86 THE BOOK OF MIGRATORY BIRDS 



it is found to be formed of no less than fifteen pieces, placed 

 like the staves of a cask, overlapping a little at the base or 

 narrow end, and seem as if capable of being enlarged or 

 contracted, perhaps by the muscular membrane in which 

 they are encased." 



In nocturnal birds it has been remarked by several 

 writers the eye, besides being comparatively very large, 

 is flat (comprirne) both before and behind, while the trans- 

 parent cornea is placed at the end of a sort of tube formed 

 by the bony portion of the sclerotic. The retina is conse- 

 quently comparatively very large and extended, and the 

 iris also ; while the membranes, being probably more soft 

 and delicate, are more susceptible of impressions from a 

 small quantity of light. The nictitating membrane is also 

 very large, and the upper eyelid, unlike other birds', is 

 moveable. 



I have adverted to the method of catching larks by means 

 of a looking-glass, referring to the remarkable curiosity 

 of birds as the probable cause of their being attracted to 

 the bright glass. Whether it is on a similar principle that 

 ravens, jays, and magpies (Corvidce), are fond of bright 

 objects we have no means of deciding. In accordance 

 with this view, a writer on natural history says: "A 

 looking-glass is a matter of great wonder to magpies. We 

 once saw one placed on the ground where two were 

 hopping about. One of them came up to it, stared at it 

 in apparent wonder, hopped off to the other, and then both 

 returned and spent at least ten minutes in nodding, 

 chattering, and hopping about the glass. " 



Colonel Montagu tells us he was ' 'assured by a gentle- 

 man of veracity that his butler, having missed a great 

 many silver spoons and other articles without being able 

 to detect the thief for some time, at last observed a tame 

 raven with one in his mouth, and watch'ed him to his 

 hiding-place, where he found more than a dozen." 



A similar story is told by a lady of a raven kept a few 

 years ago at Newhaven, in Sussex at an inn on the road 



