CHIEF DIVISIONS OF THE ANIMAL KINGDOM. 81 



may fairly be said to be " embryonic " types ; and as the oldest 

 forms of any given group are usually the least specialised, so 

 they are likewise the most " embryonic.", It must be borne 

 in mind, however, that if we speak of fossil animals as being 

 " embryonic types," we can only do so on the distinct under- 

 standing that it is not thereby implied that they were in any 

 way degraded forms, or that they were at all less perfectly 

 constructed or less thoroughly adapted for their surroundings 

 than their modern representatives. 



The following synoptical table gives briefly the leading 

 divisions of the animal kingdom, and the chief characters of 

 these : 



TABULAR VIEW OF THE CHIEF DIVISIONS OF THE 

 ANIMAL KINGDOM. 



INVERTEBRATE ANIMALS. 

 SUB-KINGDOM I. PROTOZOA. 



Animal simple or forming colonies, usually very minute ; the body 

 composed 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 digestive system, or at most but a short guHet. 



CLASS A. GREGARINID^. 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 

 prolongations of the body-substance (the so-called " pseudopodia "). No 

 mouth, in most, if not in all. 



Order 1. Monera. Ex. Protogenes. 



Order 2. Amcebea. Ex. Proteus Animalcule (Amreba). 



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



Order 4.. Radiolaria.Ex. Thalassicolla, Polycystina. 



Order 5. Spongida. 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 ; fur- 

 nished with vibratile cilia or contractile filaments ; the body usually 

 composed of three distinct layers. 



Order 1. Ciliata. Ex. Bell-animalcule (Vorticella), Paramcecium. 



Order 2. Flagellata. Ex. Peranema. 



Order 3. Suctoria. Ex. Podophrya. 

 VOL. I. F 



