52 BULLETIN OF THE 
than 2,000 fathoms the Pteropod and Heteropod shells appear to be 
nearly, if not quite, absent, — the carbonate of lime then consisting of 
the shells of pelagic Foraminifera; in less depths the Pteropod and 
Heteropod shells are present, and in depths varying from 200 to 500 
fathoms they make up the bulk of the deposits in many places. In 
several of the deposits, where the percentage of carbonate of lime is very 
high, the whole has a very chalk-like appearance ; it appears, indeed, as 
if it were in the process of transformation to true chalk. 
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. 
Phosphatic Coneretions. — The phosphatic concretions in the dredg- 
ings in Florida Strait 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 analysed the ooze of the Gulf Stream, found — 
Carbonate, of dame <4 ava) allie | 2 B5.62 
of Magnesium - 2...» . 4.26 
SWLIGH, 5. - jp 1a, Ss re ee Meee ae oe 
Aluininastae odo, Shsis ELIOT 
Oxide ohirons %. aise ce) ERI OORT 
PHOSPHATE OF hive) Dupe oN O18 
Loss) oh-ignition, sta gee te ee maha 2. Wy BS 
100.04 
In certain concretions found by the “Blake” in the Florida Strait, 
and by the ‘‘Challenger” in various parts of the world near land, the 
quantity of phosphate of lime is very much greater than in the deposits. 
These concretions appear always to be associated in an intimate way 
with organisms. 
In 125 fathoms 8. W. of Land Key, Florida, a fragment of bone was 
obtained several centimetres in diameter. It was of a dirty brown 
color, of great hardness, and had a conchoidal fracture. A microscopic 
examination of thin sections showed that the bone structure was per- 
fectly preserved. 
The following is the result of an analysis of this specimen by M. 
Klement : — 
Phosphoric ‘acid:(P;O;) ee a 28 2S 889.42 
Carboniet isi(COs) HTH as aere |} Yet 50 
