86 SOCIAL HABITATIONS. 
Here, then, we have an example of a bird laying an egg 
which is extremely small in proportion to its own size, 
while in the apteryx or kiwi-kiwi of New Zealand, we have 
an example of a bird laying an egg which is absolutely 
gigantic in proportion to its own size. The apteryx is 
not a large bird, certainly not larger than a guinea fowl, 
and yet its egg looks like that of a swan, and weighs just 
one quarter as much as the bird which produced it. 
Thus it is evident that the dimensions of an egg afford 
no certain criterion respecting the size of the bird that 
laid it, and although a large bird usually lays a large 
egg, and a small bird lays a little one, the cases may be 
reversed, as in the instance just mentioned. 
All naturalists are familiar with the gigantic egg laid 
by some bird unknown, and called by the provisional name 
of Afpyornis, or “tall-bird.” This egg makes that of the 
ostrich itself shrink into insignificance, for its lineal mea- 
surement is precisely double that of a large ostrich egg, 
and its cubic bulk is eight times as great. In fact, the 
eepyornis egg looks as gigantic by the side of an ostrich 
egg as does an ostrich egg near that of a duck. It was 
therefore imagined that the epyornis must be at least 
eight times as large as the ostrich, and a height of sixteen 
feet was attributed to the unknown bird. 
Now, it is easy to work out this problem by the rule 
of three, and to give the result in figures; but when that 
result is compared with existing facts, it becomes startling. 
On paper, a height of sixteen feet for an ostrich-like bird 
seems rather gigantic, but does not appear to carry with it 
any idea of its real magnitude. The height of a very fine 
ostrich being about seven or eight feet, we say that the 
eepyornis must be twice as tall as an ostrich, and so dismiss 
the subject from our minds. But, when we come to com- 
pare the imaginary bird with actually existing beings, 
