74 PHYSCIA. 



to a, it is differenced at length conspicuously, by the coloration- 

 of the under side. But these rock-forms are now pale beneath ; 

 and one from the Pacific coast (perhaps the named but not char- 

 acterized P. callosa, Kyi. in Flora, 1869 ; p. 119), is noticeable for 

 its coarser, thicker, rugose-verruculose thallus (Yosernite Valley, 

 Bolander; Oregon, Hall), but the scanty specimens scarcely 



afford any other than this difference. P. stellaris, a, perfectly 



characterized, has occurred in Florida with apothecia ciliate- 

 below, in the manner of P. obscura; Austin. 



7(b). P. astroidea (Fr.) Nyl. j thallus smallish, sub-cartila- 

 gineous, stellate, appressed, microphylline ; beneath pale with 

 pale fibrils ; the erose-multifid, much narrowed, flattened lobes 

 beset, for the most part, with rounded, finally confluent soredia ; 

 apothecia smallish, closely sessile, the disk blackening, sub- 



pruinose, the margin entire. Spores ^ rnic. Parmelia, Fr. 



L. E. p. 81. Physcia, Nyl. Syn. 1, p- 426. P. stellar is /?, Tuck- 

 erm. 1. c. p. 395. 



* hypomela ; commonly smooth and naked above ; brown and 

 at length black beneath, with fibrils of the same colour. 

 Parmelia obsessa, Mont. ! Cuba, p. 227, not ofAch. Tuckerm. I. c. 



Trees; New England, Pennsylvania, and Virginia, Tucker- 

 man I c. 1860. North Carolina, Curtis. South Carolina, Rav- 

 enel. Alabama, Peters. Louisiana, Hale. Texas, Wright. 



Mexico. * Louisiana, Hale ', which form proves, in Cuba, 



to be scarcely well separable always from P. crispa. This 

 smooth form varies in the colour of the under side just as P. 

 stellaris, and often well represents, in Texas, as in Cuba, the 

 coarser northern lichen. Its apothecia are often ciliate below 

 (P. leucothrix, Tayl. ! New Lich. 1. c. p. 170) as in P. obscura. 



7(c). P. crispa (Per.) Nyl. ; thallus sub-membranaceous r 

 stellate, appressed, platyphylline, greenish-glaucescent (often 

 pale roseate) beneath pale with scattered pale fibrils; the rather 

 wide, flat lobes interruptedly imbricate, palmately cut, the 

 repand edges powdery, and now ascending j apothecia smallish 

 to middling-sized, sessile, blackish -brown, the incurved margin 



crenate, or granulate. Spores as in P. stellaris. Nyl. Syn. 1 7 



p. 423. Parmelia Domingensis, Mont. Cuba, p. 225, t. 8, /. 3. 

 Physcia stellaris, v. Domingensis, Tuckerm. I. c. p. 396. 



* hypomela ; brown, and at length black beneath, with sim- 

 ilarly coloured fibrils. 



