Tribonema 183 



nema Derbes & Solier (1856). This genus was based on a single 

 species, Conferva bombycina, and in the diagnosis, for the first 

 time in the history of the species, explicit mention was made of 

 the most essential character, namely, the form of the chromato- 

 phores, although it had been previously suggested in the plates 

 of Kiitzing. The method of zoospore dispersal was also first 

 described and illustrated by Derbes & Solier. There is, then, 

 every reason for employing the name Tribonema as a memorial of 

 the discernment of these authors. 



Only a small number of forms is known to belong in this 

 genus, and the inclusion by DeToni of a long array of species of 

 Conferva and Psichohormium in the genus Conferva as emended 

 by Lagerheim, is quite unwarranted. Probably many of these 

 ought to be reduced to synonymy or placed on the list of indeter- 

 minables ; certainly very few of them have been shown to possess 

 the characters of the revised genus. The evil results of De- 

 Toni 's wholesale grouping of species of ill-defined character may 

 be seen in the very unreliable determinations of species by certain 

 American writers who seem to have pinned their faith to his work. 

 (See ''doubtful forms" under Tribonema and Mierospora.) 



There are indications in Lagerheim's work that he contem- 

 plated reviving the name Tribonema, but apparently a too conser- 

 vative instinct deterred him from abandoning Conferva. 



There is very little doubt that the action taken by Borzi,* 

 and supported by Bohlin, Blackman, and Wille, in removing this 

 genus from the Ulothricaceae is entirely justified. The structure 

 and composition of the cell-wall, the character of the chlorophyl, 

 and the absence of starch all point to the close affinity of Tribo- 

 nema with the Ophiocytiaceae. 



As noted in the introduction, however, for present expediency 

 in bringing into American literature, which has sadly confused 

 Mierospora and Conferva, the striking differences between these 

 genera, the older arrangement has been here retained. Doubtless 

 the easier course would have been to omit the genus, since some 



* Borzi, A. Boll. Soc. Ital. Mic. I : 62-70. 



Bohlin, K. Bih. Kong. Svensk. Vet.-Akad. Hand. 23 s : No. 3. 1897. 



Blackman, F. F. Ann. of Bot. 14 : 647-688. 1900. 



Wille, N. Nyt Mag. for Naturvid. 39 : 1-22. 1901. 



