314 



ESSAY ON CLASSIFICATION. 



Feel, but obtain from 

 their sensations only 

 perceptions of objects, 

 a sort of simple ideas, 

 which they are unable 

 to combine to obtain 

 complex ones. No ver- 

 > tebral column ; a brain 

 and mostly an elongated 

 medullary mass ; some 

 distinct senses; muscles 

 attached under the skin ; 

 form symmetrical, the 

 parts being in pairs. 



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), 

 Exantenuato-tracheales and Exan- 

 tennato-branchiales (Arachnids pro- 

 per). 



CL. 8. CRCSTACEA. Ord. Heterobranchia 

 (Branchiopoda, Isopoda, Amphipo- 

 da, Stomapoda), and Homobranchia 

 (Decapoda). 



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. 



VERTEBRATA. 



III. INTELLIGENT ANIMALS. ^ Feel; acquire preservable ideas; per- 



form with them operations by which they 

 obtain others; are intelligent in different 

 degrees. A vertebral column ; a brain 

 and a spinal marrow ; distinct senses ; the 

 muscles attached to the internal skeleton ; 

 form symmetrical, the parts being in pairs. 



It is not easy to appreciate correctly the system of 

 Lamarck, as it combines abstract conceptions with struc- 

 tural considerations, and an artificial endeavour to ar- 

 range all animals in continuous series. The primary 

 subdivision of the animal kingdom into Invertebrata and 

 Vertebrata 1 corresponds, as I have stated above, to that 

 of Anaima and Enaima of Aristotle. The three leading 

 groups designated under the name of Apathetic, Sensi- 



1 See above, Chap. 2, Sect. 1. 



CL. 13. FISHES. 

 CL. 14. REPTILES. 

 CL. 15. BIRDS. 

 CL. 16. MAMMALIA. 



