DESCRIPTION OF THE EXPEDITION. 127 
dependent is life on environment, and how the greatest care must be taken to study 
both together in view of questions of geographical distribution, particularly on oceanic 
islands *. 
While at Cargados we experienced continuously strong winds from the south-east, so 
that of necessity we confined ourselves to work on the leeward side of the surface-reef. 
On this side the edge of the reef-flat is very ill-defined, tailing off gradually in the centre 
to 10 fathoms in three or four miles. In this part there is a series of shoals reaching 
the surface, on some fifteen of which small islets have formed. Fish abound between 
them, and on one, Avocare, the main fishing-station of the bank is situated, having a 
complement of 42 men. Outside this area is a large stretch of shallow water with only 
six shoals marked on the chart, all of them lying outside a line joining the ends of the 
crescent. All arise within the 20-fathom line, and three—Siren, Pearl, and Frigate—are 
covered completely with land ; the first is a bird-inhabited island, and the other two have 
recently been dug for guano. The 25-fathom line is found within five miles west of 
Establishment Island, and for twenty miles beyond this there stretches out a large, flat 
area, having 25 to 35 fathoms of water, with no known coral-patches. No shoals are 
known west of long. 59° 26’ E., which is almost the position of the 25-fathom line, while 
the 35-fathom line would be in about long. 59° 8’ E., opposite Establishment Island, : 
curving round to the south almost to meet the south-west point of the main reef. The 
25-fathom line follows the same line of longitude for some distance to the north, 
Cargados itself really lying on the south of a much larger shoal, the Nazareth Bank. 
The shallow water near the main reef continues also to the north fer about 12 miles, 
and has two bird-covered islets, North and Albatross, which have seldom been visited 
by man. 
Our dredging was mainly in the arca from 25 to 35 fathoms, and gave in the first haul 
results so interesting that we determined to investigate its fauna as completely as possible. 
On Monday, Aug. 28, Cooper ran a line of soundings due west from Establishment Island, 
and took three dredgings near the edge of the bank. On Tuesday we confined ourselves 
to the area outside Establishment Island and down to Frigate Island, taking five casts. 
On Wednesday we worked to the south point of the reef with ten hauls. On Thursday 
we went over the same line but further westward with nine hauls, and on Friday we ran 
off the bank putting down our nets in three places on its westward edge. During the 
whole time we watched the nets carefully, so as to ascertain the nature of the bottom and 
* We were unfortunately unable to visit Tromelin, which lies in lat. 15° 51’ §., about halfway between 
Nazareth and Madagascar. It was surveyed in 1875 by the late Chief Hydrographer, then Commander W. J. L. 
Wharton, H.M.S. ‘Shearwater.’ It is a mere sand-bank, a mile long, about 15 feet high, covered with low bush, 
and surrounded by a fringing-reef about 150 yards wide. It is evidently of coral-formation. 
It was discovered by the ship ‘La Diane’ in 1722; and in 1761 the ‘ Flute ’'Utile* was cast away there, This 
ship had on board 80 blacks. The whites arrived safe at Madagascar, after a short voyage in a flat-bottomed boat, 
made out of the wreck; the blacks were left on the island, ‘but all died except seven women. These remained on the 
island 15 years, living on the shell-fish they could pick up, with now and then a turtle, and having nothing but 
brackish water to drink. Captain Tromelin, of the ship ‘ La Dauphine,’ had the courage and good luck to land on 
this dangerous spot and brought them to Mauritius in 1776.—Abbé Rochon. 
SECOND SERIES.—ZOOLOGY, VOL. XII. 19 
