410 REV. J. If. CROMBIE ON MADAGASCAR LICHENS. 



USNEA FLORIDA (L.), f. RUBIGINEA (Mich.). 



The discoloration of the th alius in this state of the plant is en- 

 tirely accidental, and owing either to the presence of ammonia in 

 the atmosphere, or the urine of animals (e.g., in arboreal habitats, 

 of bats), or other similar causes. 



U. xanthopoga, Nyl. in MS. ut sp. n. 



This species was formerly known to occur only in the Campbell 

 Islands, where it was gathered by M. Filhol. The specimens are 

 barren. 



U. XANTHOPOGA, f. RUBIGINESCENS. 



This state is entirely analogous to f. rubiginea of the preceding 

 species, and is owing to the same causes. 



Parmelia perlata, var. ciliata, Schcer. 

 Infertile. 



Stictina Mougeotiana (Del.). 

 Very sparingly, and sterile. 



S. umbavillaria ( Bor.), var. papyrina, Nyl. 



Only a single small specimen, but well fruited. 



S. RETIGERA, Ach. 



Fertile. 



S. DAM^ECORNIS (Sw.). 



Sparingly, but fertile. 



S. plumbea, Del., Nyl. (vide Nyl. Syn. p. 357). 



A smaller state, but otherwise sufficiently typical and fertile. 



S. variabilis, Bor. 



Only a small and barren fragment. 



S. AURATA, Ach. 



Infertile, and with paler th alius. , 



Ricasolia dissecta (Ach.), Nyl. 



In the absence of fructification (only a single apothecium not 

 rightly developed being present), the specimen (otherwise incom- 

 plete) cannot be positively determined. If in reality, as it would 

 appear, referable to this species as a smaller form (f. minor), it is 

 interesting to have its geographical range thus extended from 

 equinoctial America to Africa. 



Physcia flavicans (Sw.). 

 Infertile. 



P. leucomela, var. angustifolia, Mey. $ Flot. 

 Typical but sterile. 



