CHYTRIDIALES 213 



on deliquescence of the apex of the sporangium. Resting spores not 

 observed" (Canter, loc. cit.). 



Parasitic on Mougeotia sp., Canter (loc. cit.; 1953:282), Great 

 Britain. 



Canter (1953) states that the species exhibits endo-exogenous devel- 

 opment. 



Phlyctidium laterale (Braun) Sorokin 

 Arch. Bot. Nord France, 2: 20, fig. 15. 1883 (separate). 



Chytridium laterale Braun, Monatsber. Berlin Akad., 1855: 382; Abhandl. 



Berlin Akad., 1855: 41, pi. 2, figs. 20-21, 23-26. 1856. 

 Rhizophydium laterale (Braun) Rabenhorst, Flora Europaea algarum, 



3: 281. 1868. 



Sporangium sessile, spherical, ovoid or because of the formation 

 of a prominent lateral papilla, somewhat anatropous, 10-16 jx in diam- 

 eter, with one to three blunt, conical discharge papillae, wall smooth, 

 colorless; endobiotic part consisting of an unbranched, peglike (oc- 

 casionally bulbous) structure two to three times as long as thick, which 

 barely penetrates the host wall ; zoospores somewhat oblong, 2 a. in 

 diameter, and 10-12 [A long, with an eccentric globule, assuming motility 

 before discharge, escaping through one to three pores formed upon 

 the deliquescence of the papillae; resting spore 12 u. in diameter, color- 

 less, germination not observed. 



On living and dead cells of Ulothrix zonata, Braun (loc. cit.), Schenk 

 (1858a: 237), Germany; Stigeoclonium, Sorokin [loc. cit.), Asiatic 

 Russia, European Russia; Ulothrix zonata, Serbinow (1907: 157, pi. 

 6, figs. 18-21), European Russia; Ulothrix sp., Ingold (1940, comm.), 

 Great Britain; Ulothrix sp., Litvinow (1953:78), Latvia. 



The description is based on that given by Braun and on three other 

 undoubted records for the species. Information and figures supplied 

 by C. T. Ingold (1940, comm.) from abundant living material confirms 

 the existence of a lateral-pored chytrid with an endobiotic system com- 

 pletely devoid of rhizoids. The similar-appearing fungus identified by 

 Karling as Rhizophydium laterale (Braun) Rabenhorst (1938e), which 

 has a tuft of rhizoids terminating the haustorial axis and a part of the 

 zoospore cyst persisting as a hemispherical protrusion, is considered 

 a new species of Rhizophydium, R. karlingii (p. 243). 



