TRIBONEMA 187 
ter form (Wittr. & Nordst. Alg. Exsic. 579. 1883) merely furnishes 
a statement of the diameter, 14-16 م‎ We have seen no form 
with so great a diameter that could properly be associated with 
Tribonema bombycinum. 
Tribonema utriculosum as above characterized does indeed 
approach T. dombycinum in respect to the diameter of the cells, 
but the thicker cell-wall and usually larger chromatophores, as 
well as an indefinable general appearance, sufficiently distinguish it 
from the smaller species. By repeated observation and cultural 
experiments, we have become convinced of the specific distinctness 
of the two forms. 
It is a strange fact that none of these species of Tribonema, 
elsewhere common, have been found in Vermont during more than 
a year of collecting. 
ÊxCLUDED FORMS 
CONFERVA FONTINALIS Berk. Glean. Brit. Alg. 77. rg. f. I. 1833. 
Wolle, F. W. Ale 141. لم‎ 120. f. 17-20. 1887. 
Microspora fontinalis DeToni, Syll Alg. I: 230. 1889. 
Specimens bearing this name in the Wolle herbarium are certainly 
a Rhizoclonium, and probably the same is true of Berkeley's type. 
Berkeley supposed he was illustrating Conferva fontinalis Linn., 
but it is very doubtful if such was the case. 
CONFERVA BOMBYCINA ELONGATA Tild. Am. Alg. 27 is a A/zzo- 
clonium similar to Wolle's C. fontinadis. 
CONFERVA SESQUIPEDALIS Tild. Am. Alg. 277. is Zygnema sp. 
ConFERVA SANDWICENSIS Tild. Am. Alg. 462. Hawaii, 1900, is 
Rhizoclonium sp. showing the pyrenoids very clearly and giving a 
strong test for starch. All these examples of incorrect generic 
determination show how little the true Conferva (Tribonema) has 
been understood in this country. 
See also doubtful forms of Mierospora. 
GENERA REMOVED FROM THE ULOTHRICACEAE 
Scuizoconium Kitz. (Phyc. Gen. 245. 1843), including, accord- 
ing to the revision of Gay (91), U/othrix-like filaments which have 
stellate chromatophores and exhibit a strong tendency to longi- 
tudinal cell-division, and even to form an expanded thallus, is re- 
