PASSITO FItORiDEAE OF CRLIFOltflfl 



BY 



WILLIAM ALBERT SETCHELL 



In 1897, C. N. Nott published (Erythea, voi. 5, pp. 81-84) 

 notes on «Some Parasitic Florideae of the Californian Coast». He 

 enumerateci three species, Sterrocolax decipiens Schmitz on Ahn- 

 feldtia plìcata (Hudson) Fries, Gonìmophyllum Buffhami Batters on 

 Nìtophyllum Ruprechtianum J. Ag., and Janc^ewskia verrucaeforwis 

 Solms on Laurencia pinnalifida Lam'x and on Agardhìella tenera 

 (). Ag.) Schmitz (Rhabdonia Coulteri Harv.). Since the publication of 

 Nott's paper, several other parasitic red algae ha ve been discovered 

 or more carefully investigated, including a form which must be con- 

 sidered to be type of a new genus. 



A species of Harveyella, found at San Pedro California, by Pro- 

 fessor A. J. Me Clatchie in 1896, growing on Gracilaria multìpar- 

 tita (Clem.) Harv., although somewhat larger and even more pale 

 in color than the European form, yet seems inseparable from H. 

 mirabilis Schmitz. A not uncommon species of Actinococcus occurs 

 on a very much flattened form of Gymnogongrus linearis (Turn.) J. 

 Ag. No name has ever been given to this form, but it seems to 

 come near to Actinococcus latior Schmitz, but it is even larger than 

 the dimensions given for that species, since it often reaches a dia- 

 meter of 5-6 mm. A few specimens of a small parasitic red alga 

 have been discovered by the writer, growing on Mychodea episcopalis 

 J. Ag. This parasite was first detected by Professor W. G. Farlow, 

 who thinks that it represents the type of a new genus, but farther 

 supplies of material are awaited. 



Ali of the above parasites penetrate the host plant by means of 



