CLASSIFICATION AND EVOLUTION 513 



foregoing pages the Latin name of each species has been 

 given. Above the genus are many divisions of the same 

 nature, but higher rank. Genera are grouped into families, 

 these into orders, orders into classes, classes into phyla, and 

 in many cases it has been found necessary to institute 

 additional grades of division, such as subclasses, subphyla, 

 etc. The systematic position of the frog will serve as an 

 instance of this arrangement. The "frog is the Species 

 R. temporaria, of the Genus Rana, Family Ranidoz, Order 

 Anura, Class Amphibia, Subphylum Vertebrata, Phylum 

 Chordata, Grade Triploblastica, and Subkingdom Metazoa. 

 The following Table shows the main lines of the classification 

 of the animal kingdom : — 



I. Subkingdom Protozoa. 



Animals whose bodies have not a cellular structure. 

 Contains only the : 

 Phylum Protozoa. 



a. Class Rhizopoda. 



Protozoa which move by means of pseudopodia. 

 e.g. Amoeba, Entamoeba, Pelomyxa. 



b. Class Flagellata. 



Protozoa which move by means of flagella. 



e.g. Polytoma, Trypanosoma, Euglena (p. 533). 



c. Class Ciliata. 



Protozoa which move by means of cilia and have 

 usually nuclei of two kinds. 



e.g. Opalina, Paramecium, Balantidium, 

 Nyctotherus, Vorticella, Carchesium. 



d. Class Sporozoa. 



Protozoa which are always internal parasites, form 

 numerous spores, and have often no external 

 organs of locomotion. 



e.g. Monocystis, Plasmodium. 



II. Subkingdom Metazoa. 



Animals whose bodies have a cellular structure. 

 A. Grade Diploblastica. 



Metazoa in whose bodies there are only two 

 protoplasmic layers, ectoderm and endo- 

 derm. Contains only the : 



