392 ALGjE GLOlOCLADEiE. [Rivularia. 



globose smooth firm glossy-black, filaments deep-green slender 

 dichotomous. — Ag. Syst. Alg. p. 24. E. Bot. t. 1798. 



On marine rocks, plants, &c, very common. 



2. R. batryoides, Carm. {grape-like Rivularia); fronds minute 

 aggregated roundish wrinkled ferruginous cartilaginous, fila- 

 ments dichotomous. 



In streamlets, attached to rocks and stones, Captain Carmichael. — 

 " Fronds about a line in diameter, hemisphaerical, wrinkled and cartila- 

 ginous, scattered or running together like a bunch of grapes. Filaments 

 cohering firmly, obscurely striated, dichotomous. Colour, when fresh, 

 black; on drying, darkly ferruginous." Carm. MSS. 



3. R. Pisum, Ag. (sphcerical Rivularia); frond globose 



smooth soft shining dark-green, filaments dichotomous Ag. 



Syst. Alg. p. 25. Berk. Alg. t. 2. f. 2. — Linkia dura, Lyngb. 

 Hydroph. Dan. t. 67. Grev. Crypt. Edin. (according to Mr. 

 Arnott.) 



On aquatic plants, in subalpine streamlets. — " Fronds a line in diame- 

 ter, scattered or confluent, of a dark-green colour and fleshy firmness. 

 Filaments radiating from the base, dichotomously branched and atten- 

 uated to a point ; striae inconspicuous." Carm. MSS. 



4. R. applandta, Carm. (flattened Rivularia); fronds minute 

 gregarious orbicular depressed black, filaments simple attenu- 

 ate the apices free. 



On rocks and stones, in the sea, common. Appin, Capt. Carmichael. — 

 " Fronds a line in diameter, gregarious, often confluent, circular, de- 

 pressed, spongy, of an opaque black colour, shrinking, splitting and be- 

 coming grayish on drying. Filaments one-fourth of a line in length, 

 simple, attenuated to a point, loose at the apex, of a bluish-green colour." 

 Carm. MSS. — This minute plant is probably common on every rocky 

 coast, though hitherto overlooked. It differs from R. atra in its de- 

 pressed form, and simple filaments. 



5. R. plicdta, Carm. (wrinkled Rivularia); fronds rather 

 large densely gregarious gelatinous compresso-plicate often 

 hollow and ruptured dark-green, filaments many times dicho- 

 tomous attenuated. 



On the sea-shore about high-water mark, or in situations where it is 

 only occasionally inundated with salt-water. Appin, Captain Carmichael. 

 Torbay, Mrs. Griffiths. Eyemouth, Dr. Johnston. Innischerig Island, 

 Clare, W. H. Harvey. — " Fronds growing from a smooth gelatinous 

 stratum, from a line to half an inch in diameter, mostly confluent and 

 distorted by mutual pressure, gelatinous, and in their more advanced 

 state, often hollow and ruptured. Filaments dichotomous, tapering to a 

 fine point, obscurely striated. Globules few in number, pellucid, lodged 

 within the filaments, which at length break off, leaving the globule at- 

 tached to the base of the dismembered branch. 



6. R. calcdrea, Sm. (stony Rividaria); fronds large orbicular 

 convex, at length aggregated into a broad spongy crust, zoned 

 within, at length petrified. — E. Bot. t. 1799. Ag. Syst. Alg. 

 p. 26. — R. haematites, Dec. and Duby, (according to Mr. Arnott.) 



