Sect. I. 
KEELING ATOLL. 
11 
fathoms, the bottom is exceedingly rugged and seems 
formed of great masses of living coral, similar to 
those on the margin. The arming of the lead hero 
invariably came up quite clean, but deeply indented, 
and chains and anchors which were lowered, in the 
hopes of tearing up the coral, w T ere broken. Many 
small fragments, however, of Millepora alcicornis 
were brought up ; and on the arming from an eight- 
fatliom cast, there was a perfect impression of an 
Astrasa, apparently alive. I examined the rolled 
fragments cast on the beach during gales, in order 
further to ascertain what corals grew outside the reef. 
The fragments consisted of many kinds, of which the 
Porites already mentioned and a Madrepora, appa- 
rently the M. corymbosa, were the most abundant. As I 
searched in vain in the hollow T s on the reef and in the 
lagoon, for a living specimen of this Madrepore, I con- 
clude that it is confined to a zone outside, and beneath 
the surface, where it must be very abundant. Frag- 
ments of the Millepora alcicornis and of an Astrsea 
were also numerous ; the former is found, but not in 
proportionate numbers, in the hollows on the reef ; but 
the Astraea I did not see living. Hence we may infer, 
that these are the kinds of coral which form the 
rugged sloping surface (represented in the wood-cut 
lead, having a diameter of four inches, and the armings each time 
were cut off and brought on board for me to examine. The arming 
is a preparation of tallow, placed in the concavity at the bottom of 
the lead. Sand, and even small fragments of rock will adhere to it ; 
and if the bottom be of rock, it brings up an exact impression of ita 
surface. 
