ARTHONIA| ARTHONIACEE 481 
Orpver XXIII. ARTHONIACEA, (Part 2, p. 205.) 
Arthonia Lilliei B. de Lesd. in Bull. Soc. Bot. Fr. lvii. 
(1910).—Thallus blackish, leprose, very slight. Apothecia black, 
minute, about 0°1-0°2 mm. in diam., round, persistently plane ; 
hypothecium colourless; hymenium colourless or pale-brown ; 
paraphyses closely coherent, the apices free and capitate, the 
epithecium olivaceous; asci ventricose; spores 8 in the ascus, 
colourless, oblong or ellipsoid, 1-septate, scarcely constricted and 
the loculi equal, 10-12 » long, 4-5 p thick; hymenial gelatine 
wine-red with iodine.—Lillie in Scott. Bot. Rev. i. p. 153 (1912). 
Specimen not seen. 
Somewhat difficult to place in the lack of information as to the 
gonidia; it seems to agree with § Lecideopsis (Part 2, p. 217) rather 
than with § Euarthonia (p. 211). 
Hab. On siliceous rocks. Collected by D. Lillie at Achastle, 
Caithness. 
Orper XXVI. PYRENIDIACEZ. (Part 2, p. 264.) 
PYRENIDIUM Nyl. in Flora xlviii. p. 210 (1865) ; Cromb. 
Monogr. i. p. 81 (1894); Leight. Lich. Fl. p. 36 (1871). (Pl. 71.) 
Thallus minutely fruticose, rising from a crustaceous base, 
with a distinct plectenchymatous cortex. Algal cells Nostoc. 
Perithecia innate opening by a pore; spores oblong-ellipsoid, 
brownish, septate. 
A most interesting and unique lichen, being the only example of 
fruticose growth among the blue-green Pyrenocarpei. Crombie has 
suggested that the fruits may be parasitic fungi; unfortunately the 
specimens in the herbarium of the British Museum seem to be sterile. 
There is no record of any recent collection of the plant. 
1. P. actinellum Nyl. 1. c.—Thallus adnate and crustaceous 
at the base, or sward-like with upright or semi-prostrate branching 
fronds which are somewhat nodulose, but generally cylindrical, 
dark olive-brown in colour ; cortex very distinct, one cell thick ; 
gonidia in short chains or in groups scattered through the 
medulla. Perithecia ‘‘ minute, scarcely prominent, almost entirely 
innate, the pyrenium entirely black”; spores 4 in the ascus 
(as figured), ‘‘3-septate, brownish, 20-24 yw long, 8-9 p thick.”— 
Carroll in Journ. Bot. iii. p. 286 (1865); Cromb. Lich. Brit. 
p- 10 & Monogr. i. p. 81; Leight. Lich. Fl. p. 36 ; ed. 3, p. 37. 
Hab. On cretaceous and calcareous pebbles in moist maritime 
and upland districts.—Disti. Rare in S. and S.W. England.—B. M. . 
Anstey’s Cove, Torquay, Devon; near Brighton, Sussex; Bexley Hill, 
Kent; Shiere, Surrey. 
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