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 Anthomyiinse, where it is widely open. p. 480. 



CALYPTRATE MUSCID.E. 



A A. The alulets small or wanting; form of face varied; cell III 8 

 usually widely open. p. 484 ACALYPTRATE MUSCIDVE. 



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 5 of the wings is closed 

 or narrowly open (Fig. 588) ; but in the last subfamily this 



FIG. 588. Wing of Musca dotnestica. 



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 Ills of the wings closed or more or less narrowed at the 

 margin of the wing (Fig. 588). 

 B. Antennal bristle wholly bare. p. 481 

 BB. Antennal bristle distinctly pubescent or plumose. 



