314
ESSAY ON CLASSIFICATION.
II. Sensitive Animals.
Cl. 6. Insects. (Hexapods). Ord. Apte-ra, Diptera , Hemiptera , Lepidopte-ra, Hymenoptera , Neuroptera , Or-thoptera, Coleoptera .
Cl. 7. Arachnids. Ord. Antennato-trache-ales (Thysanura and Myriapoda ),Exantennato-tracheales and Exan-tennato-branchiales (Arachnids pro-per).
Cl. 8. Crustacea. Ord. Heterobranchia(Branchiopoda, Isopoda, Amphipo-da, Stomapoda), and Homobranchia(Deeapoda).
Cl. 9. Annelids. Ord. Apoda, Anten-nata, Sedentaria.
Cl. 10. Cirripeds. Ord. Sessilia and Pe-dunculata.
Cl. 11. Conchifera. Ord. Dimyaria, Mo-nomyaria.
Cl. 12. Mollusks. Ord. Pteropoda, Gas teropoda , Trachelipoda, Cephalopo da , Heteropoda.
>
Feel, but obtain fromtheir sensations onlyperceptions of objects,a sort of simple ideas,which they are unableto combine to obtaincomplex ones. No ver-tebral column; a brainand mostly an elongatedmedullary mass; somedistinct senses; musclesattached under the skin;form symmetrical, theparts being in pairs.
Feel; acquire preservable ideas; per-form with them operations by which theyobtain others; are intelligent in differentdegrees. A vertebral column; a brainand a spinal marrow; distinct senses; themuscles attached to the internal skeleton;form symmetrical, the parts being in pairs.
It is not easy to appreciate correctly the system ofLamarck , as it combines abstract conceptions with struc-tural considerations, and an artificial endeavour to ar-range all animals in continuous series. The primarysubdivision of the animal kingdom into Invertebrata andVertebrata 1 corresponds, as I have stated above, to thatof Anaima and Enaima of Aristotle . The three leadinggroups designated under the name of Apathetic, Sensi-
1 See above, Chap. 2, Sect. 1.