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. PI. 

 1 164. 1753), is Conferva flnviatilis , sericea vulgaris et fluitans of 

 Dillenius (Hist. Muse. 12. //. 2. f 1. 1741); this in turn is 

 Conferva Plinii Dillen. (Cat. Plant, sponte Gissam nascentium, 

 199. 171 9); the earliest description of C Plinii 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 Oedogonium. 

 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. rivularis (L.) Kiitz. This identification is 

 also confirmed by Linnaeus himself, who (Sp. PI. 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 Co?iferva 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 Tribo- 



