58 



THE AMERICAN MONTHLY 



[Feb., 



<'lasping, uoted especially in the hog- louse in which the 

 end of the tibia is a protractile disk which presses against 

 the hair. The abdomens are large, the spiracles prom- 

 inent and in some species there is a pecnliai* brusli-like 

 organ on the under side. 



The function of this organ is unknown and hitln^rtono 

 suggestion has been made as to its office. It would seem 



probable that it serves to retain the abdomen in a })ro- 

 per position for the deposition of eggs, the hair to whicli 

 the insect is attached being held between these two brushes. 



The characters most used in classification are, the form 

 of head, the number of joints in the antennai, the form of 

 sternal plate and of abdomen, the structure of the tarsi 

 and the special appendages on antennae, legs and abdomen. 



Tiie Mallophagidfp are classified mainly on modifica- 



