FOR CAGES AND A VI ARIES. 143 



of oxygen, but also vitiated by the emanations drawn up 

 by the heat from the floor of the cage, and the carbonic 

 acid exhaled from the lungs of the bird itself ; at the same 

 time, it is very desirable to provide the Nightingale with a 

 curtain or screen over a portion of its dwelling, to the 

 shelter of which it will invariably be found to retire for 

 sleep when evening has set in, as well as when it feels 

 inclined to take a nap during the daytime. This it often 

 does after a full meal, particularly of mealworms— an 

 excellent dish, but one that takes some digesting; for which 

 reason blackbeetles are preferable, or gentles or bacon 

 beetles, when the latter can be obtained, though it would 

 be well worth the amateur's while to cultivate them for 

 the benefit of his pets. 



THE NIGHTJAR. 



This is an impossible cage bird, but it has the curious 

 habit of laying its two long narrow eggs on the bare ground, 

 and has occasionally been mistaken for the Cuckoo, a circum- 

 stance that has given rise to the fable that the latter bird 

 occasionally incubates her own eggs. This bird is also very 

 commonly called the Goat-sucker, and is much persecuted 

 by rustics, and some folk who ought to know better, under 

 the pretence that it robs the cows of their milk! 



THE NORFOLK PLOVER. See Thick-Knee. 



THE NUTCRACKER. 



Properly speaking, this is not a British bird, but a 

 chance visitor to our shores at long intervals ; that is 

 sufficient, however, to have secured him a place in Morris's 

 great work. He is a fine bird, over a foot in length and 

 fairly proportioned, of a blackish-brown colour, darker on 

 the lower than on the upper parts of the body, and 



