INTRODUCTION. 17 



INVERTEBRATE ANIMALS. 



SUB-KINGDOM I.— PROTOZOA. 



Animal simple or forming colonies, usually yery minute ; the body com- 

 posed of the structureless, jelly-like, albuminous substance called "sarcode;" 

 not divided into regular segments ; having no nervous system ; no regular 

 circulatory system ; usually no mouth ; no definite body-cavity, or at most 

 but a short gullet. 



Class A. Geegarinid^ — Minute Protozoa which inhabit the interior of 

 insects and other animals, and which have not the power of throwing out 

 prolongations of their substance (pseudopodia). No mouth. 



Class B. Rhizopoda (Root-footed Protozoa). — Protozoa which are 

 simple or compound, and have the power of throwing out and retracting pro- 

 longations of the body-substance (the so-called "pseudopodia" ). No mouth, 

 inmost, if not in all. 



Order 1. Monera. — Ex. Protogenes. 



Order 2. Amcebea. — Ex. Proteus Animalcule (Amoeba). 



Order 3. Foraminifera. — Ex. Lagena, Nodosaria, Globigerina. 



Order 4. Radwlaria. — Ex. Thalassicolla, Polycystina. 



Order 5. Spcmgida. — Ex. Fresh-water Sponge (Spongilla), Venus's 



Flower-Basket (Euplectella). 



Class C. Infusoria (Infusorian Animalcules). — Protozoa with a mouth 



and short gullet ; destitute of the power of emitting pseudopodia ; furnished 



with vibratile cilia or contractile filaments; the body usually composed of 



three distinct layers. 



Order 1. Viliata. — Ex. Bell-animalcule (Vorticella), Paramoecium. 



Order 2. FlageUata. — Ex. Peranema. 



Order 3. Suctoria. — Ex. Podophyra. 



SUB-KIWGBOM IL—CCELENTEBATA. 



Animals whose alimentary canal communicates freely with the general 

 cavity of the body ; body composed essentially of two layers or membranes, 

 an outer layer or " ectoderm," and an inner layer or " endoderm." No cir- 

 culatory system or heart, and in most no nervous system. Skin furnished 

 with minute stinging organs or " thread-cells." Distinct reproductive organs 

 in all. 



Class A. Hydrozoa. — Walls of the digestive sac not separated from 

 those of the general body-cavity, the two coinciding with one another. Re- 

 productive organs external. 



Sub-class I. Htdeoida (Hydroid Zoophytes). 



Order 1. Hydroida. — Ex. Fresh-water Polype (Hydra). 

 Order 2. Corynida. — Ex. Pipe-coralline (Tubularia). 

 Order 3. Sertularida. — Ex. Sea-firs (Sertularia). 

 Sub-class II. SiPHONOPHOEA (Oceanic Hydrozoa). 

 Order 4. Calycophoridm. — Ex. Diphyes. 



Order S. Physaphoridce. — Ex. Portuguese Man-of-War (Physalia). 

 Sub-class III. DiscopHOEA (Jelly-fish). 



Order 6. MedimdcB. — Ex. Trachynema. 

 Sub-class IV. LtrcEENARiDA (Sea-blubbers). 



Order 1. Lucemariadce. — Ex. Lucernaria. 



Order 8. Pelagidm. — Ex. Pelagia. 



Order 9. EJiizostomidce. — Ex. Rhizostoma. 



