308

ESSAY ON CLASSIFICATION.

not to speak of the lowest animals, which, from want ofknowledge of their internal structure, still remain in greatconfusion. In this rapid sketch of the farther subdivi-sions which the Classes Insecta and Worms of Linnaeushave undergone under the influence of Cuvier , I have not,of course, alluded to the important contributions made toour knowledge of isolated classes by special writers, butlimited my remarks to the works of those naturalists whohave considered the subject upon the most extensivescale.

Thus far no attempt had been made to combine theclasses among themselves into more comprehensive divi-sions, under a higher point of view, beyond that of divid-ing the whole animal kingdom into Vertebrata and Inver-tebrata, a division which corresponds to that of Aristotle ,into £&>«. evcufia and avatfia. All efforts were ratherdirected towards establishing a natural series, from thelowest Infusoria up to Man; which, with many, soon be-came a favourite tendency, and ended in being presentedas a scientific doctrine by Blainville.

SECTION IV.

PERIOD OF CUVIER , AND ANATOMICAL SYSTEMS.

The most important period in the history of Zoology begins, however, with the year 1812, when Cuvier laidbefore the Academy of Sciences in Paris the results ofhis investigations upon the more intimate relations ofcertain classes of the animal kingdom to one another, 1which had satisfied him that all animals are constructedupon four different plans, or, as it were, cast in four dif-

1 Arm. du Museum d’Histoire Naturelle, to], xix; Paris , 1812.