about a line in diameter, hemispherical, wrinkled 

 and cartilaginous, scattered or running together like a bunch 

 of grapes. Filaments cohering firmly, obscurely striated, 

 dichotomous. Colour, when fresh, black ; on drying, darkly 

 ferruginous." — Carm. 



2. KlVULARIA GRANULIFERA Carm. 



Plate LXV. Figs. 1. 4. 



Char. Frond large, convex, becoming hollow underneath, 

 jieshy, lubricous, brownish olive, often including stony 

 particles, never petrijied. Filaments slender, firmly ad- 

 herent, furnished with a broad sheath. 



Harv. in Hook. Br. Fl. p. 393. ; in Manual, p. 151. 



Hab. On cliffs exposed to the trickling of water, common, 

 annual, Appin ; Captain Carmichael. — Var. hotryoides 

 in streamlets, attached to rocks and stones, co. Antrim : 

 Mr. Moore. 



" Fronds from a line to half an inch in diameter, often con- 

 fluent, convex, and at length concave underneath, fleshy, 

 dusky olive green, and extremely slippery. Filaments rather 

 thick, repeatedly dichotomous. In the substance are gene- 

 rally enclosed a number of stony particles. This species 

 comes nearest in size and form to R. calcarea, but is never 

 like that petrified with calcareous matter ; and it is moreover 



s 4 



