CHAPTER II. 

 Insects and their Near Relations. 



The animal kingdom is divided into several great groups, 

 or sub-kingdoms, in each of which the members have some 

 points in common. 



One of these groups has been given the name Arthro- 

 poda, which means ' jointed feet', or perhaps, better, ' jointed 

 limbs.' 



The arthropods are all alike in having jointed limbs, 

 and bodies that are jointed, or at least that are easil} r 

 separable into regions or sections, such as head, thorax (the 

 middle body) and abdomen ; or head and hind body ; or 

 cephalothorax (head and thorax fused together), and abdo- 

 men. Arthropods have an exoskeleton of a hard, firm 

 substance, called chitin, to which muscles are attached 

 on the inside ; this protects all the soft and delicate organs 



The arthropods in their turn are divided into four 

 classes as follows : 



Class I. Crustacea Crabs, Lobsters, Wood-lice etc. 

 ,, II. Arachnida Spiders, Mites, Scorpions, etc. 

 ,, III. Myriapoda Centipedes, Millepedes, etc. 

 ,, IV. Hexapoda Insects. 



Among the Crustacea are to be included crabs, lobsters, 

 shrimps, barnacles, etc., many of which are familiar objects 

 in most parts of the West Indies. Fig. 1 represents 

 a wood-louse, or sow- bug, one of the crustaceans. The 

 crustaceans are mostly aquatic ; a few live in damp situations 

 such as damp soil or decaying vegetable matter. They 

 breathe by means of gills, the head is provided with two pairs 

 of antennae, the abdomen has appendages which are used in 

 locomotion and the eyes are usually compound, sometimes 

 stalked. The body generally is divided into two regions, the 

 cephalothorax and the abdomen. The cephalothorax is 

 composed of the head and the thorax fused together, and 

 is often protected by a hard shell, the carapace. The 



