On the Night- Jar, 159 



The night-jar is provided with an extremely wide mouth, which 

 is beautifully constructed for taking its prey, which consists princi- 

 pally of the larger Bombycidse. I have taken sometimes seven or 

 eight moths, of the size of the yellow underwing, almost entire from 

 the stomach. So beautifully is the mouth adapted for the reception 

 of this kind of prey, that it opens like a trap, and presents a funnel- 

 like aperture to receive the insect that the bird makes a dash at. 

 The vibrissse in this bird are very strong, and can be depressed against 

 the side of the mouth, or erected at pleasure. Not only is the mouth 

 remarkably large, but the vibrissse are so directed when the mouth is 

 open, as to reflect any insect into it which might otherwise have been 

 missed by the bird in its attack. These vibrissas stand out on either 

 side of the mouth more than equal to half the width of the mouth 

 itself, by which means the bird is rendered more sure of the seizure 

 of its prey. 



The eye of the night-jar has a structure very similar to that of 

 eagles, hawks, and owls, and is, like the eyes of these, furnished with a 

 strong bony ring, which surrounds the cornea, and strengthens the scle- 

 rotic coat in that part, and renders it so unyielding, that a slight pressure 

 upon the sclerotic coat behind the ring causes the humours of the eye 

 to be forced into a degree of convexity which could not be attained 

 without this provision. By this beautiful yet simple contrivance the eye 

 can be adapted to distant or close vision, according to the increase or 

 decrease of convexity. The cornea has considerable dimensions, which 

 enables the eye to receive a great deal of light, by which means ob- 

 jects become distinctly seen, which would be otherwise invisible in a 

 paucity of light. The sketches 

 y and 8 represent two views of rJ 

 the eye of the Night-jarr : y is 

 the lateral view, and 8 is the 

 front of the same eye : a a re- 

 present the situation of the os- 

 seous ring. 



The middle toe of this bird 

 is provided with a singularly pec- 

 tinated claw, with the tooth-like 

 processes pointing, with a gentle 

 curve, inwards and backwards, 

 as the bird sits grasping its 



perch. It is a difficult thing to decide upon what use this can be 

 to the animal in its economy, for other birds, (the heron for in- 



