30 COLLEMACEl. [MAGMOPS1S. 



dark violet-blackish; spores 1-septate, colourless; bymeuial gela- 

 tine not tinged with iodine. 



From Purenidium, with which it is comparable, this differs in having 

 the thTllus pyrenopsoid and indeterminate; while from Verrucarma , to 

 which it iJiome resemblance, it differs in the apothecia not presenting 

 a true pyrenium. The genus as yet includes only two species, of which 

 one has 'been detected in Britain. 



1. M. argilospila Nyl. ex Cromb. Grevillea, xv. (1886) p. 10. 

 Thallus scattered, subfurfuraceous, very thin, olive-black. Apo- 

 thecia innate, minute, peridiura sufficiently thin, violet-black; 

 spores 0,022-2(3 mm. long, 0,007-9 mm. thick ; paraphyses slender, 

 sparingly present. Verrucaria argilospila Nyl. Flora, 1874, p. 15. 

 Verrucaria arenicola Leight. Grevillea, v. (1877) p. 155 ; Lich. Fl. 

 ed. 3, p. 470. 



The plant spreads extensively over the substratum in small, scattered, 

 more or less distinct macuke. In structure the thallus is densely and 

 minutely cellular, each cell containing a minute subglobose gonimium. 

 The apothecia in the specimens seen are numerous, and are more con- 

 spicuous where the thallus is semi-obliterated. 



Hub. On sandy and clayey soil in upland tracts. Distr. Local and 

 scarce, in W. England ; though it no doubt occurs elsewhere. B. M. : 

 Shelton Hough, near Shrewsbury, Shropshire. 



Family II. COLLEMACEl Nyl. Mem. Soc. Cherb. ii. (1854) 

 p. 8 ; Syn. i. p. 88 (cfr. Cromb. Grevillea, v. p. 76). 



Thallus foliaceous, or fruticulose, or crustaceous, turgid and 

 gelatinous when moist, black, brown, dark olive, leaden, rarely 

 glaucescent ; gonimia somewhat small, nakedly conjoined, monili- 

 form ; medulla not distinct, but confused with the gouimic layer. 

 Apothecia most frequently lecanorine, occasionally biatorine, rarely 

 endocarpoid, hypothecium colourless ; spores 8na3, rarely numerous, 

 very rarely 4na3, ellipsoid, ovoid or fusiform, simple or septate, or 

 variously divided, colourless, very rarely brown. Sperm ogones 

 usually with jointed sterigmata, occasionally with simple sterigmata, 

 aud short oblong spermatia. 



This family, as now limited by Nylander, comprehends plants which in 

 most essential respects are more closely related to each other than those 

 referred to it in his previous classification. " It consists of a higher type of 

 lichens than the Ephebacei, being superior in structure, and for the 

 most part in figure, with the gonimic granules not or scarcely ever simple, 

 but more or less (that is, two or several) moniliform (hormogonimia, 

 Nyl.). The thallus also, when moistened, is more turgid, and though 

 still somewhat Algoid in external appearance, is almost always much 

 better developed." In regard to the anatomical structure of the thallus, 

 Nylander, in his observations on "gonidia &c." (Flora, 1877, p. 359), has 

 pointed out that (in the higher genera at least) the whole thallus is to be 

 regarded as one syngonimium. This syngouimium, he adds, in litt., ori- 

 ginates either from a single primitive gonimium, or from the coalescence of 

 several gonimia into one syngonimic body. 



