208 ESSAY ON CLASSIFICATION 



subject, rather as suggestions for further researches, than as matured 

 results. ^- 



SECTION II 

 EARLY ATTEMPTS TO CLASSIFY ANIMALS 



So few American naturalists have paid special attention to the 

 classification of the animal kingdom in general, that I deem it neces- 

 sary to allude to the different principles which at different times 

 have guided zoologists in their attempts to group animals according 

 to their natural affinities. This will appear the more acceptable, I 

 hope, since few of our libraries contain even the leading works of 

 our science, and many zealous students are thus prevented from 

 attempting to study what has thus far been done. 



Science has begun in the introduction of names to designate 

 natural groups of different value with the same vagueness which 

 still prevails in ordinary language in the use of class, order, genus, 

 family, species; taking them either as synonyms or substituting one 

 for the other at random. Linnaeus was the first to urge upon natu- 

 ralists precision in the use of four kinds of gToups in natural history, 

 which he calls classes, orders, genera, and species. 



Aristotle, and the ancient philosophers generally, distinguished only 

 two kinds of groups among animals, yhos and ebos (genus and 

 species). But the term genus had a most unequal meaning, applying 

 at times indiscriminately to any extensive group of species and desig- 

 nating even what we now call classes as well as any other minor group. 

 In the sense of class, it is taken in the following case: \eyci)5e yhos, 

 olov opvida, Koi IxQ^v,^^ while el5os is generally used for species, as 

 the following sentence shows: kol ecTLv eibf) TrXetw Ixdvoiv Kal 

 opvWcov,^'^ though it has occasionally also a wider meaning. The sixth 

 chapter of book I is the most important in the whole work of Aristotle 



^^ [The preceding section represents Agassiz's effort to formulate a modern system of 

 classification. It was based primarily on the taxonomic ideas and contributions of 

 Cuvier, but contained corrections of that naturalist's work and material drawn from 

 investigations of Agassiz and others made after Cuvier had published.] 



"["By 'genus' I mean, for instance, Bird or Fish." Thompson, tr.. Hist. Anim., I. 

 1. 486''24.] 



" [" . . . and there are many species of fishes and of birds." Ibid., I. 1. 486"24.] 



