Stichococcus 159 



eluded in the genus the same species in the same order, with 

 descriptions. In his final work, Species Algaram (1849), Kutzing 

 placed H. moniliforme in its present position in Ulothrix, H. flaccum 

 in the genus Hormotrichum, and for H. velutinum, together with 

 additional forms created the section Hormidium under Ulothrix. 

 Of the three original species, the first and third are now recog- 

 nized as belonging in Ulothrix, while H. velutinum is referred to 

 Schizogonium. Clearly, then, Gay, ('91) was justified in abandon- 

 ing the name Hormidium. 



There are, however, several species among those referred to 

 Hormiscia {Ulothrix) by DeToni ('89) which form, together with 

 certain more recently described species, a group possessing char- 

 acters which furnish good reason for their separation from Ulo- 

 thrix. These were placed by Gay in the genus Stichococcus Nageli 

 ('49) because of their tendency, in common with S. bacillaris, 

 toward aerial life and vegetative reproduction. Because of the 

 supposed absence of reproduction by zoospores this genus was 

 placed with the Protococcaceae rather than with the Ulothricaceae. 

 Klercker ('96) went a step farther, and added to Stichoccoacs a 

 form which he supposed to be Ulothrix subtilis Kiitz., a species 

 which is very generally aquatic. 



Now in one of the best known Stichococcus species, S.flaccidus 

 (Kiitz.) Gay, Klebs ('96) found zoospores (there seems to be no 

 reason for doubting the correctness of the determination of the 

 species). He therefore revived the genus Hormidium, because of 

 his objection to the name Stichococcus as implying affinities with 

 the Protococaceae. Our own investigations have shown con- 

 vincingly that all the forms belonging to this group that are known 

 in America, with one possible exception, at times reproduce by 

 zoospore formation, hence there is not the slightest doubt that the 

 genus must be kept in the closest affinity with Ulothrix. 



The single species in which we have not observed zoospores is 

 Stichococcus bacillaris Nageli, the historical type of the genus. 

 Nevertheless, as we cannot say that zoospores are never formed 

 in this species, which has every appearance of close affinity with 

 the rest, and there is no other name available, it is necessary to 

 retain these forms under the name by which they are known in 

 recent literature. 



