OP ARTS AND SCIENCES : APRIL 12, 1864. 279 



A tropical potentiation of L. rubella, (Ehrh.) Schisr. (considered as 

 representing the group of which it is a member), analogous to and 

 sometimes not at once distinguishable from L. parvifoKa, which I take 

 for a similar higher expression of L. vernalis. " The latter (L. parvi- 

 folia) appears the stronger species, and is represented by a larger suite 

 of forms, externally, at least, not so well separable from each other, while 

 the hchens approaching it, yet more closely akin to L. vernalis {LL. 

 suhvernalis, Icetior, cinereo-lutescens, lutco-rufula, &c.), are also more 

 varied and distinguishable from the Northern plant than the corre- 

 sponding tropical conditions associable with L. rubella. Strikingly 

 characterized, at their centres, as both species are, in the crustaceous 

 sub-genera to which they belong, by their squamulose habit, this distinc- 

 tion disappears at the extremes, in granulose or scurfy forms not always 

 separable by the eye from Northern members of their groups. Of the 

 enumerated forms which make up a (as the lichen is represented in 

 Mr. Wright's collection), a appears, so far as all the evidence from 

 external characters goes, to pass directly into b ; of which c is (as I 

 understand it) no more than an abnormally whitened, finally deliques- 

 cent condition ; and in this case, I take it, the evidence of diversity 

 derivable from the difference of dimensions in the spores must be sub- 

 ordinated. The variety /3 is the granulose condition of the lichen, 

 analogous to the similar state of L. parvifolia, and often very like it ; 

 but the former is perhaps more readily distinguishable from its type, 

 or in other words less easily reducible to it, than the latter. The 

 apothecia of L. microphyllina are originally not unlike those of L. 

 rubella, and vary from pale-lutescent to rufous and reddish, at length 

 blackening ; and the hypothecium passes, in the same way (as in L. 

 rubella, taken in its largest sense, or as expressed in Nyl. Prodr. Lich. 

 Gall. p. 114, and Enum. Gen. Lich. p. 122), from almost colorless to 

 brownish, vinous, and black. The spores, slender in all the forms, are 

 especially diminished in c, but Mr. Wright collected another lichen, 

 with a thallus scarcely distinguishable from that of c, in which they are 

 more elongated than in any of the conditions here described,* thus 

 approaching the filiform and still more elongated spores of L. prasina, 

 Mont. & Tuck., a lichen externally most resembling Lich. Cub. n. 218. 



* In all the larger specimens of my copy of Stenh. Lich. Suec. n. 53 (the lichen 

 is Bacidia rubella, y.fallax, Koerb. Par. p. 131, and has been separated as a species 

 by Lonnroth), I find the spores remarkably elongated. 



