SUB-KINGDOM VIII. ARTHROPODA. 



Orders. 

 (I. Phyllopoda. 



. Entomostraca. 2 " stracoda - 

 ] 3. Copepoda. 



U- Cirripedia. 

 1. Leptostraca. 



2. Malacostraca. . J 2. Thoracostraca. 



Sub-Orders. 



1. Cumacea. 



2. Stomatopoda. 



3. Schizopoda. 



4. Decapoda. 



1. Amphipoda. 



2. Isopoda. 



Classes. 



1. Crustacea. .. 



3. Arthrostraca. 



2. Prototracheata. 



3. Myriapoda. 



4. Insecta. 



5. Arachnida. 



{1. Trilobita. 

 2. Xiphosura. 

 3. Eurypterida. 



IN the Arthropods the body is bilaterally symmetrical 

 and segmented, and some or all of the segments bear a 

 pair of appendages each, which differ from those of the 

 worms in being jointed. Some of the appendages near 

 the mouth are modified so as to function in mastication 

 and prehension. A chitinous exoskeleton is always present 

 and is often strengthened by the deposition of carbonate 



