THE COMMON FROG. [chap. 



notion of the way in which animals are distinguished 

 and segregated into groups, as well as the general 

 system of arrangement of those groups, and the 

 mode of bestowing names which has been adopted 

 by zoologists in common with botanists. 



When we have acquired an adequate general notion 

 of zoolo2"ical classification we shall be able to see with 

 what creatures the Frog is now admitted to be, in 

 various degrees, allied. 



The whole mass of animals of all kinds, from man 

 down to the lowest animalcula, is spoken of by the 

 fanciful term kingdom. Thus we have the animal 

 kingdom, in contrast with and in distinction from the 

 vegetable and mineral kingdoms. 



This great whole, the animal kingdom, is subdivided 

 into seven great groups or sub-kingdoms, to one or 

 other of which every animal known to us belongs. 



Each of these sub-kingdoms (like every more sub- 

 ordinate zoological group) is characterised and defined 

 by certain points of structure possessed by the 

 animals which compose it, and which serve to dis- 

 tinguish them. 



Thus, if we take up an earthworm we see that its 

 body is composed of a series of similar segments or 

 rings placed one behind the other, and we know that 

 it belongs to that great sub-kingdom of ringed 

 animals termed Anmdosa, 



If we examine a thousand-legs or a wood-louse we 

 see that here again the body is evidently composed of 

 a series of rings or segments, to most of which jointed 

 legs are attached. A successive survey of a lobster, a 

 scorpion, a bee, a beetle, or a butterfly will reveal to 



