DIGESTIVE SYSTEM OF BIRDS. 



147 



delicate insects from the recesses of trees and flowers : and the 

 type ' tenuirostrals ' ( TrocliilidcE) may suck up, also, the sweet 

 juice of the nectarium. 



The Fissirostrals, fig. 64, like the Humming-birds, feed on the 



63 



Beak of Humming-bird 

 (Oi-thorhyncus). 



Rostrum of the Caprimulgus. 



Aving, but as their food consists of volant insects, the form of the beak 

 is modified accordingly, and is remarkable for its shortness and 

 the -vvideness of its gape, fig. 64, especially in the typical families. 

 In these the mode of catching the prey is conformable to their 

 distinguishing characters ; they receive it in full flight into the 

 cavity of their mouths, which remain open for that purpose, and 

 where a viscous exudation within, and a strong fence of * vibrissas ' 

 on the exterior, assist in securing the victim. 



A strong, trenchant and pointed, but elongated and straight, 

 bill serves to cut and pierce, and characterises many Waders 

 preying upon reptiles, flshes, and animals that offer some resist- 

 ance : such a beak is found in the Herons and Bitterns. As it 

 becomes more lengthened and attenuated it is adapted to prey of 

 a lower grade of life, and to 

 get at these it is endoAved 

 A\4th a specially sensitive 

 apex. In the Ibis and Cur- 

 lew such a beak is curved 

 down, fig. 3 : in the Jabiru, 

 fig. Of 5, it is bent up. Some 

 trenchant bills are so com- 

 pressed as to resemble the 

 blade of a knife ; these offer least resistance in the swift pursuit of 

 fishes, and are seen in the Awks, Puffins, and Coulternebs, in which 



Bill of the Jahiru. 



Bill of the Skimmer. 



latter the beak may be as deep as it is long. The Skimmer 



L 2 



