NATURAL ORDER OF ANIMALS 



131 



Of these six stages of organisation, the first four comprise the in- 

 vertebrate animals, and consequently the first ten classes of the animal 

 kingdom according to the new order that we are going to follow ; the 

 two last stages comprises all the vertebrate animals and consequently 

 the four (or five) last classes of animals. 



By this method it will be easier to study and follow the procedure 

 of nature in the production of the animals that she has brought into 

 existence ; to recognise throughout the animal scale the progress 

 made in complexity of organisation and everjrwhere to verify both 

 the accuracy of the classification and the propriety of the rank 

 assigned by examining such characters and facts of organisation as 

 are known. 



In lecturing on invertebrates at the Museum, I have for some years 

 past followed this plan of always proceeding from the simplest to 

 the most complex. 



In order to bring out more clearly the arrangement and totaUty 

 of the general series of animals, I shall first present a table of the 

 fourteen classes into which the animal kingdom is divided, confining 

 myself to a very brief account of their characters and of the stages 

 of organisation which they include. 



TABLE 



OF THE ARRANGEMENT AND CLASSIFICATION OF ANIMALS 

 ACCORDING TO THE ORDER MOST IN CONFORMITY WITH 

 THE ORDER OF NATURE. 



INVERTEBRATE ANIMALS. 



I. iNFtrSOBIANS. 



Amorphous animals, reproducing by fission or 

 budding ; with bodies gelatinous, transparent, 

 homogeneous, contractile and microscopic ; no 

 radiating tentacles, or rotatory appendage ; no 

 special organ, even for digestion. 



II. Polyps. 



Reproducing by budding ; bodies gelatinous 

 and regenerating, but with no other internal 

 organ than an aUmentary canal with a single 

 aperture. 



Terminal mouth, surrounded by radiating 

 tentacles or furnished with ciliated or rotatory 

 organs. 



They mostly form compound animals. 



1st Stage. 



No nerves : 



no 



vessels ; no special- 

 ised internal organ 

 except for digestion. 



