INTRODUCTION. XXXI 



ORTHORRHAPHA. 



Nemocera vera. No holoptic head in the male sex; no bisection or bicol- 

 oration of the eyes. Antennae provided with sensitive hairs ar- 

 ranged symmetrically on the flagellum in verticils or pencils of 

 hairs (exception Mycetophilidae). No ocelli (exception Mycetophi- 

 lidae and Lestreminae). No pulvilli; empodia often but not always 

 present. 



A. Larvae peripneustic*, always terrestrial. Families Cecidomyidae, 



Mycetophilidaa. 



B. Larvae metapneustic or amphipneustic, aquatic, subaquatic, sometimes 



terrestrial. Families, Culicidae, Chironomidse, Psychodidae, (?) 

 Dixidae, Tipulidae. 



Nemocera anomala. Diptera with homologous joints to the flagellum, 

 usually., four-jointed palpi. Males frequently holoptic, sometimes 

 the females also. Pulvilli usually present. Antennae without sensi- 

 tive hairs. Ocelli usually present. Families Bibionidae, Simuliidae, 

 Blepharoceridae, llhyphidae, Orphnephilidae. 



Brachifcera. Palpi one or two-jointed, not pendulous, porrect, the second 

 joint more or less clavate, larger than the first. Joints of the flagel- 

 lum usually not homologous. 



No macrochaatae. Three well developed pulvilli. Males predominently 

 holoptic, the eyes often bisected. Antennal flagellum polymorphous. 

 Axillary incision, alula and antitegula in most cases distinctly devel- 

 oped. Discal cell usually present; usually five posterior cells. 

 Legs rather smooth. Families Stratiomyidae, Tabanidse, Acantho- 

 meridae, Leptidaa EREMOCH^TA. 



COLLECTION AND PRESERVATION OF DIPTERA. 



Flies must be collected with much more care than can be 

 safely used with such insects as coleoptera. Moisture of all 

 kinds injures or ruins them, and specimens collected in alcohol 

 are worthless. For this reason the collecting bottle should be 

 lined throughout with blotting paper, and the cyanide placed 

 in the cork ; a very little poison suffices to kill them. Nor 

 should they be allowed to become too dry before pinning. 

 The pin should be thrust through the middle of the thorax, 

 and the specimen placed just so as to enable the head of the 

 pin to be grasped by the thumb and finger safely. Very small 



* Amphipneustic larvae are those in which the spiracles are confined to the 

 first and last segments; metapneustic those in which they are confined to the 

 posterior segments; peripneustic those in which they are absent on the 

 median rings. 



