SUB-KINGDOM III.—­ANNULOIDA.

Animals in which the digestive canal is completely shut off from the cavity of the body; a distinct nervous system; a system of branched “water-vessels,” which usually communicate with the exterior.  Body of the adult often “radiate,” and never composed of a succession of definite rings.

CLASS I. ECHINODERMATA.
  Order 1. Crinoidea ("Sea-lilies"). Ex. 
   Feather-star (Comatula), Stone-lily (Encrinus*).
  Order 2. Blastoidea* ("Pentremites").
     " 3. Cystoidea* ("Globe-lilies").
     " 4. Ophiuroidea ("Brittle-stars"). Ex. 
             Sand-stars (Ophiura), Brittle-stars (Ophiocoma).
  Order 5. Asteroidea ("Star-fishes").  Ex.  Cross-fish
             (Uraster), Sun-star (Solaster).
  Order 6. Echinoidea ("Sea-urchins").  Ex.  Sea-eggs
             (Echinus), Heart-urchins (Spatangus).
  Order 7. Holothuroidea ("Sea-cucumbers"). Ex. 
             Trepangs (Holothuria). 
CLASS II.  SCOLECIDA** (Intestinal Worms, Wheel Animalcules, &c.)

SUB-KINGDOM IV.—­ANNULOSA.

Animal composed of numerous definite segments placed one behind the other; nervous system forming a knotted cord placed along the lower (ventral) surface of the body.

Division A. Anarthropoda.  No jointed limbs.

CLASS I. GEPHYREA** ("Spoon-worms"). 
CLASS II.  ANNELIDA. ("Ringed-worms"). Ex.  Leeches**
  (Hirudinea), Earthworms** (Oligochoeta),
  Tube-worms (Tubicola), Sea-worms and
  Sea-centipedes (Errantia). 
CLASS III.  CHAETOGNATHA** ("Arrow-worms").

Division B. Arthropoda or Articulata.  Limbs jointed to the body.

CLASS I. CRUSTACEA ("Crustaceans"). Ex.  Barnacles and
  Acorn-shells (Cirripedia), Water-fleas (Ostracoda),
  Brine-shrimps and Fairy-shrimps (Phyllopoda), Trilobites*
  (Trilobita), King-crabs and Eurypterids* (Merostomata),
  Wood-lice and Slaters (Isopoda), Sand-hoppers
  (Amphipoda), Lobsters, Shrimps, Hermit-crabs, and
  Crabs (Decapoda). 
CLASS II.  ARACHNIDA. Ex. Mites (Acarina), Scorpions
  (Pedipalpi), Spiders (Araneida). 
CLASS III.  MYRIAPODA. Ex. Centipedes (Chilopoda),
  Millipedes and Galley-worms (Chilignatha). 
CLASS IV.  INSECTA ("Insects"). Ex.  Field-bugs (Hemiptera);
  Crickets, Grasshoppers, &c. (Orthoptera); Dragon-flies
  and May-flies (Neuroptera); Goats and House-flies
  (Diptera); Butterflies and Moths (Lepidoptera);
  Bees, Wasps, and Ants (Hymenoptera); Beetles
  (Coleoptera).

SUB-KINGDOM V.—­MOLLUSCA.