314 CHAPTERS ON THE NATURAL HISTORY 



Titmice often construct long, pendulous nests, and many swal- 

 lows and swifts attach their nests to the surfaces of various 

 kinds, the nests being really 1ml half a nest. As examples of this 

 we have our common Barn swallow and the Chimney swift. The 

 latter, however, uses only small twigs foe the purpose, and these 

 are made to adhere together by the aid of an adhesive secretion, 

 the product of two glands possessed by the bird that are in some 

 respects analogous to salivary glands. 



The nests of the Esculent swift (Collocalia esculenta), so exten- 

 sively used as an article of food in China, are somewhat of this 

 variety. Entire books have been written about the nidification 

 of this extraordinary species. Unique nests are likewise made 

 by the famous Hornero (Fiirnarhis rufus), or Oven bird; the 

 Water ousel (Oinclus), the Hammer-head (Scopus), and a perfect 

 host of others. Xests as made by hundreds of other birds, as, for 

 example, the birds of paradise and other East Indian forms too 

 numerous to mention, are as yet entirely unknown to science, nor 

 have oni- naturalists as much as even seen them. 



