vi ANTENN ATA OUTER ORGANISATION 443 



Order 16. Diptera. 



Insects with complete metamorphosis, with sucking and sometimes also piercing 

 mouth parts. Fore-wings membranous, transparent. Hind-wings transformed into 

 halteres. Larvse maggot-shaped (without legs), with or without head. 



Sub- Order 1. Pupipara. 



Viviparous. The larvse are born shortly before entering ^ the pupal state. 

 Parasites. Wings often rudimentary. Melophayus, Braula, Nyctcribia. 



Sub-Order 2. Brachycera, Flies. 



Feelers short, generally three -jointed. Many families: Muscidce, Conopidce, 

 Oestridce, Syrphidce, Empidce, Asilidce, Bombyliidce, Therevidce, Tabanidce, Leptidce, 

 Xylophagidce, Sir atiomy idee. 



Sub-Order 3. Nemocera (Tipularia), Gnats. 



Feelers long, many -jointed, in the male often plumose. Fam. Bibionidce, 

 Fungicolce, Noctuiformes, Culiciformes, CuUtidce, Gallicolce, Limnobiidce. 



Of the above enumerated orders that of the Dermaptera is usually placed as a 

 family of the Orthoptera. The Epliemeridce, Odonata, Plecoptera, Corrodentia, and 

 Thysanoptera are often united into the order of the Pseudoneuroptera, and the 

 Panorpata incorporated with the Neuroptera. 



I. Outer Organisation. 1 



A. The Body. 



Myriapoda. 



The body consists of a head and a large number of uniform trunk 

 segments, the anterior 3 of which correspond with the 3 thoracic 

 segments of the Hexapoda (Insecta). The head has almost certainly 

 arisen from at least 4 fused segments. 



Symphyla (Scolopendrella). The trunk in this division, which 

 probably stands nearest to the common racial form of the Myriapoda 

 and Hexapoda, consists of 12 distinct leg-bearing segments, and an 

 anal segment with 2 processes which may be described as spinning 

 stylets (Fig. 301). Two feelers, which lie in front of these spinning 

 processes, are perhaps transformed legs, and indicate the existence of 

 a 13th pre-anal segment. If so, the whole number of trunk segments 

 would be 13 or 14, and would then almost exactly correspond with 

 the original number of segments in the Hexapodan trunk, in which 

 the thorax has 3 and the abdomen 10 (perhaps 11) segments. The 



1 This representation of the outer organisation can only be of the most general char- 

 acter. For details, which are of great zoological importance, we must refer the reader 

 to systematic works on Entomology. 



