328 CYCLOCARPINEA: [LECANORA 
then becoming superficial, the disc concave, black, the thalline 
margin rather prominent, entire or subcrenulate; paraphyses 
slender, coherent, flexuose, septate, moniliform upwards, the 
epithecium dark-brown ; spores ellipsoid, 15-24 » long, 9-16 p 
thick; hymenial gelatine bluish, then quickly Wine-red with 
iodine-—Cromb. Monogr. i. p. 473. Sagedia levata Ach. Lich. 
Univ. p. 327, t. 6, fig. 5 (1810). 
Ezxsicc. Johns. n, 273. 
Evidently a rare lichen, though of wide distribution on the conti- 
nent and N. America. According to Nylander (Lich. Fret. Behr. 
p. 30, 1888) the spermatia measure 20-32 » long, *5 » thick. I have 
been unable to find spermogones on our specimens. 
Hab. On damp siliceous rocks in subalpine districts.—Dzéstr. 
Rare in W. England and the Grampians, Scotland.—B. M. Wastdale 
Lake-side, Cumberland, Glen Callater, Braemar, Aberdeenshire. 
86. L. lacustris Th. Fr. in K. Sv. Vet.-Akad. Handl. vii. 2, 
p. 24 (1867).—Thallus determinate or somewhat effuse, thin, 
firm, smooth, irregularly and finely cracked-areolate or con- 
tinuous, pale-reddish or -yellowish (K—CaCl—). Apothecia 
small, persistently immersed, the disc pale rose-coloured or 
brownish, the thalline margin tumid, often indistinct ; paraphyses 
coherent, slender, flexuose, septate, slightly thicker and more 
closely septate at the tips, the epithecium brownish- or yellowish- 
granulose ; spores ellipsoid, usually 13-18 long, 6-9 » thick but 
sometimes larger ; hymenial gelatine blue then quickly wine-red 
with iodine.—Leight. Lich. Fl. ed. 3, p. 195 (excel. f. punctata) ; 
Cromb. in Grevillea xix. p. 58 (1891) (excl. var. cyrtaspis?) & 
Monogr. i. p. 477. L. gibbosa subsp. lacustris Cromb. Lich. Brit. 
p. 55 (1870) (excl. var. punctata); £. lacustris Leight. Lich. Fl. 
p. 210 (1871) pro parte. Lichen lacustris With. Arr. ed. 3, iv. 
p. 21, t. 31, fig. 4 (1796). DL. Acharii Westr. ex Ach. Lich. 
Suec. Prodr. p. 33 (1798); Engl. Bot. t. 1087. Urceolaria 
Acharii Ach. Meth. Lich. p. 150 (1803) (exel. var. cyrtaspis) ; 
S. F. Gray, Nat. Arr. i. p. 457; Hook. Fl. Scot. ii. p. 47 (inel. 
var. cyrtaspis pro parte) & in Engl. Bot. v. p. 172 (inel. var. 
cyrtaspis pro parte) ; Tayl. in Mackay Fl. Hib. ii. p. 132. 
Exsice. Cromb. n. 71 ; Johns. n. 275. 
The thallus is normally pale ochraceous or whitish, but may be 
rusty from infiltration of iron, as it grows on rocks subject to inunda- 
tion. In some of our specimens the spores are larger than the sizes 
given above, measuring up to 24x 12,y. There is considerable 
doubt as to the position of the variety cyrtaspis, the description of 
which in some cases agrees well with DL. lacustris, and Lichen 
punctatus, cited as a synomym, is probably a form of L. Prevostii. 
Hab. On rocks in streams in upland and subalpine districts.— 
Distr. Local though plentiful where it occurs throughout the British 
Isles.—B. M. Withiel, Cornwall; Tavy Cleave and Dartmoor, Devon ; 
Lyndhurst Moor, New Forest, Hants; Nannau, Dolgelly and Bar- 
