Perichaena 265 



of slender, branched, yellow threads 1.5-2.5 /x diani., minutely 

 warted or marked with regular close-set constrictions at intervals 

 of 0.5-1 )u, and with irregular expansions. Spores yellow, min- 

 utely warted, 8-12 m diam. (Plate 14, fig. 5.) 



Type locality: Belgium. 



Habitat: On dead wood and bark, occasionally on leaves. 



Distribution: Common throughout North America. 



Illustration: Lister, Mycetozoa ed. 3. pi. 189. 



This species usually forms small developments. Typical spo- 

 rangia are distinguished from P. corticalis by their larger size, 

 flattened and polygonal shape, more abundant capillitium and 

 smaller spores. There are many intermediate forms approaching 

 P. corticalis. The yellow dehiscence area is usually a prominent 

 feature of the species. P. quadrata is a phase of P. depressa with 

 small, nearly quadrate sporangia, and somewhat elevated or con- 

 vex lids, and is often seen among typical sporangia in one develop- 

 ment. Forms with crystalline lime on the outer wall are fre- 

 quent, as in P. corticalis and occasionally in P. vermicularis. 



6. Perichaena pedata (A. & G. Lister) G. Lister, Jour. Bot. 75: 

 326. 1937. (N. Y. B. G. no. 8964, authentic material.) 



Perichaena variabilis Rost. var. pedata A. & G. Lister, Jour. Bot. 42: 139. 



1904. 

 Perichaena vermicularis (Schwein.) Rost. var. pedata Lister, Mycetozoa ed. 2. 



253. 1911. 



Plasmodium? Sporangia usually stalked, occasionally sessile 

 or forming plasmodiocarps, minute, reddish brown; sporangial 

 wall membranous, single, smooth or papillose, showing a tendency 

 to break into areolae, clothed with granular refuse matter. Stalk 

 black, 0.1 to 0.5 mm. high. Capillitium a flexuose network of 

 pale yellow or brownish threads 2-2.5 /x diam., smooth or minutely 

 warted and usually marked with close-set or irregular constric- 

 tions. Spores pale yellow, minutely warted, 9-10 n diam. 



Type locality: England. 



Habitat: On dead leaves. 



Distribution: *Pennsylvania, Quebec. 



Illustration: A. & G. Lister, Jour. Bot. 42: pi. 459, figs. 3a, 

 3b, 4. 



This little species was formerly placed with P. vermicularis, 

 and later as a minute, stalked phase of P. chrysosperma (Lister, 

 Mycetozoa ed. 3. 244. 1925). The Pennsylvania collection was 



