226 SUPPLEMENT. 



the plant lying upon the surface in irregularly plicated masses becomes loosened, 

 and if it is not at once covered with snow, which is not always the case, the wind 

 carries it about in all directions. Sometimes it is blown out to sea, where one can 

 pick it up on the surface of the ice, over a depth of probably one hundred fathoms. 

 It has been found at a distance of two miles from the land, where the wind had 

 carried it. At this distance from the land it was infested with Podurce, and 1 

 accounted for this fact by presuming that the insects of the previous year had de- 

 posited their ova in the plant upon the land, where also the same species could be 

 seen in myriads upon the little purling rivulets, at the side of which the Nostoc 

 was very abundant." At p. 205 of his Journal, Dr. Sutherland further mentions 

 having tried it as an article of food, and found it preferable to the Tripe de Roche 

 of the arctic hunters. Its nutritive qualities are probably equal to those of the 

 jelly derived from other Algae. (ChlorospermeoB, p. 113.) 



Nostoc flagelliforme, BERK, and CURT. 



Terrestrial ; frond cartilaginous, linear, very narrow, compressed and often channelled, much 

 branched, irregularly dichotomous; branches solid, densely filled with moniliform curved 

 threads. Berk, and Curt. No. 3809. 



Hab. On naked aluminous soil, at San Pedro, Texas, Mr. Charles Wright, (v.s.) 



Fronds several inches in length, half a line in diameter, lying prostrate on the surface of the 

 soil, much branched in an irregularly dichotomous manner ; branches exactly linear, com- 

 pressed, often channelled on one or both sides, thinned in the middle and incrassated to the 

 edge. Substance firm and elastic, cartilaginous, solid, densely filled with moniliform, curved or 

 curled, interlaced threads, which are set longitudinally in the frond, and lie nearly parallel to 

 each other. Color dark olive. 



A very curious and most distinctly marked species, differing from others of this 

 genus, much in the same manner that Cheetophora endivicefolia does from the ordi- 

 nary globose forms of Chcetophora. (CJilorospermeoz, p. 115.) 



Nostoc microscopicum, CAHM. 



Fronds densely aggregated, very minute, globose or oblong, immersed in a blackish crust ; fila- 

 ments few. Carm. in Hook. Brit. Fl. 2, p. 399. Harv. Man. Ed. I, p. 184. N. muscorum, 

 Hass. Br. Fr. Wat. Alg. p. 292, t. 74, fig. 4. 



Hab. " Stones in a small stream, Baffin's Bay," Dr. Sutherland, fide Prof. Dickie. 



I have not seen American specimens. In Britain this species grows among 

 mosses on exposed calcareous rocks, but not in water. The above specific charac- 

 ter is taken from the British plant. The fronds are rarely more than the tenth of 

 an inch in diameter, and contain two or three beaded filaments lying in a copious 

 transparent jelly. (Chlorospermece, p. 115.) 



Genus HYDRURUS, Ac. 



Frond fixed at base, cylindrical or compressed, elongated, branched, gelatinous. Structure: 

 seriated, but separate, cellules, filled with bright-green endochrome, inclosed in gelatinous parallel 

 tubes, ranged longitudinally in the frond, and surrounded by a common gelatinous envelope. 



