CYPSELIDA, ; 289 
Family CYPSELIDA, or SWIFTS *. 
The Swifts are a very well-defined group of birds, which most ornitholo- 
gists regard as being nearest related to the Humming-birds. Sclater and 
Gadow suppose them to be also closely allied to the Goatsuckers, but 
Forbes hesitated to confirm this opinion. There seems, however, to be 
many points in which they are closely allied to the Passerine birds. 
Huxley says that they essentially resemble the Swallows in the general 
form and arrangement of the bones which enter into the composition of 
their palates ; on the other hand, they do not possess the clefts on the 
posterior margin of the sternum which characterize the Passerine birds, 
the Goatsuckers, the Hoopoes, the Cuckoos, and many other families. In 
their pterylosis they also differ much from the Passerine birds, approach- 
ing nearest in this respect to the Goatsuckers ; but in their digestive organs 
they resemble very nearly the former family and differ widely from the 
latter. In their myology they are said to be nearest allied to the Owls, 
and not distantly so to the Birds of Prey. 
The Swifts moult twice in the year, in spring and autumn. Newton and 
Dresser do not allude to this subject; and Naumann states positively, 
both of the Common and Alpine Swifts, that, like the Swallows, they only 
moult once in the year, in their winter-quarters, shortly before they leave 
for their breeding-grounds +. 
In their external characters the Swifts very closely resemble the 
* The Swifts and the six families that follow them were formerly included among the 
Passeres ; further researches showed that they differed in many important respects from 
this group of birds, and for some time they were known by the ludicrous appellation of 
“ Non-Passerine Passeres.” Sclater associates them with several families, not represented 
in the British fauna, in an Order which he calls Picariz. Probably this is a natural 
group, but should include the Owls. It contains a number of birds which appear 
to be not very distantly allied to the Passeride, and may represent the least changed 
descendants of their common ancestors. 
y That this is not the case I have satisfied myself by a careful examination of a series 
of skins. Two examples in my collection of the Alpine Swift (one shot by Mr, Robson on 
the 3rd of August, 1875, near Constantinople, and the other on the 12th of April, 1878, by 
Captain Napier, in the valley of the Atreck river) are both moulting a quill-feather in 
each wing. This is also the case with an example of Macropteryx comatus collected by 
Wallace in Malacca in the autumn of 1854, The probability of a double moult is also 
confirmed by the appearance of many other examples which are very slightly abraded 
VOL. II. 
