86 Descriptive Zoology. 



CHARACTERISTICS OF ARTHROPODS. 



1. Arthropods have an external skeleton, or exoskeleton. 



2. This skeleton consists of a series of rings, movable 

 upon one another, i.e. the skeleton is segmented. 



3. Some of these rings, or segments, bear appendages 

 that are segmented. 



CLASSIFICATION OF ARTHROPODA. 

 ARTHROPODA. 



Crustacea (Class I). (Tracheata.) 



1. Aquatic (generally) breathe i. Aerial breathe by air tubes 



by gills. or " lungs." 



2. Antennae 2 pairs. 2. Antennae i pair (or none). 



(Class'll) (Class III) (ClasTlV) 



Arachtiida. Myriapoda. Insecta. 



1. Head. 



Other rings r i. Head. 



Parts of ii. Head-thorax. A , 



Iwo Many all alike. Ihree<2. Ihorax. 



Body. / 2. Abdomen. 



2. Body worm- (.3. Abdomen. 



like. 



Legs. 4 pairs. Many pairs. 3 pairs. 



Antennas. None. I pair. I pair. 



Jaws. 2 pairs. 2 or 3 pairs. 2 pairs. 



