82 GUIDE TO THE AUSTRALIAN MUSEUM. 



XL 



INSECTA. 



The perishable nature of the specimens, and their liability to fade 

 when exposed to the light, unfortunately precludes the exhibition 

 of anything approaching a complete collection of this class, 

 but a representative series, showing the more important types of 

 the variotis orders, is arranged in cases in the Central Halh 

 Upper Floor. Cases I — III contain Australian species ; while 

 in cases IV and V, a series of Foreign species is exhibited for 

 comparison with the native forms. 



The following table, drawn up by Mr. Dallas, will give some 

 idea of the points of structure which have been made use of in 

 classifying the diflerent families of insects, but it should be used 

 with caution, as it is impossible in a few words to frame a defini- 

 tion which will in every case serve for the discrimination of the 

 Orders : — 



I.— INSECTS WITH A PERFECT METAMORPHOSIS. 



A. With biting mouths, the jaws always distinct : — 



1. Fore-wings horny or leathery, forming a pair of sheaths or 



cases (elytra), covering the abdomen and hind wings, and 

 generally meeting in a straight line down the middle. 1. 

 Coleoptera. 



2. All the wings membranous : — 



a. Veins in the wings few ; prothorax united with the 

 mesothorax. 2. Hijmenoptera, 



h. Veins in the wings numerous; prothorax free. 3. Neu- 

 roj)tera. 



B. With sucking mouths : — 



1. Wings four, scaly ; maxillae forming a spiral proboscis. 4. 



Lepidopteray 



2. Wings not more than two : — 



a. Two wings ; provided with halteres, or balancers ; thoracic 

 segments united ; proboscis formed of the labium, enclosing 

 bristles. 5. Diptera. 



h. Wings none ; thoracic segments distinct. 6. Aphanipttera. 



