44 THE HAMILTON ASSOCIATION. 
Millepora is dead, three species of Nullipora flourish. One grows 
like lichen, on old trees, in thin sheets ; the second in strong knobs, 
as thick as a man’s finger, radiating from a common centre; the 
third moss-like, thin, perfectly rigid branches. The latter is a 
beautiful bright peach color. 
We shall hereafter see that these coral reefs are protected by a 
similar thick growth of Nullipora on the outer margin. When these 
plants die, remarks Sir A. Geckie, their remains are cast ashore and 
pounded up by the waves. Being singularly durable, they form a 
white calcareous sand by the action of the wind. This sand is blown 
inland, rain water percolating solidifies and cements the particles. 
Changes of this kind have taken place on a great scale at Bermuda, 
where all the dry land consists of limestone formed of compacted 
calcareous sand, mainly the detritus of sea weeds. 
Our local limestones of the Silurian age, in the immediate vicin- 
ity of the City of Hamilton, present little for comparison. Corals 
are few and their absence may be owing to the infilteration of 
mineral salts, antagonistic subsequently to their preservation. It 
seems to the writer to be a matter for a closer chemical investigation. 
Occasionally one may notice, even in what the United States Geolo- 
gist, Dr. Jas. Hall, calls ‘“‘The old Clinton Limestones,” hollow 
receptacles, which once held corals, which disappeared. 
Independent of what the Nullipora contribute to the building 
of these reefs, other things take part in their formation—sea weeds, 
star fishes, shells, etc. ‘These are cemented by dissolved carbonate 
of lime, and furnish a platform for a fresh growth of coral. When 
crinoids were numerous in portions of the Silurian Sea bottom, we 
may not be surprised at finding their remains numerous in the Anti- 
costi reef. One layer of limestone in the blue building series here 
reminds me strongly of an ancient coral reef. 
The writer obtained from the fishermen at Anticosti some years 
ago, about 8 or ro beautiful branching Nulliporee, colored ones, 
which got entangled in the hand lines used in Cod fishing, in what 
is known to naturalists as the Nullipora Zone. 
In calling your attention to modern coral reefs, it may be neces- 
sary to explain that such things existed from early Silurian days to 
modern times. Perhaps no country can show such an extraordinary 
number of these fossils as the succeding formation, the Devomian 
