PBECHING BIRDS. 141 



billed birds. These have, as you see in Fig. 117, the head 

 of a Shrike or Butcher-bird, a notch or tooth near the 

 extremity of the upper bill or mandible. This is like the 



Fig. IIT Head of Shrike. 



noth seen in the upper mandiWe of birds of prey (§ 214) ; 

 and accordingly we find that those which have this notch 

 ■well developed are really birds of prey, living on small 

 birds and reptiles, as well as the insects and worms which 

 are the common food of all this group. The Shrikes, 

 Thrushes, and Warblers are examples of this division. 

 3. Tenuirostres [tenuis, thin, slender, and rostrum), slen- 

 der-billed birds. These slender bills are specially fitted 

 either for sucking up vegetable juices or for picking up 

 insects. The Humming-birds are the typical birds of 

 this group. 4. Fissirostres {fissura, a slit, and rosti~um), 

 gaping-billed birds. The bills or mandibles are very 

 broad and flat toward their base, and the slit or fissure 

 between them is carried far back under the eye. This 

 arrangement gives them, when the mandibles are moved 

 apart, a very broad and widely-opened mouth, as seen in 

 the Goatsucker, Fig. 118 (p.l42). This, you see, is strong- 

 ly in contrast with Fig. 116. The purpose of this conform- 

 ation is to allow these birds to take insects on the wing; 



