PHYLUM PROTOZOA 



Classes Orders 



( 1. Foraminifera. 



1. Gymnomyxa J 2. Eadiolaria. 



(Sarcodina) [ 3. Others not found fossil. 



2. Flagellata or Mastigophora (not fossil). 



3. Infusoria (not fossil). 



4. Sporozoa (not fossil). 



The Protozoa include the lowest forms of animals, such as 

 Amoeba, Vorticella, and Globigerina. The body is usually 

 very small, and consists in many cases of one cell only, in 

 others of more than one, but the cells never form tissues 

 as they do in all other animals. A cell consists of proto- 

 plasm — a viscid or semi-fluid living substance containing 

 granules ; in the centre of the cell is a denser, usually 

 spherical body called the nucleus — sometimes more than 

 one is present. 



In some Protozoa (the Gymnomyxa) the protoplasm is 

 naked, and consists of an inner granular mass and a thin, 

 clear, outer layer ; such forms are further characterised by 

 having no definite shape, by being able to take in food 

 at any part of the body, and by possessing the power of 

 throwing out lobes or filaments of protoplasm known as 

 pseudopodia. In others (the Flagellata and Infusoria) 

 the protoplasm is surrounded by a firm membrane or 

 cuticle which gives the animal a definite form ; the food 

 is generally taken in at one permanent aperture, and 



