CHAPTER XII. 



CLASSIFICATION OF ANIBIALS. 



The classification of animals is in a very unsatis- 

 factory condition. There is no general agreement 

 among naturalists concerning it. The following ar- 

 rangement of the principal groups of animals will 

 serve as a kind of background, or map of the animal 

 Kingdom, in which the student may locate the ani- 

 mals he has studied and see the extent of untraveled 

 territory. 



BRANCH I. PROTOZOA. Single-celled animals. 



CLASS 1. Rhizopoda. — Amceba. 



2. Sporozoa. — All parasitic. 



3. Flagellata. — Each animal is provided with a 



■ flagellum, or large vibrating hair. 



4. Infusoria. — Vorticella, Paramoecium, etc. 



BRANCH II. PORIFERA. Sponges. 



CLASS 1. Calcarea. — Spicules calcareous. 



2. Cornacuspongia. — Fresh- water and commercial 



sponges. 

 8. Spiculispongia. — Uniaxial or tetra-axial siliceous 



sponges. 

 4. Hyalospongia — Six-rayed siliceous spicules. 



BRANCH III. CCELENTERATA. Animals with a per- 

 manent body cavity. 



CLASS 1. HydromeduscB. — Hydra. 



2. Seyphomedusce. — Jelly fishes. 



3. Arithozoa. — Corals. 



4. Ctenophora. Ctenophores. 



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