128 BOTANICAL GAZETTE [FEBRUARY 
Hormothamnion solutum Born. and Grunow.—Plant mass floc- 
cose, entangled, mucous, green or blue-green; not uncommon here 
and there along the coral reefs, in shallow waters and in tidal 
pools. 
SCYTONEMACEAE 
Plectonema nostocarum Bornet.—Filaments graceful, elongate, 
at first much branched, later sparingly branched; collected in 
warm pools in the vicinity of Kilauea Crater, an active volcano on 
the island of Hawaii. 
Scytonema rivulare Borzi.—Colonies widely extended, woolly, 
blackish, tending toward reddish or brown; forming dark brownish 
or purple-red cushions on stones in the mountain streams; plentiful. 
S. crispum (Agh.) Bornet.—Colonies caespitose, entangled, 
woolly, green, becoming brown or olive; in ponds, rice fields, 
taro patches, and other quiet or stagnant waters on the lowlands. 
S. azureum Tilden—Cell contents deep purple-blue; with 
other thermophilous algae forming a layer covering rocks on the 
bottoms and sides of hot springs in the Puna district, Hawaii. 
S. varium Kuetz.—Colonies 2-3 mm. high, cushion-shaped, 
bluish green or brownish; often found on wet cliffs near waterfalls, 
chiefly in the rain forests. 
S. javanicum (Kuetz.) Bornet var. hawaitiensis Lemm.—Colo- 
nies cushion-shaped, dark blue-green; collected among the wet 
mosses, etc., in the forests near Kilauea Crater, Island of Hawaii. 
S. ocellatum Lyngb.—Colonies cushion-shaped, black or gray, 
becoming bluish; on moist shaded rocks and wet cliffs. 
S. guyanense (Montagne) Born. and Flah.—Colonies dense, 
cushion-shaped, 1-2 mm. thick, widely expanded, blackish green; 
on moist stones. 
S. mirabile (Dillwyn) Born.—Colonies woolly, widely expanded, 
spongy tomentose, brownish black or blackish green; collected in 
shallow pools on the slopes of Mauna Kea, Hawaii. 
S. fuliginosum Tilden.—Colonies thin, bluish green; forms 
thin layers on the bottoms of shallow tidal pools, along the plat- 
form reefs and rocky shores; fairly common. 
Tolypothrix lanata (Desv.) Wartmann.—Colonies caespitose- 
floccose, blue-green, becoming brownish with age; found in shallow 
