166 



On the Ornithology of Wilts. 



some crevice ; the little creeper can pick out his insect prey from 

 the bark. 



The fourth and last tribe of perchers again derives its name 

 " Fissirostres" (wide billed) from the formation of the beak. The 

 members of this division like the last are almost wholly insecti- 

 vorous ; but unlike them, they feed more or less on the wing ; 

 many of this tribe are remarkable for their wonderful power of 

 flight, soaring high in the air, skimming over the water, and 

 darting here and there the livelong day with the most rapid evolu- 

 tions imaginable. As they feed so much on the wing, we find 

 them provided with a very short beak, much depressed, as if flat- 

 tened downwards, and of a triangular form ; the tip sharp and 

 furnished with a slender notch ; but their width of gape is very 

 great, enabling them more readily to seize their prey, as they shoot 

 through the air, and the edges of the upper mandible are armed 

 with a row of bristles of immense assistance to them when feeding 

 on the wing, by increasing the means of capture with the mouth. 

 The swallows, the nightjars, and the bee-eaters, are examples of 

 this peculiarity, and of the absence of much beak, where so little is 

 required. 



We have now reached the third order, "Rasores," which live upon 

 grain and various kinds of seeds and berries. This forms their 

 principal food, though occasionally they will devour insects and 

 sometimes buds and green leaves ; and therefore we shall be pre- 

 pared to see, though not so strongly exemplified, the short, strong 

 bill adapted to the hard nature of their customary diet ; the upper 

 mandible is often considerably arched, the edges overhanging and 

 the tip blunt. Birds of this order, however, do not always possess 

 a bill capable of very great exertion: in some cases, as in the 

 pigeons, it is rather slender and weak ; in all the other families it 

 is stronger ; but yet perhaps taken alone it seems scarcely so well 

 adapted as the preceding ones to the grain-eating habits of the 

 bird; but if we push our inquiries farther, we shall find these 

 ground birds furnished with a peculiar repository for their food, 

 whither it is conveyed whole by the beak ; this repository is called 

 the crop, it is globular, and is nothing more than an enlargement 



