182 ULOTHRICACEAE 
branching, as well as the simple, filamentous algae. He adopted 
the genus from Dillenius. The first species mentioned by Lin- 
naeus, Conferva rivularis, is undoubtedly the oldest of his group, 
so far as the history of these ill-defined forms can be determined. 
This species, according to the synonymy of Linnaeus (Sp. Pl. 
1164. 1753), is Conferva fluviatilis, sericea vulgaris et fluitans of 
Dillenius (Hist. Musc 12. ei 2. f. 7. 1741); this in turn is 
Conferva Plinii Dillen. (Cat. Plant. sponte Gissam nascentium, 
199. 1719); the earliest description of C. Piot that we have 
seen is in L’Obel’s Plantarum Observationes, 664. 1576, but 
undoubtedly the name is of more ancient origin. 
Now no one would imagine that the ancient herbalists or even 
Linnaeus could distinguish the numerous filamentous forms known 
to us only by the use of good microscopes. Indeed, the fact that 
Linnaeus described only two unbranched species is sufficient 
proof of this. Conferva rivularis, as collected by him, was very 
likely at one time a Spirogyra and at another an ۰ 
This type species, however, as interpreted by the earlier algol- 
ogists, e. g., Dillwyn, Lyngbye and Mueller, is very evidently a 
form belonging to what is now known as Rhizoclonium, and has 
come down to us as R. zzvularis (L.) Kütz. This identification is 
also confirmed by Linnaeus himself, who (Sp. Pl. Ed. 14. 1784) 
quotes the figure of C. rivularis from Flora Danica. 
There is, therefore, a moderately strong argument in favor of 
employing the name Conferva for the genus Rhizoclonium if it is 
to be retained at all in modern algology. It would, perhaps, be 
better to reserve the name for the numerous species of confervoid 
algae whose character and proper position is not sufficiently 
known to permit their disposition in the more clearly defined 
modern genera. 
At any rate, there is no warrant whatever for employing the 
name Cozferva to designate the genus recognized under that name 
in Lagerheim's revision, for there is no evidence that these species 
were ever collected by Linnaeus, and certainly none of them were 
distinguished by him from other simple filamentous forms. 
For Lagerheim's group of species, as for all genera, the adop- 
tion of a generic name based on a recognizable species, as a type, 
is essential. The earliest such name in the present case is 77750- 
