170 ULOTHRICACEAE 
larger size and shorter cells. Judging from all specimens we have 
seen, it is more distinct from the latter than is M. Loefgreni. In 
the Central Park station, where we have observed it at several dif- 
ferent seasons, it shows a very constant character, and is never 
mixed with any other Microspora. There it is usually found with 
Cladophora and Rhizoclonium, in a stream gushing from and over 
rocky ledges to feed the lower lake. 
In other cases, where it has been found in connection with 77. 
amoena (588) and M. Loefgrenii (632), no intergrading forms have 
been seen, and there has been no evídence of any developmental 
relationship. 
In two specimens of the exsiccata above quoted, nothing but 
27 amoena has been found, but Professor Wille's forma crassior is 
based on this material. His characterization of the form consists 
only of a statement of the diameter of the cells (without any refer- 
ence to synonyms), but judging from this point alone the form is 
to be included here. 
N 
MICROSPORA AMOENA (Kiitz.) Rabenh. Flor. Eur. Alg. 3: 321. 
1868. Lagerh. Ber. Deutsch. bot. Gesell 5: 417. 1887. 
DeToni, Syll. Ale 1: 227. 1889. Kirchn. Mik. Pflanz. 12. 
pl. 2. f. 26. 1891. Hansg. Prod. Ale Böhm. 2: 222. 1892. 
De Wild. Flor. Alg. Belg. 46. 1896. 
Conferva amoena Kütz. Spec. Alg. 372. 1849; Tab. Phyc. 
3: M. 45. f. 5. 1852. Kirchn. Krypt. Flor. Schles. 2': 79. 1878. 
Wille, Öfvers. Vet. Akad. Förhand. 1881?: 21. fl. ro. f. 57. 
1881. Hansg. Prod. Ale Böhm. 1: 77. 1886. Wolle, F. W. 
Alg. 140. pl. 121. f. 1-5. 1887. 
Filaments forming long green skeins or tangled masses; cells 
nearly cylindrical, often slightly contracted at the dissepiments, 
21.5-25 # in diameter, 1-2 times as long; cell-wall 2.5—3 y thick ; 
chromatophore rather dense, generally covering the cell-wall and 
obscuring the nucleus which is 6.5—7.5 x in diameter ) pl. 25, کر‎ 7). 
Exsıc.: Phyc. Bor. Am. 616, û. p., Bridgeport, Conn., April, 
1893 (I. Holden); 793 (as Ulothrix zonata), Melrose, Mass., 
April, 1894 (F. S. Collins); Tild. Am. Alg. 7394 (as M. floccosa), 
Forest Grove, Oregon, Feb., 1896 (F. E. Lloyd). 
In brooks, streaming in masses from sticks and stones on 
which it is caught. 
M اس‎ 5 
