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. 
E. 
i. 
iT, 
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. 
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 ceso- 
phagus, whilst the rest are differently distributed on the 
abdomimal surface. This nervous system lies in the same 
cavity with the viscera, enclosed by the soft skin into which 
the muscles are inserted. 
Articulates (Animalia articulata). The central parts of the 
nervous system consist of ganglia, of which one lies in the 
head above the cesophagus: 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 xx. 1812, p. 73—84. Afterwards in his classical work entitled, 
Le Régne animal distribué d’aprés son organisation, IV. vol. 8vo. Paris, 1817, (and 2nd 
edition v. vol. Paris, 1829, 1830). 
VOL. I. 3 
