THE MICROSCOPE IN ZOOLOGY. 181 



SUB-KINGDOM III. ANNULOIDA. 



CLASS I. ECHINODERM AT A. Integument calcareous or 

 leathery ; adult radiate. 



Order 1. Crinoidea. Ex., Comatula. 



Order 2. Blastoidea. (Extinct.) 



Order 3. Cystoidea. (Extinct.) 



Order 4. Ophiuroidea. Ex., Brittle-star. 



Order 5. Aster oidea. Ex., Star-fish. 



Order 6. Echinoidea. Ex., Sea-urchins. 



Order 7. Holothur oidea. Ex., Sea-cucumbers. 



CLASS II. SCOLECIDA. Soft-bodied, cylindrical, or flat ; 

 nervous system not radiate ; of one or two ganglia. 



Order 1. Tceniada. Ex., Tapeworms. 



Order 2. Trem,atoda.Y.x., Flukes. 



Order 3. Tarbellaria Ex., Planarians. 



Order 4. Acanthocephala. Ex., Echinorynchus. 



Order 5. Gordiacea. Ex., Hairworms. 



Order 6. Nematoda. Ex., Round worms. 



Order 7. Rotifera. Ex., Wheel animalcules. 



SUB-KINGDOM IV. ANNULOSA. 



DIVISION A. ANARTHROPODA. Locomotive appendages 

 not distinctly jointed or articulated to the body. 



CLASS I. GEPHYREA. Ex., Spoon-worms. 



CLASS II. ANNELIDA. Ex., Leeches (Hirundinidse). 

 Earth-worms (Oligochseta). Tube-worms (Tubicola). 

 Sand-worms and Sea-worms (Errantia). 



CLASS III. CH^TOGNATHA. Ex., Sagitta. 



DIVISION B. ARTHROPODA. Locomotive appendages 

 jointed to the body. 



CLASS I. CRUSTACEA. Ex., Decapoda. Isopoda. Xi- 

 phosura. Cirripedia. 



CLASS II. ARACHNIDA. Ex., Podosomata (sea-spiders). 

 Acarina (mites). Pedipalpi (scorpions). Araneida (spi- 

 ders). 



