ANIMAL LIFE AS A GEOLOGICAL AGENCY. S1 
with them, and, in rare cases, in the stomachs of some of them, 
are those of yet extant plants; and besides this evidence, the 
discovery of works of human art, deposited in juxtaposition 
with fossil bones, and evidently at the same time and by the 
same agency which buried these latter—not to speak of human 
bones found in the same strata—proves that the animals whose 
former existence they testify were contemporaneous with man, 
animals, they would soon form aggregations which might almost be called 
mountains. There were’ in the United States, in 1870, as we shall see here- 
after, nearly one hundréd ‘iiillions of horses, black cattle, sheep, and swine. 
There are great numbers of all the same animalsin the British American Prov- 
inces and in Mexico, and there are large herds of wild horses on the plains, 
and of tamed among the independent Indian tribes of North America. It would 
perhaps not be extravagant to suppose that all these cattle may amount to 
two thirds as many as those of the United States, and thus we have in North 
America a total of 160,000,000 domestic quadrupeds belonging to species intro- 
duced by European colonization, besides dogs, cats, and other four-footed 
household pets and pests, also of foreign origin. 
If we allow half a solid foot to the skeleton and other slowly destructible 
parts of each animal, the remains of these herds would form a cubical mass 
measuring not much short of four hundred and fifty feet to the side, ora 
pyramid equal in dimensions to that of Cheops, and as the average life of these 
animals does not exceed six or seven years, the accumulations of their bones, 
horns, hoofs, and other durable remains would amount to at least fifteen times 
as great a volume in a single century. It is true that the actual mass of 
solid matter, left by the decay of dead domestic quadrupeds and permanently 
added to the crust of the earth, is not so great as this calculation makes it. 
The greatest proportion of the soft parts of domestic animals, and even of the 
bones, is soon decomposed, through direct consumption by man and other 
carnivora, industrial use, and employment as manure, and enters into new 
combinations in which its animal origin is scarcely traceable ; there is, never- 
theless, a large annual residuum, which, like decayed vegetable matter, be- 
comes a part of the superficial mould; and in any event, brute life immensely 
changes the form and character of the superficial strata, if it does not sensibly 
augment the quantity of the matter composing them. 
The remains of man, too, add to the earthy coating that covers the face of 
the globe. The human bodies deposited in the catacombs during the long, 
long ages of Egyptian history, would perhaps build as large a pile as one 
generation of the quadrupeds of the United States. Jn the barbarous days of 
old Moslem warfare, the conquerors erected large pyramids of human skulls. 
The soil of cemeteries in the great cities of Europe has sometimes been raised 
several feet by the deposit of the dead during a few generations. In the East, 
