DISTRIBUTION SHARPLY DEFINED 143 



circumstance that I do not feel so well qualified to discuss 

 as I do the fauua of the two great divisions — for naturally 

 the divisions are two — east and west. North and south 

 the species do not vary sufficiently to make a very marked 

 division ; at most they are sub-divisions, and the variation 

 of species on the central plains, so far as I have seen, is 

 utterly unimportant. 



Perhaps the most widely distributed of Australian 

 birds is the emu. It is found all over the continent, 

 certain restricted areas excepted ; but the birds of the two 

 sides certainly differ. On the east the Dromcens novce 

 hollandice is a larger bird, and less mottled in plumage 

 than Dromceus irroratus of the western plains. The latter 

 is also a lighter coloured bird, but advancing inland, 

 toward the centre of the continent, I have found an inter- 

 mediate variety, and I am not sure that it is correct to 

 speak of two species. At any rate, as the two varieties 

 approach each other on the northern central plains, the 

 difference between them becomes very much less discern- 

 ible, and I am sure that the two species, if species they 

 are, interbreed. I have seen the two birds paired, but I 

 have not observed any difference in the young. The eggs 

 of both species are green in colour, but there is great 

 difference in the shade of the hue. Some clutches, those, 

 I think, of very young birds, are quite a light green, while 

 those of old birds are a dark rifle-green. This opinion, 

 which is the result of careful observation, seems to be 

 confirmed by the number of eggs in a clutch. If they are 

 light in colour, there are usually no more than seven or 

 eight in a clutch ; if intermediate in hue, nine or eleven ; if 

 very dark the full number of thirteen. I have never seen 

 more than thirteen in a clutch, nor fewer than seven, and I 

 think that the number in a complete clutch is always an 

 odd one. But rarely have I seen even numbers in either 

 clutch or brood of young birds, and I think that the incu- 

 bating cock (it is always the male bird which performs this 

 duty) has some reason for prefering an odd number to sit 

 upon : for I have often found a single egg lying on the 

 ground a few yards from the nest as if it had been ejected 



