134 ZOOLOGICAL PHILOSOPHY 



My object in the exposition is to enable the reader to recognise the 

 rank in the general series that is occupied by the animals which I have 

 often had occasion to cite in the course of the present work, and to 

 save him the trouble of having recourse to other works on zoology 

 for this purpose. 



I shall, however, here give merely a list of genera and of the main 

 groups ; but this hst will suffice to show the extent of the general 

 series, the arrangement of it that is most in conformity with nature, 

 and the places necessarily occupied by classes and orders as well perhaps 

 as by families and genera. We must of course refer to the good works 

 on zoology that we possess for a study of the details of all the animals 

 named in this list, for that does not come within the scope of the 

 present work. 



GENERAL CLASSIFICATION OF ANIMALS. 

 Forming a series in conformity with the actual order of nature. 



INVERTEBRATE ANIMALS. 



They have no vertebral column and consequently no skeleton ; those 

 which have fulcra for the movement of their parts have them under 

 the integument. They lack a spinal cord and exhibit great variety 

 in the complexity of their organisation. 



FIRST STAGE OF ORGANISATION. 



No nerves or gangUonic longitudinal cord ; no vessels for circulation ; 

 no organs of respiration ; no specialised internal organ but that for 

 digestion, 



{Infusorians and Polyps.) 



INFUSORIANS. 



(Class I. of the Animal Kingdom.) 



Amorphous animals, reproducing by fission ; with bodies gelatinous, 

 transparent, homogeneous, contractile, and microscopic ; no radiating 

 tentacles, or rotatory appendage ; internally no special organ, even for 

 digestion. 



Observations. 



Of all known animals the infusorians are the most imperfect, the 

 most simply organised and possessed of the fewest faculties ; they 

 certainly have not the faculty of feeling. 



