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ESSAY ON CLASSIFICATION.
gate among themselves: at icaXovVTai f]p,iovoi hi opcoioTrjra,ovk ovaai airXCK to avro ethos' teal yap oyevomai tcai yevvcovraie£ aXXrjXav. In another passage yevos applies, however, toa group exactly identical with our modern genus Equus:e7ret eaTiv ev ti yevos /cal eVi rot? eleven %aiTrjv, Xocjyovpoi ? na-Xovp,evois, oXov Xiririp Kal ova> Kal opei /cal yivvcp ical ivvco /cal rot?ip 'Zvpla KaXovpievais rj/aiovois.
Aristotle cannot be said to have proposed any regularclassification. He speaks constantly of more or less ex-tensive groups under a common appellation, evidentlyconsidering them as natural divisions; but he nowhereexpresses a conviction that these groups may be arrangedmethodically, so as to exhibit the natural affinities ofanimals. Yet he frequently introduces his remarks re-specting different animals in such an order and in suchconnexions as clearly to indicate that he knew their rela-tions. When speaking of Fishes , for instance, he neverincludes the Selachians.
After Aristotle , the systematic classification of animalsmakes no progress for two thousand years, until Linnaeus introduces new distinctions and assigns a more precisemeaning to the term class (genus summum), order {genusintermedium), genus {genus proximum ), and species, thetwo first of which are introduced by him for the first timeas distinct groups, under these names, into the system ofZoology .