tia ULOTHRICACEAE 
lins) would seem, judging by the meager description, to be asso- 
ciable with Conferva Loefgrenii Suecica Wittr., but examination 
proves it to be very different from that variety as issued in Wittr. 
& Nordst. Alg. Exsic. 578. 1883. In the character of the chro- 
matophore and in other features, Mr. Collins’ specimen seems to 
be more closely allied to M. floccosa. 
4. MicRosPoRA Wittrock (Wille) Lagerh. Ber. Deutsch. bot. 
Gesell. 5: 417. 1887; Flora, 72: 208. 1889. DeToni, Syll. 
Ale 1: 228. 1889. 
Conferva Wittrockü Wille, Öfers. Vet. Akad. Förhand. 17 : 
20. M. 9. f. 7-77. 1881. (?); Jahrb. wiss. Bot. 18: 461. fl. 17. 
f. 35-42. 1887. 
Filaments forming long, silky skiens, light green in color; cells 
perfectly cylindrical, never constricted at the dissepiments, 19.5— 
20 in diameter, 1-2 17 times as long; cell-wall thinner than in 
M. amoena and M. Loefgrenii, about 1.5 مم‎ thick, not exhibiting its 
lamellated structure in the vegetative state; chromatophore thin, 
often perforated or sieve-like in appearance, sometimes retreating 
from one end of the cell so as to be thimble-shaped, the large nu- 
cleus (5—6.5 » in diameter) nearly always clearly showing through 
CA. 25, f. I 
In a brook draining a swamp, Van Cortlandt Park, New 
York, April, May (287, 348, 415). Meadow brook, Norwich, 
Vermont, May, 1902 (675). 
This form, which has not before been reported in this country, 
was observed and collected several times in the spring of 1900. 
It was always growing without other accompanying species than 
the small form Mierospora stagnorum. During the spring of 1901, 
all search for it in the same brook was fruitless, but M. Loefgreni 
was found in abundance, although during the preceding season the 
nearest station of the latter species was in another stream half a 
mile or more distant. This circumstance cast suspicion on the 
distinctness of the form determined as M. Wittrockii. 
However, a very careful reéxamination of various collections 
preserved by different methods, has shown in the most convincing 
manner that the specimens in question are not to be confused with 
M. Loefgrenii or M. amoena. Our form is distinguished by its per- 
fectly cylindrical cells, the thin walls of which do not show the 
lamellated structure until after maceration, and by its thin chro- 
