r n 



THE 



CANADIAN 



NATURALIST AND GEOLOGIST 



Volume III. AUGUST, 1858. Number 4. 



ARTICLE XXIV. — Agassiz 1 Contributions to the Natural His- 

 tory of the United States. (Vols. 1 & 2. Boston.) 

 (Concluded from our last.) 

 The second chapter is one of the most important in the work. 

 It treats of the actual basis in nature of the various ranks of 

 groups in which animals are arranged, — the Branch or Province, 

 the Class, the Order, the Family, the Genus, the Species. Is 

 there any reason in nature why this particular gradation should 

 he adopted, or is it merely an artificial convenience. Agassiz 

 thinks that it is natural, and that naturalists, like many other 

 workers, have reached to a truly scientific system without know- 

 ing it. He believes that the successive subdivisions of the animal 

 kingdom are based on the following considerations : — 

 " Branches or types are characterised by the plan of their struc- 

 ture. 

 Glasses by the manner in which the plan is executed, as far aa 



ways and means are concerned. 

 Orders by the degrees of complication of structure. 

 Families by their form, as far as determined by structure. 

 Genera by the details of the execution in special parts. 

 Species by the relations of individuals to one another and to the 

 world in which they live, as well as by the proportions of 

 their parts, their ornamentation, &c." 



