170 



THE LOWER FUNGI— PHYCOMYCETES 



radish. Another, A. parasiticus Coker (1923: 165), attacks 

 Achlya, and others have been described by Drechsler (1928; 1929) 

 from oats, tomatoes, and beets. 



Two somewhat imperfectly known genera, Aphanomycopsis 

 Scherffel (1925) and Sommerstorffia Arnaudow (1923), fall near 

 Aphanomyces. In both of these genera the intramatrical 

 mycehum is characteristically swollen and distorted, and both 

 are based on parasitic species. 



Fig. 63. — Aphanomyces steUatus de Bary. (o) Hyphae bearing oogonia 

 and antheridia. (6) Stellate oogonium with a single spherical oosphere. (c) 

 Germinating oospores. {After de Bary 1860.) 



The genus Aphanomycopsis contains the single species, A. 

 bacillariacearum Scherffel, occurring in Pinnularia, one of the 

 diatoms. 



The genus Sommerstorffia was based on S. spinosa Arnaudow 

 parasitic in the body of Rotiferae. The fungus has been collected 

 in America and has been discussed and figured by Sparrow (1929). 



14. Leptolegnia de Bary (1888: 631). 



Until recently the type species, L. caudata de Bary constituted 

 the genus. It has been reported from America only by Coker 

 (1923: 158), but has been studied in Europe by several investi- 



