SKEATS : CHEMICAL COMPOSITION OF LIMESTONES. 79 
similar to that of Mango. It consists of a rim of elevated limestone, 
rising to a height of 300 to 350 feet, with a central depression. The’ 
island is elliptical in shape, nearly five miles long, with a greatest 
breadth of three miles. On the north-west face the limestone is 
broken through by a conical hill 470 feet high, which is of volcanic 
origin. 
Chemical. — The only limestone examined came from a height of 250 
feet, and contains 34.5 per cent of magnesium carbonate. 
Calcium Magnesium 
Height. Carbonate. Carbonate. 
250° 65.5 34.5 
Microscropical. 250'.— The matrix of the rock consists largely of a 
fine gray ‘‘ mud,” which under the high power is in places seen to con- 
sist of minute crystals of dolomite. Apparently the organisms have 
not shared in the dolomitization as, for the most part, they seem to be 
fresh and unaltered. Carpenteria shows its brown color, Lithotham- 
nion, aleyonarian spicules, and echinid spines are apparently unaltered, 
while Heterostegina preserves its structure except for small wedge- 
shaped parts of the shell, which were probably aragonite and have now 
disappeared. 
Stneatoka (Viti Levu). — This district is on the south-western 
border of the island of Viti Levu, the largest of the Fiji Archipelago.’ 
The locality from which the specimens were collected is at the mouth 
of the Singatoka River, in latitude 18° 10! S., longitude 177° 30! E., 
where large deposits of upraised bedded limestone, dipping at 15°, form 
cliffs of 250-300 feet in height. Beneath these limestones a compact 
blue limestone is found dipping at 50°, while below this occurs an im- 
mense block of dolomite, practically perpendicular, and consisting of two 
hills, 1000 and 1500 feet respectively above the river. 
Chemical. — The four specimens analyzed were taken in vertical suc- 
cession from the upraised bedded limestones, which have a dip of 15°. 
All the rocks are limestones containing only from 3 to 6 per cent of 
magnesium carbonate. They are interesting chiefly on account of the 
relatively large quantity of insoluble matter which they contain. The 
rock from the reef has a smaller quantity, about 1 per cent, but the three 
specimens from the cliffs yielded on analysis 1.9, 2.09, and 2.31 per 
. cent respectively of insoluble matter. 
1 Bull. Mus. Comp. Zool., 1900, Vol. XXXVIIL., pp. 13-14. 
