82 COLLEMACEI. [PYRENIDIUM. 
L. mécroscopicum they are unequal. In the few authentic specimens 
seen, the apothecia are sparingly present; and the other specimens, 
referable to this or another species, are sterile. 
Hab. On cretaceous and calcareous pebbles in moist maritime and 
upland districts.—Distr. Very sparingly in 8. and S.W. England.—B.M. : 
Box Hill and ? Shiere, Surrey; ?near Brighton, Sussex; Anstey’s Cove, 
Torquay, S. Devon. 
Family III. LICHENACEI Nyl. Mém. Soc. Cherb. ii. 
(1854) p. 10; Syn. i. p. 141. 
Thallus polymorphous, filamentose, foliaceous, squamose, crus- 
taceous, pulverulent, or obsolete, or none, varying from mem- 
branaceous to coriaceous and from filmy to tartareous, extremely 
variable in colour, white, greyish, yellowish, reddish, brown, 
blackish, but little or. non-gelatinous; gonidial layer usually 
distinct, formed of true gonidia or rarely of gonimic granules. 
Apothecia either stipitate or sessile, lecanorine, patellate, lecideine, 
or pyrenoid, very variable in colour, but rarely concolorous with 
the thallus. Spermogones either immersed or prominent, with 
simple or articulate sterigmata and various spermatia. 
The plants belonging to this, by far the largest family of Lichens, are 
very variable with respect both to the thallus and the fructification. 
They differ from the preceding families in being only very occasionally 
gelatinous, and especially in having, except in a comparatively few 
instances, a distinct stratum of bright green, rarely orange, gonidia. 
The apothecia in most cases have the thalamium furnished with para- 
physes, which are generally distinct. In the lower genera some plants 
approximate to the Ascomycetous Fungi. 
Series I. Epiconiodei Nyl. Syn. i. (1860) p. 141. 
Thallus either (1) horizontally expanded and crustaceous, some- 
times none proper, with the apothecia usually stipitate, capituliform, 
occasionally sessile, or (2) fruticuloso-erect, with the apothecia 
in terminal capitula of the thallus, nuclear, at length widely 
open; spores naked, usually collected into a pulverulent mass on 
the surface of the mature fructification. 
Though in other respects varying considerably, the two tribes which 
constitute this series agree in having the spores, except in a few species, 
accumulated as a conglutinate powder or sporal mass (mazedium, 
Ach.) on the surface of the mature fruit. It is only in the young 
apothecia that the spores are seen in theca ; when more advanced, they 
occur only free in the mazedium. 
Tribe I. CALICIEI Nyl. Syn. i. (1860) p. 141. 
Thallus horizontal, crustaceous, granulose, or obsolete, or none 
proper. Apothecia stipitate, capituliform, or sessile; spores 8nm, 
in evanescent thecw, spherical or oblong, simple or variously septate, 
