LINDSAY, ON ABllOTHALLUS, 49 



of a free cavity. On tlie same apotliecia I have sometimes 

 fovmd the spores of both species of AbrothaUus, as well as 

 stylospores ; aiicl^ on the thallus, the spores of various Le- 

 cideas and other lichens may also he met with. This illus- 

 trates the dissemination of the spores of lichens by the winds, 

 rains, and other agencies. 



So far as my observations enable me to decide, this species 

 possesses no spermogones of the ordinary type — that is, of 

 the structure usual in those of most lichens. I shall pre- 

 sently show that I am inclined to regard the pycnides as 

 another or extraordinary type of spermogones, — in certain 

 exceptional cases taking their place and fulfdling their 

 functions. A. Smithii and A. oxysjjorus are frequently so 

 intimately associated that the one may appear to possess 

 spermogones and the other pycnides. In a few cases, I have 

 seen spermogones intermixed with, and apparently belonging 

 to, A. Smithii ; and pycnides scattered among, as if pertain- 

 ing to, a young state of A. oxysporus ; but in the former case 

 they really belonged to A. oxysporus, and in the latter to 

 A. Sinithil, the apotliecia of which were also interspersed. 



Of fifty-four sheets of specimens of A. Smithii (generally 

 associated witii A. oxysporus, and growing on furfui-aceous 

 states of P. saxatilis), I found pycnides present in thirty- 

 four cases, or about 63 per cent. ; while in forty-two sheets 

 of A. oxysporus {similarly growing, and with which A. 

 Sinitliii was associated), Spermoffoiies occurred only in five 

 instances, or about 12 per cent. The pycnides Avere there- 

 fore upwards of five times more frequent in A. Smithii, than 

 the spermogones in A. oxysporus. Hence the normal, or 

 usual, type of spermogones is comparatively rare in the genus 

 Abrothallus ; while the pyenidian, or exceptional, type is 

 somewhat common. This is one of the characteristic fea- 

 tures of the genus. In twenty-seven of the thirty-four cases, 

 in which pycnides occurred, they were associated with the 

 apotliecia of A. Smithii ; in four cases they were found alone, 

 chiefly on the bluish or lead-coloured squamules already 

 described ; and in three instances they were intermixed with 

 young apothecia of A. oxyspor-us, to which species they 

 appeared (but erroneously) to belong. In site and external 

 appearances, the pycnides closely resemble the spermogones 

 of ^. oxysjmrus, hereafter to be described; and are extremely 

 apt to be mistaken therefor or confounded therewith. Like 

 the latter, they occur as minute, black points, scattered gene- 

 rally over the surface, or only towards the periphery, of the 

 squamules or lobes. Each point or spot is perforated by a 

 simple or stellate pore, whose edges may be flattened, raised. 



