ARTHROPODS 177 



throughout the world. People of all languages use the same name 

 for the same plant or animal in their scientific works, and as a 

 result there is no confusion, nor any need for learning a new set of 

 names. Common local names are always uncertain, for there are 

 often several names for the same plant or animal. With the scien- 

 tific names there is but one possible, and therefore there can be 

 no chance for mistake. 

 Scientific names have these advantages: 



1. They are absolutely definite. 



2. They are used by people of all languages. 



3. They are usually descriptive. 



4. They are easier to study than separate descriptions. 



5. They show relationship and descent. 



COLLATERAL READING 



Applied Biology, Bigelow, pp. 358-404; General Zoology, Linville and 

 Kelly, pp. 138-156; Animal Studies, Jordan, Kellogg and Heath, pp. 

 109-129; Economic Zoology, Kellogg and Doane, pp. 106-125; Economic 

 Crustacea, U. S. Fish Commission Report, 1889-1893; Life and her Chil- 

 dren, Buckley, pp. 153-177; Zoology Text, Colton, pp. 54-77; Elementary 

 Zoology, Kellogg, pp. 144-156; Zoology Text, Shipley and MacBride, pp. 

 118-135; Elementary Zoology, Galloway, pp. 232-265. 



SUMMARY 



Meaning of name: . Number of members. 

 Characteristics : 



1. Jointed appendages. 



2. External skeleton. 



3. Three-body regions. 



Head, food-getting and sense organs. 



Thorax, locomotion. 



Abdomen, reproduction, less specialized. 



4. Dorsal heart and ventral nervous system. 

 Animal Kingdom divided into 



1. Branches, which are divided into 



2. Classes, which are divided into 



3. Orders, 4. Families, 5. Genera, 6. Species. 

 Note: 



Larger groups have fewer points in common, more individuals. 

 Smaller groups have more points in common, fewer individuals. 

 Smaller groups have all characteristics of the larger groups of which 

 they are a part, and certain peculiar to their own. 



