﻿RELATIONS AND DIVISIONS OF INSECTA. 7 



nida, and Myriapoda ; the complete metamorphosis un- 

 dergone by the former is, however, a good distinguishing 

 feature from the other classes. In no other animals do 

 so many external changes take place ; first the egg, then 

 the caterpillar, moulting its skin and changing appear- 

 ance and size several times, next the pupa or chrysalis, 

 and finally the imago or perfect insect. 



It may be remarked that the great number of species 

 of insects, their multiplicity of form, and the high de- 

 velopment of parts in some, accompanied by the habitual 

 exercise of the most profound instinct, would almost 

 seem to warrant their holding a better rank than at pre- 

 sent accorded to them ; but it must be remembered that 

 the highest type of a group is often more developed than 

 many of the lower examples of the next above it, for na- 

 ture does not work in a continuous and even line. 



Many divisions of the Insecta have from time to time 

 been proposed, but perhaps the following orders are now 

 most usually recognized, viz. — Coleoptera, Euplexoptera, 

 Orthoptera, Thysanoptera, NeuroiJtera, Trichoptera, Hy- 

 menoptera, Strepsiptera, Lepidoptera, Hemiptera (sub- 

 orders, Heteroptera and Homoptera) , Aphaniptera, and 

 Diptera. 



It will not be necessary to notice any of these but the 

 first, except perhaps the Strepsiptera, which are by 

 many now considered to belong to the Coleoptera. The 

 insects composing this order are small in size (the 

 largest not being a quarter of an inch long), and soft; 

 with forked antennse ; large cellular eyes ; mouth with 

 two rudimentary jaws, and a pair of two-jointed palpi ; 

 the prothorax and mesothorax very small and collar- 

 like, the latter having two narrow, curved appendages, 

 variously considered as balancers or false elyira; the 



