SPILONEMA.] SIEOSIPHEI. 21 



while the monoecious fructification, the apothecia, and the spermogones 

 prevent all confusion between them. The apothecia are rarely seen in British 

 specimens, though the spermogones are not unfrequent ; they are minute 

 black tubercules, with sterigmata 4-6-articulate, spermatia 0,002-0,0025 

 mm. long, 0,005-0,001 mm. thick. 



Hub. On schistose rocks in maritime and subalpine tracts. Distr. 

 Local and scarce in N. Wales, and the S.W. Highlands of Scotland ; 

 though no doubt it will be detected in other similar localities. B. M. : 

 Barmouth, Merionethshire ; Barcaldine, Argyleshire. 



2. S. revertens Xyl. Flora, 1865, p. 601. Thallus effuse, mi- 

 nutely coralloideo-compact, in somewhat small, verruculose pul- 

 vinuli, blacker brownish-black. Apothecia lecideine, adnate, some- 

 what convex, immarginate, Mack, dark-greyish within ; spores 

 oblong, simple, 0,008-0,011 mm. long, 0,005-6 mm. thick ; para- 

 physes thickish, incrassate and denigrate at the apices ; hymenial 

 gelatine bluish, the apices of the thecse deep-blue with iodine. 

 Cromb. Journ. Bot. 1874, p. 331 ; Leight. Lich. Fl. ed. 3, p. 11. 



In this species the pulvinuli are more or less crowded, and in a young 

 or poorly developed state are frequently somewhat discrete. Sirosiphon 

 saxicola Naeg. in great part is apparently a sterile leprarioid condition 

 of this plant. In the only British specimen seen the apothecia are but 



ringlv present. On the thallus of the same specimen pycnides are 

 visible, which are minute, globose, immersed, colourless, with some- 

 what curved stylospores. 



Hab. On moist schistose rocks in subalpiue districts. Distr. Very 

 local and rare, at least in a mature condition, being known only from the 

 Central Grampians, Scotland. B. M. : Craig Tulloch, Blair Athble, Perth- 

 shire. 



3. S. scoticum JS'yl. Flora, 1869, p. 82. Thallus effuse, mi- 

 nutely cofalloid, in small, compact, verrucose, somewhat convex 

 pulvinuli. black or brownish-black. Apothecia minute, thinly 

 margined, black, epithecium impressed or slightly convex, vaguely 

 obscure, hypothecium colourless ; spores oviformi-oblong, 1-septate, 

 0,010-14 mm. long, 0,0045mm. thick, paraphyses some what slender; 

 hymenial gelatine bluish, the thecae violet with iodine. Cromb. 

 Journ. Bot. 1869, p. 105 ; Lich. Brit. p. 1 ; Leight. Lich. Fl. 

 p. 12, ed. 3, p. 11. 



The pulvinuli are usually discrete, though occasionally approximate, 

 on the crustaceous thalli, or the decayed mosses on which the plant 

 occurs. It is closely allied to the preceding, but is well distinguished by 

 the apothecia and the spores. The sterile thallus seems to be not un- 

 common ; but the apothecia are very rare. As in S. revertens, no sper- 

 mogones have yet been detected, so that both species are only temporarily 

 placed in Spilonema. 



Hab. On mica-schist rocks, and on dead mosses (also on Stereo- 

 caulon conde mat uni) in subalpine tracts. Distr. Probably not un- 

 frequent in the mountainous districts of our Islands, though known only 

 from N. Wales, N. England, and the S. Grampians, Scotland. B. M. : 

 Llyn Aran, Dolgelly, Merionethshire ; Teesdale, Durham ; Ben Lawers 

 and Craig Calliach, Perthshire. 



