STICHOCOCCUS 159 
cluded in the genus the same species in the same order, with 
descriptions. In his final work, Species Algarum (1849), Kützing 
placed ZZ. moniliforme in its present position in Ulothrix, H. fraccum ` 
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, (’gI) 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 U/o- 
trix. These were placed by Gay in the genus Stichococcus Nägeli 
(49) because of their tendency, in common with S. bacillaris, 
toward aérial 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 Stichoccocus a 
form which he supposed to be Ulothrix subtilis. Kütz., a species 
which is very generally aquatic. 
Now in one of the best known Séichococcus species, S. flaccidus 
(Kütz.) 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 tothis 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 U/othrix. 
The single species in which we have not observed zoospores is 
Stichococcus bacıllarıs Nägeli, 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. 
