160 THE iVORTH AMERICAN S LIME-MOULDS 



entirely, and in which the capillitium, as Persoon regarded the 

 case, is formed of a network of reticulate threads surrounding 

 the spores. Schrader redefined the genus ; opposed Persoon's 

 view as to the capillitial nature of the net, and separated the 

 genus Dictydium, but by imperfect limitations, in fact, chiefly 

 because of the more completely evanescent peridium. Fries 

 follows Schrader. Rostafinski first clearly separated the two 

 genera, and his classification is here adopted. 



As to the habitat of the Cribrarias, the remark of Schrader is 

 still pertinent " in vetustissimis plenariae destructionis proxi- 

 mis arborum truncis " for all the species. Rotten coniferous 

 wood seems to be preferred, but the decayed logs of trees of 

 other orders are by no means refused. Rotten oak forms a 

 very common habitat. 



Key to the Species of Cribraria. 



A. Sporangia with spores ochraceous or brownish. 



a. Sporangia larger, .5 mm. or more. 



1. Net poorly developed, sometimes merely indicated, 



i. C. argillacea 



2. Net conspicuous, nodes expanded. 



i. Calyculus reticulately thickened . 2. C. macrocarpa 

 ii. Calyculus marked by simple radiant lines or ribs ; free 

 ends in the net almost none, 5. C. aurantiaca 

 iii. Nodules well developed. 



* In the net free ends common, 6. C. dictydioidcs 

 ** Nodules joined by parallel threads, 



7. C. intricata 



b. Sporangia small, less than .5 mm. 



1 . Nodes not expanded . . . . 3. C minutissima 



2. Nodes well shown. 



i. Calyculus distinctly marked by radiant lines, 



9. C. tenella 



ii. Calyculus minute or none . . 10. C. microcarpa 

 iii. Calyculus replaced by ribs . . 4. C. splendens 



B. Sporangia more or less marked with purple or violet tints. 



a. Purple or violet throughout. 



1 . Net poorly developed . . . 1 1 . C. -violacea 



2. Net well developed. 



i. Meshes regular and the nodes distinct, 13. C. elcgans 

 ii. Meshes and nodules irregular . 12. C. purpurea 



