480 
THE STUDY OF INSECTS. 
family. The first of these is into two groups of subfamilies, 
and is based upon the size of the alulets. The division is 
not a satisfactory one; and it is only given here because it 
is commonly employed by writers on the Diptera, and a 
more definite one has not yet been discovered. 
A. The alulets large; face with a depression or vertical grooves 
beneath the antennae; cell Ills closed or narrowly open, except in 
the Anthomyiinae, where it is widely open. p. 480. 
CALYPTRATE MUSCIDiE. 
A A. The alulets small or wanting; form of face varied; cell III* 
usually widely open. p. 484. Acalyptrate MusciDiE. 
I. CALYPTRATE MUSCID^E (Ca-lyp'trate). 
To this division belong our most familiar representatives 
oi the family, of which the House-fly and the flesh-flies are 
good illustrations. As a rule cell III B of the wings is closed 
or narrowly open (Fig. 588); but in the last subfamily this 
cell is widely open (Fig. 589). Five subfamilies are classed 
here ; these can be separated by the following table, which 
is based on one given by Professor Williston. 
A. Cell Ilia of the wings closed or more or less narrowed at the 
margin of the wing (Fig. 588). 
B. Antennal bristle wholly bare. p. 481. TACHININ.E. 
BB. Antennal bristle distinctly pubescent or plumose. 
