PREFACE. 



The object of this work is so fully given in the title-page, that 

 little more remains to be said in the preface. 



Beginning with the simplest and most natural form of habita- 

 tion, namely, a burrow in the ground, the work proceeds in the 

 following order: — 2d, those creatures that suspend their homes 

 in the air ; 3dj those that are real builders, forming their domi- 

 ciles of mud, stones, sticks, and similar materials; 4th, those 

 which make their habitations beneath the surface of the water, 

 whether salt or fresh ; 5th, those that live socially in communi- 

 ties ; 6th, those which are parasitic upon animals or plants ; 7th, 

 those which build on branches. The last chapter treats of mis- 

 cellanea, or those habitations which could not be well classed in 

 either of the preceding, groups. 



In all these classes a definite order has been preserved, the 

 Mammalia having precedence, and being followed in regular or- 

 der by the other members of the group. Thus, in the first few 

 chapters, which treat of the Burrowers, the following system has 

 been observed : — First comes Man, the chief of all the mamma- 

 lia, and in due zoological order follow the Moles and Shrews, 

 the Foxes, the Weasels, the Eodents, and the Edentates. The 

 White Bear alone is removed from its legitimate place, on ac- 

 count of its singular habitation in the snow. The Burrowing 

 Birds come next in order, those which burrow in the earth tak- 

 ing precedence of those which make holes in wood. Burrowing 

 Eeptiles follow next in order; and then come the Burrowing 

 Invertebrates, headed by the Crustacea. The same system is 

 followed throughout, so as to give the reader a clear and defi- 



