36 COLLEMACEI. [LEPTOGIDIVM. 



rather difficult to arrange in the series. From the gonimia, it seems 

 to have its most appropriate place in this tribe. 



1. L. dendriscmn Nyl. Flora 1873, p. 195 (note). Thallus very 

 much branched, intricate, slender, rounded or obsoletely compressed, 

 opaque, greenish, or pale-yellowish at the base. Apothecia small, 

 pale or pale-red, the epithecium at length somewhat convex : spores 

 0,010-16 mm. long, 0,006-8 mm. thick. Cromb. Journ. Bot. 1874, 

 p. 337 ; Leight. Lich. Fl. ed. 3, p. 13. Leptoc/ium dendriscum Nyl. 

 Syn. i. (1858) p. 135. Leptogium Mooreii Hepp, Carroll, Journ. 

 Bot. 1865, p. 287 ; Cromb. Lich. Brit. p. 10 ; Leight. Lich. Fl. 

 p. 27. Ephebe byssoides Caning. Trans. Bot. Soc. Edinb. vii. p. 411, 

 t. 10. f. 2. 



This is one of the exotic lichens which find their way from sub- 

 tropical regions to the S.W. of Ireland. It has a somewhat general 

 resemblance to Leptoyium muscicola, near to which it was originally 

 placed by Nylander; but the gouimia and other characters remove 

 it from Leptogium to an inferior position in the family. The apothecia 

 are not visible in any of the Irish specimens, the organs described as 

 such being spermogones. These, however, though not unfrequent as 

 minute pale-brown tubercles, have not been seen rightly developed. 



Hob. On mossy trunks of trees in moist upland situations. Distr. Very 

 local and rare in S.W. Ireland. B. M. : Glengariff and Glena, Killarney, 

 co. Kerry. 



Tribe II. COLLEMEI Nyl. Mem. Soc. Sc. Nat. Cherb. ii. 

 (1854) p. 9 ; Syn. i. p. 93 (cfr. Cromb. Grevillea, v. p. 76). 



Thallus usually membranaceous, lobed, laciniate or microphylline, 

 occasionally fruticuloso-ramose, rarely crustaceous or granulose ; 

 gonimia glaucous-green, more or less inoniliform ; cortical layer 

 either cellular or indistinct. Apothecia lecanoriue, sometimes 

 biatorine, rarely endocarpoid ; spores 8nse, rarely numerous, ellip- 

 soid, ovoid or rarely fusiform, usually septate and divided, occa- 

 sionally simple, colourless. Spermogones with the sterigmata ar- 

 ticulate, occasionally simple or subeimple, and oblong, ellipsoid or 

 bacillar spermatia. 



This extensive tribe (notwithstanding its recent limitation) consists of 

 genera diverse m various particulars, yet sufficiently connected by mutual 

 links. It contains the best-developed members of the family, and in 

 number of species, if not in their frequency of occurrence, is verv well 

 represented in our Islands. The plants for the most part very greedily 

 imbibe moisture and we often find a marked contrast in the appearance 

 of the thallus when moist or dry. 



12. SYNALISSA Fr. PI. Horn. (1825) p. 297; Nyl Syn 

 i. p. 93. Thallus pulvinate, thinly crustaceous or fruticuloso- 

 divided ; gonimia (speirogonimia) either solitary or few, usually 

 scattered among the filaments : cortical layer obsoletely eel- 



