30 A Monograph of the Myxogastres. 



walls, chlorophyll, starch, hence in this respect are more typical 

 plants than the Myxogastres ; but in the fungi the check to pro- 

 gress was due to the degeneration of chromatophores, already 

 evolved by their ancestors, whereas in the Myxogastres the 

 check was due to their inability to differentiate these essentials. 



MYXOGASTRES. 



Order. PERITRICHEAE. 



Wall of sporangium not incrusted with lime; capillitium 

 absent or formed from wall of sporangium. 



Sub-Order. Tulmlinae. Wall of sporangium not perforated. 

 Sub-Order. Cribrariae. Wall of sporangium perforated. 



Order. COLUMELLIFEUAE. 



Wall of sporangium without lime ; capillitium originating 

 from a central, usually elongated columella. 



Sub-Order. Stcmonitac. Capillitium springing from every 

 part of an elongated columella. 



Sub-Order. Lamprodemnae,. Capillitium springing from the 

 apical portion of a short or elongated columella. 



Order. LITHODERMEAE. 



Wall of sporangium with an external deposit of lime; 

 capillitium present. 



Sub-Order. Didymeae. Threads of capillitium without lime. 

 Sub-Order. Physarae. Capillitium containing lime. 



Order. CALOTRICHEAE. 



Wall of sporangium without an external deposit of lime ; 

 capillitium present, not springing from a columella. 



Sub-Order. Ti'ickcac. Threads of capillitium free, simple or 

 branched, not anastomosing to form a network. 



Sub-Order. Arcyriae. Threads of capillitium either attached 

 by one end with the free tips more or less branched, or combined 

 to form an irregular network. 



The following diagrammatic arrangement is an attempt to 

 illustrate my ideas of relationship between the several orders. 



The bracketed generic names represent the points of contact 



