402 Mr. Home on the different Structures and Situations 
through them is very rapid, and is rendered still more so by 
the stones of a large size employed in the gizzard passing out 
at the anus. This I learnt from Sir Joseph Banks, who was 
present at the Cape of Good Hope when one of these birds, 
to his great astonishment, voided nearly half a bucket full of 
stones. 
In the American ostrich there will be less waste of the food 
than in the cassowary, as the solvent glands are of a more 
complex structure, as there is a less ready outlet from the 
gizzard, and as the intestines are longer and have a variety of 
convolutions. 
In the African ostrich the means of oeconomising the food 
are greater than in other birds ; the glands have the same 
structure as in the American species, are more numerous, are 
spread over a larger surface, there is a more extensive cavity 
in which the substances it feeds upon are triturated ; and be- 
yond this, a grooved gizzard for the more accurate breaking 
down of the food. The intestines also are longer and more 
varied in their course. 
All these provisions of nature fit this bird to live in the 
sandy deserts, of which it is the natural inhabitant ; and are 
not bestowed upon the others that live in countries where food 
is more abundant. 
It is a curious circumstance that the situation of the solvent 
glands, the shape of the cardiac cavity and position of the 
gizzard in the alca alle among carnivorous birds is nearly the 
same as that of the African ostrich among birds that live 
principally on vegetable food. 
