tfcytortemu.] algm confervoide.e. 365 



cumbent branched densely interwoven into blackish tufts, 

 branches suberect dichotomous and fasciculate, within furnished 

 with transverse rings." Grev. — Ag. Syst. Alg. p. 38. Lyngb. 

 Hydroph. Dan. p. 97. /. 28. Grev. Edin. Crypt, p. 302. 

 _ Moist rocks in the PeiUland hills, Messrs. Arnoti and Greville. — I 

 give this on Dr. Greville's authority. I have examined his specimens; 

 but can find little to distinguish them from the young of S. pannifmne. 

 The annuli are often bipartite. 



3. S. minutnm, Ag. {dwarf Scytonemd) ; filaments minute 

 erect rigid flexuose fastigiate collected in a dark crust, branches 

 short.— Ag. Syst. Alg. p. 39 — S. crustaceum, Aq. Syst. Ala. 

 p. 39? 



On rocks and crustaceous lichens; common in alpine districts. 

 Appin, Captain Cannichael. (arrigataha, near Caher, and at Killarnev, 

 W. H. Harvey. — Plant either spreading in a black suborbicular crust or 

 scattered in little tufts i filaments erect, minute, closely packed, oliva- 

 ceous; branches irregular, obtuse, ascending. I have made S. cru.sla- 

 ceum, Ag. a synonym, more on Carmichael's authority than on my own 

 observations; he remarks, " The difference between them hardly 

 amounts to a specific one; without the aid of the dark central line, it 

 would be nothing. But this, so far from being peculiar to-£. criistaceum, 

 is of common occurrence in all the species; so much so, that it might 

 perhaps be adopted with advantage into the generic character, were it 

 not that it seems to indicate a defect rather than a peculiarity, perhaps 

 a failure from sterility in the sporaceous matter of the filaments." 

 Carm. MSS. 



4. S. myochrous, Ag. (Mouse-shin Scytonema) ; filaments 

 elongate mostly decumbent subrigid flexuose slender yellow- 

 brown, branches issuing in pairs at right angles with the stem. 



— Ag. Syst. Alg. p. 40. Lyngb. Hydrop/t. Dan. t. 27 Conferva 



myochrous, Dillw. Conf. t. 19. E. Bot. t. I.Vjo. — Conferva 

 mirabilisy E.Bot. t. 2219, (according to the original specimens.) — 

 Scyt. ocellatum, Lyngb. Jfydroph. Dan. t. 28. (not of British 

 authors). 



Alpine bogs and rivulets. — Filaments decumbent, rarely tufted, closely 

 interwoven into a daik-brown stratum, very flexuose; branches .simple, 

 issuing in pairs at right angles, often adhering together throughout their 

 whole length, but more generally soon divaricating, wr\ rarely solitary. 

 St//,/- distant. The manner in which the branches are riven off in 

 this species is yery curious, and quite unlike what takes place in S. 

 ocellaiuoi, so that this, wen- there no other characters, would afl 

 abundant grounds of distinction between them. At first Bight, they 

 appear to Be oppositional, or resulting merely from the lateral coherence 



Of two simple filaments. ThlS, howe\cr, IS not th 



by the tube above and below the point of ramification being continuous 



and unbroken, at the opposite tide from the branches, as well as bj tra- 

 cing the various stages of the plant with a good microscope. Hm tin, 

 are at first simple continuous tube-, containing a coloured iporace 

 mass (end which is closelj marked with tranarerse stria* and 



broken, Bsifbj dissepiments, at uncertain distano 

 diss* pimrntsH rupture takes place on one tide of the sheath, and th< 

 dochnmc issues in two columns, ;u fust resembling lammilht, but finally 



