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ESSAY ON CLASSIFICATION.

times as many as Linnaeus had done. Again, Linnaeus divides his classes into orders; next, he introduces genera,and finally, species; and this he does systematically inthe same gradation through all classes, so that each ofhis six classes is subdivided into orders, and these intogenera with their species. Of families, as now understood,Linnaeus knows nothing.

The classification of Cuvier presents no such regularityin its framework. In some classes he proceeds, imme-diately after presenting their characteristics, to the enu-meration of the genera they contain, without groupingthem either into orders or families. In other classes, headmits orders under the head of the class, and then pro-ceeds to the characteristics of the genera, while in othersagain he admits under the class not only orders and fami-lies, placing always the family in a subordinate positionto the order, but also a number of secondary divisions,which he calls sections, divisions, tribes, etc., before hereaches the genera and species. With reference to thegenera again, we find marked discrepancies in differentclasses. Sometimes a genus is with him an extensive groupof species, widely differing one from the other, and ofsuch genera he speaks as “ grands genresothers arelimited in their extent, and contain homogeneous specieswithout farther subdivisions, while others again are sub-divided into what he calls sub-genera, and this is usuallythe case with his “ great genera.”

The gradation of divisions with Cuvier , then, varieswith his classes, some classes containing only genera andspecies, and neither orders nor families nor any othersubdivision. Others contain orders, families, and genera,and besides these a variety of subdivisions, of the mostdiversified extent and significance. This remarkable in-