5° BOTANICAL GAZETTE [JANUARY 
HoweE;,' in a digest of our present knowledge of the lime-secreting 
algae as reef makers, shows that in the famous boring at Funafuti, 
which was driven to a depth of 114.5 ft., Lithothamnion was found — 
to be more or less abundant through the entire length of the boring; 
Halimeda was locally very abundant from 28 to 1096 ft. According 
to the same paper Lithothamnion is now recognized to be a dominant 
reef builder in the reefs of Fiji, Gilberts, Dutch East Indies, Ber- 
-mudas, and other groups.® He states that the lime-secreting sea- 
weeds flourish and are effective reef builders in greater depths than 
is the case with corals. There are numerous records of these forms 
at depths of 100 fathoms, in situ, and occasionally at 250-350 
fathoms, whereas 25-40 fathoms is the greatest depth attained by 
the reef-building corals. Howe continues: 
Besides flourishing in greater depths than the corals, the lime-secreting 
seaweeds are much less dependent upon high temperatures than are the corals. 
. . The coralline algae are, locally at least, abundant from 73°5’ south 
latitude to 79°56’ north latitude... .. He specifies the seas off the coasts of 
Spitzenberg, Nova Zembla, Iceland, Greenland, and Norway, where banks of 
Lithothamnion cover the bottom for areas of many square miles... . . The 
massive beds of Halimeda opuntia off the Florida Keys (the same species . . . - 
that is filling the lagoons of some of the South Sea atolls) are striking, as are 
the banks of Goniolithon strictwm in the Bahamas, and reefs of Lithophyllum 
antillarum and L. daedaleum along the shores of Porto Rico. ... . The lime- 
secreting plants appear to be much more generally and widely distributed, 
both horizontally and vertically, than are the corals. 
The Hawaiian corallines inhabit the shallow waters, as well as 
occurring at considerable depths. In the former situations they 
form beautiful rose, purple, and lavender incrustations. On the 
faces of cliffs that are washed by the sea the incrustation appears 
as a conspicuous rose or purple band, extending from high tide 
mark or the uppermost wash of the surf, down to the zone of mini- 
mum illumination. The lower margin of the coralline zone has 
not been investigated in the Hawaiian Islands, but it undoubtedly 
reaches as great depths as in the island groups already cited. The 
upper margin is often somewhat above high tide mark, as these 
5’ Howe, M. A., Building of coral reefs. Science, N.S. 35:837-842. 1912. 
§ See also S—warp, A. C., Algae as rock-building organisms. Science Progress 
2210-26, 1894. 
