LINDSAY, ON ABllOTHALLUS. 43 



treraely probable tliat tliey are not independent species^ but 

 merely malformations of some more familiar lichens. This 

 idea^ Berkeley mentions, has also occurred to Sir W. Hooker. 



I. A. Smithii. — Of 71 sheets^, containing about 250 specimens 

 of A. Smithii and A. oxys2i07'us, generally intermixed, the 

 former species occurred in 54 cases, or about 7Q per cent. ; 

 while the latter was found in 42 cases, or about 59 per cent. 

 Of the two species, therefore, A. Smithii is the more 

 abundant, though the preponderance is not very greatly in 

 its favoui*. The young apothecia appear firet to occiu* as 

 spherical, blackish v/arts in the medullary tissue of the 

 matrix (by v/hich name I mean to designate the deformed 

 portions of the thallus of P. saxatilis, and other lichens, on 

 which the parasite occurs) . Increasing gradually in size and 

 colour, such an apothecial wart pushes its way to the surface, 

 and perforates the cortical layer, either by a slow process, 

 whereby the latter is thinned without fissuring, or rapidly, 

 wliereby more or less extensive radiate-fissuring is produced. 

 In the former case the cortical border of the nascent 

 apothecium is comparatively entire ; in the latter it is irregu- 

 larly broken by the stellate fissures, which, like the apothecium 

 itself, generally appear black. After its evolution through 

 the cortical layer, the apothecium swells, becoming globose ; 

 and its margins gradually overlap the cortical border. To 

 the latter the margins are at first more or less closely ap- 

 pressed : sometimes they become agglutinated ; at other 

 times they remain, or become, with age, free. The latter 

 condition seems to be assisted, if not produced, by a 

 gradual contraction, as the apothecium becomes mature and 

 old, of its base, — the hypothecial tissue. This process goes 

 on till the apothecium falls away, leaving a saucer-shaped 

 cavity or foveola, closely resembling, at a later stage of its 

 development, or rather retrogression, the cyphellae of the 

 Stict(S. With age, such cavities or pits become more 

 urceolate, and their edges better defined. The latter are 

 frequently distinctly raised and dark coloured; while the 

 cavity of the foveolse may remain whitish, reddish, saffron- 

 coloured, or it gradually assumes a brownish tint. These 

 foveolse are peculiar to A. Smithii, and are frequently seen 

 on the old thallus, especially in Highland districts. I have 

 never noticed them in A. oxysporus. When young and 

 emergent, especially if deplanate, the apothecia of A. Smithii 

 resemble somewhat the nascent apothecia of A. oxysporus ; 

 but a microscopic examination will at once detect the 

 difference. In specimens of A. Smithii from the neighbour 



VOL. V. F 



