394 THE MOUNTAIN. 



The central nervous mass consists of a cervical ganglion, 

 with or without a chain of abdominal ganglia. 



CLASS VI. HELMINTHES. 

 CLASS VII. TURBELLARII. 

 CLASS VIII. ROTATORII. 

 CLASS IX. ANNULATI. 



FOURTH GROUP. 



MOLLUSCA. 



Animals of a varied form, and whose bodies are sur- 

 rounded by a fleshy mantle. The central nervous masses 

 consist of ganglia, some of which surround the oesophagus, 

 and others, connected by nervous filaments, are scattered 

 through the body. 



CLASS X. ACEPHALA. 

 CLASS XI. CEPHALOPHOEA. 

 CLASS XII. CEPHALOPODA. 



FIFTH GROUP. 



ARTHROPODA. 



Animals having a perfectly symmetrical form, and articu- 

 lated organs of locomotion. The central masses of the 

 nervous system consist of a ring of ganglia surrounding the 

 oesophagus, from which proceeds a chain of abdominal 

 ganglia. 



CLASS XIII. CRUSTACEA. 

 CLASS XIV. ARACHNIDA. 

 CLASS XV. INSECTA. 



By inspecting the above classification some conception 

 may be had of the extent of this division of the animal 

 kingdom. From Infusoria to Insect is a vast range of or- 

 ganization, and all possible modification of type and form 

 would seem to have been called into requisition. 



