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CHARACTERISTICS OF FAMILIES OF DIPTERA. xv 
Family Zachinide. 
Antennal bristle bare, or covered with minute pubescence. Thorax 
short. First posterior cell closed, or only faintly open. Abdomen 
more or less oval, beset with bristles. Legs short. 
Family Dexide. 
Antennal bristle hairy or pectinated. Thorax short. First pos- 
terior cell as above. ‘Tegulz large. Abdomen with long bristles on 
at least the last two segments. Legs long. 
Family Sarcophagide. 
Antennal bristle plumose or hairy ; apex bare. First posterior 
cell as above. Tegule large. Legs stout. 
Family Muscide. 
Antennal bristle entirely plumose or pectinated. Body stout, 
thorax short. First posterior cell only slightly opened or else closed 
at the border of the wing. 
Family Anthomyide. 
Antennal bristle naked or pectinated. Thorax with a complete 
transverse suture. First posterior cell fully open. Tegulz not very 
large. Abdominal bristles often absent. 
Family Cordyluride. 
Neuration complete. Both posterior basal cells large. Auxiliary 
separated from the first longitudinal vein. Whole lateral border of 
the front bristly ; anterior border of mouth with numerous strong 
vibrissz. 
Family Phycodromide. 
Front bristly ; border of the mouth hairy, with no distinct vibrissz. 
Legs stout ; tibize with spurs, and each with a small bristle on the 
outside, near the tip; the first joint of posterior tarsi not abbreviated : 
last joint of all the tarsi enlarged, with stout claws and long pulvilli. 
Costa without bristles ; basal cells not small. 
Family Helomyzide. 
Front bristly on its upper half only. <A stout bristle at each side 
on the anterior border of mouth. Costa bristly. First longitudinal 
vein not abbreviated, but bare. All the tibiz with spurs, and with 
a more or less developed erect bristle on the outside near the tip. 
