ON THE ART OF CLASSIFYING. 33 



ceived that the invertebrate division had only negative charac- 

 ters: these animals so greatly differ amongst themselves, that in 

 order to say any thing precise of their organisation, they must be 

 spoken of specially as Soft Animals, Insects, or Zoophytes. He 

 adopted, therefore, in the place of the division of invertebrate ani- 

 mals three others, and thus divided the whole animal kingdom into 

 four large groups, whose characters we here subjoin. 



I. Vertebrate Animals (Animalia vertebrata). The central parts 

 of the nervous system, the spinal cord and the brain, in these 

 animals lie on the dorsal surface, in a bony or cartilaginous 

 cavity formed by the vertebral column, of which the more 

 developed anterior portion is called the skull. The limbs, 

 when present, are never more than four in number. The 

 muscles cover the bones, and are inserted into them. The 

 mouth has two jaws placed horizontally. 



II. Molluscs (Animalia mollusca) . The central parts of the ner- 

 vous system consist of ganglia, of which usually one, that 

 from which the nerves of sense arise, lies above the oeso- 

 phagus, whilst the rest are differently distributed on the 

 abdominal surface. This nervous system lies in the same 

 cavity with the viscera, enclosed by the soft skin into which 

 the muscles are inserted. 



III. Articulates (Animalia articulata). The central parts of the 

 nervous system consist of ganglia, of which one lies in the 

 head above the oesophagus : the rest in a row in the middle 

 of the body, on the abdominal surface, and are connected by 

 two nervous cords. The covering of the body is divided 

 into rings, and has different degrees of hardness : the muscles 

 are placed within these rings, and are affixed to them. 

 When limbs or feet are present, they are usually six, fre- 

 quently more : when the mouth is armed with jaws, they are 

 placed sideways, and arranged in pairs. 



IV. Radiates (Animalia radiata). A special nervous system is 



not always present : when found, it appears as a ring, near 

 the mouth, surrounding the beginning of the intestine, 



Ann. du Museum XIX. 1812, p. 7384. Afterwards in his classical work entitled, 

 Le R&gne animal dislribue d'aprds son organisation, IV. vol. 8vo. Paris, 1817, (and 2nd 

 edition V. vol. Paris, 1829, 1830). 



VOL. I. 3 



