98 Mycetozoa of North America 



the sporangial wall, which is pale lilac in color. The species is 

 closely related to D. globosum and connected therewith by forms 

 with varying spores. It differs by the more closely connected 

 sporangial walls, and the usually paler, smaller spores. 



6. Diderma globosum Pers. Neues Mag. Bot. 1: 89. 1794. 



Diderma cruslaceum Peck, Rept. N. Y. State Mus. 26: 74. 1874. (N. Y. 

 B. G. nos. 7958, 7959, 7960, 11606, 11607, 11608, type and authentic 

 material.) 



Plasmodium white (Lister). Sporangia subglobose, sessile, 

 crowded, often forming large colonies, 0.5 to 1 mm. diam., rarely 

 forming plasmodiocarps, smooth, white or cream-colored, usually 

 seated on a well-developed, white or cream-colored hypothallus; 

 sporangial wall of two layers, the outer eggshell-like, composed of 

 globular lime-granules 1-2 n diam., often separating widely from 

 the membranous, inner layer. Columella hemispherical or sub- 

 globose, usually small, white or pale flesh-colored. Capillitium 

 consisting of slender, irregularly branching and anastomosing, 

 pale purplish threads, often with irregular expansions toward the 

 base, enclosing a few lime-granules. Spores dark purplish brown, 

 spinulose, 10-14 fx diam. 



Type locality: Europe. 



Habitat: On dead leaves, twigs, etc. 



Distribution: Common in the United States and Canada. 



Illustration: Lister, Mycetozoa ed. 3. pi. 85. 



The eggshell-like outer wall, distinctly and often widely sepa- 

 rated from the inner one, is the important character separating 

 this species from D. s pumarioides . The spores vary considerably 

 in size and color, and occasional specimens have spores overlap- 

 ping those of D. s pumarioides. Various specimens from collec- 

 tions made by Dr. C. H. Peck, and named D. cruslaceum, are in 

 the Herbarium of the New York Botanical Garden. The speci- 

 men from Karnak, New York, has dark spores, 12-14 /x diam., 

 and in the one from Memphis, New York, the spores are also dark 

 and measure 12 /x diam. In other specimens the size is irregular, 

 but they are imperfectly developed, a condition often found in 

 the species. Following the Lister conception of the species, which 

 is based on the examination of an authentic specimen of Rosta- 

 finski, the conclusion here is that D. cruslaceum is typical D. glo- 

 bosum Pers. as interpretated by Rostafinski. The reader is 



