1898 - 99 .] Soundings obtained by s.s. ‘ Britannia .’ 429 
concretions occur all through the Straits of Florida, some of them 
being fragments of Manatee hones. 
Around all coral reefs the deposit consists of Coral Sands and 
Muds (yellow colour). At some distance from the reefs, and at 
greater depths, the coral deposits pass into a Pteropod Ooze (pale 
green colour), and in some cases it is impossible to say whether the 
sample should he called a Coral Mud or a Pteropod Ooze. Where 
rivers enter the sea, and generally off coasts where rocks belonging 
to ancient formations are exposed, the deposit is usually a Blue 
Mud (blue colour) principally made up of land detritus. In some 
places the quantity of volcanic detritus is so abundant as to give 
the deposit the character of Volcanic Mud, as in one sample 
obtained by the 1 Britannia ’ (bright red colour). In the northern 
part of the Gulf of Mexico, owing to the influence of the 
Mississippi and other rivers, Blue Mud is found at a great distance 
from land and in very deep water. In the deepest water of the 
Caribbean Sea and the Gulf of Mexico, far removed from land, it 
will be observed that the deposit again passes into Globigerina 
Ooze. 
It should be remarked that the limits of many of these deposits, 
as laid down on the map, especially in shallow water, are to a 
1 ■'.rge extent hypothetical, owing to the small number of deposits 
vhich have been carefully examined up to the present time. 
} iture investigations will no doubt extend the limits of some of 
ie deposits as laid down on the map, especially as regards 
°lobigerina Ooze, Pteropod Ooze, Coral deposits, Blue Mud, and, 
n fact, all the shallower water deposits. 
