482 119. Acolium. 4. CENOTHALAMEAE. Pl.cell.aph. 
XXIX. 1 19. ACOLIUM. Acharius. Acolium . 
Thallus crustlike, flat, expanded, adnate, uniform ; apo- 
thecia cuplike, nearly sessile, cartilaginous, composed of a 
compact powdery mass forming a naked centre, the upper 
part flat or nearly globular. 
1. Acolium tigillare. Rafter acolium . 
Crust in beds, wartlike, rather bald, lemon-yellow; apo - 
thecia, sessile, deep black, opake, centre flat, border swollen. 
Lichen tigillaris, Achar . Prod. 67 ; Engl. Bot. 1530. 
Tiecidea tigillaris, Achar. Meth. 46; Lick. 164. 
On old timber-work. 
2. Acolium lympanellum. Little-drum acolium . 
Crust cartilaginous, smooth, afterwards rather warty, 
uneven, gray; apothecia sessile, black, centre flat, with a 
greyish hoar; border thin, even with the centre. 
Lichen inquinans, Engl. Bot. 810. 
Calicium tympanellum, Achar. Meth. 89 ; Lich. 233. 
On timber-work. 
When touched stains the fingers black. 
3. ylcolium stigonellum. Dimpled acolium . 
Crust scarcely cracked, uneven, whitish, or 0; apothecia 
sessile, nearly globular, black, bald ; centre dotlike, after- 
wards flattish, opake; border thin, naked. 
Lichen gelasinatus, Withering Bot . Arr. 4. 
Lecidea gelasinata, Achar. Meth. 33. 
Sphaerocarpus sessilis, Ehrh. Crypt. 320. 
Sphseria sphincterica, Sowerby Bril. Fnngi y 386, 1. 
Calicium sessile, Persoon Tent. Fang. Suppl . 59. 
Calicium stigonellum, Achar. Meth. 88; Lich. 232. 
On the bark of oak-trees, and on the crust of porina per- 
tusa. 
XXX. 120. PHACOTRUM. Acharius. Phacotrum . 
Thallus crustlike, flat, expanded, adnate, uniform; apo- 
thecia podicilled, centre powdery, flat or globular, border 
prominent. — The centre of the apothecia sometimes falling 
out, they are left hollow. 
1. Phacotrum microcephalum. Small-headed phacotrum. 
Crust rather tartarlike, not broken, wrinkled, olive- 
colour ; apothecia nearly globular, black, shining ; centre 
depressed, opake; podicils short, similar in colour. 
Lichen microcephalus, Engl. Bot. 1865. 
Calicium microcephalum, Achar. Syn. Lich. 57,8. 
On oak-wood. 
