400 PROCEEDINGS OF THE AMERICAN ACADEMY 



Appears to be inseparable from the species, and equally so from the 

 European variety (the Louisiana specimens being quite as depauperate 

 as most of my foreign ones), .but generally a finer plant than the latter, 

 and when perfect, scarcely differing from states of P. applanata, except 

 in color, and in the colorless hypothecium. Parmelia viridis, Montag. 

 Crypt. Guyan., & Syll. p. 329, {Parm. picta, Montag. Cuba, p. 221, 

 tab. 9, fig. 3, non Ach.), appears to be scarcely separable from the 

 North American Lichen ; and these varying conditions are perhaps 

 comparable with the American forms of the European P. astroidea. 



Pyxine Meissneri, Tuckerm. in litt. : thallo orbiculari cartilagineo 

 radiatim laciniato glabro glaucescente intus sulphureo ; laciniis subplanis 

 appressis pinnatifidis imbricatis subtus nigris ambitu fibrillosis ; apothe- 

 ciis primitus thallo concoloribus excipulo thallino subintegro tumidulo 

 discum planum nigrum cingcnte mox superne nigricantibus margine 

 demum tenuescente nitido disco convexo subexcluso. Sporce suboctonsB, 

 oblongo-ellipsoideaj, uni-septat?e, mox fuscescentes, diam. plusquam 3-plo 

 longiores. On trees in Cuba, and also in Nicaragua, M?-. Wright. And 

 I possess a fine Brazilian specimen, referred to Physcia by Dr. Meiss- 

 ner of Halle, from my kind friend, the late Professor Kunze of Leipzig. 

 Thallus differing from that of the next species in its entire smoothness, 

 and its light-yellow medullary layer. The apothecia are at first ex- 

 ceedingly like those of Physcia applanata, but the exciple soon blackens 

 above, and presents finally a convex disk enclosed by a shining margin 

 of the same color, thinner than the original thalline border, and often 

 looking, but not really, distinct from it. Professor Fries, in estab- 

 lishing this genus (PI. Homon. p. 266), indicated its relations to Um- 

 hiliearia, but did not regard either as Parmeliaceous. In venturing, 

 some years since, to take this view with respect to Pyxine (Synops. 

 Lich. N. E. p. 24, and 35) the writer had before him only the more 

 northern Lichen {Pyxine sorediata, Fr.), the " at first closed, palish " 

 apothecia of which, " becoming patellisform, and, with the altered thai- 

 line margin, black," he considered as indicating " a modification of Par- 

 melia, near to " the section " Amphiloma, Fr." ; a conclusion which the 

 foliaceous thallus, with its compact, crust-like centre, and often dense 

 hypothallus, served to strengthen. But the present species is as clearly 

 inseparable from Parmelia, in the sense of Fries, as it is from Pyxine ; 

 and its position as respects the new tribe Parmeliei, as acutely limited, 



