WHAT ARE BATS? 



537 



preceded in early Tertiary times by others which were more or less 

 intermediate in structure. This is not the case as regards hats. 

 Bats, as soon as they appear at all, appear as thoroughly and as per- 

 fectly organized bats as are those living among us now. 



This leads us to speculate upon questions of origin ; but, before so 

 doing, let us see that we have a clear idea of "what a bat is, and can 

 give a good definition of it. 



In order that we may have this clear idea, we must consider for a 

 few moments zoological classification. 



The whole group of animals is fancifully termed the animal king- 

 dom, in contradistinction to the world of plants the vegetable 

 kingdom. 



Fig. 7. Skeleton of Flting-Fox. Side-View op Sternum. 



This vast mass of animals is subdivided into a number of very 

 large groups, each of which is a called a sub-kingdom. Thus, we have 

 the sub-kingdom to which we ourselves belong the vertebrate sub- 

 kingdom ; the sub-kingdom of insects, etc. ; that of snails, cuttle- 

 fishes, etc., and so on. 



Each of these various sub-kingdoms is again divided into certain 

 subordinate, but still very large groups, each of which is called a 

 class. 



Thus, the sub-kingdom Vertebrata is made up of the class of 

 man and beasts, that of birds, that of reptiles, that of frogs, toads, and 

 efts, and that of fishes. 



