PLATE 2. 



Mrysipbeae. 



Uncinula Salicis, (D C). 



Fig. 1. Natural size on leaf of Salix flavescens, var. Scouleriana, 

 from Montana. 



2. Part of a leaf with perithecia magnified. 



3. A perithecium highly magnified. 



4. An ascus. 



5. Three sporidia. 



6. A conidiabearing hypha. 



7. Five conidia. 

 3. Initial hyphae forming a perithecium. 



