198 BOTANICAL GAZETTE | SEPTEMBER 
It is necessary at this point to correct a mistake made in 
labeling the above species in American Algae, Century II. 
When the algae were first studied, before distributing them, 
although careful examination was made of various portions of 
the formalin material, it happened that no sheaths were found 
containing more than a single trichome. This made the plant 
appear very much like Phormidium purpurascens, as may be under- 
stood by referring to Gomont’s description, and it was placed 
under this name. Later investigations have shown clearly that 
the Phormidium-like simple filaments are but young stages of 5 
calcicola. 
SYNECHOCOCCUS AERUGINOSUS Naeg. Einz. Alg. 56. 1849. 
Cells 3.2-8m in diameter, spherical or oblong, aeruginous, 
with thin sheath, for the most part solitary but at times four 
or five joined in a pseudo-filament. (Plate VIIT, fig. 6.) 
With the lower power of the microscope these cells are read- 
ily seen, as they occur for the most part in heaps or masses and 
are bright blue-green in color. They are found only in the inte- 
rior of the thallus. 
GLCoOcaAPSA VIOLACEA (Corda) Rabenh. Fl. Eur. Algar. 2:41. 
1865. (Plate VITI, fig. 5.) Forming the reddish or grayish violet 
portions of the interior of the thallus, mucilaginous ; cells glo- 
bose, 6.4—14.4m in diameter ; tegument not lamellose ; cytoplasm 
aeruginous, granulate. These cells, for the most part empty and 
colorless, are very numerous throughout the interior portions of 
the structure. 
Valley of the Nez Perces creek, Lower Geyser Basin, Yellow- 
stone National Park. June 29, 1896. 
~ Another species belonging to this group, Phormidium lamino- 
sum, is exceedingly abundant in the hot waters of the Park. In 
its normal condition it forms wide sheets, delicately granulose 
in substance, of no definite shape. It also formed hollow strings 
(suggesting a Tetraspora growth) rising from the bottom of hot 
springs and expanding at the surface into flat or bulbous masse€s. 
In a few instances it formed long narrow appendages supported 
by submerged grass stems ( figs. 7-8). It is probable that 
| 
| 
| 
