36 
the sporidia are olive, ellipsoid-oblong in the young state, 
containing 2 polar nuclei instead of regular loculi and septa. 
It appears to me absurd to separate these parasites in dif- 
ferent genera, or from the genus Verrucaria ; nor am I satisfied 
as to the propriety of distinguishing them even as species. 
It would be quite as scientific, and much more convenient, 
to regard E. erraticus as a mere polysporous variety of 
V. gemmifera. 
8. On Lecanora polytropa, Ehrh. 
Summit of Ben Lawers; gathered by myself in June, 1856. 
The apothecia are studded over with a parasite, which is 
probably Thelidium epipolytropum, Mudd. (Brit. Lich., 
p- 298).1. It occurs as microscopic, black, punctiform, 
conceptacles, externally resembling Torula lichenicola. 'The 
asci are, however, 4-spored, while in Mudd’s plant they are 
8-spored. Sporidia variable in form and size: generally 
ellipsoid, 2-locular, pale yellow, becoming pale blue under 
iodine. They cannot be confounded with the sporidia of the 
Lecanora, which are simple, oval, and colourless.? 
9. On Lecanora subfusca, Ach. 
(a) Var. albella, Pers. Corticolous, collected on Morchone, 
Braemar, in August, 1856. Next to Torula lichenicola, the 
most interesting of many parasites I have found on L. sub- 
fusca are the following. In the Morchone plant two parasites® 
produce deformity or disease of the apothecia of the Lecanora, 
sometimes rendering them quite black, and their surface 
rough or verrucose, by the close aggregation of numerous 
minute papilleeform conceptacles. Externally the two series of 
parasitic perithecia are alike, but their internal structure is 
very different. One series contains asci that give a blue with 
iodine, and are therefore presumably referable to a Lichen. The 
sporidia are 2-locular, pale yellow,* pyriform, sometimes 
resembling those of certain forms of Verrucaria epidermidis. 
This parasite causes only partial discoloration of the apothecia 
on which they grow. The other parasite deeply and wholly 
blackens the apothecia, which it affects. Its sporidia are 
brown, 2-locular, and figure-8-shaped. 
(6) Corticolous form of type: growing on birch, Corra- 
1 Vide “ Observations on W. Greenland Lichens,” p. 366, plate |, fig. 23. 
? Ibid., p. 366, plate |, figs. 22, 23, 24, and 25. 
3 Ibid., p. 366, plate |, fig. 16. 
* Another parasite, with somewhat similar sporidia, affecting var. alryuca, 
Ach., is mentioned among my “ New Lichenicolous Micro-Fungi,” p. 541. 
