232 NEMATOGEN.E. 



Trichomes compact, densely interwoven at the periphery, 

 joints cask-shaped, or compressed sphserical, close together, 

 uniform. Heterocysts subglobose. Spores oval, with a thick 

 tegument, smooth. 



SIZE. Joints -004--005 mm., heterocysts -006 mm., spores 

 005 x -007 mm. 



Born. & Thuret Notes Alg. p. 108. Eabh. 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, 330. 



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. Jig. 8. Nostoc spkcericum nat. size ; fig. 9, trichome x 400 ; 

 fig. 10, portion of trichome x 600 ; fig. 11, spores x 600. 



Nostoc mpestre. 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 

 sphaerical, sheaths often coloured, contrasting with the generally 

 uncoloured jelly. Spores oval with a smooth tegument. 



SIZE. 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. &c. 



This species is mixed up by Hassall with Nostoc mitscorum, if it be not 

 in reality the whole of that species, for there is some doubt whether N. 

 muscorum, as defined by Bornet and Thnret was known to him. 



Plate XCI. Jig. 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, t. 14, f. 2. 



Fronds very small, punctiform, geruginous-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. 



SIZE. 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. 



