234 SCYTONEMILE. 



Hub. On the 'trunk of a living elm at Oundle, North- 

 amptonshire : Rev. M. J. Berkeley. 



I doubt much whether this species be a true Hassallia. 

 It is much more like an Oscillatoria, the filaments being simple, 

 of equal diameter, regularly striated, and very brittle. The 

 only character which seems to unite it with Scytonema is its 

 erect habit. It might possibly be better placed in Kiitzing's 

 genus Symphosyphon: if not, it should perhaps form the type 

 of a new genus. The genus Symphosyphon is thus charac- 

 terized. 



" Trichomata erecta vel adscendentia, vagina cartijaginea 

 multistriata (lamellosa) eaepe fasciculata, involuta, basi conflu- 

 entes, lateraliter concreta." 



5. HASSALLIA ? LIMBATA Hass. 

 Plate LXVII. Fig. 6. 



Char. " Filaments thick, Jlexuous, ceruginous, with a broad, 

 pellucid margin, loosely interwoven in a dense dull ceru- 

 ginous green stratum." Grev. 



O. limbata Grev. Crypt. Flor. Syn. p. 40. and t. 246. 

 (O. rupestris}. Scytonema (Brugineo-cinereum Kiitzing, 

 Phyc. General, p. 214. Ocellatoria limbata Harv. in 

 Hook. Brit. Flor. p. 375. ; also in Manual p. 164. 



Hob. On perpendicular rocks, exposed to the trickling of 

 water, Pentland Hills: Dr. Greville. 



On first examining an authentic specimen of this plant, I 

 was impressed with the idea that it ought to be referred to 

 the genus Scytonema, but from not discovering branches on 

 the filaments, I did not feel quite certain on this point. 

 Kiitzing having made the species the type of his genus Scy- 

 tonema, there can be but little doubt but that it really 

 belongs to the family Scytonemea. " Plant covering the face 

 of the rock for several inches together, and when old, peeling 

 off in rather large pieces. Externally it is mostly of a dull 

 and brownish green colour, but within more of a verdigris 



