290 BRITISH BIRDS. 



Swallows; they have the same long pointed wings, the same tendency 

 to have a forked tail, and the same very small bill, combined with a very 

 wide gape. They differ from this group of birds in having ten primaries 

 instead of nine, and ten tail-feathers instead of twelve. The hind toe, 

 especially its claw, is proportionately smaller in the Swifts than in the 

 Swallows, and is often directed forward. 



There are about fifty species of Swifts, which are distributed throughout 

 the world except in the Arctic regions and in New Zealand. Two species 

 breed in Europe, one of which is a regular summer migrant to our islands ; 

 but the other can only be regarded as an accidental visitor, in which cate- 

 gory may also be included one of the Siberian species. 



The Swifts may be divided into two groups, the Cypselinse and the 

 Chseturinse. In the former the middle and outer toes have only three 

 phalanges, a character which is correlated with feathered tarsi ; in the 

 latter the middle toe has four and the outer toe five phalanges, a character 

 which is correlated with bare tarsi. 



Genus CYPSELUS. 



The Swifts were associated with the Swallows by Linnseus in his genus 

 Hirundo; but in 1777 his specific name for the Common Swift was raised 

 into a generic title for the Swifts by Scopoli (Intr. ad Hist. Nat. p. 483). 

 This name cannot be retained for the Swifts, Schaffer having, in 1756, 

 established a genus Apus for a group of Crustaceans. Although Linnseus 

 degraded this generic name to a specific one, later writers re-established 

 it; and not only was it in use between the years 1766 and 1777, but it is 

 still retained for the same group. In 1810 Wolf established the genus 

 Micropus to contain the Swifts ; but his name was equally unfortunate, 

 for it had already been used by Linnseus in 1767 (Syst. Nat. ii. p. 580) 

 for a genus of plants. In the following year, however, the Swifts were 



both iii spring and autumn. In this Family, the members of which are so entirely depen- 

 dent for their food on their powers of flight, the moult takes place very slowly. An 

 example of Cypselus affinis collected by Dr. Scully in Nepal on the 7th of June has appa- 

 rently only just commenced its autumn moult ; whilst two examples of C. apus from South 

 Africa, in the British Museum, appear to be nearly completing their moult the one shot on 

 the 14th of October, and the other on the 9th of December. The moulting of the wing- 

 feathers probably takes place as slowly as in the Birds of Prey, so that after the first 

 plumage it is impossible to obtain an example, especially in tropical climates, in which 

 the pale black of the new feathers has not become faded, by exposure to sunshine, to 

 a more or less rusty grey. 



