HYPHOCHYTRIALES 749 



the wall or extend greatly beyond it. Zoospores pyriform, slightly cla- 

 vate, 1.8-2.3 \i X 3-3.5 [i, hyaline to greyish granular in appearance 

 with one small slightly refringent globule; flagellum 5-6.5 \x long. Rest- 

 ing spores * hyaline and smooth, spherical, 10-14 [jl, or oval, 8 x 12 jx, 

 or oblong; content coarsely granular, germination unknown" (Karling, 

 loc. cit.). 



Parasitic in Ectocarpus mitchellae and E. siliculosus, killing and de- 

 stroying the contents of infected cells, United States. 



Some cytological details of the species are given by Karling (op. cit.). 



Anisolpidium rosenvingii (H. E. Petersen) Karling 



Amer. J. Bot., 30: 641. 1943 



Pleotrachelus rosenvingii Petersen. Oversigt Kgl. Danske .Vidensk Sels- 

 kabs. Forhandl., 1905: 453, fig. Ill, 1, 5, 6. 



Sporangium completely filling the host cell and assuming its shape 

 or lying free in it and somewhat spherical, with faintly yellow wall and 

 contents, wall not reacting to chloriodide of zinc, 10-31 \i long by 18-36 

 (jl in diameter, with one to three discharge tubes up to 25 [i in length; 

 zoospores elliptical or pyriform, 2-3 \x long, with a single anterior 

 flagellum. 



In Pylaiella littoralis, H. E. Petersen (loc. cit.), Sparrow (1934c: 19, 

 pi. 4, fig. M), Denmark; Aleem (1953: 7, pi. 1, fig. 1), Sweden. 



The description is based entirely on the living material studied by 

 Petersen and Sparrow. A form from Greenland studied only in preserved 

 condition by Petersen may also belong here. Petersen characterized it 

 as follows: 



"Sporangia colorless, smooth-walled, turning violet with chloriodide 

 of zinc, filling or nearly filling the host cell, 20-68 \i long by 24-41 [x in 

 diameter, with from 1-4 discharge tubes 4-6 jjl long by 4-5 u. in diameter; 

 zoospores not observed." 



In Pylaiella littoralis, coll. A. Jessen, Greenland. 



1 See Johnson (1957a) where these are shown to be sexually formed. 



