PTERYGIUM] LICHINACE 45 
Differs from the preceding genus in the more or less crustaceous 
thallus, in the spore characters and in the habitat. The sterigmata 
are also unlike those of Lichina. 
1. Pt. filiforme A. L. Sm.—Thallus crustaceous, granular in 
the centre, laciniate-radiate at the circumference, the Jacinie 
narrow, centrifugal, chestnut-brown or blackish-brown. Apothecia 
doubtful.— Pt. centrifugum Nyl. in Bull. Soc. Bot. i. p. 328 
(1854); Cromb. Monogr. i. p. 34. Parmelia jiliformis Garov. ex 
Nyl. in Bot. Not. 1853, p. 164. 
I have not seen the fructification of this species which is mostly 
sterile. Apothecia have been described as small, reddish, with a paler 
margin; spores 8 in the ascus, elongate, ellipsoid or fusiform, colour- 
less, 3-septate, 14-15 » long, 6-7» thick. It seems doubtful if they 
are the apothecia of this species. 
Hab. On caleareous rocks, rare.—Recorded from Cheddar Cliffs, 
Somersetshire. 
2. Pt. lismorense Cromb. in Grevillea v. p. 108 (1877).— 
Thallus thin, subfurfuraceous, thinly or obsoletely radiate, adnate, 
irregularly cracked or confluent, blackish or olive-black. Apothecia 
small, thinly margined, the epithecium bluish-black ; hypothecium 
cellular, violet-blackish ; spores ovoid, l-septate, 10-11 » long, 
5-6 yw thick ; hymenial gelatine bluish then dark-yellowish with 
iodine.—Ny]l. in Flora lx. p. 221 (1877); Leight. Lich. FI. ed. 3, 
ES. 
Ezsicc. Cromb. n. 101. 
Crombie has described the thallus as spreading extensively though 
not continuously, the radii being more discrete in younger states. It 
is allied to Pt. asperellum Nyl., a Scandinavian species. 
Hab. On calcareous rocks in maritime tracts.—B. M. I. of Lismore, 
Argyll (the only locality). 
3. Pt. pannariellum Ny]. in Sillsk. Faun. Fl. Fenn. Not. iv. 
p. 236 (1859).—Thallus crustaceous, rather thin, composed of 
minute crowded granulate squamules, areolate, generally radiate 
at the circumference, olivaceous-brown or -black. Apothecia 
small, plane or slightly convex, black ; spores ellipsoid, 3-septate, 
15-20 pw long, 6-8 p thick ; hymenial gelatine deep-blue with 
iodine.—Cromb. in Grevillea v. p. 108 (1877); Leight. Lich. FI. 
ed. 3, p. 12. Pannaria nigra subsp. triseptata Nyl. ex Cromb. in 
Grevillea i. p. 171 (1873). 
The minute crowded laciniz give a finely granular appearance to 
the thallus. The radiate circumference is not developed on the 
British specimen. There is only one record in our Islands. 
Hab. On schistose rocks in alpine situations.—B. M. Craig 
Tulloch, Perthshire. 
4. Pt. kenmorense A. L. Sm.—Thallus of stoutish small 
crowded or scattered squamules with an irregularly granular 
