I2 Rhodora [JANUARY 
figured in Grønlands Havalger, p. 965, fig. 56. The writer found it 
scattered rather sparingly among the filaments of Pe/rocelis cruenta J. 
Ag., at Seal Harbor, Mount Desert, Maine, in July, 1899. 
In company with the last-named species was another green alga, 
Codiolum Petrocelidis Kuckuck, Wissentliche Meeresuntersuchungen, 
New Series, vol. i, p. 259, fig. 27. The two are not likely to be con- 
founded, as the Codiolum is drawn out below into a slender stipe, 
while there is no stipe in the Chlorochytrium. ‘The history of this 
alga is rather curious. It was described and figured in 1865 by Cohn, 
in Rabenhorst, Beiträge zur Kentniss und Verbreitung der Algen, Heft 
2, p. 33, but under the supposition that it was a rudimentary state of a 
Cladophora. It is referred to by Farlow in the Manual of the New 
England Marine Algae, in 188r, but without a name. In Hedwigia, 
vol. iv, p. 125, 1886, Wollny incorrectly referred it to Codtolum 
gregarium, and it received a name of its own only in 1894, twenty- 
nine years after it was described and figured, quite accurately. 
Ralfsia Bornetti Kuckuck, Meeresuntersuchungen, vol. i, p. 245, 
fig. 15, was found by the writer at Seal Harbor in July, 1899, growing 
on a small pebble below low water mark. ‘There was nothing external 
to distinguish it from the common Æ. verrucosa, but the free filaments 
accompanying the uhilocular sporangia are very slender below, the 
lower cell being even twenty times as long as broad, and nearly, if not 
quite, colorless; the upper cells are shorter than broad, with dark 
chromatophors. The plurilocular sporangia, described by Kuckuck, 
were not found; they are quite different from anything found on our 
American species of Ralísia. 
Rhodochorton parasiticum Holmes, seems to be not uncommon on 
Laminaria from Cape Ann, north. ‘The writer has found it on Z. /ongi- 
cruris and on Z. digitata, especially on the larger forms of the latter, 
with flattened stipe. When well developed, it covers the stipe with 
a dense red plush. It resembles Æ. Rothii Naeg., common on rocks 
along our coast; but the basal filaments, instead of forming a horizon- 
tal layer, penetrate rather deeply into the substance of the host. 
Ulothrix variabilis Kuetz. var. marina Wille, has been found by 
Isaac Holden in brackish water at Bridgeport, Conn. It has slenderer 
filaments than any other of our marine Ulothrix, 5-7 diameter; it has 
been distributed as No. 615 of the Phycotheca Boreali-Americana. 
In the Bulletin de la Societé Botanique de France, vol. xlvi, 
Gomont describes two new species of Plectonema, occurring within 
