CHYTRIDIALES 429 



of collective swarming before escaping; resting spore not observed. 



Saprophytes inhabiting insect exuviae. 



Obelidhun in its method of development, general structural features, 

 possession of a subsporangial apophysis, type of zoospore discharge, 

 and habitat is very similar to the other exuviae-inhabiting fungi, 

 Siphonaria, Rhizoclosmatium, and Asterophlyctis. There is little doubt 

 but that they are all closely related forms. It is probable that when 

 resting spores of Obelidium are found and their method of development 

 followed, further similarities will be discovered. 



Obelidium mucronatum Nowakowski 

 Cohn, Beitr. Biol. Pflanzen, 2: 86, pi. 5, figs. 1-5. 1876 



Sporangium ranging from 20-23 \x in height by 7-8 \x in diameter to 

 48-56 u, in height by 17-20(x in diameter, consisting of a thick-walled 

 cuplike or funnel-like base 4-12 u, in diameter by 4-10 \i in height, a 

 narrowly to broadly ovoid, thin-walled mid-region, and a single solid 

 refractive apical spine (rarely two, opposite) which is seldom more than 

 one third of the total sporangial height; rhizoids profusely branched, 

 extensive, radiating for 100 \x or more from their point of origin, in 

 large specimens gradually increasing in diameter (up to 5 u,) as they 

 approach the small subsporangial apophysis to which they are attached; 

 zoospores spherical or slightly ellipsoidal, 2.5-3.5 u, in diameter, with 

 a small eccentric highly refractive colorless globule and a flagellum 20 \x 

 in length, movement hopping or amoeboid; resting spore not observed. 



Saprophytic in empty submerged exuviae of Chironomidae, Nowa- 

 kowski (Joe. cit.), Germany; wing of submerged fly, Sorokin (1883: 22, 

 fig. 20), Asiatic Russia; Phryganeidae, H. E. Petersen (1909:412; 

 1910: 547), Denmark; Chironomidae, Sparrow (1938d: 1, figs. 1-44), 

 chitin bait, from moist soil, Karling (1948c: 509), United States. 



small male cell attached to resting spore; /, immature sporangium, showing 

 fusiform apophysis. J-K. Asterophlyctis sarcoptoides H. E. Petersen: /, very 

 young thallus showing irregular shape of reproductive rudiment, and apoph- 

 ysis from which rhizoids emerge; K, mature sporangium. All fungi figured 

 occurred in insect exuviae. 



(A-E, Sparrow, 1938d; F-K, Sparrow, 1937a) 



