290 THREE CRUISES OF THE “ BLAKE." 
though there are reasons for supposing it was. 
The ooze which came 
up from the same place was of a reddish or brownish tinge, and con- 
tained an immense number of pteropods, heteropods, and pelagic fora- 
minifera; the percentage of lime was not so high as in the white chalk 
rock, and the residue was much darker in color. 
“ Calcareous concretions and nodules of manganese were also dredged 
in this district.” ! 
In the district around the shores of the Antilles there is a 
gradual transition from the coarser volcanic bottom deposits of 
shallow waters to the finer sands and muds, which at a distance 
from the islands pass into ooze. 
While dredging in the passages 
between the islands the trawl often came up well filled with 
rounded pebbles of volcanic rocks. 
Their shape may be due 
either to the action of the strong currents rushing between the 
islands, or perhaps to the disintegrating action of the warm 
water. 
coarse voleanie sands found in the West Indian waters. 
This process may account for the abundance of the 
Below 
six or seven hundred fathoms the bottom in the Caribbean is 
composed of calcareous ooze, consisting in great part of ptero- 
pod shells, and 1n a less degree of foraminiferous remains. 
1 «Off the Barbados, in 221 fathoms, 
a very hard calcareous concretion was 
obtained, which showed perfectly how 
the rock was formed by erystallization of 
carbonate of lime around the shells of 
foraminifera and other centres. A zone 
is seen around the shells, composed of 
fibro-radiate calcite ;' the crystals of cal- 
cite, coming from the various centres, 
abut against each other, and frequently 
leave an empty space between them. 
When these spaces are filled by a further 
deposition of lime, the whole becomes 
very compact and massive. 
“The centres of the foraminifera are 
frequently filled with a gray or yellowish 
substance, which does not, however, give 
the reactions of phosphate of lime. 
“The mineral particles were very few 
in number, among them fragments of 
quartz and plagioclase being observed. 
This coneretion was about two inches in 
diameter, and had a rough areolar sur- 
face on which serpule and polyzoa were 
growing. 
“A similar and somewhat larger con- 
eretion from 200 fathoms (Station 291) 
was. also obtained off Barbados, which, 
was much more overgrown with organ- 
isms, and ón its upper surface had a large 
cavity in which a hermit-erab, Polycheles 
Agassizii, had lived. (See Bulletin M. 
C. Z., VIII. No. 1.) 
* Off the north eoast of San Domingo, 
in 772 fathoms (Station No. VI), were 
obtained several small manganese nodules 
and a few fragments of a, Corallium 
coated with manganese, preeisely similar 
to that dredged by the ‘Challenger’ in 
1,525 fathoms near Cape Verde. (See 
Narrative of the Challenger, p. 125.) 
The nodules were of a light brownish 
color inside, composed in all cases of a 
mass of pelagic foraminifera. The largest 
of these nodules had a diameter of about 
two inches.” 
