DR LAUDER LINDSAY ON NEW LICHENICOLOUS MICRO-FUNGI. 543 



spherical, -00033'' in diameter, generally with double contour — rough or granulate 

 externally — resembling, in some respects, those of Sphwropkoron ; than which, 

 however, they are much larger. Sometimes in age they become oval and 

 unequally figure-8-shaped, as if in process of fission. What appear to be the nuclei 

 of the spores also occur abundantly, as much smaller spherical corpuscles, 

 •00016" to -00020'' in diameter, pale yellow, gradually becoming olive and brown, 

 exhibiting like the spores themselves double contour. Nylander describes (Prod. 

 91) its spores as black and spherical, and thinks the plant should be referred to 

 the genus Spilomium * ( Uredinew). 



10. M. vesicularia. Parasitic on thallus of Lecidea vesicularis, Ach., Switzer- 

 land ; in Herb. Kew. Occurs as small but distinct black papillae, closely aggregated ; 

 superficial ; scarcely immersed ; externally resembling those of M. pygmcea. It 

 resembles that species further in its asci being polysporous ; but the sporidia are 

 1-3-septate, according to age ; most usually the latter in maturity. The smaller 

 ones, when 1-septate, resemble those of M. pygmcea. Hymenium gives no blue 

 with iodine. Asci -0027" long, and -00083" broad. Sporidia -00033" to '00050' 

 long, -00016" broad, but variable in size ; fusiform or oval; brown. 



Also having brown, minute sporidia, which are here, however, oval or 

 ellipsoid, and are sometimes concatenate, is a parasite that affects the sterile 

 thallus of what appears to be a Pertusaria, in Balthayock Woods, Perth, June 

 1856, W. L. L. No part of the hymenium gives blue reaction with iodine. The 

 thallus of Pertusaria communis is the seat of a parasitic fungus, Spilomium 

 Pertusariicolum, Nyl. (Enum. Gener. p. 91, and Synopsis, p. 144), which is conidio- 

 sporous, the spores being oblong and blackish. The same thallus is affected by 

 Lecidea parasitica, Flk., Sphinctrina turbinate^ Pers., and var. microcephalia, Nyl., 

 Trachylia stigonella, Ach., Pseudogr aphis elatina, Ach., and Opegrapha anomcea, 

 Nyl.f 



My Herbarium contains a number of other lichenicolous parasites, having 

 (more or less) characters resembling those of the Microthelice above described. But 

 I cannot at present venture to assign names, or a specific place in classification, 

 on account of the imperfections of their reproductive structure, the doubtful 

 nature of their habitats, or other difficulties as regards their determination or 

 description. The following are illustrations of this heterogeneous group of 

 parasites : — 



1. Associated with Verrucaria epldermidis, Ach., var. analepta, Ach. ; banks 

 of Crinan Canal, Argyleshire ; on birch ; Aug. 1856, W. L. L. — It has quite 

 the thallus and aspect of a Verrucaria {e.g. gemmata); and it is impossible 

 to determine whether the thallus is that of V. epidermidis or other Verrucaria, 

 or belongs to the plant now to be described. Intermixed with the apothecia of 



* A genus not mentioned in Berkeley's " British Fungology" (1860). 

 t Vide Paper on " Parasitic Micro-Lichens" (antea citat.). 



