HIRUNDO. 169 
Subfamily HIRUNDININ&A, orn SWALLOWS. 
The Swallows are distinguished 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 scutellated 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. Hight species are found in the Western Palearctic Region, four 
of which are included in the British list. 
Genus HIRUNDO. 
The genus Hirundo was admitted by Linnzeus, in 1766, in the twelfth 
edition of his ‘Systema Nature,’ vol. i. p. 343. The Barn-Swallow, the 
species named first both by Linnzus 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. 
* In 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. 
