NARRATIVE OF THE CRUISE. 
805 
was composed of layers made up of different sized particles, the larger particles forming 
the lower layer, seemed to have consolidated, to have undergone decomposition, and to 
have been subsequently broken up by some disturbance, after which a deposit of manganese 
peroxide was formed in the cracks and fissures and on the upper surface. Mixed up with 
these nodules were one hundred and sixteen Sharks’ teeth, eleven referable to the genus 
Carcharodon and the remainder to Carcharias, Oxyrhina, and Lamna. One of the 
Carcharodon teeth was the largest taken during the cruise, and is represented in fig. 291. 
This tooth is hollow, and has a slight coating' of peroxide of manganese on the outer and 
Fig. 291 .—Carcharodon megalodon. 6th October 1875 ; 2386 fathoms. 
inner surface of the hard dentine, which is indeed all that remains of the tooth. Mr. 
Murray compared this tooth with many fossil specimens in British and Continental 
Museums, and could detect no difference of importance between it and specimens of 
the Carcharodon megalodon found in the Tertiary deposits of many parts of the world ; 
it is as large as, if not larger than, any of the fossil specimens preserved in collections. 
It is to be observed, however, that there is no large base to this tooth, as is usually the 
case with the fossil specimens. The tooth was covered on one of its surfaces by the 
branching Rhizopod, Rhizammina algceformis, Brady. The bones of Cetaceans consisted 
of six tympanic bones and three petrous bones, all belonging to the family of Dolphins. 
