OF FILAMENTOUS, FRUTICULOSE, AND FOLIACEOUS LICHENS. 241 
elaborate series of investigations, to ascertain whether all lichens did not possess 
similar organs ; and the result was one of the most valuable contributions ever 
made to the natural history of the lichens,—one which is the basis of all our 
recent and improved information on their minute structure.* The years 1850 
and 1852, the dates of the publications respectively of Irzicsoun and TULASNE, 
may be thus said to constitute an important era or epoch in the history of 
lichenology. The labours of the German and French lichenologists, during the 
years 1848-52, have certainly given a powerful and much-wanted impetus to 
lichenology. 
Specimen 1.—On old ash trees, roadside, Balthayock, near Perth, June 1856, 
W.L.L. The spermogones are old, containing no free spermatia; they are 
mostly confluent, very irregular and quite distinct to the naked eye. Soabundant 
are they, that they give a coarsely warted character to the whole thallus. In 
none of the spermogones, whether isolated or confluent, is there a distinct ostiole. 
Specimen 2.—On trees, old Castle of Melgund, Forfarshire; coll. A. Croat, 
1853. Here also the spermogones are old; they are of a deeper brown colour 
than the thallus, and are irregular large warts, frequently,confluent, scattered about 
the ends of the laciniz. The ostiole is seldom recognisable when young; when 
old, it sometimes becomes a narrow elongated fissure. 
Specimen 3.—A specimen in Herb. Botanical Society, Edinburgh (no habitat 
given), has young and mature spermogones, containing spermatia. The spermo- 
gones are very abundant as brown papillee rather than warts. The ostiole is seldom 
round, generally elongated or stellate-fissured. The spermogones are generally 
grouped, frequently confluent; they are distinct on account of the pale grayish- 
brown colour of the thallus. This is one of the best specimens I have ever met 
with of the spermogones of P. ciliaris. The spermatia are rod-shaped, about 
goth long. 
SpEcizes 2, P. leucomela, Mich., 
A beautiful species, growing in Europe, Africa, Asia, America, and Australia. 
The spermogones are essentially those of the last species in site and structure ; 
but they are usually smaller and more regular, and, from the whitish colour of 
the thallus, and their own brown or blackish colour, they are usually much more 
easily recognised than in P. ciliaris. 
Specimen 1.—On rocks by the sea, near Ballycotton, County Cork; coll. 
CarroLt. There are a few old spermogones, closely resembling those of 
_P. ciliaris ; they are largish brown tubercles or papillze, scattered about the ends 
of the lacinize, and very distinct from the contrast of their deep-brown colour with 
the almost pure white of the thallus. The cavity is sinuous, as in P: ciliaris, 
* Mémoire pour servir, &c., ol. citat, 
VOU, XXII. PART 1. 3Q 

