MYRIANGIALES 



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localized in definite regions of the stromata, i.e., they are differentiated 

 into sterile and fertile parts. 



The first type may be illustrated by Kusanoopsis guianensis in British 

 Guiana, which on dicotyledonous leaves forms dark-colored pulvinate 

 stromata, up to 1 mm. in diameter, erumpent from the interior of the host 

 at maturity (Fig. 136). They lack a definite rind, although the pseudo- 



Fig. 137. — Myriangium Diiriaei. A. Habit (natural size). B. Same (X5). C. 

 Section through an immature fructification (X 30). D. Section of conceptacle (X 100). 

 E. Ruptured ascus and mature ascospores (X 250). {After Millardet.) 



parenchymatous structure is always more marked in the sterile periphery 

 than in the fertile core. The asci are spread in several layers over the 

 whole interior, except the basal intramatrical portion, of the stroma, 

 which projects like a foot into the mesophyll. The asci are spherical, the 

 ascospores are hyaline and dictyosporic. 



The second type is shown by Myriangium (Phymatosphaeria) . The 

 majority of its species are parasitic on insects, especially plant lice. Like 



