96 LICHENACEI. (CALIcIUM. 
Hab. On old pales in upland tracts.—Distr. Only sparingly in 8S. 
England.—B. M.: Wheatfield Park, Oxfordshire. 
14. C. populneum De Brond. in Dub. Bot. Gall. (1880) ii. 
p. 638.—Thallus hypophleodal, macular, subleprose, pale or whitish. 
Apothecia minute, scattered, entirely black, somewhat shining ; 
stipes very short, slender; capitulum turbinate; spores 1-septate, 
blackish, 0,010-11 mm. long, 0,005-6 mm. thick.—Mudd, Man. 
p- 257, t. iv. f. 104; Leight. Lich. Fl. p. 45, ed. 3, p. 44; 
Cromb. Grevillea, xv. p. 14.—Calcium curtum 3. populinum Turn. 
& Borr. Lich. Br. p. 149; Sm. Eng. Fl. v. p. 140. Calicium 
triste Cromb. Lich. Brit. p. 13. 
The thallus is somewhat smooth and shining, appearing as a very thin 
film. From C. parietinum, which it somewhat resembles, distinguished 
by its place of growth, the minute, fragile apothecia and the larger 
spores. 
Hab. On the smooth bark of poplars in wooded upland tracts.— Distr. 
Only sparingly from the 8.W. Highlands of Scotland and S.W. Ireland. 
—B. M.: Airds, Appin, Argyleshire. Killarney, co. Kerry. 
15. C. diploellum Nyl. Flora, 1868, p. 161.—Thallus effuse, 
very thin, greyish-white, but doubtfully proper. Apothecia minute, 
scattered, entirely black; stipes very short; capitulum turbinate, 
open; sporal mass scarcely prominent; spores simple or at length 
1-septate 0,006-9 mm. long, 0,003-4 mm. thick.—Carroll, Journ. 
Bot. 1868, p. 100; Cromb. Lich. Brit. p. 13; Leight. Lich. Fl. 
p. 39, ed. 3, p. 39. 
Apart from other marks of distinction, this may be recognized by its 
very small size, being the most minute of all Calicier, so that it is very 
Hable to be overlooked. tis closely allied to C. disseminatwm, a European 
species, which has not yet been detected in Great Britain, 
Hab, On the bark of holly in upland wooded districts—Distr. Ex- 
tremely local and scarce, in S.W. Iveland.—B. M.: Cromaglown, Kil- 
larney, co. Kerry. 
16. C. retinens Nyl. Flora, 1868, p. 161.—Thallus effuse, thin, 
subfarinaceous, opaque, whitish. Apothecia minute, sessile, leci- 
deiform, black; sporal mass indistinct; spores oblong or oblongo- 
cylindrical, conspicuously 1-septate, 0,008-11 mm. long, 0,0025- 
35 mm. thick; hypothecium brownish-rubricose.—Leight. Ann. 
Mag. Nat. Hist. ser. 4, i. p. 482; Lich. Fl. p. 45, ed. 3, p. 44; 
Cromb. Grevillea, xv. p. 14. 
It is doubtful if the thallus be really proper. This may be decided 
by additional specimens. With its lecideiform apothecia and indistinct 
mazedium and definitely 1-septate spores it seems referable to Trachylia ; 
but it rather presents, according to Nylander, in Hit#., an affinity with 
species of the present genus, especially in the longer spores. At the 
same time it shows that there are no decided limits for the two genera. 
Hab. On the trunk of an old oak in a maritime district.— Distr. Met 
with only once, and very sparingly, in the Channel Islands, on the coast 
of Jersey. 
