MORPHOLOGY OF ANIMALS 



4. Chief subdivisions of the Plant Kingdom are into two Sub- 

 kingdoms, 4 Divisions, at least 6 Subdivisions, about 50 

 classes, 130 orders, several thousand genera, and nearly 

 half a million species (see Laboratory Directions p. 11). 

 The "Subdivisions" of plants correspond more or less to 

 the "Phyla" of animals, while the Classes, Genera, and 

 Species in the two kingdoms are of approximately co- 

 ordinate value. 



5. Chief Subdivisions of the Animal Kingdom. The main 

 subdivisions of the animal kingdom are called Phyla; 

 these differ in adult structure so widely that it is difficult 

 or impossible to find connecting links between them. 

 These phyla are subdivided into Subphyla, Classes, Or- 

 ders, Families, Genera, Species. At present we recognize 

 14 phyla of animals, 50 classes, about 200 orders, about 

 50,000 genera, more than half a million species. The 

 phyla, orders and classes of the animal kingdom are shown 

 in the table, pages 12 and 13, of the Laboratory Directions 

 and in the tabular classification at the end of this publi- 

 cation. 



6. Binomial Nomenclature. The entire classification of any 

 plant or animal involves its assignment to its proper 

 Phylum, Class, Order, Family, Genus, and Species, but 

 its scientific name consists merely of the Latin name of 

 the genus and species to which it belongs (e.g. Euglena 

 viridis, Amoeba proteus). This method of naming ani- 

 mals and plants was instituted by Linnaeus (1707-1778) 

 and is known as binomial nomenclature. 



In the following pages continual reference is made to 

 the different phyla, classes, and genera of animals and it is 



c 33 



