PERICH^NA 259 



4. Pericilena marginata Schw. 



Trans. Am. Phil. Soc. II. 4 : 258. 1832. 

 PI. XVII, Figs. 441, 442. 



Sporangia depressed, globose, polygonal as they become approxi- 

 mate or crowded, hoary-canescent, sessile; peridium rather thick, 

 persistent, circumscissile in dehiscence, covered without by minute 

 whitish scales, within punctate by the imprint of the spores; hypo- 

 thallus distinct, white; capillitium scant or none; spores in mass dull 

 yellow, by transmitted light pale, nearly smooth, 12-15 /x. 



Lister, following Rostafmski, includes this form with the preceding. 

 The differences between the two forms are, it seems to us, sufficient 

 to make convenient their separation as by Schweinitz. Apart from 

 the peculiar incrustation in the present species, the larger spores, 

 and especially the peculiar white hypothallus, are distinctive. The 

 method of dehiscence is also different. In P. corticalis the line of 

 cleavage before spore dispersal is indicated by a definite band sur- 

 rounding the sporangium. Nothing similar appears in the gray speci- 

 mens of the present form, although the dehiscence is quite as certainly 

 circumscissile. The habitat in American specimens is the outer surface 

 of the bark, which causes the species generally, by protective coloration, 

 to be overlooked. 



Not common. Pennsylvania, Ohio, Missouri. 



5. Pericilena tessellata G. List. 



Jour. Bot. 69 : 298. 1931. 



Sporangia scattered, globose, purplish black, 0.1-0.5 mm. in diam- 

 eter, the dark outer wall breaking up into polygonal areolae and 

 exposing the shining, translucent inner wall; capillitium composed 

 of slender yellow tubular threads marked with minute warts and 

 constrictions; spores bright yellow, closely and minutely warted, 9-10 fx. 



Allied to P. depressa Lib. from which it differs in the scattered, 

 globose sporangia and the areolate dehiscence. 



Japan. 



6. Pericilena microspora Penz. & List. 



Myx. Buit. 76. 1898. 



Plasmodiocarps slender, short, long or net-like, 0.25-0.35 mm. broad, 

 salmon pink, glossy; wall single, membranous, smooth, yellowish, with 

 granular matter near the base; capillitium a network of slender, 

 yellowish pink, minutely spinulose threads, 1 .5-2 \x in diameter, reg- 

 ularly constricted at intervals of 1-2 n, more or less attached to the 



