344 AQUATIC PHYCOMYCETES 



when present branched, arising from the base of a spherical (about 

 7 u. in diameter) or occasionally fusiform subsporangial apophysis; 

 zoospores spherical, 6 u. in diameter, with an eccentric colorless glob- 

 ule and a long tlagellum, emerging in a compact mass probably 

 surrounded by a slime sheath through an apical pore formed within 

 the collarette of teeth and resting motionless for a time before as- 

 suming individual motility, movement hopping or amoeboid; resting 

 spore not observed. 



On Oedogonium rivulare, de Bary (in Rosen, 1887), France (Stras- 

 bourg); Vaucheria polyspenna, Scherffel (1926a: 224, pi. 10, figs. 

 105-106), Hungary; substratum (?), Karling (1932:49, fig. 19), 

 Cladophora sp., Sparrow (1933c: 523, text fig. I, 4, resting spore?), 

 United States; Cladophora sp., Sparrow (1936a: 445, fig. 4 o), Great 

 Britain. 



A glycerin mount of the type material is in the British Museum 

 (N. H.), in the de Bary collection, but it was not available for ex- 

 amination. 



Scherffel (loc. cit.) used the binomial Rhizidium quadricorne de Bary; 

 there appears to be no evidence, however, that de Bary ever cited his 

 fungus in this manner. 



A thick-walled subspherical resting body 15 [x in diameter has been 

 found in certain sporangia of this species (Sparrow, 1933c). It may 

 belong to an extraneous parasitic organism. 



The teeth of the fungus figured by Karling (loc. cit.) are more like 

 those of Phlyctochytrium zygncmatis (Rosen, op. cit., pi. 13, fig. 12, 

 lower), being shallowly rather than deeply incised. Too little is known 

 at present of these species to judge how much weight is to be given 

 variations of this nature. 



A form with nearly spherical sporangia and four strongly diverging 

 bipartite teeth found by Sparrow (1938c: fig. 33) on Cladophora in 

 Michigan is perhaps referable to this species. 



Phlyctochytrium bullatum Sparrow 



Occ. Papers Boston Soc. Nat. Hist., 8:296. 1937; Amer. J. Bot., 25:487, 



figs. 7-14. 1938 



(Fig. 19 H, p. 318) 



