. Journal of researches into the natural history and geology of the countries visited during the voyage round the world of 'Beagle,' under the command of Captain Fitz Roy. hewoodcut, certain cryptogamic plants (Marchantiae) often seen ondamp walls. The surface of the fronds is beautifully glossy ; andthose parts formed where fully exposed to the light, are of ajet-black colour, but those shaded under ledges are only have shown specimens of this incrustation to several geologists,and they all thought that they were of volcanic or igneous origin !In its hardness and translucency—in
. Journal of researches into the natural history and geology of the countries visited during the voyage round the world of 'Beagle,' under the command of Captain Fitz Roy. hewoodcut, certain cryptogamic plants (Marchantiae) often seen ondamp walls. The surface of the fronds is beautifully glossy ; andthose parts formed where fully exposed to the light, are of ajet-black colour, but those shaded under ledges are only have shown specimens of this incrustation to several geologists,and they all thought that they were of volcanic or igneous origin !In its hardness and translucency—in its polish, equal to that ofthe finest oliva-shell—in the bad smell given out, and loss ofcolour under the blowpipe—it shows a close similarity withliving sea-shells. Moreover in sea-shells, it is known that theparts habitually covered and shaded by the mantle of theanimal, are of a paler colour than those fully exposed to thelight, just as is the case with this incrustation. When weremember that lime, either as a phosphate or carbonate, entersinto the composition of the hard parts, such as bones , of all living animals, it is an interesting physiological. io ST. PAULS ROCKS chap. fact * to find substances harder than the enamel of teeth, andcoloured surfaces as well polished as those of a fresh shell, re-formed through inorganic means from dead organic matter—mocking, also, in shape some of the lower vegetable productions. We found on St. Pauls only two kinds of birds—the boobyand the noddy. The former is a species of gannet, and thelatter a tern. Both are of a tame and stupid disposition, andare so unaccustomed to visitors, that I could have killed anynumber of them with my geological hammer. The booby laysher eggs on the bare rock ; but the tern makes a very simplenest with seaweed. By the side of many of these nests a smallflying-fish was placed ; which, I suppose, had been brought bythe male bird for its partner. It was amusing to watch howquickly a la
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Keywords: ., bookcentury1900, booksubjectge, booksubjectvoyagesaroundtheworld
