232 NEMATOGENE. 
Trichomes compact, densely interwoven at the periphery, 
joints cask-shaped, or compressed spherical, close together, 
uniform. Heterocysts subglobose. Spores oval, with a thick 
tegument, smooth. 
Sizz. Joints 004-005 mm., heterocysts ‘006 mm., spores 
005 x ‘007 mm. 
Born. & Thuret Notes Alg. p. 108. Rabh. Alg. Eur. No. 
746. Harv. Man. 184. Gray Arr. i, 352. Eng. Fl. v., 400. 
Hass. Alg. 289, t. 76, f.5(?). Dickie Bot. Guide, 310. 
Nostoc vesicarium, Menegh. Nost. Ital. p. 108 (not Harvey). 
Ulva pisiformis, Huds. Fl. Ang. ii., 572. 
In springs and mountain rivulets. 
“Fronds from half a line to two lines in diameter, globular, firm, 
smooth, solid, heaped on each other like a parcel of small shells. In- 
ternal filaments rather thinly scattered through the mass.”—Carmichael. 
Plate XCI. fig. 8. Nostoe sphericum nat. size ; fig. 9, trichome x 400; 
fig. 10, portion of trichome x 600; fig. 11, spores x 600. 
Nostoc rupestre. Kutz. Spec. Alg. p. 296. 
Fronds soft, globose, olive, becoming brownish, often forming 
an irregular crust. 
Trichomes much spaced out, of unequal size, joints nearly 
spherical, sheaths often coloured, contrasting with the generally 
uncoloured jelly. Spores oval with a smovth tegument. 
Sizz. Joints :005--008 mm., heterocysts ‘007 mm. 
Rabh. Alg. Eur. ii., 163. Thuret Notes Alg. p. 112. Borzi 
Alghe Fico. p. 283. 
Nostoc microscopicum, Carm. Harv. Eng. Fl. ii., 399. Harv. 
Man. 184. Mack. Hib. 245. 
On rocks, overrunning mosses, &e. 
This species is mixed up by Hassall with Nostoe muscorum, if it be not 
in reality the whole of that species, for there is some doubt whether N. 
muscorum, as defined by Bornet and Thuret was known to him. 
Plate XCJ. fig.12. Involved trichomes of N. rupestre x 400 ; figs. 13, 
14, 15, young plants in course of development x 400, after Borzi. 
-Nostoc macrosporum. Meneg. Mon, Nost. 116, ¢. 14, f. 2. 
Fronds very small, punctiform, eruginous-green, or brownish- 
olive. 
Trichomes large, bluish-green, or brownish, joints cylindrical, 
a little constricted at their junction. Sheaths broad, brownish 
or yellowish-brown. Heterocysts globose. Spores globose with 
a smooth tegument, 
Sizz. Joints -008-009 mm., heterocysts °009-'01 mm. 
Born & Thuret Notes Alg.p.112. Rabh. Alg. Eur. ii., 163. 
Hass. Alg. 293, t. 73, f. 1,2. Borzi Alghe Fico. p. 283. 
