Protococcus.] ALGM CHLOROSPERMEiE. 245 



sub-orbicular; granules elliptical. Grev. — Crypt Fl. t. 243./. 2. 

 Harv. in. Hook. Br. Fl. v. ii. p. 396. 



In heathy places, in moist situations. 



4. P. kyalina, Lyngb. Green pellucid Palmelta. Frond 

 globose or somewhat elongated, pellucid green, the granules 

 globose, green. Grev.— Grev. Crypt. Fl. t. 247. Harv. in 

 Hook. Br. Fl. v. ii. p. 397. 



In fresh water streams, &c. 



82. Nostoc. Vauch. Nostoc. 



Frond gelatinous, or coriaceous, lobed, hollow, or solid ; filled 

 with crisped, momWfovm filaments, which are finally dissolved 

 into sporules. — Name, of unexplained meaning. — This genus 

 differs from Palmelta, solely in the filamentous arrangement 

 of the sporules. To Berkeley s genus Monormia (Gr. Alg. 

 p. 46. t. 18J it is still more closely allied, but appears suffi- 

 ciently distinct. 



1. Olive-green, terrestrial. 



1. N. commune, Vauch. Common Nostoc. Terrestrial ; 

 frond expanded, polymorphous, plicato-undulate green. Harv. 

 in Hook. Br. Fl. v. ii. p. 398.— Tremella Nostoc, E. Bot. *.461. 



Gravelly soils, among- rocks, &c. after rain. 



2. N. foliaceum, Ag. Leafy Nostoc. Ceespitose, membra- 

 naceous, plicato-rugose, somewhat erect. Ag. Syst. p. 19. 

 Harv. in Hook. Br. Fl. v. ii. p. 399. 



On clayey, moist ground. 



3. N. microscopicum, Carm. 31inute Nostoc. Fronds densely 

 aggregated, very minute, polymorphous, immersed in a blackish 

 crust. Harv. in Hook. Br. Fl. v. ii. p. 399. 



On rocks, and among mosses. At the " Wilderness," Clonmel. 

 Fronds exceedingly minute, hyaline or pale olive, of various shapes, 

 containing a few, lax, nioniliform filaments. 



2. Olive-green, submersed. 



4. N. verrucosum, Vauch. Plaited Nostoc. Fronds large, 

 gregarious, confluent, subglobose, plaited, at length hollow, 

 blackish green. Harv. in Hook. Br. FL v. ii. p. 400. 



On stones in alpine rivulets. 



83. Protococcus. Ag. Protococcus. 

 Plant consisting of aggregated, naked globules, filled with mi« 



