4 CLASSIFICATION. 



of order and precision, to a close and accurate com- 

 parison of objects presented to our notice, and to a 

 clear and neat perception of their distinctive cha- 

 racters; it gives a facility of expression to our de- 

 scriptions, and in this Avay its importance, as a branch 

 of education, can scarcely be exaggerated. 



Perhaps nothing has contributed so much to the 

 advancement of the science of Natural History as the 

 happy expedient first adopted by Linnaeus, of giving 

 to every object in Nature a double name, whereby its 

 identity is at once satisfactorily indicated. Thus, in 

 the examples given above, we say Mus musculus, Mus 

 rattus, Mus messorius. The first of the two names is 

 that of the genus, and, therefore, common to all the 

 species of that genus ; the second is the specific name 

 — that is, points out the species to which we refer, just 

 in the same manner as in the names of persons. The 

 family name Milton or Shakspeare may belong to' 

 anybody, but John Milton and William Shakspeare 

 are individuals at once recognisable. The only dif- 

 ference is that in this case the specific name is placed 

 first, instead of after that of the genus. To under- 

 stand the importance of this gTcat step in Zoological 

 Science, it is only necessary to read the descriptions 

 of old authors who, after devoting half a page to 

 the identification of an animal, leave you in doubt 

 whether they are speaking of a cat, a rat, or a hippo- 

 potamus. 



With regard to the classification of the immense 

 series of living beings composiug the animal creation, 

 various systems have been at different times sketched 

 out by the master minds of science, all of which have 

 more or less fallen short of their gi^eat object. Of 

 these, the most useful and most generally adopted is 

 that of Cuvier, and as this will be more or less om* 

 guide throughout the following pages, a knowledge 

 of its leading features becomes indispensable. 



According to the system of Cuvier, all living 

 animals are divided into — 



1st. Those that have back-bones (yertehrse) ; 



