iO ST. PAUL'S KOCKS. [chap 



shells, of all living animals, it is an interesting physiological 

 fact * to find substances harder than the enamel of teeth, and 

 coloured 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. Paul's only two kinds of birds— the booby 

 and the noddy. The former is a species of gannet, and the 

 latter a tern. Both are of a tame and stupid disposition, and 

 are so unaccustomed to visitors, that I could have killed any 

 number of them with my geological hammer. The booby lays 

 her eggs on the bare rock ; but the tern makes a veiy simple 

 nest M'ith seaweed. By the side of many of these nests a small 

 flying-fish was placed ; which, I suppose, had been brought by 

 the male bird for its partner. It was amusing to watch how 

 quickly a large and active crab (Graspus), which inhabits the 

 crevices of the rock, stole the fish from the side of the nest, as 

 soon as we had disturbed the parent birds. Sir W. Symonds, 

 one of the few persons who have landed here, informs me that 

 he saw the crabs dragging even the young birds out of their 

 nests, and devouring them. Not a single plant, not even a 

 lichen, grows on this islet ; yet it is inhabited by several insects 

 and spiders. The following list completes, I believe, the ter- 

 restrial fauna ; a fly (Oliersia) living on the booby, and a tick 

 which must have come here as a parasite on the birds ; a small 

 brown moth, belonging to a genus tliat feeds on feathers; a 

 beetle (Quedius) and a woodlouse from beneath the dung ; and 

 lastly, numerous spiders, which I suppose prey on these small 

 attendants and scavengers of the waterfowl. The often repeated 

 description of the stately palm and other noble tropical plants, 

 then birds, and lastly man, taking possession of the coral islets 

 as soon as formed, in the Pacific, is probably not quite correct ; 

 I fear it destroys the poetry of this story, that feather and dirt- 



* Mr. Horner and Sir David Brewster have described (Philosophical 

 Transactions, 1836. p. 65) a singular " artificial substance resembling shell.'' 

 It is deposited in fine, transparent, highly polished, brown-coloured laminae, 

 possessing peculiar optical properties, on the inside of a vessel, in which 

 cioth, first prepared Avith glue and then with lime, is made to revolve rapidly 

 in water. It is much softer, more transparent, and contains more animal 

 matter, than the natural incrustation at Ascension ; but we here again see 

 tlie strong tendency which carbonate of lime and animal matter evince to 

 form a solid substance allied to shell. 



