42 BULLETIN OF THE 
Residue, 52.36 per cent, a green.sand, consists of Minerals [40.00], m. di. 
0.3 mm., many glauconitic grains, quartz, mica, felspars, hornbleude, magne- 
tite, augite, phosphatic grains. Svliceous organisms [8.00], Sponge spicules, Dia- 
toms, Radiolarians, and many fine glauconitic casts of Foraminifera. Fine 
washings [436], traces of argillaceous matter, fine mineral particles, fragments 
of Diatoms, and much green amorphous matter. 
Station 317.— Lat. 31°57! N. Long. 78° 18! 35” W. Depth, 333 
fathoms. From this place, where the ground was said to be hard, there 
was procured a very remarkable concretion that appears to have been 
formed in the position from which it was dredged. 
This was irregular in form, the greatest diameter being about nine 
inches, and of a mottled black, red, and brown color. The surface was 
somewhat 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. Imbedded in 
the concretion were two sharks’ teeth, resembling ZLamna, the largest 
being 2} inches in length and one inch across the base. This tooth is 
similar to many found by the “Challenger” in great numbers in the 
greater depths of the Central Pacific, frequently forming the centres of 
manganese nodules. In the specimens 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 respect resembling the sharks’ 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 per- 
oxide. When thin sections are prepared and examined with the micro- 
scope, the preparation has a variegated appearance ; all the grains being 
closely cemented together. There are numerous sections of pelagic and 
other calcareous Foraminifera, of Pteropods, and fragments of Echino- 
derms. The interior of the Foraminifera is sometimes completely filled 
with calcite, and the same crystals are found cementing many of the 
fragments of which the rock is composed. Small fragments of quartz, of 
felspars, and of zoiene are also seen in the sections. But the most char- 
acteristic element is formed by small rounded grains of a brownish or 
yellow-green color, having much the aspect of glauconite, which is also 
present. Chemical reactions show that these grains are phosphatic. 
