808 
THE VOYAGE OE H.M.S. CHALLENGER. 
rate of accumulation of oceanic deposits. In deposits in more or less close proximity to 
continents and islands, they become covered over and imbedded in the detritus brought 
down from the land, and hence the chance of taking them in the dredge is small. The 
same is the case in the regions occupied by Pteropod and Globigerina oozes, where they 
become covered over and masked by the shells of pelagic Molluscs and Foraminifera. 
But in those red clay regions far removed from land, where the depth is too great for 
the calcareous surface shells to reach the bottom, they are not at all, or but slightly, 
covered up by, or mixed up with, other matters, and hence the dredge takes them in 
great numbers. 
Some of the bones were in a much better state of preservation than others ; in some 
the coating of manganese was very thin, and the Haversian canals and lacunae were but 
little impregnated by that substance, so that a fractured surface was greyish white ; in 
others, not only were the bones thickly encrusted, but the canals and lacunae were nearly 
all infiltrated with the manganese, so that the fractured surface was brown or black, and the 
bones very brittle. The great majority of the large cancellated bones of the Whales 
appeared to have been removed from the deposits through the chemical action of the 
sea water. The chemical composition of those which remained was entirely altered, and 
this was more especially the case with the fragments of flat bones and others of a more 
porous texture (see Appendix V.). 
The preservation of the earbones and of the fragments of the beaks of Ziphioid 
Whales is accounted for by the great density of these portions of the skeleton, and the 
consequent small amount of surface presented to the action of the sea water when 
compared with the cancellated bones. Professor Turner points 
out that he could not identify any of the bones as belonging 
to the Great Sperm Whale ( Pliyseter mcccroceMhalus), although 
the track of the Challenger, where such hauls of Cetacean 
bones were made, was through the part of the Pacific 
frequented by that huge Cetacean. 
The Sharks’ teeth, several hundreds of which, as stated 
above, were taken in a single dredging, have a distribution in 
the deposits similar to that of the bones of Cetaceans, 
although they were dredged more frequently. They are 
most abundant in the red clay areas far removed from land, 
and especially in those of the Central South Pacific ; they 
were less frequently taken in the organic oozes of the deep 
Fig. 294. — wxyrhina (Uxurhina trigo- . . -.111 i 
notion, Agass. ) tooth. 16th September sea, and only in one or two instances m the blue muds, green 
1875 ; 2350 fathoms. _ . _ ,. . 
muds, and volcanic muds surrounding continental land or 
oceanic islands. As in the case of the bones of Cetaceans, the occurrence of these teeth 
in greatest abundance in the red clay areas of the abysmal regions, and their rarity in 
