PERIOD OF CUVIER.

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Cl. 4. Acephala. Ord. Testacea, Tunicata .

Cl. 5. Brachiopoda . No subdivisions into orders or families.

Cl. 6. Cirrhopoda. No subdivisions into orders or families.

Third Branch. Animalia Articulata.

Cl. 1. Annelides . Ord. Tubicolm, Dorsibranchise, Abranchim.

Cl. 2. Crustacea. 1st Section: Malacostraca. Ord. Decapoda , Sto-mapoda, Amphipoda, Lmmodipoda, Isopoda. 2 nd Section:Entomostraca. Ord. Branchiopoda, Poecilopoda, Trilobitas.

Cl. 3. Arachnides . Ord. Pulmonarim, Trachearise.

Cl. 4. Insects. Ord. Myriapoda , Thysanura, Parasita, Suetoria, Co-leoptera, Orthoptera , Hemiptera , Neuroptera , Hymenoptera ,Lepidoptera , Rhipiptera, Diptera .

Fourth Branch. Animalia Radiata.

Cl. 1. Echinoderms. Ord. Pedicellata, Apoda.

Cl. 2. Intestinal Worms. Ord. Nematoidea (inch Epizoa and Enfco-zoa), Parenchymatosa.

Cl. 3. Acalepuie. Ord. Simplices, Hydrostatics.

Cl. 4. Polypi. (Including Anthozoa , Hydroids, Bryozoa , Corallins,and Spongis.) Ord. Carnosi, Gelatinosi, Polypiarii.

Cl. 5. Infusoria. Ord. Rotifera and Homogenea (including Polygas-trica and some Algaj).

When we consider the zoological systems of the pastcentury, that of Linnaeus , for instance, and compare themwith more recent ones, that of Cuvier , for example, wecannot overlook the fact, that, even when discoveries haveadded little to our knowledge, the subject is treated in adifferent manner; not merely in consequence of the moreextensive information respecting the internal structure ofanimals, but also respecting the gradation of the highergroups.

Linnaeus had no divisions of a higher order than classes.Cuvier introduced, for the first time, four great divisions,which he called “ embranchemens” or branches, underwhich he arranged his classes, of which he admitted three

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