48 THE BEAUTIES OF NATURE chap. 



less condition." Even Man himself presents 

 traces of gill-openings, and indications of 

 other organs which are fully developed in 

 lower animals. 



MODIFICATIONS 



There is in New Zealand a form of Crow 

 (Hura), in which the female has undergone a 

 very curious modification. It is the only case 

 I know, in which the bill is differently shaped 

 in the two sexes. The bird has taken on the 

 habits of a Woodpecker, and the stout crow- 

 like bill of the cock-bird is admirably adapted 

 to tap trees, and if they sound hollow, to dig 

 down to the burrow of the Insect ; but it 

 lacks the horny-pointed tip of the tongue, 

 which in the true Woodpecker is provided 

 with recurved hairs, thus enabling that bird 

 to pierce the grub and draw it out. In the 

 Hura, however, the bill of the hen-bird has 

 become much elongated and slightly curved, 

 and when the cock has dug down to the 

 burrow, the hen inserts her long bill and 



