Family — XT I R U N D I N I D M . 
This is one of the best-defined families in the Order, and in consequence its 
nearest allies are quite problematical, and here Newton may be quoted : 
“ But altogether the family forms one of the most circumscribed and there- 
fore one of the most natural groups of Oscines, having no near allies ; for, 
though in outward appearance and in some habits the Swallows bear a con- 
siderable resemblance to Swifts, the latter belong to a very different Order, 
and are not Passerine birds at all, as their structure, both internal and external, 
proves. It has been sometimes stated that the Hirundinidce have their nearest 
relations in the Muscicapidce , but the assertion is very questionable, and 
the supposition that they are allied to the Ampelidce (Waxwings), though 
possibly better founded, has not as yet been confirmed by any anatomical 
investigation. An affinity to the Indian and Australian Artamus (the species 
of which genus are often known as Wood-Swallows, or Swallow-Shrikes) has 
also been suggested ; and it may turn out that this genus, with its neighbours, 
may be the direct and less modified descendants of a generalised type 
whence the Hirundinidce have diverged ; but at present it would seem as if 
the suggestion originated only in the similarity of certain habits, such as 
swift flight and the capacity of uninterruptedly taking and swallowing insect 
food on the wing.” 
There are four species and genera of Swallows in Australia, and while 
one is referred to the widespread and typical extra-limital genus the other 
three are endemic forms with their range limited to the Australian Region. 
These genera were named by Cabanis and by Gould more than fifty years ago 
and have more or less been in common usage since. It is noteworthy that 
generic separation has been continually allowed for single species in this 
family all over the world, and the fact that the species are so well distinguished 
as to allow such generic application indicates that the family is undoubtedly 
an ancient one, and that it is quite proper that it should be treated early in 
the description of the Passerine birds. It is unfortunate that we know so little 
of the anatomy of these small birds that we cannot select any features and 
definitely determine the status from such. 
When Sharpe and Wyatt monographed this group they admitted that 
the genera might almost be diagnosed by their nesting-habits and gave a 
key with this feature emphasised. It, however, is not constant, and they 
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