May 31, 1912] 
““nullipores’?’ in a living condition at 
depths of from 250 to 350 fathoms. Ac- 
cording to Dr. Vaughan, it is generally 
conceded ‘‘that 25 fathoms is the greatest 
depth’’ at which the reef-building corals 
work effectively, ‘‘although an occasional 
reef species may extend downward to a 
depth of 40 fathoms.’ 
Besides flourishing in greater depths 
than the corals, the lime-secreting sea- 
weeds are much less dependent upon high 
temperatures than aré the corals. Sir 
John Murray has remarked'* that ‘‘in 
the polar seas and in the cold water of the 
deep seas there is, as is well known, a feeble 
development of all carbonate of lime struc- 
tures in marine organisms,’’ a statement 
that may be true enough in a comparative 
way for organic nature as a whole, but is 
manifestly much more true of the corals 
than of the coral-like red alge. The coral- 
line alge are, locally at least, abundant 
from 734° south latitude to 79° 56’ north 
latitude.t® The late Professor Kjellman, 
of Upsala, has stated™’ that off the coasts of 
Spitzbergen and Nova Zembla Lithotham- 
nion glaciale “‘covers the bottom in deep 
layers for several miles’’ mostly in 10 to 
20 fathoms of water, and he adds that ‘‘in 
the formation of future strata of the 
earth’s crust in these regions it must be- 
come of essential importance.’’ Another 
species of Lathothamnion is said to form 
banks on the coasts of Iceland and of 
Greenland. Foslie® states also that 
% Bull. Mus. Comp. Zool. Harvard Coll., Vol. 14, 
p. 287, 1888. 
4 Natural Science, Vol. 11, p. 26, 1897. 
* Foslie, M., ‘‘Corallinacee, in National Ant- 
arctic Expedition, Natural History,’’ Vol. 3, 1907. 
* Kjellman, F. R., ‘‘The Alge of the Arctic 
Sea,’’ Kongl. Sv. Vet.-Akad. Handl., Vol. 20, No. 
5, p. 96, 1883. 
“ Kjellman, loc. cit. 
*%JTn Gardiner, ‘‘The Fauna and Geography of 
the Maldive and Laceadive Archipelagoes,’’ Vol. 
1, p. 462. 
SCIENCE 
841 
North of the polar circle on the coast of Nor- 
way banks haye been met with which cover the 
bottom for several miles and plants appear in 
immense masses, frequently representing only one 
species. 
A good account of ‘‘ Aloe as Rock-build- 
ing Organisms,’’ with special reference to 
their occurrence in ancient limestones, was 
contributed to Science Progress® in 1894 
by Professor A. C. Seward, of Cambridge 
University. An interesting feature of 
Professor Seward’s paper is his summary 
of the results of J. Walther’s studies of a 
Inthothamnion bank in the Bay of Naples 
about 30 m. below the surface of the water: 
By action of the percolating water the Litho- 
thamnion structure is gradually obliterated, and 
the calcareous mass becomes a structureless lime- 
stone. Walther applies his knowledge of this 
recent algal deposit to the examination of a Ter- 
tiary ‘‘ Nulliporenkalk’’ near Syracuse. In many 
parts of this formation there occur well-preserved 
specimens of Lithothamnion, but in others a 
gradual obliteration is observed of all plant 
structures until the rock becomes entirely struc- 
tureless. A similar instance of structureless lime- 
stone is described from the Lias of Todten 
Gebirges [Todtes Gebirge]. 
In Bermuda, southern Florida and the 
West Indies one finds among the living 
reef-building organisms and in their distri- 
bution and association many of the general 
types described by Gardiner and others for 
the Pacific and Indian oceans, even though 
“true atolls’? of the Pacifie type may be 
rare or quite wanting. There are banks 
and reefs that appear to consist almost 
wholly of calcareous plants others that are 
almost ‘‘pure stands’’ of corals, and yet 
others where these two elements are inter- 
mingled. In the last case, the ‘‘nulli- 
pores’’ often seem to be overgrowing and 
smothering the corals, as has been observed 
in the Pacifie and elsewhere. In view of 
all of the evidence now available it would 
be a bold man who would venture to say 
Y Vol. 2, pp. 10-26. 
