CLASSIFICATION OF INSECTS. 203 



these organs are disposed like rays round a centre ; their 

 respiratory organs are seated on the surface of the body : 

 many animals of this division are a mere homogeneous 

 pulp : this is a double group.* 



It will be evident to every one who has read the preced- 

 ing Book, that insects must belong to the third of these 

 divisions the annulated animals. This division comprises 

 two very distinct groups : first , worms or apoda, which 

 have soft bodies without legs ; secondly, condylopodes or 

 condylopoda, which have their bodies in a hard case, and 

 have articulated legs. The province of condylopoda is 

 divided into tribes by the number of legs, thus : insects or 

 hexapoda have six legs; spiders or octopoda have eight 

 legs ; shell-fish, as crabs or anisopoda, have from ten to 

 eighteen legs ; and centipedes or myriapoda, have from 

 twenty to two hundred legs. 



Insects are divided into two tribes, by the circumstance 

 of possessing wings or wanting them; those which have 

 wings are termed winged insects or tetraptera; those which 

 are without wings are termed wingless insects or aptera. 

 The winged insects are again divided into four classes, 

 founded on the mode of metamorphosis ; that is, on the 

 degree of similarity which the larva and pupa states bear 

 to the perfect state : as in the preceding higher division, 

 three of these are double classes, and one is a single 

 class. In a former chapter it has been said that insects 

 are termed amorphous or amorpha, in which there is no 

 resemblance between the pupa and imago ; necromorphous 

 or necromorpha, in which there is a similarity, though im- 

 perfect ; isomorphous or isomorpha, in which the similarity 



* The characters of the four provinces of animals are from Cuvier's 

 { Regne Animal.' 



