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 Cypseline and the 
Cheeturine. In the former the middle and outer toes have only three 
phalanges, a character which is correlated with feathered tars ; 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 Linnzeus 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 Linneus 
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 Linnzeus in 1767 (Syst. Nat. 1. p. 580) 
for a genus of plants. In the following year, however, the Swifts were 
both in 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 afinis 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. 
