422 ORDERS OF PTILOTA. 



provided at the base with two articulated organs, which have 

 been regarded as antenna:, but which are the maxillary palpi ; 

 the true antennae being lodged in a cavity behind the eyes ; 

 the legs are strong, and formed for leaping to a great dis- 

 tance ; the tarsi are five-jointed. 



The flea undergoes a series of transformations as striking 

 as those of the bee or beetle. From the eggs are hatched 

 long worm-like grubs, which twist about in all directions, and 

 which, having attained their full size, form for themselves 

 silken cocoons, in which they become incomplete pupae, having 

 the rudiments of all the limbs of the future insect visible. 



Having arrived at the perfect state, they commence their 

 attacks upon us or upon our animals, as well as pigeons, 

 swallows, &c. 



The Jigger (Pulex penetrans) also belongs to this order, 

 differing from the common species by its habit of burrowing 

 into the flesh of the feet in tropical climates. 



