298 THE INDUCTIONS OF BIOLOGY. 



same principle of co-ordination would be still further mani- 

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

 condary, and tertiary classes, it will be found that the 

 largest are marked off from each other by some attribute 

 which connotes 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 smaller classes 

 bound up with it ; and that so, each successively smaller 

 class, has an increased 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- 

 naeus. He grouped them thus :* 



CL. 1. MAMMALIA. Ord. Primates, Bruta, Terse, Glires, Pecora, Belluai, 

 Cete. 



CL. 2. AVES. Ord. Accipitres, Picse, Anseres, Grallse, Galliuae, Passeres. 



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



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



CL. 5. INSECTA. Ord. Coleoptera, Hemiptera, Lepidoptera, Neuroptera, 

 Diptera, Aptera. 



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

 phyta. 



This arrangement of classes, is obviously based on ap- 

 parent gradations of rank ; and the placing of the orders 

 similarly -be trays 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 

 classification, its detailed groupings are determined by 

 the most conspicuous external attributes. Not only Lin- 

 naeus, 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 more or less close external resemblance." This con- 

 ception survived till the time of Cuvier. "Naturalists," 



* This classification, and the three which follow it, i quote (aurid^iug soino 

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



