180 EXrEDITIOX OF THE " ALllATKOSS,'' 1S<JD-1 9(10. 



teeth belonging to species clianictoristic of the middle or late Tertiaries in 

 Europe and America, hence implying that these bodies have been lying on 

 the sea-floor at least ever since the Pliocene, becoming buried with incon- 

 ceivable slowness by the gradually accumulating sediment.^ Large numbers 

 of these teeth, together with hundreds of Cetacean bones, were obtained by 

 the " Challenger" Expedition in 1875, all of them more or less impregnated 

 with, and their substance sometimes entirely replaced by the oxides of iron 

 and manganese. These accumulations of vertebrate remains are not limited 

 to any one ocean, but are most abundant at extreme depths in the red clay 

 areas*^ of tlie central Pacific and other oceanic deposits, being only excep- 

 tionally found in calcareous oozes or telluric deposits. The "Challenger" 

 collections were described in great detail by Murray and Renard in their 

 Report on Deep-Sea Deposits,- published in 1891, which was the first 

 attempt to deal systematically with deep-sea deposits and the geology of the 

 sea-bed throughout the whole extent of the ocean. The Mammalian bones 

 were still further investigated and described by Professor Sir William 



Turner.^ 



No additional material of this nature was obtained until Mr. A. Agassiz 

 in 1880 dredged of!" the eastern coast of North America a few Cetacean 

 bones and one or two sharks' teeth from the existing sea-bed at a depth of 

 only 333 fathoms." The teeth belonged to the genus Lamna, and differed 

 from those dredged by the " Challenger " in that the root and vasodentine 

 remained essentially unaltered, hence implying a comparatively recent 



> The excessively slow rate of dcpositiou of .se.lini.'nt m the central Pacific since the Glacial 

 period is indicated by tlie unique assortment of continental rock fragments, coated with a thin layer 

 of manganese, which was dredged by Mr. A. Agassi/, in 1890 at Station 2 of the "Albatross" Expe- 

 dition. Cy. Mem. Miis. Corap. Zool., Vol. XXVI. (iy02), pp. 71, 110. 



2 Murra,/, J., and Renard, A. F., Report on Deep-Sea Depo.sits ; Scient. Results " Chall." Kxp. 

 (1801) pp 267-27G. Chapter IV. of this volume, dealing with the materials of organic origin, was 

 written whollv by Sir John Murray- Not more than four genera appear to be represented with 

 certainty by the sharks' teeth, namely, Lamna, Oxyrhina, Carcl.arodon, and either Galeus or Car- 

 chari.T8; and owing to their imperfect con.lition, accurate specific determinations are in most cases 

 impos-sible. Neverthele.ss, Mr. Murray regards these same organic remai.is, together with the 

 associated manganese nodules, volcanic lapiUi, and zeolitic minerals, as " by far the most inteiestii.g 

 result of the dredgings between Tahiti and Valparaiso." {Loc. cil., 1891, p. 1«1.) 



« Turner, W., Report on Bones of the Cetacea ; Zoiil. -Chall." Exp., Vol. I. (1881)), pt. iv., pp. l-4o. 

 * Ayassiz, A., Three Cruises of the " Blake " : Bnll. Mas. Comp. Zo61., Vol. XIV. (1888), p. 276. 

 Murray, J., " Blake " Deposits ; llA>i., Vol. XII. ( 18S5), p. Il2. 



