26 THE CORAL REEFS OF THE MALDIVES. 



were unable to carry out this line, and owing to the heavy sea were com- 

 pelled to abandon sounding at a distance of about three miles south of Addu 

 (Nos. 33, 34), where we sounded in seven hundred and eighteen fathoms, 

 with a bottom of coral sand mixed with fragments of Pteropod shells. At 

 a distance of one and one-half miles south of Addu we found three hundred 

 and seventy-six fathoms (No. 32), with a bottom of small fragments of coral 

 coated with manganese. 



Line from Murdu (Ihavandiffulu) to Colombo. 



On our way back to Ceylon from Ihavandiffulu we took a few soundings 

 to fill gaps in the hydrography of that part of the Indian Ocean. Thirty- 

 six miles from Murdu, in latitude 7° 4' north, longitude 73° 34' east, we 

 obtained fourteen hundred and sixty fathoms (No. 77), with a bottom of 

 fine green ooze and Globigerinae. Fifty-five miles to the eastward of this 

 sounding, in latitude 7° 4' north, longitude 74° 27' east, we obtained fif- 

 teen hundred and forty-seven fathoms (No. 78), with a bottom composed 

 of fine green Globigerina ooze. Ninety miles still further to the east, in 

 latitude 7° 7' north, longitude 75° 46' east, we ran into nine hundred and 

 sixty-four fathoms (No. 79), with a bottom of fine green sticky ooze filled 

 with Globigerinae. These soundings are intercalated with others already 

 on the chart, and make a fairly good section from the Maldives to Ceylon. 

 The soundings on the chart round the northern extremity of the Maldives 

 give the slope of that part of the plateau. 



The line towards Colombo brings out clearly the deep wide tongue of 

 the Indian Ocean, of fully fifteen hundred fathoms, which extends north- 

 ward and separates the Maldivian plateau from the ridge of the Indian 

 continent and its continental shelf. 



Mr. Gardiner, 1 while on the steamer " Ileafaee," sounded across three of 

 the western and two of the eastern channels of the central Maldives. His 

 soundings across the western Kudahuvadu Channel, being somewhat to 

 the east of those made by the " Amra," are shallower ; one deeper sound- 

 ing indicates the western terminus of a deeper bight, running west from 

 the centre of the eastern Kudahuvadu Channel. 



1 hoc. cit., pp. 9, 152, PL X. 



