SUB-KINGDOM I. PROTOZOA. 



Classes. Orders. Sub-Orders. 



11. Imperforata. 

 II. Foramimfera | 2 Perforata. 



1. Bhizopoda j 2. Radiolaria. 



(3. Others not found fossil. 



2. Infusoria. 



3. Sporozoa or 



Gregarinida. 



THE Protozoa includes the lowest forms of animals, 

 such as Amceba, Vorticella and Globigerina. The body 

 consists in many cases of one cell only, in others of more 

 than one, but the cells never become differentiated to 

 form tissues as they do in all other animals, which are 

 for this reason grouped together as the Metazoa. 



In some protozoans the protoplasm is, with the ex- 

 ception of the nucleus, of uniform character throughout ; 

 these are characterised by having no definite external 

 form, by being able to take in food at any part of their 

 body, and by possessing the power of throwing out lobular 

 or filamentous processes of protoplasm known as pseudo- 

 podia. In other forms the central uniform mass is sur- 

 rounded by a denser cortical layer, which gives the animal 

 a definite shape. In these the food is generally taken in 

 at one permanent aperture which functions as a mouth. 

 They never give out pseudopodia, but are in many cases 

 provided with cilia or flagella, which are threads of proto- 

 plasm having a definite form and a rhythmic movement. 



Reproduction in the Protozoa takes place asexually by 



