116 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
into more or less rectangular blocks with rounded corners, often left 
stranded almost like boulders on the summit of the ledge from which 
they have originated. 
Retracing our steps, we may now take up the description of the great 
coral reef flats which we examined between the Hope Islands and Lizard 
Island." About five miles north of the Hope Islands we come upon b 
Reef, situated off the northwest extremity of Endeavour Reef (Plate V.). 
It is a long flat sandy islet, with a conical heap of coral débris at the 
southern extremity of the reef flat adjoining it; at the northern end of 
the flat there are a few negro heads. с and а Reefs are only sand 
patches (Plates XXXII.-XXXIV.). 
For nearly an hour we steamed slowly along the western edge of 
Cairns Reef, nothing but one mass of negro heads of all sizes, form- 
ing a belt along the western edge of the reef flat (Plates XIII, XIV., 
XV.). The western edge of this reef flat shows perhaps better than any 
other flat we have examined the belt of dead corals on its surface: and 
the remnants of the old elevated reef on its lee side (Plates XIT., XIV.). 
On the slopes extending to the main channel, or to the channels sepa- 
rating Cairns Reef flat from the nearest flats, corals were growing abun- 
dantly and in large masses and patches close to the upper edge of the 
flat, rising from six to seven fathoms of water. At less than a cable’s 
length the bottom specimens brought up on the lead were already discol- 
ored by admixtures of littoral deposits. Оп e Reef (South Turtle Reef) 
we found one to two feet of water; a third of a mile off the northwest 
side of the centre of the reef we anchored in ten fathoms, muddy bottom. 
Coral heads begin to appear on the slope of the reef in from four to 
five fathoms; in deeper water, the bottom along the slope of the reef is 
clean coral sand. The slope of the reef is covered with isolated patches 
1 On Plate XXX. Kent has represented the aspect of the surface of one of the 
reef flats which, as he justly remarks, is in very striking contrast to those coral flats 
which are only rarely exposed at the lowest tides, and on which corals still flourish 
in great profusion, and which form the subjects of the many reef views illustrating 
the “Great Barrier Reef.” They are the only Plates which have been published 
giving an idea of the appearance of a coral reef. Previous writers had only ex- 
amined as far as they could be observed from the surface the upper belt of growing 
corals in from seven to ten fathoms and upward, and from their descriptions 
alone, no matter how vivid, it was impossible to give to the reader who had not 
seen a coral reef an adequate conception of what a coral reef really looks like. 
The illustrations of Haeckel in the * Arabische Korallen," while giving an ex- 
cellent idea of the brilliancy and great variety of coloring in the masses of a coral 
reef (Plate 3, Arab. Korallen, 1876), are of course not to be compared in their scope 
with the photographs of Kent. 
