CHYTRIDIALES 227 



to 24.4 \i in diameter, wall smooth with a single inconspicuous exit 

 pore at maturity; zoospores spherical, 1.6 u, to 2.0 (j. in diameter. 

 Resting sporangia clavate, stalked, 4.1 (x x 16.4 \l to 6.1 \i x 25.1 \i, 

 at maturity stalk empty of protoplasm, apical portion filled with num- 

 erous small oil globules. Germination of resting sporangia not ob- 

 served" (Whiffen, loc. cit.). 



Parasitic on Rhizophydium macrosporum, Whiffen (loc. cit.), cyst of 

 microscopic animal. Sparrow (1952d: 762), United States; Rhizo- 

 phydium spp., Rhizidium richmondense, Rhizophlyctis sp., Willoughby 

 (1956: 135, figs. 8-9), Great Britain. 



LOBORHIZA Hanson 



Amer. J. Bot., 31: 169. 1944 



(Fig. 19 J-K, p. 318) 



"Thallus epi- and endobiotic, monocentric, eucarpic; epibiotic part 

 forming the rudiment of the sporangium or resting spore, endobiotic 

 part forming a polylobate haustorium; sporangium inoperculate, ses- 

 sile; zoospores posteriorly uniflagellate, fully formed within the spo- 

 rangium and emerging singly; resting spore thick walled, stipitate, 

 usually formed by the fusion of isomorphic motile gametes [gametan- 

 gia] one of which has previously come to rest and germinated on the 

 host; germination unknown" (Hanson, loc. cit.). 



The genus is distinct from the closely related Phlyctidium and Rhi- 

 zophydium by reason of formation of a polydigitate absorbing organ 

 and true internal proliferation of the sporangium. 



The type of sexual reproduction here is like that found in Phlyctidium 

 eudorinae (see "Sexual Reproduction," p. 70). 



LOBORHIZA METZNERI Hanson 



Amer. J. Bot., 31 : 169, figs. 1-31. 1944 



"Zoosporangia pyriform 17 x 31 [j. to 46 x 67 \x in diameter, im- 

 bedded except for their apices in the gelatinous sheath of coenobia, 

 sessile on cellular elements of all phases of Volvox cartcri with the 

 exception of the purely vegetative cells of each phase and the thick 

 walled zygote of female colonies, secondary and tertiary sporangia 



