1925] Setchell-Gardner: Melanophyceae 525 



yet also lead us to keep Halorhipis Winstonii distinct because of the 

 lack of the pluricellular paraphyses so characteristic of both Aspero- 

 cocctis and HaJoglossum. It differs from a Punctaria, as we under- 

 stand that g'enus, in having: the thallus decidedly differentiated into 

 two sorts of tissues, and in having the zoosporangia superficial. 



19. Soranthera Post, and Rupr. 



Fronds spherical and solid in the juvenile stage, later becoming 

 hollow, inflated and membranaceous, sessile, attached by a rather 

 broad and penetrating base, composed of two kinds of tissue, an 

 inner one 4-5 cells deep, of large, nearly colorless cells, and a surface 

 layer of small, angular, color bearing cells ; reproduction by zoo- 

 sporangia in very distinct, conspicuous sori, scattered promiscuously 

 over the surface of the frond ; paraphyses pluricellular ; hyaline hairs 

 grouped in the center of the sori ; gametangia unknown. 



Postels and Ruprecht, Illustr. Alg., 1840, p. 19. 



The type species of the genus is S. ulvoidea discovered "Ad 

 insulam Sitcha, parasitica in fronde Rhodomelae Laricis," (fide 

 Postels and Ruprecht, Joe. cit.). The question of parasitism of the 

 genus has been investigated by Miss E. S. Barton and was discussed 

 by her in an article in the Journal of the Linnaean Society (1898, 

 p. 479). She questions the statement quoted above from Postels and 

 Ruprecht as to the parasitism of the species, taken in the sense that 

 we understand parasitism. However, her investigation shows that 

 the fronds are attached by a mass of rhizoidal filaments which sur- 

 round the host, many of which actually penetrate into the cells even 

 far into the interior of the host. She saw and figured what she inter- 

 preted as ' ' haustoria. ' ' Whether these plants and many others among 

 all four of the large sections of the algae which penetrate in a similar 

 waj', actually obtain food from the host has not been satisfactorily 

 determined, so far as we are aware. 



Soranthera ulvoidea Post, and Rupr. 



Fronds membranaceous, comparatively thin, oval, ellipsoidal or 

 nearly spherical, entire or irregularly lobed, up to 7 cm, diam. ; color 

 olive brown ; sori abundant, conspicuous, distributed fairly evenly 

 over the whole free surface of the frond ; zoosporangia clavate, 70-100/x 

 long, interspersed among numerous clavate, pluricellular paraphyses 

 which surpass them in length. 



