 INTRODUGTEON. 
1. Definition of Zoology, and its Place among the 
Sciences.—The province of Vatural History is to describe, 
compare, and classify natural orice These fly Bas have 
been divided into the “organic” and the “ inorganic,” or those 
which are, and those w hich are not, the pr oduct ts of life. Bi- 
ology is the science of the former, and Mineralogy the science 
of the latter. Biology again separates into Botany, or the 
Natural History of Plants, and Zoology, or the Natural His- 
tory of Animals; while Mineralogy divides into Mineralogy 
proper, the science of mineral species, and Zithology, the 
science of mineral aggregates or rocks. Geology is that com- 
prehensive knowledge of the earth’s structure and develop- 
ment which rests on the whole doctrine of Natural History. 
If we examine a piece of chalk, and determine its physical 
and chemical characters, its mode of occurrence and its uses, 
so as. to distinguish it from all other forms of matter, we have 
its Mineralogy. But chalk occurs in vast natural beds: the 
examination of these masses—their origin, structure, position, 
and relation to other rocks—is the work of the Lithologist. 
Further, we observe that while chalk and marble are chem- 
ically alike, they widely differ in another respect. Grinding a 
piece of chalk so thin that we can see through it, and putting 
it under a microscope, we find imbedded in it innumerable 
bodies, about the hundredth of an inch in diameter, having a 
well-defined, symmetrical shape, and chambered like a Nautilus. 
We can not say these are accidental aggregations, nor are they 
crystals: if the oyster-shell is formed by an Oyster, these also 
must be the products of life. Indeed, the dredge brings up 
similar microscopic skeletons from the bottom of the Atlantic. 
So we conclude that chalk is but the dried mud of an ancient 
