Phycotheca Boreali-Americana

Collins, Holden & Setchell.

1714. Plectonema roseolum Gomont.

Gomont, Monogr. des Oscill., p. 122, Pl. I, 6gs. 9 & 10, 1893.

Forti, Syll. Myx., p. 494, 1907.

Tilden, Minn. Algae, Vol. I, p. 210, Pl. XI, fig. 8, 1910.

On window of conservatory, University of California, Berkeley,
California, May 16, 1906.

N. L. GARDNER.

Phycotheca Boreali-Americana

Collins, Holden & Setchell.

1715. Tolypothrix tenuis Kuetz.

Kuetzing in Bornet & Flahault, Revision des Nost. Het., part 3, p.
122, 1887.

Forti, Syll. Myx., p. 545, 1907.

Tilden, Minn. Algae, Vol. I, p. 229, 1910.

In company with T. lanata Wartmann, forming a coating on a
wooden chute, Ieehouse Pond, Eastham, Massachusetts, Sept., 1909.

F. S. COLLINS.

The extremes of size in this material are quite typical of the
two species mentioned, but there are intermediate forms that cast
some doubts on the distinctness of the two species.