We dredged from the ship as she lay at anchor in twenty-one to twenty-two fathoms, over a bottom which was mainly composed of coral débris, and among the living organisms brought up were three species of stony corals. This circumstance is of interest as regards the bathymetrical distribution of corals, inasmuch as Dana, judging from the results of observations made by various authorities, considers that twenty fathoms may be regarded as the limit in depth at which reef-forming corals live. Polyzoa were numerous. I noticed representatives of the genera Retepora, Crisia, Eschara, Cellepora, Lepralia, and Myriozoum. There were also some examples of Sertularia and other flexible hydroids.
Our gropings over the platform of fringing reef, which formed the foreshore at low water, resulted in the acquisition of several species of holothurians. Among these was a large Synapta, which was abundant, and a very tough-skinned holothurian—of the genus Moliria—provided with organs resembling teeth at its posterior extremity.
On March 23rd we moved over to Poivre Island—a few miles distant—where we anchored, and remained for part of two days.
Poivre Island was colonized for the first time in the year 1820. It is now the property of a Frenchman residing at Paris, and is managed by his agent, a Monsieur Bertaut, who, with his wife and family, and some twenty negroes and their wives, form the population of the island, altogether amounting to twenty-seven. Of course the staple produce is cocoa-nut oil, and the island having been planted with cocoa-nuts at an early period in its history, the trees are in good condition for bearing, and cover every available spot of ground. Among the other trees on the island I noticed a Casuarina and a Ficus. Two shrubs were common; one, called the "Bois d'Aimanthe" (Suriana maritima), formed a sort of hedge around the island, and the other was a Tournefortia, which seems to be the first plant to establish itself on these islands. The fauna included a black-and-white rabbit—of course introduced—which was very abundant, and some pigeons of a dark-brown plumage. Pigs and domestic poultry seemed to be largely favoured by the colonists, and were indeed in a thriving state.
Like all the Amirantes, Poivre Island is low and flat, and is only exceptional in being the most prosperous island of the group, for which it is indebted to the zeal of the earlier colonists who planted its splendid grove of cocoa-nuts. The island is oval in shape, about two miles in circumference, and it has a broad fringing reef composed of drift coral and sand, but exhibiting no live corals and very few shells.
We cast anchor off the north-west side of Isle des Roches on the evening of the 25th of March, and stayed there for four days. This is the largest island of the Amirante Group, being three and a half miles long, and having an average width of half-a-mile. It is visible for a long distance off, on account of its possessing several large groves of tall Casuarina trees, many of which are one hundred and eleven feet in height. On the shore, immediately opposite to our anchorage, was the settlement, which then exhibited a rather desolate appearance, as many of the houses were in an abandoned condition, most of the inhabitants having recently gone back to Seychelles. Only two individuals remained, French creoles, who seemed to have acquired, from their solitary situation, habits of taciturnity, which they found it difficult to break through. At all events, we could not succeed in extracting much information from them. They were well off for supplies, having a large stock of pigs and poultry, besides fruit and vegetables. Cocoa-nuts had been planted extensively, but as yet few of these trees were old enough to bear fruit. At the time of our visit, the natives were engaged in planting vanilla cuttings about the bases of the casuarina trees, which furnished excellent supports for the creeper to attach itself to.
The flora was more extensive than that of the other islands. There was a large-leafed shrub with thick branches like cabbage-stalks, the Scævola kœnigii, which over ran the island. There were also herbaceous plants of the families Malvaceæ, Solanaceæ, Cinchonaceæ, and Convolvulaceæ. Among the trees I noticed a Ficus, which, however, may have been introduced; and here I obtained the only fern met with among the Amirantes, the Nephrolepis exaltata; it was growing near the sea beach at the eastern end of the island.
There were six land-birds: viz., a red-legged partridge, a pigeon, a large brown finch, and a small yellow-breasted finch, a red-capped weaver-bird, and a waxbill (?). Of these I could only obtain specimens of the small finch and the weaver-bird. The yellow-breasted finch is gregarious, and mostly frequents the tops of the cocoa-nut trees and the upper branches of the tall casuarinas, where it keeps up an incessant melody of song, pleasant to the ear in the variety and succession of the notes, and somewhat resembling the song of the canary. In the large casuarina grove, near the western end of the island, I succeeded, but with much difficulty, in procuring some male specimens of the weaver-bird (Foudia madagascariensis). The females were nesting. I observed one of the latter flying away from the tree in which its nest was constructed, and from which I had disturbed it. It differed from the male in having the red-coloured feathers confined to the head, the rest of the plumage being of a dull brown. The nest was an oblong affair, having a lateral opening, and was constructed of a parasitic plant of creeping habit, which the creoles use for making a substitute for tea. The nest hung from the extremity of a casuarina branch which projected horizontally. The male bird was to be seen perched singly on the summits of the large casuarinas, where it made its presence known by a peculiar and characteristic twittering note which it emits about four times in a minute. It was very wary, and difficult to approach within a sixty yards' range, so that it was only by most careful stalking that I could succeed in bringing down a specimen. The brown finch was not abundant, and seemed to confine its range to the plantations of young cocoa-nuts, where it was continually shifting its perch. The waxbill was a very small bird, which was to be seen every now and then flitting in large flocks among the maize plants and low bushes. I was much surprised to find that the four small birds above mentioned were so very wary, as there were no predatory birds on the island, and it was unlikely that they had ever been shot at before. Nevertheless, the motion of raising one's gun at a distance of sixty yards or more was enough to scare away any of them.
The partridge was identical with that already seen at Eagle and Darros Islands. The pigeon, which I have included among the list of the birds, I saw only once. But one of the creoles living on the island told me that it was an indigenous species, and was quite distinct from the domestic pigeons which roost about and restrict their range to the houses and trees about the settlement.
Although this island has been classed as one of the Amirante Group, it would be more correct to look upon it as distinct and apart from the main group, inasmuch as the bank on which it rests is separated from the Amirante bank by a deep water channel eleven miles wide. We sounded across this channel, and obtained no bottom with one hundred fathoms of line. Isle des Roches is, moreover, peculiar in forming part of an atoll, most of which is submerged, and is covered with from two to five fathoms of water. The circumscribed patch of deep water in the interior has a depth of about fifteen fathoms.