INTRODUCTION. 



1 . Definition of Zoology, and its Place among the 

 Sciences. The province of Natural History is to describe, 

 compare, and classify natural objects. These objects have 

 been divided into the " organic " and the " inorganic," or 

 those which are, and those which are not, the products of life. 

 Biology is the science of the former, and Mineralogy the sci- 

 ence 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 Lithology, 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, po- 

 sition, and relation to other rocks is the work of the Li- 

 thologist. Further, we observe that while chalk and marble 

 are chemically 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 diame- 

 ter, having a well-defined, symmetrical shape, and chambered 

 like a Nautilus. We cannot say these are accidental aggre- 

 gations, nor are they crystals : if the oyster- shell is formed 

 by an oyster, these also must be the products of life. In- 

 deed, 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 sea, the cemetery of count- 



