TRIBONEMA 181 
MICROSPORA AMOENA forma THERMALIS Tild. Bot. Gaz. 25: 92. 
Së rx 1968. 
The author remarks: “It is difficult to decide whether this 
plant should be classed as a Conferva or a Microspora, as the 
structure of the chloroplastids could not be made out." That this 
form having a diameter of 11-14 م‎ should be associated with a 
species ranging from 20—24y, in a genus of such fine distinctions 
as Microspora, is a manifest absurdity. The form should have 
been “placed provisionally " among doubtful forms in the discov- 
erer's herbarium, until its essential character could be determined. 
MicRosPoRA Ween Did. Bot. Gaz. 25: 93. pl. 8 f. 13. 
1898; Am. Alg. 275. 
The figure furnishes a strong support to the suspicion that the 
author has no adequate conception of the difference between 
Microspora and Tribonema,; the chromatophores certainly have 
the appearance of the latter. No satisfactory conclusion can be 
drawn from the poor specimens distributed. 
IV. TRIBONEMA Derbes & Solier, Mem. sur Physiol. Alg 
18. 1856 | 
Conferva Lagerheim, Flora, 72: 194-209. 1889. Not Con- 
ferva Linn. Sp. Pl. 1164. 1753. 
Filaments at first attached by a special basal cell, later floating. 
Chromatophores disk-shaped, yellowish-green, without starch, but 
producing oil, two or several in a cell. Cell-wall thin, formed b 
deposition of layers composed largely of pectic acid with little 
cellulose. For the dispersal of the zodspores, the cells pull apart 
from the middle, so that H-shaped sections are left. 
Asexual reproduction through zoospores, produced to the 
number of one to four in each cell; they are destitute of a red 
eye-spot, furnished with two cilia, one of which is short and re- 
flexed. 
Inhabitants of fresh water. Type T. bomdyeinum Derb. & Sol. 
[Etym. 204/80 worn, and va, filament. ] 
The name Conferva is very ancient, going back to the time of 
Pliny. As a modern generic name it has received most varied 
treatment, and covered at different times very diverse groups of 
plants. 
Under this name Linnaeus included a very large part of the 
