CHYTRIDIALES 527 



rubrum, Ceramium sp., coll. Rosenvinge, Petersen (loc. cit.), C. strictum, 

 Petersen {op. cit., p. 488, "no. 5"), Delessaria sanguinea, Callithamnionsp., 

 Petersen {loc. cit.), Ceramium fruticulosum, Sparrow (1934c: 23, pi. 4, 

 figs. E-G), Denmark; Pylaiella litoralis, coll. Rosenvinge, Petersen {loc. 

 cit.), Greenland; Polysiphonia fibrillosa, Ceramium rubrum, Sparrow 

 ( 1 936b : 255, text fig. 3 1), United States ; Callithamnion ? sp., apical cells 

 of Polysiphonia spp., Herposiphonia tenella, Aleem(1950d: 435, fig. 26), 

 ? Chondria tenuissima, Pylaiella litoralis, Feldmann (1954: 132), ? Chon- 

 dria tenuissima, J. and G. Feldmann (1955: 248), France. 



The species as described here is undoubtedly a composite one and 

 much work will be needed to separate the varieties or even the species 

 which it now embraces. 



Cohn's fungus had irregularly pyriform sporangia, 25-33 [jl in diam- 

 eter, which rested with their broad bases on the alga. The wall was 

 somewhat thickened, dark, and punctate, and no rhizoids were observed. 

 At maturity an operculum 13 \x in diameter was dehisced from the 

 protruding apex, allowing the zoospores, 2.5 [jl in diameter, to escape. 

 Petersen's specimens differed in having the operculum slightly subapical 

 and the sporangium wall colorless and smooth; an unbranched rhizoid 

 was observed. He {op. cit., p. 487) suggests that the coloration and 

 punctation of the sporangium wall described by Conn were probably 

 caused by age. Sparrow's Danish material differed from Cohn's chiefly 

 in having a smaller operculum (7 [x in diameter), larger zoospores (4 \i 

 in diameter), and a smooth colorless sporangium wall, and from Peter- 

 sen's in having an apical operculum and rhizoids, which were probably 

 branched, arising from a central stalk. 



Rhizophydium olla Petersen on Pylaiella from Greenland cannot be 

 distinguished morphologically from R. polysiplwniae on the basis of the 

 description and figures given. Colin has called attention to the fact that 

 his fungus was confounded with the spermatia of Nitophyllum by Derbes 

 and Solier. Other instances of early investigators confusing the fungus 

 with an organ of the alga are given by Wright (1879b). 



J. and G. Feldmann's recent record (1955) for the species, from the 

 figures given, does not seem to relate to C. polysiplwniae. Furthermore, 

 their fungus did not attack Ceramium but only Chondria. 



