of the Herbarium of Acharius, 311 
that I was very curious to ascertain to what species he had re- 
ferred it in his herbarium—+to C. pyaidata or to C. fimbriata. 
I found that he had not distinguished this variety, and that he 
had placed it sometimes under one, and sometimes under the 
other of these Acharian species. 
All lichenographers know of the controversy which existed 
so long between Florke and Acharius on C. pyxidata (L.). I 
have examined the herbaria of these two masters, and I am 
bound to say that, although Florke in general knew the Cla- 
donie better than his rival, nevertheless he was wrong on this 
question. 
10. Cladonia pocillum, (Ach.) Syn. p. 253 et hb. ejusd. 
It is long since lichenographers considered C. pocillum as a 
distinct species, they having more recently made it a variety of 
C. pyxidata (L.). I find nevertheless that this form does not 
differ sufficiently from the type to enumerate it as a variety, 
especially in so polymorphous a group as the genus Cladonia. 
When a station is examined where C. pyaidata grows in 
abundance, we see that all the young individuals approach more 
or less to C. pocillum, and that intermediate forms passing into 
pyxidata are much more common than the two types. Acharius 
himself had often a difficulty in distinguishing these two forms ; 
and more than one specimen in his berbarium bears at the same 
time the two names C. pyaidata and C. pocillum. I would 
therefore recommend the var. pocillum to be erased from our 
floras. 
11. Cladonia pityrea, (Ach.) Syn. p. 254 et hb. ejusd. 
The Acharian types, although not numerous, are nevertheless 
good and very characteristic; but his two varieties acuminata 
and decorticata differ very little from each other, and represent 
the same type. The former has the thallus subuliform, granular, 
simple, or branched; the latter is a little more decorticated, 
whiter, and sometimes bears squamose leaflets. This latter ap- 
proaches sufficiently near to C. decorticata of Florke to be 
regarded as synonymous. ‘The plants of Florke have, however, 
all the characters so well defined that I can easily conceive how 
this author was tempted to make of it a distinct species. 
The variety acuminata, Ach., is not sufficiently distinct from 
the type of the species to deserve mention in our floras, as may 
be seen in my ‘Cladonie Belgice,’ Nos. 93 & 94. The form 
decorticata, on the contrary (not that, however, which is found 
in the Acharian collection, but that which is represented in the 
herbarium of Flérke), deserves to be cited. It may be easily 
confounded with C. macilenta in a sterile condition, or, in the 
squamulose forms, with C. squamosa frondosa of Délise. 
