90 



THE UNIVERSE. 



ample wings ; nevertheless naturalists have discovered many 

 species of this order which are wingless. But although we 

 see some individuals of this group deprived of these organs, 

 others exhibit the vestiges of them to show the gradation. 



38. Phalcena hyemalis, male and female. 



39. Phalcena nuda, male and female. 



Thus, for instance, though the female of the Phalcena 

 nuda (a kind of moth) is entirely deprived of wings, we 

 find by the side of it the Phalcena hyemalis, the female of 

 which possesses rudimentary ones, thus forming a transition 

 to the other species of an order, the members of which have 

 four very large wings. 



40. Stenopteryx of the Swallow : 

 Stenopteryx hirundinis. 



41. Melophagus of the Sheep: 

 Melophagus ovis. 



In like manner, when we examine the lower members of 

 the order of flies or Diptera, we find the same modifications 

 there also. 



