508 AQUATIC PHYCOMYCETES 



ed protuberance, resting on a short basal cylindrical stalk which is 

 slightly expanded at its terminus, wall smooth, colorless; rhizoids not 

 observed; zoospores probably fully formed within the sporangium 

 spherical, 3 \x in diameter, with a centric colorless globule and a fairly 

 long fiagellum, emerging upon the dehiscence of the operculum and 

 forming a compact spherical mass at the orifice before dispersing; 

 resting spore not observed. 



Parasitic on Melosira varians, Tabellariasp., United States. 



This species was doubtfully assigned to Chytridium epithemiae Nowak. 

 in a previous publication (Sparrow, 1933a: 68, fig. 1 d-f). Since little 

 is known of Nowakowski's fungus save from his short description and 

 his two figures, one of an empty sporangium, the other of an undischarg- 

 ed one, and since the operculum in his organism was subapical, it has 

 been thought best to segregate from it the species on Melosira and 

 Tabellaria. 



A further study of the original drawings and a few sporangia still 

 available in a glycerin mount seems to indicate that the sporangium 

 stalk is extramatrical rather than within the alga as previously supposed. 

 The subapical protuberance no doubt arises from a type of development 

 similar to that found in Chytridium schenkii, where an unexpanded 

 portion of the wall of the original zoospore persists. 



Chytridium chaetophilum Scherffel 

 Arch. Protistenk., 53: 45, pi. 2, figs. 87-94. 1925 



Sporangium sessile, short and sausage-shaped, broad-ovoid from 

 above, 9-11 \x long by 6 (jl in diameter, resting crosswise on the seta of 

 the alga, wall thin, colorless, the upper half bearing a tuft of long solid 

 delicate unbranched hairs; rhizoid, so far as is known, consisting of a 

 short peglike tube which just pierces the cell wall; zoospores spherical, 

 2-3 \x in diameter, with a prominent eccentric colorless oil globule and 

 a long delicate fiagellum, discharged after the gelatinization of a basal 

 part of the sporangium or by a bursting apart of the sporangium, 

 remaining motionless for a time after discharge, movement dancing 

 or hopping; resting spore epibiotic, sessile, nearly spherical, 5-8 \x 



