THE MICROSCOPE IN ZOOLOGY. 181 



SUB-KINGDOM III. ANNULOIDA. 



CLASS I. ECHINODERMATA.. 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 sj^stem not radiate ; of one or two ganglia. 



Order 1. Tceniada. Ex., Tapeworms. 



Order 2. Trematoda.Ex., Flukes. 



Order 3. Tarbellaria Ex., Planarians. 



Order 4. Acantkocephala. 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^ETOGNATHA. Ex., Sagitta. 



DIVISION B. ARTHROPODA Locomotive appendages 

 jointed to the body. 



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

 phosura. Cirri pedia. 



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

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

 ders). 



