SUN-BIRDS AND HUMMING-BIRDS, 155 



that the tongue is less extensible ; but it is constructed 

 in exactly the same way by the inrolling of the two 

 laminae of which it is composed. 



The tubular tongue of the sun-birds is a special 

 adaptive modification acquired within the family 

 itself, and not inherited from a remote ancestral form. 

 This is shown by the amount of variation this organ 

 exhibits in different members of the family. It is 

 most highly developed in the Arachnotherse, or spider- 

 hunters, of Asia, which are sun-birds without any 

 metallic or other brilliant colouring. These have the 

 longest bills and tongues, and the most developed hyoid 

 muscles ; they hunt much about the blossoms of palm- 

 trees, and may frequently be seen probing the flowers 

 while fluttering clumsily in the air, just as if they had 

 seen and attempted to imitate the aerial gambols of 

 the American humming-birds. The true metallic sun- 

 birds generally cling about the flowers with their strong 

 feet ; and they feed chiefly on minute hard insects, as 

 do many humming-birds. There is, however, one species 

 (Chalcoparia phoenicotis) always classed as a sun-bird, 

 which differs entirely from the rest of the species in 

 having the tongue flat, horny, and forked at the tip ; 

 and its food seems to differ correspondingly, for small 

 caterpillars were found in its stomach. More remotely 

 allied, but yet belonging to the same family, are the 

 little flower-peckers of the genus Diceum, which have 

 a short bill and a tongue twice split at the end ; and 

 these feed on small fruits, and perhaps on buds and on 

 the pollen of flowers. The little white-eyes (Zosterops), 

 which are probably allied to the last, eat soft fruits and 

 minute insects. 



