INVESTIGATIONS IN THE INDIAN OCEAN. 335 



found. Naturally, land animals were scarce, but 42 insects were secured, 

 four-tifths from the guano. 



Cooper for the most part took the dredgings, and he reported to me 

 that he found near Cargados ' a wonderfully constant depth of 30-,3,5 

 fathoms over the body of the bank, while towards its western edge there 

 was a slight but uniform rise to 27 fathoms, thus suggesting an incipient 

 atoll with its eastern side slightly tilted up above its western. Over the 

 plateau, where more than thirty hauls were made in different directions, the 

 bottom was either coral rubble, white sand, shell rubble, or weed. The 

 three latter occurred only in the central parts of the bank, wliilo the 

 coral rubble, though also found there, alone formed the raised edge of 

 the western side, being mostly in the form of large lumps. From this 

 rubble, which is of a bright red coloui*, due to an encrusting nullipore, we 

 obtained a rich variety of animal life, nearly all forms tinted with red, 

 The absence of living corals from the rim, as well as from the plateau, 

 in all depths over 20 fathoms, was a noticoaV)le feature." About twenty- 

 iive different species of algai (not lithophytes) were dredged, several from 

 40-50 fathoms on the outer slope, though none have been secured 

 from more than 00 fathoms. 



Snya de Malha Banhs. 



In the channel midway between Nazareth and Saya do Malha banks 

 we found a depth of 222 fathom?, the connection being a ridge rapidly 

 tailing off on its western side to more than 800 fathoms. Saya de Malha 

 really consists of three banks — a northern, a very large central, and asmall 

 south-eastern. The north bank we found to be separated by a channel of 

 G;>G fathoms from the central, while the depth between the latter and the 

 southern is only 130 fathoms. All are more or less of the atoll form, but 

 tlie south side of the central bank differs from all the other parts of the 

 same banks and from the Nazareth bank in tailing off very gradually 

 from 65 fathoms, the general depth in the centre, to 200 fathoms. The 

 area in this part beyond 120 fathoms, which is to some degree protected 

 from the pi-evailing south-east currents, formed a rich collecting ground, 

 the bottom being composed of a white rubble of bivalve and sea-urchin 

 shells, evidently all swept off the shallower bank above. From 80 to 100 

 fathoms, where it is more exposed, the bottom is hard, being swept bare 

 by the currents, but still further north, at GO fathoms, where the eastern 

 edge of the bank has only 10 to 20 fathoms of water, is soft mud with casts 

 of pelagic foraminifera, A considerable number of dredgings were taken 

 at depths above 30 fathoms, and fair collections were obtained. Only 

 the regular deep-living coral.-; were secured, but two hauls at 2G and 29 

 fathoms gave between them more than twenty species of corals typical of 

 .shallow reefs. To the nortli of the banks we dredged between 300 and 

 500 fathoms, tho bottom being of the usual character at such depths of! 

 coral reefs, though with r.ather more rubble. 



Leaving the Saya de Malha, we ran a line of soundings to the shallow 

 bank which surrounds the Seychelles, the greatest depth found being 941 

 fathoms. Thus our soundings prove the existence of a crescent-shaped 

 ridge, 1,100 miles long, with less than 1,000 fathoms of water, arising on 

 either side from a general depth of 2,200 fathoms. 



