31 



where similar phases occur, hut the spores there have small, 

 uniformly distributed, spines. 



Genus 7. DIACHEA 



In this genus of a few species the capillitium is a network of 

 purplish threads without lime-knots. The peridium has no lime 

 and is membranous, and hyaline or iridescent. There is granular 

 lime, however, in the stalk and columella, both of which are 

 usually present. The abundant species hereabouts is D. leucopo- 

 dia having cylindrical, blue or purple, iridescent sporangia with 

 white, brittle, calcareous stalks and columellae. It cannot be 

 confused with any other species of Mycetozoa. There is a glo- 

 bose variety which is close to other globose species of the same 

 genus, and cannot be determined so readily unless in company 

 with the typical form. 



Genus 8. DIDYMIUM 



This is one of the four genera of the Mycetozoa in which 

 lime is present in crystalline form. In Didymium it is often in 

 stellate clusters sprinkled on the sporangium-wall, or in a closely 

 compacted layer forming an outer layer of the peridium. The 

 capillitium in nearly all species consists of hyaline or purplish 

 threads without lime in normal developments. Sometimes, when 

 abnormal, there are traces, and in one species, D. Stiirgisii, it 

 is normal and prominent. Most of the species form sessile spo- 

 rangia or plasmodiocarps and are seldom collected in this region. 

 Three species having stalks and columellae are abundant and 

 are separated mainly on the differences in those characters. 

 Columellae otherwise are rare. D. squamulosiim has white, 

 subglobose, umbilicate sporangia on short, white, stalks which 

 usually spread at the bases, and white or yellowish columellae. 

 It also forms sessile sporangia and plasmodiocarps. D. xantho- 

 pus has more hemispherical, umbilicate, white sporangia on 

 much longer stalks, which are yellow or reddish -brown, trans- 

 lucent, and free from lime. The columella is white. D. melano- 

 spermum has sporangia like D. xanthopus but somewhat larger, 

 on short, dark, opaque stalks, and the columella is dark. D. 

 xanthopus and D. melanospermum do not form sessile sporangia 

 or plasmodiocarps; and all three species have the lime crystals 

 sprinkled on the sporangium-walls. 



