170 GRAMMAR OF ENTOMOLOGY. 



are symmetrically arranged on the two sides of an 

 axis ; in this division, 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.* 



628. It will be evident to every one who has 

 read the preceding Book, that insects must belong 

 to the third of these divisions the annulated 

 animals. This division comprises two very distinct 

 groups : first, worms (apoda\ which have soft 

 bodies without legs ; secondly, condylopodes (con- 

 dylopoda), which have their bodies in a hard case, 

 and have articulated legs. 



629. The province of condylopoda is divided 

 into tribes by the number of legs, thus : insects 

 (hexapoda) have six legs ; spiders (octopoda) 

 have eight legs ; shell-fish, as crabs (anisopodd), 

 have from ten to eighteen legs ; and centipedes 

 (myriopoda), which have twenty to two hundred 

 legs : the last is a single group ; each of the others, 

 double. 



630. Insects are divided into two tribes, by the 

 circumstance of possessing wings or wanting them ; 

 those which have wings are termed winged insects 

 (tetraptera) ; those which are without wings are 

 termed wingless insects (aptera). 



631. The winged insects are again divided into 



* The characters of the four provinces of animals are from 

 Cuvier's " Regne Animal." 



