122 THE NICOBAR MEGAPODE. 



to me that the birds first collected a heap of leaves, cocoanuts, 

 and other vegetable matter, and then scraped together sand 

 which they threw over the heap, so as not only to fill up all 

 interstices, but to cover everything over with about a foot of 

 pure sand, — I say sand, but this term is calculated to mislead, 

 because it does not contain much silex, but consists mainly of 

 finely triturated coral and shells. After a certain period, whe- 

 ther yearly or not I cannot of course say, the birds scrape away 

 the covering sand-layer from about the upper three-fourths of 

 the mound, cover the whole of it over again with vegetable 

 matter, and then cover the whole in again with the sand. In 

 the large mound, an old one, into which I carefully cut a narrow 

 section from centre to margin, this arrangement was very per- 

 ceptible ; in it I thought I could trace, by the more or less 

 wedge-shaped portions of pure sand along the base (the rem- 

 nants of successive outer coverings of sand, the basal portions 

 of which have never been removed), ten or perhaps eleven 

 successive renovations of the mound ; even the central portion 

 was perfectly cool. The vegetable matter had in a great mea- 

 sure disappeared, leaving only the hard woody portions behind, 

 but showing where it had been by the discolouration of the sand. 

 The decay of the vegetable matter, and the bird's habit (as I 

 judge from appearances) of not removing the basal portion of 

 the sandy covering at each renovation, sufficiently explain why 

 the mounds increase so much more in radius than in height. 



A smaller mound, one as I take it still in use, though I could 

 find no eggs in it, contained a much greater amount of vege- 

 table matter, and was sensibly warm inside. I could make no 

 section of it, as it was too full of imperfectly decayed vegeta- 

 tion. I believe that the bird depends for the hatching of its 

 eggs solely on the warmth generated by chemical action. The 

 succulent decaying vegetation, constant moisture, and finely 

 triturated lime, all combined in a huge heap, will account for 

 a considerable degree of artificial heat. 



I am by no means satisfied that only one pair of birds use 

 the same mound ; on the contrary, the Nicobarese I had with 

 me that day explained, as I understood, that, though one pair 

 begin the mound, they and all their progeny keep on using 

 and adding to it for years ; and they told us that they had, 

 during the previous month, taken at one time some twenty eggs 

 out of one and the same mound, which also they took us to see, 

 and which was perhaps five feet high and sixteen or eighteen 

 feet in diameter, and which was the freshest-looking I had 

 seen. 



The eggs are excessively elongated ovals, enormously large 

 for the size of the bird. They vary a great deal in size, and a 

 good deal in shape ; all are much elongated, but some are more 

 like Turtles' eggs than those of a bird. When first laid, they 

 are of a uniform ruddy pink, as we know from having obtained 



