ORNITHOLOGICAL OBSERVATION IN ICELAND. 217 



have made out, with certainty, in the case of three other species, 

 representing altogether three different families and, moreover, 

 all these four species habitually pair on the nest. Now, if it 

 were known with certainty that the structure which we call a 

 nest, and which, in the great majority of birds (as I suppose, or 

 will assume), is put to that use, and that use only, which the 

 word implies for us, had been originally put to the very different 

 one of coition, and that this had come about through that act 

 having been repeatedly performed in one and the same place, so 

 that the female, waiting in that place for the male, had some- 

 times laid her eggs there, and thus, through the operation of 

 Natural Selection, came, in time, to incubate them, an office 

 which had been previously left to the sun, as in reptiles, and as 

 it still is, with birds, in the case of the Megapodes, which stand 

 lowest and therefore nearest to reptiles* — if these things were 

 known, I think it will be admitted that the above facts would be 

 held to receive a simple and natural explanation in the process 

 of evolution through which the nest had passed. Since birds 

 used to pair on the archaic nest, before they laid their eggs 

 there, no one could wonder that, by inherited association, the 

 ideas of pairing and nest-making were still connected in the 

 minds of many of them, whilst some continued to act like 

 their ancestors. Similarly, it will, I think, be also allowed that 

 if it were known that the actual process of nidification had 

 grown out of the objectless snatching up by birds of sticks, 

 twigs, leaves, &c, from the ground, and dropping them again 

 upon it, when sexually excited, either before, after, or during 

 copulation, it would not then be held strange that they should 

 sometimes now act in this manner, as I have, in fact, observed 

 them to do. If, then, certain facts, if known, would be accepted 

 as an explanation of certain other facts which are known, the 

 postulation of these unknown facts, to explain the known ones, 

 must be held legitimate, so long as they are not irreconcilable 

 with other facts belonging to the subject. I submit that all the 



* " The Megapodiidce, with the Cracidce, morphologically seem to be 

 the lowest of the order, with which apparent fact may perhaps be correlated 

 their singular habit of leaving their eggs to be hatched without incubation," 

 — Prof. A. Newton, ' A Dictionary of Birds,' vol. i. p. 539. A. & C. Black, 

 1893-1896. 

 Zool. 4th ser. vol. XVIII., June, 1914. s 



