PERCHING-BIRDS. 115 
Section B. ACROMYODI. Sincinc-Birps (p. 107). 
Family I. ArRIcHORNITHID. ScRUB-BIRDS. 
Only two small Australian species of the genus Atrichornis (1801) 
are included in this family, peculiar among Passerine birds in having 
the clavicles (merry-thought) rudimentary. The wings are so small 
that the powers of flight are limited, and they live among the dwartf- 
ferns and dense thickets, where they are only to be detected by their 
loud note. 
Family IT. Hirunpinip#. Swatiows. 
This well-defined cosmopolitan family, formerly associated with the 
Swifts (Cypselide) on account of their similarity in general appearance 
and habit of hawking insects on the wing, are now recognised as 
belonging to the Passerine Birds. The long powerful wings, feebly 
developed feet, small flattened bill and wide gape are the most striking 
external features, possessed in common with the Swifts ; but the latter 
may always be distinguished by having 10 instead of 12 tail-feathers. 
The anatomical differences between the two families are many and 
striking. Many of the Swallows breed in colonies, and two or even 
three broods are reared in a season. About 116 species are recognised 
and divided into two subfamilies—the Hirundinine, including the true 
Swallows and Martins, and the Psalidoprocnine, or Rough-winged 
Swallows (1815), in which the outer margin of the first flight-feather is 
provided with hooked barbs. 
Of the former the Common Swallow (Hirundo rustica) (1808) is 
typical, and one of the most familiar and beloved of our summer-visitors. 
It ranges north in summer over Europe and Asia, extending beyond 
the Arctic Circle, and winters in South Africa and the Malay Peninsula. 
Many other species are equally migratory, and traverse immense 
distances on their periodical journeys. The Red-rumped Swallow 
(H. rufula) (1808 a) has been recorded from Kent as an accidental 
visitor. ‘Two other well-known visitors to the British Islands are the 
House-Martin (Chelidon urbica) (1802), which builds mud-nests under 
the eaves of houses and on the ledges of cliffs, and is easily recognised 
by its feathered toes; and the Sand-Martin (Cotile riparia) (1805), 
which excavates a tunnel in a bank terminating in a nesting-chamber. 
Both these birds lay pure white eggs, but those of the Swallow are 
spotted with reddish-brown and lavender-grey. 
Family III. Muscrcarips. Frycarcuers. 
This somewhat vaguely defined family includes a very large number 
of insect-eating species peculiar to the Old World, and may generally be 
12 
[Case 71.} 
[Case 71, ] 
