PHYSCIA.] PHYSCIEI. 319 



smaller. Physcia olscura subsp. lithotea Cromb. Grevillea, xv. 

 p. 78 ; form lithotea Leight. Lich. Fl. ed. 3, p. 137. ParmeUa cydo- 

 sdis fi. lithotea Ach. Meth. (18U3) p. 199. 



Subsimilar to P. obscura, but differs in being firmer, more or less furfti- 

 raceous, and especially in the cellular structure of the cortex, which - 

 consists of rounded cells, being more distinct. In age r.early the whole 

 thallus and the margins of the lacinise are covered with a dark furfur. 

 The state sciastra (Ach. Meth. Suppl. p. 49) differs merely in being 

 darker and sorediate only at the margins of the lacinise. The apothecia 

 when present (for it is usually sterile) are small and few. 



Hab. In depressions of rocks which are frequently moistened by the 

 sea and by lakes and streams in maritime and mountainous districts. 

 Distr. Local and scarce in N. England, N. Wales (Jide Leight.), among 

 the S. Grampians, Scotland, and in N.W. Ireland. B. M. : Near New- 

 ton, Cleveland, Yorkshire ; Teesdale, Durham. Loch Dochart and Ken- 

 more, Perthshire. Connernara, co. Gal way. 



23. P. alothrix Nyl. Flora, 1875, pp. 360, 442. Thallus orbicu- 

 lari-stellate, greyish-glaucous or dark-brown, sometimes sublivid, 

 esorediate; beneath black-fibrillose ; lacinise discrete, narrow, linear, 

 multifid, plane, ciliate at the margins, the cilia rigid, horizontal 

 (K~, CaCl~). Apotbecia moderate, dark-brown, tbe thalline mar- 

 gin entire, at length inflexed, the receptacle at the base black- 

 fibrillose ; spores oblong, 0,015-25 mm. long, 0,009-12 mm. thick. 

 Cromb. Linn. Soc. Journ. Bot. xvii. p. 571. Physcia obscura var. 

 ulothrix Cromb. Lich. Brit. p. 39 j Leight. Lich. Fl. p. 149, ed. 3, 

 p. 137. Borrera obscura $. ulothrLv Mudd, Man. p. 110. ParmeUa 

 ulothrix Tayl. in Mack. Fl. Hib. ii. p. 146. Lichen ulothrix Acb. 

 Prodr. (1798) p. 113. Lichen virellv.s Eng. Bot. t. 1696 (lower 

 fig.). Lichen ciliatus Dicks. Crypt, fasc. iii. p. 16; With. Arr. 

 ed. 3, iv. p. 30. Lichen stellaris var. 4, With. I. c. p. 31. Lichcn- 

 oides viride, segmentis angitstis distortis, scutellis pulUs Dill. Muse. 

 178, t. 24. f. 72 A. Brit. Kvs. : Leight. n. 80. 



Usually regarded by more recent authors as a variety of the preceding ; 

 this was rightly viewed by Acharius as a distinct species, as warranted 

 more especially by the peculiar character of the marginal cilia and in a 

 minor degree by the radiating fibrillose receptacle of the apothecia. In 

 this latter respect, as already observed, it is analogous to subsp. Farmelia 

 carporhizans, though in old plants this character is less apparent. When 

 sterile it is readily distinguished by the horizontal marginal cilia of the 

 thallus. The apothecia are numerous and often crowded, and the sperrno- 

 gones, which seem to be rather rare, are as in P. obscura. 



Hab. On the trunks of trees, rarely on old pales and walls in maritime 

 and upland districts. Distr. Occurs only here and there in England, S. 

 Scotland and the Highlands, and S. Ireland. B. M. : Lakenham and 

 near Yarmouth, Norfolk ; Brighton and Alboume, Sussex ; near Pen- 

 zance, Cornwall ; Cirencester, Gloucestershire ; Gopsall Park, Leicestei- 

 shire ; Buxton, Derbyshire ; near Worcester. New Galloway, Kirkcud- 

 brightshire ; Appin, Argyleshire ; Fiularig, Killin, and Glen Fender. Blair 

 Athole, Perthshire. Carrigaloe, near Cork. 



