THE HOUSE-MARTINS. 337 



Nest. This is described by Mr. Seebohm as a " very hand- 

 some little structure, almost entirely formed of green moss, with 

 here and there a few scraps of lichen, and a downy feather or 

 two. The inside is sparingly lined with fine dry grass and 

 hairs. The nest-cavity measured about two inches in dia- 

 meter, and one and a-half inch in depth." 



Egjs. From five to seven in number. They approach in 

 colour the eggs of the Robin and the Common Flycatcher, but 

 are not so heavily marked as those of the latter bird. The 

 ground-colour is greenish-white, with reddish spots and blotches, 

 sometimes collecting round the larger end. Others are nearly 

 uniform creamy-buff, clouded with obscure reddish mottling. 

 Axis, 0-65-07 inch; diam., o'55-o'6. 



THE SWALLOWS. FAMILY HIRUNDINID^E. 



These birds differ considerably from the other Passer if ormes, 

 and they possess a striking difference in their pterylosis, the 

 spinal feather tract being forked on the back. The primary- 

 quills are only nine in number, the tail-feathers twelve. The 

 bill is broad and flat, and the gape is very wide as with 

 Swifts and Goatsuckers, which, like the Swallows, catch their 

 food on the wing, The front of the tarsus is smooth, and the 

 hinder aspect is bilaminated longitudinally. Swallows are 

 found in nearly every portion of the globe, from very far north 

 to very far south. In the northern portion of their range they 

 are strictly migratory, and only come in summer, and, unlike 

 other Passerine birds, they moult only in their winter home, 

 and do not renew their plumage in the autumn before taking 

 their long journey southward. 



THE HOUSE-MARTINS. GENUS CIIELIDON. 

 Chelidoti) Boie, Isis, 1822, p. 550. 



Type, C. urbica (Linn.). 



The House-Martins are very easily recognisable by their 

 feathered feet and toes, and by the broad white band across 

 the rump, which is very conspicuous when the birds are flying. 

 There are five species of Chelidon, one, C. urbica^ being the 

 species which visits England ; a second, C. dasypus, represent- 

 ing it in Japan and the far east ; while the intermediate area 

 is occupied by the Siberian House- Martin, C. lagopus. Two 



