Classification 429 



Section B. Primates ( ) 



Order 9. Primates ( ) 



Section C. Ungulata ( ) 



Order 10. Artiodactyla ( ) 



Order 11. Perissodactyla ( ) 



Order 12. Proboscidea ( ) 



Order 13. Sirenia ( ) 



Order 14. Hyracoidea ( ) 



Section D. Cetacea ( ) 



Order 15. Odontoceti ( ) 



Order 16. Mystacoceti ( ) 



BRIEF CHARACTERIZATIONS OF THE MAJOR GROUPS 



OF ANIMALS 



The principal groups of animals are given below with brief diagnoses 

 which may serve as definitions. It must be understood that the charac- 

 ters given will often not be sufficient to distinguish all the forms in a 

 group, for there is much variation within the groups. They are intended 

 to give the student a general conception of the phyla, subphyla and 

 classes. 



Phylum PROTOZOA ( ). Single celled 



animals without true organs or true tissues. If colonial, the cells are all 

 potentially alike. 



Class RHIZOPODA ( ,. Protozoa with 



changeable protoplasmic processes (pseudopodia). Amoeba. 



Class MASTIGOPHORA ( ). Protozoa with 



one or more vibratile processes (flagella) which serve for locomotion and 

 for taking food. Euglena. 



Class SPOROZOA ( ). Parasitic protozoa, 



usually without motile organs or mouth, reproducing by spores. Mala- 

 rial parasite. 



Class INFUSORIA ( ). Protozoa having 



numerous slender vibratile processes (cilia), a cuticle, and fixed openings 

 for the ingestion of food and the extrusion of indigestible matter. 

 Paramoecium. 



Phylum PORIFERA ( ). Diploblastic, radially 



symmetrical animals with body wall penetrated by numerous pores. 

 Body usually supported by a skeleton of spicules or spongin. Sponges. 



Class CALCAREA ( ). Sponges with spicules 



composed of calcium carbonate, monaxon, or tetraxon in form. 



