of the Herbarium of Acharius. 307 
rium (and also of those of Délise, in the Museum of Paris, and 
of Flérke, at Rostock, the results of which will form separate 
papers) is to fix the synonymy of the species and the diverse 
varieties of these authors, to simplify the nomenclature by 
the suppression of a great number of useless varieties, and to 
indicate some new ideas on a certain number of the species, 
—thus constituting a prodromus for a new monograph of the 
genus Cladonia. 
1. Cladonia papillaria, Hffm., (Ach.) Syn. p. 248 et hb. ejusd. 
This species, although poorly represented in the Acharian 
herbarium, is found there in all states of development, except 
with perfect apothecia. The localities indicated, as for most of 
the other species, are France, Germany, and Sweden. 
2. Cladonia retipora, (Ach.) Syn. p. 248. 
No specimen. Acharius knew it only from the description 
and figure of Labillardiére. 
3. Cladonia cespititia, (Ach.) Syn. p. 249 et hb. ejusd. 
The specimens are very insignificant. A specimen from Lap- 
land merits notice by reason of the high latitude of its habitat. 
Most modern lichenographers consider C. cespititia to be a 
distinct species, whilst others regard it as a variety of C. squa- 
msoa. Frequent study and observation of this plant in the 
woods of Héverlé, near Louvain, and in the pine-forests of 
Meirelbeke, near Gand, convince me that it is only a variety of 
Cladonia pyaidata, pityrea. On some oaks in the wood of Hé- 
verlé, now unfortunately felled, | have for many years observed 
all the transitions between C. fimbriata (Ach.) and C. pityrea 
(Ach.), and between this latter and C. cespititia. I believe, 
therefore, we must henceforth regard C. cespititia as a variety 
of C. pyaidata (L.). 
4, Cladonia strepsilis, (Ach.) Syn. p. 249 et hb. ejusd. 
This Acharian species has always been problematical. Dr. 
Nylander, who had examined the Acharian herbarium, refers it 
to C. cespititia (Lich. Scand. p. 57, and Syn. p. 211); on the 
contrary, Flérke, who had also examined the Acharian specl- 
mens, recognizes it only as a sterile and macrophylline form of 
C. cariosa (Comm. p. 14). In reality, both these learned li- 
chenologists have foundation for their opinions. The principal 
specimen of C. strepsilis of Acharius (alone preserved entire, for 
the others have been mutilated) is positively the C. cespititia ; 
but the variety plumosa (Ach. Syn. p. 250) is a sterile form of 
