RINODINA | PHYSIACEX 249 
50. RINODINA S. F. Gray Nat. Arr. i. p. 448 (1821) pro 
minima parte; emend. Massal. Ric. Lich. Crost. p. 14 (1852) ; 
Mudd Man. p. 142. Lecanora sect. Rinodina Ach. Lich, Univ. 
p. 344 (1810) pro minore parte. (PI. 50.) 
Thallus crustaceous, rarely squamulose, non-corticate except 
in highly developed species. Algal cells Protococcus. Apothecia 
dark-coloured, generally with a prominent thalline margin : 
paraphyses slender, broader, septate, brown and often shortly 
branched at the tips; spores 8 in the ascus (rarely more) 
l-septate, more or less distinctly polarilocular, brown. 
The spores of this genus, as in Physcia, are nearly always 
distinctly polarilocular with the cell-lumens rather near the median 
wall. The thallus in most species is coloured some tinge of grey, in 
others it becomes very dark. The genus is distinguished from Bwellia 
by the thalline margin of the apothecium and also by the more or 
less distinctly polarilocular spores. The same type of spores occurs 
in Buellia discolor, B. interpolata, B. biloculata and B. polospora 
(Brit. Lich. ii. p. 168). The first two species have a colourless 
hypothecium, and are clearly allied to Rinodina; the two latter 
having a dark hypothecium are more truly lecideine. 
Thallus isidioid-squamulose. 
1. R. isidioides Oliv. Lich. Eur. fase. 2, p. 186 (1909).— 
Thallus effuse, consisting of somewhat coralloid isidia-like 
processes, scattered or rarely united into a squamulose structure, 
simple or sometimes divided unevenly, cylindrical or slightly com- 
pressed, whitish or pale greyish-green (IKK + yellowish, CaCl — ). 
Apothecia small or moderate in size, plane, the disc blackish, 
the thalline margin entire or crenulate-isidioid ; paraphyses 
slightly clavate, septate and brown at the tips; spores fusiform- 
ellipsoid, sometimes constricted in the middle, colourless then 
dark-brown, large, 26-30 p long, 12-15 p thick.—Parmelia 
isidioides Borr. Engl. Bot. Suppl. t. 2808 (1837). Lecanora 
isidioides Ny]. in Mém. Soc. Sci. Nat. Cherb. v. p. 115 (1857); 
Cromb. Lich. Brit. p. 49 & Monogr. i. p. 402; Leight. Lich. Fl. 
p. 224; ed. 3, p.214. Borrera isidioides Mudd Man. p. 106 (1861). 
An endemic species well characterized by the peculiar thallus ; it 
has recently been rediscovered in the New Forest by R. Paulson. 
The structure of the minute “radiate” thallus is almost wholly 
cellular with the gonidia massed towards the centre; there is no 
definite cortex. 
Hab. On mossy and naked trunks of trees in inland or upland 
districts.—Distr. Rare in N. Wales and S$. England.—B. M. Cadnam, 
New Forest, Hants ; Cwm Bychan and Dolymellynen, Merioneth. 
Thallus crustaceous, grey or whitish. 
On trees or wood. 
2, R. polyspora Th. Fr. Lich. Arct. p. 126 (1860).—Thallus 
very thin, smooth or granulate-verrucose, whitish or greyish 
