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SUBMARINE DEPOSITS. 281 
over eighty per cent. The variation in the percentage of lime 
in pteropod ooze is from sixty-eight to eighty-three. In the 
coral muds and pteropod and globigerina ooze, the lime is re- 
placed in part, in accordance with the locality, by a greater or 
smaller amount of siliceous organisms or by argillaceous matter. 
The variations of lime in globigerina ooze range from thirty-two 
to seventy-two per cent, in proportion to the proximity of the 
shore, the percentage of mineral residue varying from sixty-four 
to twenty-seven, in addition to the changes due to a larger or 
smaller proportion of siliceous organisms or argillaceous matter. 
While sounding, it was easy to follow the depth and the dis- 
tance from shore by the gradual decrease of bright tints in the 
bottom specimens ; these were probably colored more intensely 
by organic matter when close in shore, but became bleached 
with increasing depth. Along the lines of soundings in the 
Caribbean, we found the coral muds to be of a light greenish- 
gray or yellowish tint. Pteropod ooze varied from a chalky 
gray to white, while globigerina ooze passed from dark brown 
to reddish, reddish brown, and light brown, or cream-color. 
The river muds were usually gray or brown. 
The globigerina and pteropod ooze of the central parts of the 
basins of the Gulf of Mexico and the Caribbean, like those 
found in proximity to the Greater and Lesser Antilles, differ ma- 
terially from similar deposits in the great oceanic basins. The 
siliceous organisms consist of radiolarians and sponge spicules, 
with a few diatoms ; but these seldom make up more than three 
or four per cent of the whole deposit. An unusual number of 
otoliths of fishes were detected in the bottom specimens of the 
Guif of Mexico; they occurred at considerable depths, from 392 
to 1,568 fathoms. Fish teeth were also found in some of the 
mud deposits, from over 500 fathoms. 
I take the following from Murray’s Report : — 
“The phosphatic concretions in the dredgings in the Straits of Flo- 
rida are very interesting. In a great many deep-sea deposits there is 
usually a small percentage of phosphate of lime, but near the shore, 
in some instances, the quantity is very considerable. Sharples, who 
analyzed the ooze of the Gulf Stream, found over eighty-five per cent 
of carbonate of lime, and only 0.18 per cent of phosphate of lime. 
