PERICH^ENA 183 



litium of long, sparingly branched threads furnished with pro- 

 jecting spinules remarkable for their length, about twice the 

 diameter of the thread ; spores yellow, minutely but distinctly 

 warted, about 12 /*. 



This is the common species everywhere on the inner side of 

 the bark of fallen trees, Ulmus, etc. It is readily distin- 

 guished at sight by the peculiar annular, looped, and U-shaped 

 plasmodiocarps, with their dark umbrine or blackened surface. 

 From the preceding it is especially distinguished by the spin- 

 ulose capillitium and larger spores. 



Not rare. New England, New York, Pennsylvania, Ohio. 



2. Perichsena Fries. 



1817. Perichtzna Fries, Symb. Cast., p. n. 



Sporangia flattened, sometimes small and roundish, more 

 often larger, polygonal by mutual interference, or irregular, 

 the peridium thickened outwardly by a dense reddish or 

 brownish layer of scales ; dehiscing by circumcission or by a 

 lid ; capillitium often scant, of slender, warted, yellowish 

 threads, attached betimes to the upper wall ; spores yellow, 

 oval or spherical. 



Key to the Species of Perichsena 



A. Sporangia plainly flattened. 



a. Very flat, sporangia i mm. or more in width . I. P. depressa 



b. Depressed ; sporangia smaller . . . .2. P. qiiadrata 



B. Sporangia more or less spherical. 



a. Chestnut brown . . . . . . 3. P. corticalis 



b. Gray or canescent 4. P. marginata 



i. PERICH^NA DEPRESSA Libert. 



PLATE XVII., Fig. 10. 

 1837. Perichcena depressa Lib., Fl. Crypt. Ard,, IV., No. 378. 



Sporangia sessile, applanate, crowded, polygonal by mutual 

 contact, rufous or chestnut brown, shining, opening by a def- 

 inite lid ; spore-mass and capillitium yellow, the capillitium 



