HUMMING-BIRDS. 347 



and the most singular feature about the tree-swifts is their mode of nesting. 

 Nearly twenty years ago, Sir Hugh Low's native collector brought to him in 

 Labuan a tree-swift's nest, which he said he had found lying 

 under the bird's body when he shot it. The nest was of about The Tree Swifts, 

 the size of half-a-crown, and contained one white egg, which Sub-family 

 had been broken in the fall. From what we know now of Macroptery- 

 the nesting of the genus Macropteryx, it is evident that in gince. 



the above instance the shot must have carried away the top 

 of the stump on which the nest had been placed, as Mr. Hume has presented 

 to the British Museum a similar nest obtained by Mr. K. Thompson, who found 

 one in India. Mr. Hume says : "The stem to which the nest was attached is 

 about 0'8 inch in diameter ; against the side of this the nest is glued, so that 

 the upper margin of the nest is on a level with the upper surface of the 

 branch. The nest itself is half of a rather deep saucer, 175 inches in dia- 

 meter, and about 0'6 inch in depth internally. The nest is entirely composed 

 of thin flakes of bark, cemented together by the bird's saliva, and is about an 

 eighth of an inch in thickness." Only one white egg seems to be laid. 



The humming-birds are exclusively a New World group. The species de- 

 scribed up to the present time are nearly 500 in number, and among them 

 are found some of the tiniest birds in the world, some of 

 them not being larger than a bumble-bee. The bulk of the The Humming. 

 species are from South and Central America, a few only Birds. 

 reaching to the southern United States, and only a small Sub-order 

 number migrating north in summer to Canada, and even as Trochili. 

 far as Alaska. 



The plumage of the humming birds is usually of a brilliantly metallic 

 nature, and they are admitted to be some of the most beautiful and interesting 

 of all birds. Their classification is extremely difficult, for the characters 

 blend from one genus into another, until it is almost impossible to say where 

 the series should begin and where it should end. So much so is this the 

 case, that Mr. Osbert Salvin, when he wrote the sixteenth volume of the 

 British Museum " Catalogue of Birds," was forced, for want of more definite 

 characters, to divide the humming-birds into three sections, those with a well- 

 defined saw-like edge near the margin of the tip of the upper mandible, those 

 with this serration faintly marked, and those without any serration at all. 



It is impossible in the space at our disposal to pass in review all the genera 

 and species of humming-birds, for they are of every size, shape, and variety 

 of metallic plumage. The largest of all is the giant humming-bird (Patagona 

 giyas), from the Andes of Ecuador to Chili. This bird measures about 8^ 

 inches in length, whereas some of the smallest species, such as Calypte helence 

 of Cuba, and Chcetocercus bombus of Ecuador, only measure 2^ inches. 



The tongue in this order of birds is very peculiar, and its structure is only 

 equalled by that of the woodpeckers (Pici) and sun-birds (NectariniidcK). 

 The structure is thus described by Sir William Flower in the "Bird-Gallery" of 

 the British Museum : " The tongue is slender, and very long and extensile. 

 As in the woodpeckers, the two branches of the hyoid bone which support its 

 base, curve, when the tongue is drawn within the bill, upwards around the 

 back of the skull, and then forward over the top of the head. Instead of 

 the tongue being, as in the woodpeckers, solid and ending in a barbed horny 

 point, it is hollow, and divided at the free end into two slender branches, 

 each of which bears a thin membranous fringe on its outer margin." 



The wings of the humming-birds are strong, and the primaries are ten in 



