HIRUNDO. 169 



Subfamily HIRUNDININ^, oe SWALLOWS. 



The Swallows are distinguislied by their long, pointed wings, slender, 

 wide bills, and small legs and feet. They have no bastard primary, and 

 the second primary is generally the longest. The tarsus is seutellated in 

 front, and the tail is generally forked. The most marked feature in the 

 Swallows is that they have no autumn moult, their new dress being assumed 

 in February*. 



In their distribution the Swallows are cosmopolitan. The number of 

 species and subspecies known is nearly a hundred, which have been by 

 some ornithologists divided and subdivided into more than five and twenty 

 genera. Eight species are found in the Western Palsearctic Region, foUr 

 of which are included in the British list. 



Genus HIEUNDO. 



The genus Hirundo was admitted by Linnseus, in 1766, in the twelfth 

 edition of his ' Systema Naturae,' vol. i. p. 343. The Barn-Swallow, the 

 species named first both by Linnaeus and Brisson, has been by common 

 consent accepted as the type. 



The chief characteristic of the species in this genus is said to be that 

 the nostrils are not only bordered behind and inside, but also overhung 

 internally by a membrane. Many species have the upper parts glossy 

 blue-black, but others are plain brown. The rictal bristles are almost 

 obsolete. 



This genus probably contains about sixty species, and is cosmopolitan in 

 its distribution. Only five species are found in Europe, three of which are 

 regular summer migrants to the British Islands. 



In tropical countries Swallows are generally resident, but are only 

 summer visitors to colder countries. They chiefly frequent the well-culti- 

 vated districis, and are especially fond of the neighbourhood of water. 



* Iq treating of the Shrikes, I remarked that the Woodchat, the Red-backed Shrike, 

 and the Lesser Grey Shrike appear to moult only in spring ; but I did not at the time 

 realize the significance of the fact. It appears to me that these birds, which have no 

 autumnal moult, must be comparatively recent importations from the southern hemisphere. 

 On their arrival in their new northern home they were compelled to change their time of 

 breeding with the changed seasons, but they have not yet altered the period of their annual 

 moult to correspond. 



