1889 - 90 .] Dr J. Murray & Mr R. Irvine on Coral Beefs. 99 
which a considerable quantity of organic tissue is associated with 
the carbonate of lime, disappear in solution more rapidly than the 
shells of the Foraminifera, which contain little organic matter. 
During the whole of the “ Challenger” cruise only two bones of fishes, 
other than the otoliths and the teeth, were dredged from the 
deposits, and all traces of the cetacean bones were removed, except 
the dense earbones and dense Ziphioid beaks. The remains of 
crustacean animals were almost wholly absent from deep-sea de- 
posits, with the exception of Ostracode shells and the hard tips of 
some claws of crabs. 
Turning now to the lagoons and lagoon channels of coral islands, 
it is believed that large quantities of carbonate of lime are in the 
same way being dissolved from these shallow basins as well as from 
the deposits of the deep sea, but under somewhat different circum- 
stances. In the case of a shell falling to the bottom of the sea, it 
is continually brought in contact with new layers of water, which 
has the same effect as if a continuous stream of water were passing 
over the shell. In the case of the lagoons this last is what takes 
place. The water which flows in and out of the lagoons twice in 
twenty-four hours passes over great beds of growing coral, and from 
all the observations we have is largely charged with carbonic acid, 
owing probably to the large number of living animals on the outer 
reef over which the water passes on its way to the lagoon. This 
water passes continually over the dead coral and sand of the lagoon, 
and takes up and removes large quantities of carbonate of lime in 
solution (as well as suspension) for in these lagoons the spaces 
covered by dead coral debris always greatly exceed the patches of 
growing coral. Owing to the fact that the water of the lagoon is 
continually in motion, and constantly renewed, the layer in contact 
with the bottom of coral sand can never become saturated or unable 
to take up more lime, as is apparently the case in the layers of 
water in contact with the Globigerina ooze and other calcareous 
deep-water deposits. 
From the foregoing discussion and observations it is evident that 
a very large quantity of carbonate of lime is in a continual state of 
flux in the ocean, now existing in the form of shells and corals, 
but after the death of the animals passing slowly into solution, to 
go again through the same cycle. 
