OF ARTS AND SCIENCES. 227 



Sect. II. The subfoliaceous at length subgranulose thallus arising 

 from a flbrillose hypothallus, which is adnata to the matrix. 



Subsect. III. Pyxine, Tuckerm. 



34. P. sorediata, Tuckerm. Thallus subcrustaceous-foliaceous, la- 

 ciniate-multifid, from green becoming glaucescent, and cinerascent; 

 black on the under side, and thickly clothed with greenish-nigrescent 

 fibres; lacinise sublinear, canaliculate, incised, obtuse, irregularly im- 

 bricate, and concrete at the centre (often sorediiferous) ; apothecia at 

 first pale, and concave, becoming black, convex, and finally prolifer- 

 ous-papillate and irregular. Lecidea, Ach. Syn. p. 54. Tuckerm. Fur- 

 ther Enum. I. c. Lichen alomatus, Willd. herb. ! Pyxine., Fr. cit. 

 Eschw. 



Trunks, common (abundantly fertile in mountain forests), and also 

 on rocks ; New England. Pennsylvania, Muhl. ! Rocky Mountains, 

 Herb. Hook. ! (Southward to Texas !) I have not seen the descrip- 

 tion of Fries, and am uncertain whether his Pyxine is founded on our 

 Northern Lichen (which is probably what Acharius described), or on 

 the West Indian and South American Lecidea sorediata of Eschweiler. 

 The latter seems distinct, and has been separated as Circinaria Berte- 

 riana by Fee (Crypt. Exot. p. 128). Our Lichen appears to me a 

 modification of Parmelia, near to Amphiloma, Fr. The apothecia 

 have some of the features of those of Umbilicaria, and illustrate 

 Fries's observation, that this genus is related to Parmelia. 



Subsect. IV. Amphiloma, Fr. 



35. P. rubiginosa, Ach. Thallus membranaceous, suborbicular, not 

 pruinose, livid-glaucous, laciniate-multifid at the circumference ; hy- 

 pothallus indeterminate, tomentose, bluish-black ; apothecia reddish- 

 brown, with an incurved, crenate margin. Fr. Lichenogr. p. 88. — /5. 

 conoplea, Fr. ; the centre of the thallus passing into a bluish, pulvera- 

 ceous-granulose crust ; ' apothecia symphycarpeous, immersed, convex, 

 granulose-marginate.' Fr. I. c. P. conoplea, Ach. 



Rocks and trunks. ^ has occurred at the White Mountains ; and I 

 have u from the South. 



36. P. Russellii, Tuckerm. Th. orbicular, coriaceous-membrana- 

 ceous, minutely farinose-granulose, submonophyllous, irregularly radi- 

 ant, pale-fuscescent-lead-colored ; lacinise somewhat ascendant ; hypoth. 

 indeterminate, of very short white fibres becoming lead-colored at the 

 margins; apoth. (central, very numerous) reddish-chestnut and nigres- 



