550 AQUATIC PHYCOMYCETES 



figures are obscure and observed with difficulty. Around each of the 

 nuclei a portion of the protoplasm is cleaved out and the resultant zoo- 

 spores are uninucleate, the nucleus lying posterior to the oil droplet. 

 (See also under "Sexual Reproduction," p. 78.) 



Zygorhizidium verrucosum Geitler 

 Arch. Protistenk., 96: 116, figs. 1, 2. 1942 



Sporangium sessile, nearly spherical, transversely ellipsoidal or some- 

 what pyriform, up to 10 by 12 [x, mostly smaller, with a somewhat lateral 

 or apical broad operculum, wall smooth and thin; endobiotic system 

 consisting of an at first small nearly spherical swelling, 0.5-1 \i in diam- 

 eter, which later becomes finger-like, irregular, hemispherical or 

 clavate and often somewhat lobed, 2-2.5 u. in diameter, without rhizoids ; 

 zoospores up to 64 in a sporangium, sometimes fewer, those from large 

 sporangia somewhat elongate and almost reniform or grape-seed-like, 

 dorsiventrally flattened, 3-3.5 u, long by 1.5-2.2 \x broad, those from 

 smaller sporangia more spherical and 2-3 jj. in diameter, with a flagellum 

 laterally inserted near forward end of spore but directed backwards 

 during motility, with a single anterior globule; male plant 2 by 3 \x, with 

 1-3 often very long conjugation tubes, 0.5 \x in diameter; receptive 

 thallus larger, the endobiotic part lacking rhizoids, after conjugation 

 forming a broadly ellipsoidal resting spore 5-5.5 by 6-6.5 [i, rarely up 

 to 7 [i broad, with a thick wall covered by coarse warts about 4.5 (j. high, 

 contents with several large oil globules, germination not observed. 



Parasitic on Mesotaenium caldariorum, Austria. 



The two types of zoospores produced suggest some sort of sexual 

 differentiation. 



Zygorhizidium parallelosede Canter 

 Trans. Brit. Mycol. Soc, 37: 128, figs. 8-9, pi. 5, figs. 5-6. 1954 



(Fig. 11 F-G, p. 110) 

 "Thallus monocentric, eucarpic sporangium developed from body of 

 an encysted zoospore. Rhizoid a fairly thick unbranched or little branch- 

 ed thread. Sporangium broadly cylindrical to cigar shaped, 3-6 \x high 

 and 8-26 \i long; oblong to oval, 3-4 [i high and 4-5.5 u. long; oper- 

 culate, not collapsing after dehiscence. Zoospores 4-40, fully formed in 

 the sporangium, spherical (2 \x in diameter, posterior flagellum 1 1 a 



