78 THE LOWER FUNGI— PHYCOMYCETES 



(Atkinson 1909 a : 338) . The swarmsporangia are usually slender 

 and vermiform, and put out as many as ten short exit tubes 

 arranged in one or two definite rows (Fig. 13, 6.). Resting 

 spores are unknown. Another species, E. perforans Petersen 

 (1905: 466), is described from Denmark in Licniophora and 

 Synedra, and several other species on the same or related hosts 

 have been described by Scherffel (1925: 10). 



6. Pleotrachelus Zopf (1884: 173). 



This genus was founded on a single species, P. fulgens Zopf, 

 occurring in Pilobolus. In parasitized host plants sporangia, 

 normally present, are suppressed and only zygospores are 



Fig. \A.— Pleotrachelus fulgens Zopf in Piloholus. {After Zopf I884.) 



developed. The sporangia of the parasite are globose and 

 resemble those of Olpidium but differ in emitting a number of 

 long slender exit tubes which protruiie in many directions 

 (Fig. 14). About ten other species have been described from 

 algae and roots of higher plants {Saccardo, Sylloge Fungorum, 

 21: 24). 



7. Pleolpidium Fischer (1892: 43). 



The members of this genus occur as parasites in the hyphac 

 or sporangia of various relatively rare water moulds. The out- 

 standing character of the genus is indicated in the derivation 

 of the name Pleolpidium (pleos: filled, and Olpidium), which 

 refers to the tendency of the parasite to fill the host cell. In 

 those species which occur in the sporangium of the host the 

 thallus enlarges until it completely fills the sporangium, the wall 



