428 



AQUATIC PHYCOMYCETES 



Fig. 27. Rhizidiaceae 

 A-E. Obelidium mucronatum Nowakowski: A, nearly complete thallus 

 with sporangium slightly tilted; B, mature sporangium; C-E, stages in dis- 

 charge of zoospores. F. Siphonaria variabilis H. E. Petersen, discharging 

 sporangium. G. Rhizoclosmatium aurantiacum Sparrow, empty sporangium 

 and two zoospores. H-I. Rhizoclosmatium globosum H. E. Petersen: H y 



