Chap. III. PERIOD OF LINN^US. 189 



in such an order and in such connections as clearly to indicate that he knew their 

 rehitions. When speaking of Fishes, for instance, he never includes the Selachians. 



After Aristotle, the systematic classification of animals makes no progress for 

 two thousand years, until Linnieus introduces new distinctions and assigns a more 

 precise meaning to the terms class, [genus sunimum,) order, [genus intermedium,) genus, 

 [genus proximunu) and species, the two first of which are introduced by him for the 

 first time as distinct groups, under these names, in the system of Zoology. 



SECTION III. 



PERIOD OF LINN^US. 



When looking over the " Systema Naturae " of Linna?us, taking as the standard 

 of our appreciation even the twelfth edition, which is the last he edited himself, 

 it is hardly possible, in our day, to realize how great was the influence of that 

 work upon the progress of Zoology.' And yet it acted like magic upon the age, 

 and stimulated to exertions far surpassing any thing that had been done in pre- 

 ceding centuries. Such a result must be ascribed partly to the circumstance that 

 he was the first man who ever conceived distinctly the idea of expressing in a 

 definite fonn, what he considered to be a system of nature, and partly also to 

 the great comprehensiveness, simplicity, and clearness of his method. Discarding 

 in his system every thing that could not easily be ascertained, he for the first time 

 divided the animal kingdom into distinct classes, characterized by definite features ; 

 he also for the first time introduced orders into the system of Zoology besides 

 genera and species, which had been vaguely distinguished before.^ And though 

 he did not even attempt to define the characteristics of these different kinds of 

 groups, it is plain, from his numerous writings, that he considered them all as 

 subdivisions of a successively more limited value, embracing a larger or smaller 

 number of animals, agreeing in more or less comprehensive attributes. He expresses 



' To np])rcciate corrcftly Ibo successive improve- reprints of the second; the seventh, eighth, anil ninth 



ments of tlie chissilioiUion of Linna?us, we need only are reprints of the sixth ; the eleventh is a reprint of 



compare the first edition of tlie " Systema Naturjv," the tenth ; and the thirteenth, published after his 



publisiied in 17.35, with the second, puhlished in 1740, death, by Gmelin, is a mere compilation, deserving 



the sixth publisliiil in 174S, the tenth published in little confidence. 



1758, and the twell'lh publisiied in 17GG, as they are ^ See above, Sect. 2, p. 188. The yirr, (ityima 



the only editions he revised himself. The third is of Aristotle correspond, however, to tlie classes of 



only a reprint of the first, the fourth iind fifth are Liun%us ; the vfVj/ ^fj-nila to his orders. 



