208 Mycetozoa of North America 



and Martin (Myxomycetes 227) have studied the type and another de- 

 velopment, and report differences between the two sufficient to create 

 doubts that the form belongs in the genus, although recognized by them. 

 It may be a phase of one of the better known species of Licea, altered 

 somewhat by methods of laboratory culturing, as such forms do occur. 

 It is hoped that a natural fruiting from the field may be found, so that its 

 position may be satisfactorily determined. 



Genus 30. ORCADELLA VVingate, Proc. Acad. Nat. Sc. 

 Phila. 1889: 280. 1889. 



Hymenobolina Zukal, Oester. Bot. Zeitschr. 43: 133. 1893. 

 Kleistobolus Lippert, Verh. Zool.-Bot. Ges. Wien 44 (Abh.): 70. 1894. 



Sporangia stalked or sessile, minute; sporangial wall opaque 

 with granular deposits except in the upper part, where it forms a 

 membranous lid; spores smooth. 



Type species: Orcadella operculata Wing. 



The members of this genus show a distinct advance in struc- 

 ture over those of Licea by the presence of a firm lid, which does 

 not open or rupture until the spores are perfectly mature, and 

 protects against premature dispersal. The highest development 

 of the lid in form, attachment, and ornamentation, is seen in 

 Orcadella pusilla. 



Sporangia usually stalked. ' 10. operculata 



Sporangia usually sessile. 



Sporangia almost black. 2, 0. parasitica 



Sporangia brown. 3. 0. pusilla 



1. Orcadella operculata Wing. Proc. Acad. Nat. Sc. Phila. 1889: 

 280. 1889. (N. Y. B. G. nos. 6168, 6169, 7618, type 

 material.) 



Licea operculata (Wing.) Martin, Mycologia 34: 702. 1942. 



Plasmodium dull orange (Minakata). Total height 0.4 to 0.9 

 mm. Sporangia scattered, usually stalked, rarely sessile, urn- 

 shaped or subglobose, 0.1 to 0.3 mm. diam., brown or nearh' 

 black, with a convex, dull yellow, glossy lid; sporangial wall 

 cartilaginous, opaque from deposits of refuse matter; lid mem- 

 branous, minutely papillose. Stalk cylindrical, rough, furrowed, 

 nearly black from dark refuse matter. Spores yellowish in mass, 

 almost colorless by transmitted light, smooth, 8-11 m diam. 



Type locality: Philadelphia, Pennsylvania. 



Habitat: On bark. 



