INVESTIGATIONS IN THE INDIAN OCEAN. 337 



depth of 1,088 fathoms between, is peculiar in having no fringing reef. 

 It is simply an elevated coral island, reaching to a height at present of 

 about 30 feet, surrounded by overhanging cliffs, so that landing is 

 extremely difficult. Its rock is entirely coral. 



Alphonse and Francois are sandbanks on the rims of two reefs 

 scarcely 2 miles apart. Both reefs are of atoll formation, the lagoon of 

 Alphonse (not shown in any chart) being 3 to 8 fathoms deep and of 

 considerable size. 



Amir ante Group. 



The Amirante Islands are sandbanks, no parts of any being more than 

 10 feet above the high-tide level. The hills represented in the separate 

 enlarged plans of Dari-os, St. Joseph and Desroches do not exist, and 

 probably owe their presence thereon to the imagination of the draughts- 

 man.' Desroches is really an atoll by itself, lying 10 miles to the east, 

 and being separated by a channel 874 fathoms deep. The rest of the 

 islands and reefs lie on a bank about 50 miles long by 20 miles broad, 

 with an average depth of about 30 fathoms. Eleven separate reefs reach 

 the surface, of which St. Joseph alone has a lagoon, being really a small 

 atoll with about 4 fathoms of water in the centre. With the exception 

 of Eagle, Darros, and Bertaut, all the reefs lie on the rim of the bank, 

 but its edge is in most places covered by at least 8 to 10 fathoms of 

 water. Its slope is steeper than is customary off coral reefs, no possible 

 dredging-ground existing between 60 and 500 fathoms. 



All the islands of the Amirante group, with the exception of Marie- 

 Louise and Eagle, are now planted for coconut oil, but the indigenous 

 vegetation still remains in places. The land plants and animals are 

 almost the same as at Coetivy and in the Chagos, the additions due to 

 the proximity of Africa and the Seychelles being relatively few. The 

 marine fauna and flora were markedly richer than even at Coetivy. 



Of other work, we took about sixty dredgings ofi' the islands we visited 

 down to more than 800 fathoms, and tow-nettings at various depths to more 

 than 1,000 fathoms. We have, consequently, rich collections, but obviously 

 no estimate of them can be at present formed. We have also serial tem- 

 peratures in a series of positions, and water samples have been taken 

 throughout down to various depths. Further, magnetic observations 

 liave been secured at intervals along the line between Madagascar and 

 the Seychelles. 



The Seychelles Archipelago. 



We reached Mahe on October 21, and after despatching our collectiorls 

 home we spent eight weeks in examining the group. We camped for 

 eighteen days on Praslin, and then separated, Mr. Forster Cooper being 

 responsible for Silhouette, the fauna of which appeared to have been less 

 collected, while I visited various parts of Mahti and examined its reefs 

 and neighbouring islets. Unfortunately, the weather was exceedingly 

 dry during the first half of our stay, and correspondingly wet during th6 

 second half. However, we managed to obtain fairly representative 

 collections of land animals from the endemic jungles, particularly of 

 Mah^. 



' If we had had any idea of this earlier we shov\ld probably have spent our time 

 in visiting Cssmolet'.o and Aldabra. 



1906, a 



