Clinton and Niagara :ifrafa. — Sarlc. 295 
Thus these colonies of Fisfulipora with the associated Hfe 
drawn about them by the very favorable conditions affording 
attachment, food and shelter, are seen to have formed low, ir- 
regular, dome-shaped prominences, upon the broad, level, 
floor of a shallow sea. They are not known to have ever 
reached an elevation exceeding ten feet, the approximate hight 
of the largest yet known. A mass about one-fourth of a mile 
above that at the third watchman's hut, was estimated to be 
fifteen by fifty feet. 
Their distribution we have seen was irregular, sometimes 
isolated, oftener in groups covering considerable areas, or, as in 
one known instance, coalescing to form an extended layer. 
In this ancient coral-maker* (for professor Agassiz consid- 
ers the bryozoan animal such) and the rich concourse of asso- 
ciates indicated, we find life conditions according so well with 
those observable in the modern reef or coral-field, as described 
by Darwin, Dana, Agassiz and Kent, that no hesitation is felt 
in pronouncing these to be ancient coral reefs. While having 
many of the features common to such structures in general, 
these little reefs present a more striking analogy to a peculiar 
kind described as follows by professor Charles F. Hartt if "So 
far I have only spoken of fringing reefs, but there are other 
coral structure of greater interest in these waters. Corals grow 
over the bottom in small patches in the open sea, and, without 
spreading much, often rise to the hight of forty to fifty feet or 
more, like towers, and sometimes attain the level of low water, 
forming what are called on the Brazilian coast 'chapeiroes', 
(signifying, big hats). At the top these are usually very ir- 
regular, and sometimes spread like mushrooms, or, as the fish- 
ermen say, like umbrellas. Some of these chapeiroes are only 
a few feet in diameter. A few miles to the eastward of the 
Abrolhos is an area, with a length of nine to ten and in some 
places a breadth of four miles, over which these structures grow 
very abundantly, forming the well-known Parcel dos Abrolhos, 
on which so many vessels have been wrecked." Professor Hartt 
in describing a visit to the northwestern part of this reef, men- 
tions, among other facts : "The chapeiroes, as a general thing, 
are rarely ever laid bare by the tide." "They are here, as else- 
*There is much difference of opinion regarding the position of these fistulip- 
orids. Some are inclined to consider them corals. 
^Geology of Brazil, 1870. pp. 199-200; also p. 191. 
