162 SETCHELL— PARASITISM AMONG RED ALG^. 



new genus of parasitic red alg^e belonging to the Rhodomelaceas, 

 which he named Bensaitenia. The single species is parasitic on 

 other Rhodomelacese. Finally, M. A. Howe (1914, p. 90) has made 

 known the genus Lohocolax, which he refers doubtfully to the 

 " Nemalionacese " (Helminthocladiacese Auctt.)- The single species 

 forms tubercles on Prionitis decipiens (Mont.) J. Ag. 



To summarize the genera thus far proposed of parasitic red 

 algse, there were nineteen recorded by Schmitz and Falkenberg in 

 1897, and six have been proposed since that time. In addition, it 

 may be stated that there are four additional genera as yet unde- 

 scribed in the collections of the writer. The total number of genera 

 known to the writer, therefore, amounts to twenty-nine. These are 

 all reduced or condensed as to the thallus, penetrating and appar- 

 ently forming protoplasmic connections with the host plants and 

 varying from full deep red to pure shining white. 



In regard to species, the number assigned thus far to these genera 

 and fairly certain, number about fifty and it seems best to give a 

 list of these arranged by families and to indicate in connection with 

 each its host or hosts, in order that the basis for further discussion 

 may be made clear. In this list there have been included only those 

 species which seem fairly certain as representing definite and distinct 

 parasites. All decidedly doubtful species are omitted. An * is 

 placed against those species which are credited to hosts among the 

 red algse but not of the same family as the parasite and a f against 

 those parasitic on Phseophycese. The rest are parasitic on red algae 

 of the same family as themselves. 



Helminthocladiace.e. 



*i. Lobocolax deformans Howe (1914), on Prionitis decipiens 

 Mont. J. Ag. 



Gelidiace.e. 



*2. Choreocolax polysiphonicc Reinsch (1874-75), on Polysiphonia 



fastigiata (Roth) Grev. 

 *3. Choreocolax tumidus Reinsch (1874-75), on Ceramium and 



Cystoclonium piirpuracens (Huds.) Kuetz. 

 *4. Choreocolax cysfoclonii Kylin (1907), on Cystoclonium pur- 



purascens (Huds.) Kuetz. 



