238 Cruise of the "Alert" 



penetrable thicket of " Bois d'Aimanthe." Herbaceous plants were 

 numerous, and comprised species of the families Solanacece, Mal- 

 vace&, EupharbiacecB) and Granuicece. 



The fauna, which was not extensive, included a brown rat, 

 which was to be seen climbing along the upper branches of the 

 trees, apparently in search of small birds or their eggs ; a lizard ; 

 a large brown dove, pronounced by Mr. Bowdler Sharpe to be a 

 new species of Turtur ; a Zosterops l and a sun-bird, a large crab 

 of the genus Birgus ; terrestrial hermit-crabs, and many spiders. 



We did not find any fresh water. The soil on the upper parts 

 of the island was a dark loam ; and although sea-birds in the 

 shape of gannets and frigate-birds were abundant and bred on 

 the island, I saw very little guano. 



I spent the forenoon of the following day in examining the 

 broad fringing reef, a great extent of which was laid bare by the 

 low-water spring-tide. It was composed of coral sandstone and 

 coral breccia, and presented a rather sterile appearance, being 

 entirely devoid of living corals, and containing very few zoophytes 

 in its rock pools. I was, however, interested at finding on the 

 surface of this reef a few isolated rounded stones which were quite 

 foreign to the surrounding formation, and whose source remains 

 a mystery difficult of solution. One was an oblong block of hard 

 black basalt, about a foot long, by four inches in width, while the 

 other was a lump of clear quartz the size of an orange, and much 

 worn by attrition. Darwin, in his "Journal of a Naturalist," 

 mentions a similar occurrence at the Keeling Islands ; and in 

 endeavouring to account for it, inclines to the belief that such 

 stones have been transported by floating trees, in whose roots 

 they were originally entangled, and from whence they have become 

 detached after the stranding of the dead tree. 



From the rock-pools we picked up some large Cone-shells, as 

 well as a few Murices, Littorinas, and Turbos. We also saw some 

 Ophiurids, and one Holothurian. 



We got under way again on the 5th of May, and, after spending 



