CHYTRIDIALES 151 



? Olpidium algarum var. brevirostrum Sorokin 

 Arch. Bot. Nord France, 2: 30, fig. 32 bis. 1883 (separate) l 



Sporangium spherical or broadly ellipsoidal, variously oriented in 

 the algal cell, wall thin, smooth, colorless, discharge tube arising from 

 one of the ends, short, narrow, isodiametric, protruding slightly beyond 

 the outer wall of the alga; zoospores with a swollen, somewhat reni- 

 form apex and a colorless basal globule, fiagellum fairly long; resting 

 spore not observed. 



In Sphaerozosma vertebratum, European Russia, Asiatic Russia. 



As suggested by Fischer (1892:25) and Minden (1915:243) the 

 species is only doubtfully distinct from Olpidium entophytum. 



The sporangia have been calculated to be 4 by 6-9 \i; the zoospores, 

 1 [i. in diameter, and the discharge tube, about 2 \± long. 



? Olpidium immersum Sorokin 

 Arch. Bot. Nord France, 2: 31, fig. 34. 1883 (separate) 2 



Sporangium broadly and somewhat irregularly saclike, slightly con- 

 stricted in the region of the isthmus of the semicells of the host, wall 

 thin, smooth, colorless, discharge tube narrow, markedly swollen where 

 it meets the inner wall of the host, projecting for a variable distance 

 extramatrically; other characters not observed. 



In various desmids, Staurastrum, Sorokin (loc. cit.), Asiatic Russia; 

 Cosmarium, Staurastrum, de Wildeman (1893b: 51, pi. 7, figs. 12-15, 

 17), Belgium; Cosmarium sp., de Wildeman (1895a: 65, pi. 2, figs. 

 1-6), Switzerland; desmid, coll. Massart, de Wildeman (1896b: 45, 

 pi. 3, figs. 27-28), Norway. 



Scherffel (1926a: 213) believes this to be the same organism figured 

 by Reinsch (1878: pi. 17, figs. 11-12). The fungus in Cosmarium from 

 Denmark, called by Petersen (1910: 538, fig. XVld) Myzocytium ir- 

 regulare, also resembles Olpidium immersum. It is unfortunate that, 

 in spite of the relatively numerous collections of this fungus, no ob- 

 servations on the zoospores have been made. Only after this has been 

 done can its true relationships be decided. 



1 Ibid., 85, pi. 80, fig. 101. 1889. 



2 Ibid., 136, pi. 79, figs. 91-92. 1889. 



