228 PROCEEDINGS OF THE AMERICAN ACADEMY 



cent, with a thick, inflexed, at length rugose, thalline margin. Tuckerm. 

 Enum. Lich. N. Amer. p. 50. 



Trunks and dead wood ; Hingham, Mr. Russell. Ipswich, Mr. 

 Oakes. 



37. P. Crania, Tuckerm. Th. orbicular, membranaceous, smooth, 

 radiant, submonophyllous, dark-bluish becoming pale-lead-colored ; la- 

 cinise plane, with elevated, darker margins (beset with elevated, often 

 blackish points, and isidioid branchlets) ; hypoth. determinate, dark 

 caerulescent. 



Rocks among mosses, common on the coast of Massachusetts, and 

 resembling a Collema; infertile. It is very distinct from P. plumbea. 



38. P. lanuginosa., Ach. Th. membranaceous, white, pruinose ; in 

 the circumference lobed and crenate; hypoth. tomentose, bluish-black; 

 apoth. rufous-fuscous, with a pulverulent thalline margin. Fr. Lichen- 

 ogr. p. 88. — /?. (granulosa), Fr. ; thallus, at the centre, or mostly, gran- 

 ulose-pulverulent. Fr. I. c. — * (leproso-byssina) ; the whole thallus 

 dissolved into a leprous-byssine mass. Fr. I. c. Lepraria, Ach. 



Rocks in the mountainous districts and on the coast of New Eng- 

 land ; rarely fertile. 



Subsect. V. PsoROMA, Fr. 



39. P. microphylla, Stenh, Scales of the thallus cartilagineous, im- 

 bricate, crenate, livid-cinereous, compacted at length into a cinereous 

 crust ; hypothallus becoming black ; apothecia superficial, disk fuscous- 

 black, finally convex, and excluding the thalline margin. Fr. Lichen- 

 ogr. p. 90. Lecidea, Ach. 



Rocks in woods, fertile ; New England. 



40. P. triptophyUa, Fr. Scales of the thallus membranaceous, livid- 

 fuscescent, at first stellate-expanded, and lacerate-dissected, at length 

 granulose-coralline ; hypoth. bluish-black ; apoth. somewhat immersed, 

 disk rather plane, rufous-fuscous, margin erect, persistent. Fr. Li- 

 chenogr. p. 91. — a. coronata, Fr. ; apoth. produced from the thallus, 

 with a thalline margin, and either simple or symphycarpeous. Fr. I. c, 

 Lecanora brunnea, Ach. part. — (3. Schraderi, Schser. ; apoth. pro- 

 duced from the hypothallus, plane, destitute of a thalline margin. Fr. 

 I. c. — /. corallinoides, Fr. ; crust blackish from the predominant hy- 

 pothallus, squamules wholly coralline. Fr. I. c. 



Rocks in woods ; New England. New York, Halsey. Pennsylva- 

 nia, Dill. Northward to Arctic America, Rich. 



