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. pyxidata 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- 

 donice 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 

 diflPer 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. pyxidata 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 herbarium bears at the same 

 time the two names C. pyxidata 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 (7. 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 * Cladonise Belgicae,' 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 Florke), 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 Delise. 



