NOSTOCE-E. 229 



carneum. Aq. Syst. Alg. p. 22. 



Frond indefinitely expanded, bullate and undulate, flesh 

 coloured, rufescent or purplish. 



Trichomes loosely interwoven, joints equal, sheath none, in- 

 distinct, or uacoloured, spores oval. 



SIZE. Joints -OOoT-'OOl mm., heterocysts '006 mm. diam., 

 spores -006 X '009 mm. 



Rabh. Alg. Ear. ii., p. 180. Born, and Tliuret, Notes Alg. p. 



91. 



Nostoc variegalum, Harv. Man. 183. Kutz. Sp. Alg. 301. 

 Hass. Alg. p. 287, t. 74, f. 3. 



Nostoc purpurascens, Kutz. Tab. Phyc. ii., t. 11, f. 4. 

 Nostoc rufescens, Ag. Syst. 22. Rabh. Alg. Eur. ii., 179. 



On rocks. 



"First collected in Ireland in 1836, growing on the face of a moist 

 bank over which water trickled. When recent it formed a soft gelatinous 

 mass, of a livid colour, bearing the closest resemblance, both in substance 

 and colour, to those gelatinous medusee which are cast ashore along the 

 coast."- Moore. 



Plate XC. Jig. 1. Nostoc cavneum, natural size ; fig. 2, trichomes 

 X 400 ; fig. 3, development of spores X 600. 



II. GELATINOSA. Fronds soft and gelatinous, adherent, joints of 

 trichome cylindrical^ elongated in the young filaments. Spores 



oblong, large. 



Nostoc spongiaeforme. Ag. Syst. Alg. p t 22. 



Frond at first subglobose, then indefinitely expanded, be- 

 coming rather firm, pale seruginous or olive green, surface 

 tuberculated. 



Trichomes heterogenous, composed of two sorts of joints, one 

 cylindrical the other cask-shaped, or compressed sphserical. 

 Heterocysts globose. Spores smooth, oblong. 



SIZE. Joints '004 mm., heterocysts G07-'OOS mm., spores 

 006--007 x -01--012 mm. 



Born. & Thuret Notes Alg. p. 92. Rabh. Alg. Eur. ii. 178. 

 Kutz. Tab. Pbyc. ii., t. 9, f. 4. 



Nostoc inundatum, Kutz. Spec. Alg. 299. Rabh. Alg. Eur. 



ii., 171. 



Hormosiphon inundatum, Kutz. Tab. Phyc. ii., t. 27, f. 2. 

 Hormosiphon stagnalis, Kutz. Tab. Phyc. ii., t. 27, f. 3. 

 Hormosiphon natans, Kutz. Tab. Phyc. ii., t. 27, f. 4. 



In wet or inundated places. 



Plate XC. fg. 4. Nostoc spongioeforme, natural size ; fig. 5, young 

 trichome ; fig. 6, mature trichome X 4UO ; fig. 7, portion of mature 

 trichome X 600. 



