62 COLLEMACEI. [COLLEMODITJM. 



Hub. On calcareous stones in upland situations. — Distr. Very local in 

 S.W. Enprland. — B. M. : Near Cirencester, Gloucestershire. 



8. C. Schraderi Xyl. ex Cronab. Grevillea, xv. (1886) p. 12. — 

 Thallus effuse, coespitoso-fruticulosc, somewhat erect, dichotomously 

 branched, dull olive-green or dark reddish-brown ; branches sub- 

 linear, irregularly sulcato-rugose and somewhat angular, dilated in 

 the middle, constricted at the base and at the apices. Apothecia 

 lateral, small, concave, reddish, the margin entire, paler : spores 

 ellipsoid, 3-o-septate and submurali-divided, 0,023-33 mm. long, 

 0,011-15 mm. thick. — Leptogium Schraderi !Mudd, I^[an. p. 49 ; 

 Cromb. Lieh. Brit. p. 9; Leight. Lich. Fh p. 36, ed. 3, p. 34. 

 Pohjchidlum Schraderi Gray, Nat. Arr. i, p. 402. Collema Schraderi 

 Eng. Bot. t. 2284; Sm. Eng. El. v. p. 213. Lichen Schraderi 

 Bernh. in Schrad. Journ. i. (1799) p. 22, t. 2. f. 5.— Brit. Exs. : 

 Larb. Lich. Hb. n. 4. 



This usually forms small tufts which shrivel up very much in a dry 

 condition. The branches, which are at first appressed, become nearly 

 erect and fastigiate at the apices, being paler at the base. Ithasmouili- 

 form gonimia. It is rarely seen fertile, and the apothecia 8.re few. 



Hab. On cretaceous and calcareous soil, rarely on the mortar of old 

 walls in maritime and upland situations. — Distr. General, though no- 

 where very common in England (chietly in the S.), very rare amongst 

 the S.W. Grampians, Scotland, and rare in the Channel Islands, in N. 

 and S. Ireland. — B. M. : Island of Herm ; Moulin Huet, Island of Guern- 

 sey. Caistor Church, Norfolk ; Martham, Suffolk ; Shiere, Sm-rey ; 

 Shanklin, Isle of Wight ; The Downs and near Brighton, Sussex ; Bab- 

 bicombe and near Plymouth, S. Devon ; St. Minver, Cornwall; Cheddai* 

 Cliffs and Bathampton Downs, Somersetshire ; near Siddington, Glou- 

 cestershire ; MiUer's Dale, Derbyshire ; Island of Anglesea, N. Wales ; 

 near Mihithorpe, Westmoreland. Appin, Argyleshire ; Glen Lyon, Perth- 

 shire. Blackrock, near Cork ; Muckross, Killamey, and Dunkerron, co. 

 Keny ; Dawros, co. Galway ; Sheep Walk, co. Armagh. 



16. LEPTOGIUM Gray, Nat. Arr. i. (1821) p. 395 ; Nyl. Mem. 

 See. Cherb. (1855) p. 165, emend. — Thallus microphyUine, fruticulose 

 or rarely granulose, sometimes foliaceous and macrophylline, in- 

 ternally cellular or with tubular interwoven cavities ; gonimia more 

 or less moniliform ; cortical layer more or less distinct, usually 

 formed of a simple series of cells. Apothecia lecanorine or biatoroid ; 

 spores 8n8e, more or less oblong, variously septate and divided, 

 colourless ; hvmeuial gelatine deep blue with iodine. Spermogones 

 immersed, with shortly articulate sterigmata and straight si)ermatia 

 obsoletely incrassate at both apices. 



As now limited, this genus, though better defined than formerly, is 

 still closely related to Collema. It is distinguished by the thallus in the 

 foliaceous species being thinner and less turgid when moist, by the apo- 

 thecia being often biatoroid, and more especially by having a distinct 

 coi-tical layer, though sometimes entirely cellular within. The spermo- 

 gones, as in Collinut and ('ulUmodium, have tiie sperniatia identical in 

 size, viz. 0,0035-0,0040 mm. long, scarcely 0,001 mm. thick. According 



