62 THE BLACK SILVERHORNS 



interesting character of the genus is the pre- 

 sence of a row of minute hooks attached to the 



-" ** - : -\^"~^T^ ^ .^ ^ __^_ - 



Mystacides 

 nigra. 



FIG. 33. Hooks connecting the anterior and posterior 

 wings of Mystacides nigra. 



upper edge of the posterior wing towards 

 the extremity, and fitting into a groove in 



the anterior wings. 

 This is illustrated in 

 Fig. 33- 



It is probable that 

 the hooks lock the 

 wings together when 

 the insect is flying, 

 and give extra sus- 

 taining power to 

 these active little 

 flies. These hooks 

 are not confined to 

 Mystacides, but occur 

 in many other genera 



FIG. 34. Genitaliaof-Wjufa- ,,, Fnrnnean and 

 tides nigra, 6 , from above. botn -t-Uropean and 



extra -European. 



The male genitalia of Mystacides nigra are 

 shown in Fig. 34. 



