328 PYRENOCARPRI [aRTHOPYRENIA 



Ach. Lioh. Univ. p. 282 (1810); Cromb. Lich. Brit. p. 120; 

 Leight. Lich. Fl. p. 441 ; ed. 3, p. 471. 



Often confused with A. microftpiln, owing to the dark-coloured 

 tlialhis which in botli occurs in rather small patches. 



Hab. On bark of trees. — Distr. Very rare throughout the British 

 Isles. — B. M. St. Leonard's Forest, Sussex; Airyholm, Cleveland, 

 Yorkshire ; Killin, Perthshire. 



29. A. Cerasi Massal. Ric. Lich. p. 167 (1852).— Thallus 

 greyish or brownish, thin, more or less shining, subdeterminate. 

 Perithecia small, more or less elliptical, numerous, black, shining ; 

 perithecial wall dimidiate ; paraphyses breaking up, often 

 becoming almost obsolete ; spores colourless, elongate-oblong, 

 blunt at the ends, 3-septate, 0,015-25 mm. long, 0,004-8 thick. 

 — Verrucaria Cerasi Ach. Meth. p. 119 (1803); Leight. Lich. Fl. 

 p. 441 ; ed. 3, p. 471. 



Distinguished by the shining thallus and the elliptical perithecia, 

 a character that is sometimes rather obscure. 



Hah, On the bark of cherry and other trees. — Distr. Bare in S. 

 and S.W. England. — B. M. Hurstpierpoint, Sussex. 



30. A. Crombei A. L. Sm. — Thallus effuse, thin, yellowish- or 

 reddish-brown, rather shining. Perithecia scattered, small, hemi- 

 spherical, immersed, the small poriform ostiole emerging ; peri- 

 thecial wall dimidiate ; asci obovoid-cylindrical, about 0,055 mm. 

 long, 0,017-20 mm. thick ; paraphyses few, stoutish, entangled; 

 spores 8 in the ascus, oblong-clavate, 3-septate, round at the 

 ends, almost breaking up into halves, 0,20-22 mm. long, 

 0,005-6 mm. thick. 



Differs from A. suhmicans in the form of the spores and the 

 presence of paraphyses. The two specimens in the British Museum 

 were collected at the same locality by Crombie, and one of them was 

 determined by Nylander as A. grisea Koerb. ; the latter, however, has 

 1 -septate rather fusiform spores. 



Hah. On bark of trees (alder). — B. M. Banks of the Garry, Blair 

 Athole, Perthshire. 



31. A. suhmicans A. L. Sm. — Thallus yellowish or pale- 

 reddish-brown, thin, effuse. Perithecia numerous, small, hemi- 

 spherical, shining, black, the ostiole minutely poriform ; peri- 

 thecial wall dimidiate ; paraphyses very scanty or none ; asci 

 obclavate, rather short ; spores 8 in the ascus, linear-oblong or 

 slightly clavate, 4-guttulate, 1- then 3-septate, colourless, some- 

 times becoming brownish, 0,016-22 mm. long, 0,004-6 mm. 

 thick. — Verrucaria suhmicans Nyl. in Flora Iv. p. 363 (1872); 

 emend. Leight. Lich. Fl. ed. 3, p. 471 (1879). 



The spores originally described by Nylander as 2-celled only, 

 remain so for a long time, the presence of the large guttulae also tends 

 to obscure the additional septa. 



Hah. On trees. — Distr. Rare in S. and N. England, Wales and 



