242 THE NORTH AMERICAN SLIME-MOULDS 



is especially distinguished by the spinulose capillitium and larger 

 spores. 



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



2. Perichaena Fries 



1817. Perichaena Fries, Symb. Cast., p. 11. 



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 circumscission 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 Perlchsena 



A. Sporangia plainly flattened. 



a. Very flat, sporangia 1mm. or more in width . 1. P. depressa 



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



B, Sporangia more or less spherical 



a. Chestnut brown 3. P. corticalis 



b. Gray or canescent ...... 4. P. marginata 



1. Perichaena depressa Libert. 



Plate XVII., Fig. 10. 

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



Sporangia sessile, applanate, crowded, polj^gonal by mutual con- 

 tact, fuscous or chestnut brown, shining, opening by a definite lid ; 

 spore-mass and capillitium yellow, the capillitium well developed, 

 of slender yellow threads of various widths, almost smooth ; spores 

 minutely warted, 10-12 /x. 



Easily recognized by the peculiar, polygonal, depressed-flattened 

 sporangia and consequent shallow spore-cases in which lie the yellow 

 spores and scanty capillitium. Rostafinski refers here .P. vaporaria 

 Schw., No. 2311, but the meagre description seems rather to apply 

 to the next species. The original material is no longer accessible. 



In the crevices and or. the inside of bark of fallen logs of various 

 sorts, walnut, maple, etc. 



Not commonly collected. Specimens are before us from New 



