LEPTOGIUM. | COLLEMET. 65 
concave, concolorous ; spores 4—8ne, plurilocular or variously sep- 
tate, ovoid or oblongo-ovoid, 0,020-34 mm. long, 0,008-16 mm. 
thick.—Cromb. Journ. Bot. 1885, p.195.—To this Nylander (én litt.) 
refers Leptogium tetrasporum Fr. fil. Vet. Ak. Férh. 1864, p. 276. 
As observed by Nylander, J. c., this has externally the appearance of 
Lecidea uliginosa Ach., from which it is far removed by the structure of 
the thallus and apothecia. It is near the preceding species, from which 
it is distinguished by the less-developed thallus and the smaller con- 
colorous apothecia. In the British specimens the apothecia are few, with 
the spores usually 4na, ovoid, 0,027-84 mm. long, 0,013-16 mm. thick. 
Hab. On mortar of walls ina maritime district.— Distr. Rare in the 
Channel Islands.—B. M.: Port Gorey, Island of Sark. 
4, L. pusillum Nyl. Mém. Soc. Cherb. v. (1857) p. 90; Syn. i. 
p. 121.—Thallus very minute, lobulato-granulose, thin, adnate, 
olive- or greenish-brown. Apothecia minute, concave, elevated, 
reddish, prominent in the thalline exciple, the margin of which is 
concolorous with the epithecium ; spores ovoid or narrowed at either 
apex, 3—4-septate, 0,018-26 mm. long, 0,008-10 mm. thick.— 
Cromb. Lich. Brit. p. 7; Leight. Lich. Fl. p. 30, ed. 3, p. 27.— 
Brit. Exs.: Larb. Cesar. n. 54, 
An inconspicuous plant, apt to be overlooked. Scarcely any of the’ 
gonimia are moniliform. The British specimens are usually little deve- 
loped and more or less effuse (form effusum Nyl.). The apothecia are very 
small and somewhat scattered. 
Hab. On mortar of old walls in maritime districts — Distr. Local 
and rare in the Channel Islands and in S. and W. England.—B. M.: 
St. Brelade’s Bay, Island of Jersey; St. Peter’s Port, Island of Guernsey. 
Shiere, Surrey; Freshford, near Bath, Somersetshire; Kemble, Glou- 
cestershire. 
5. L. subtile Nyl. Mém. Soc. Cherb. v. (1857) p. 90; Syn. i. 
p. 121.—Thallus effuse, very minutely divided, somewhat laci- 
niato-dissect or granuloso-crenate, dark- or brownish-green. Apo- 
thecia minute, gyalectoid, pale-brown or reddish, the margin thin, 
entire, subconcolorous; spores ovoid, 3-5-septate, with longitu- 
dinal septules, 0,020-23 mm. long, 0,008-10 mm. thick.—Mudd, 
Man. p. 46, t.1.f.8; Cromb. Lich. Brit. p. 8; Leight. Lich. Fl. 
p. 31, ed. 3, p. 29.—Collema subtile Sm. Eng. Fl. v. p. 218; Tayl. 
in Mack. Fl. Hib. ii. p. 111.—Polychidium subiile Gray, Nat. Arr. 
i. p. 401.—Lichen subtilis Schrad. Spic. (1794) p. 95; Dicks. Crypt. 
fasc. iv. p. 28; Eng. Bot. t. 1008. 
The more distinctly laciniate thallus when fully developed, and the 
much smaller and thinly margined apothecia, distinguish this from L. 
tenuissimum, with which it agrees in its entirely cellular structure. The 
spores also are smaller, with fewer loculi. The apothecia are generally 
numerous and somewhat crowded. 
Hab. On cretaceous rocks, on the ground, rarely on the roots of old 
trees, in upland districts.—Dvstr. Pretty general, though not very com- 
mon, in 8, and W. England; rare in the Channel Islands, N. England, 
; F 
