322 ZOOLOGY 



which is of the utmost value in any system of classification. 

 The character of the wings, and the relation of the prothorax 

 to the rest of the thorax, are connected with the powers of flight. 

 In some sub-orders wings are entirely absent, and in others, 

 although they are fully developed, they may be thrown off, as 

 in the ants, and in the workers amongst the white ants or 

 Termites. The degree of metamorphosis which an insect under- 

 goes in passing from the egg to the adult, though possibly a 

 good criterion for phyletic relationship, is of less use for 

 practical purposes of classification, inasmuch as it assumes the 

 life-history of the insect to be known, and this is by no means 

 always the case. 



The Insecta are divided into eight orders — 



1. Aptera. 



2. Orthoptera. 



3. Neueoptera. 



4. Lepidoptera. 



5. Hemipteka. 



6. coleopteea. 



7. DiPTERA. 



8. Hymenopteka. 



Before considering the subdivisions and characteristics of 

 these orders, it will be advisable to obtain an insight into the 

 structure and anatomy of some fairly typical insect form, and 

 the common cockchafer, Mdolontha mdgaris, one of the Coleop- 

 tera, both on account of its size and its frequency, will form a 

 convenient type. 



The cockchafer is about |^ to 1 inch long, and the chief 

 divisions ' of an insect body into head, thorax, and abdomen 

 are easily recognised. The head bears a pair of antennae, and 

 three pairs of mouth appendages. The antennae differ in the 

 two sexes ; they consist of ten segments, the first of which is 

 known as the scape. In the male the last seven joints, and in 

 the female the last six joints, are flattened out into a series of 

 plate-like processes, which have given the name LameUicornia 

 to the subdivision of the Coleoptera to which the cockchafer 

 belongs. They are much longer and larger in the male than 

 in the female, and in both, each lamella bears an enormous 



