380 THE INDUCTIONS OP BIOLOGY. 



fested. On studying the definitions of these primary, sec- 

 ondary, and tertiary classes, it will be found that the largest 

 are marked off from one another by some attribute which con- 

 notes sundry other attributes ; that each of the smaller classes 

 comprehended in one of these largest classes, is marked off 

 in a similar way from the other smaller classes bound up with 

 it; and that so, each successively smaller class has an in- 

 creased number of co-existing attributes. 



100. Zoological classification has had a parallel history. 

 The first attempt which we need notice, to arrange animals 

 in such a way as to display their affinities, is that of Lin- 

 nasus. He grouped them thus : * 



CL. 1. MAMMALIA. Ord. Primates, Bruta, Ferae, Glires, Pecora, 

 Belluse, Cete. 



CL. 2. AVES. Ord. Accipitres, Picas, Anseres, Grallse, Gallinae, 

 Passeres. 



CL. 3. AMPHIBIA. Ord. Reptiles, Serpentes, Nantes. 



CL. 4. PISCES. Ord. Apodes, Jugulares, Thoracici, Abdominales. 



CL. 5. INSECTA. Ord. Coleoptera, Hemiptera, Lepidoptera, Neu- 

 roptera, Diptera, Aptera. 



CL. 6. VERMES. Ord. Intestina, Mollusca, Testacea, Lithophyta, 

 Zoophyta. 



This arrangement of classes is obviously based on ap- 

 parent gradations of rank; and the placing of the orders 

 similarly betrays an endeavour to make successions, begin- 

 ning with the most superior forms and ending with the 

 most inferior forms. While the general and vague idea of 

 perfection determines the leading character of the classifi- 

 cation, its detailed groupings are determined by the most 

 conspicuous external attributes. Not only Linnaeus but 

 his opponents, who proposed other systems, were "under 

 the impression that animals were to be arranged together 

 into classes, orders, genera, and species, according to their 



* This classification, and the three which follow it, I quote (abridging 

 some of them) from Prof. Agassiz's " Essa7 on Classification." 



