A SHORT ACCOUNT OF THE MORE IMPORTANT CHAR- 
ACTERISTICS OF THE FAMILIES OF DIPTERA. 
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Family Pulicde. 
Parasitic insects, with scale-like rudimentary wings ; long legs, 
very large coxze, tibiz spurred. Eyes may or may not be present. 
Thorax composed of three distinct segments. 
Family Cecidomyide. 
Ocelli often absent. Thorax with no transverse suture. Antennz 
moniliform, 24-jointed in ¢, 12 to 14 inthe 2. Wings with only 
few nervures. Coxze not elongated, femora not thickened, no spurs 
on tibie. 
Family Mycetophilide. 
Ocelli two or three ; often so small they can only just be discern- 
ible. Thorax with transverse suture. Antennz usually 16-jointed. 
Eyes generally round. Few nervures in wings, no discal cell. 
Tibize spurred, coxze elongate. 
Family Brbionide. 
Ocelli three. Thorax without transverse suture, pro-thorax largely 
developed. Eyes of ¢ large and contiguous, smallin 9. Antenne 
g-jointed. No discal cell in wings. Feet armed with long em- 
podium, pulvilli present in some genera. 
Family Simulide. 
Ocelli none. Thorax without transverse suture. Posterior tibiz 
and first joint of hind tarsi dilated. Antennz cylindrical, 11-jointed. 
Family Chironomide. 
Head small, retracted; often partly covered by thorax. Ocelli 
none. No transverse suture on thorax. Eyes reniform. Antennze 
from 6 to 15 joints; pectinate in 4, simple and composed of fewer 
joints in ¢°. Wings without vein along the posterior margin ; costal 
vein ending near the tip of the wing. 
