THREE CRUISES OF THE / BLAKE." 
216 
color. The surface was irregular, and presented many ovoid, smooth 
projections, the largest of which were about one centimetre in diameter. 
The whole mass was overgrown with sponges, corals, and annelids. 
(Fig. 189.) Imbedded in the concretion were two shark’s teeth, re- 
sembling Zamna, the larger being 24 inches in length and one inch 
Fig. 189. — Сопсгейоп. 332 fathoms. (Blake Station 317.) 2. 
across the base. This tooth is the same as many found by the * Chal- 
lenger’ in great numbers in the greater depths of the central Pacific, 
frequently forming the centres of manganese nodules. In the speci- 
mens from the deep water of the Pacific, the interior of the tooth had 
been in every instance completely removed, only the hard outer dentine 
remaining. In the tooth imbedded in this concretion, on the contrary, 
the vaso-dentine of the interior of the tooth is well preserved, in this re- 
spect resembling the shark’s teeth of the same kind found in various 
tertiary deposits, as for instance in South Carolina and in the island of 
Malta. The vessels of the tooth are infiltrated with peroxide of iron 
and manganese, and phosphate of lime. The whole mass has a breccia- 
like appearance, the several fragments being cemented by deposits of 
carbonate of lime and manganese peroxide." 
1 «When thin sections are prepared calcite, and the same crystals are found 
and examined with the microscope, the cementing many of the fragments of 
preparation has a variegated appearance. which the rock is composed. Small frag- 
All the grains are closely cemented to- ments of quartz, of feldspar, and of zoi- 
gether. There are numerous sections of ene are also seen in the sections. But the 
pelagic and other calcareous foramini- most characteristic element is formed by 
fera, of pteropods, and fragments of small rounded grains of a brownish or 
echinoderms. The interior of the forami- yellow-green color, having much the as- 
nifera is sometimes completely filled with pect of glauconite, which is also present. 
