SWALLOWS. 507 



answer each other from various parts of the thickets. They have a variety of other 

 notes resembling those of the wrens, and correspond with them also in most of their 

 habits, hunting their insect prey in the vicinity of the ground or on low trees, often 

 holding their tails erect, and usually so shy that they can only be seen by patient 

 watching, when curiosity often brings them within a few' feet of a person; and, 

 as long as he sits quiet, they will fearlessly hop around him as if fascinated." 



The mocking-birds (MiMiD.E) are hardly entitled to family rank independent of 

 the Troglodytidae, from which they chiefly differ in having well-developed bristles at 

 the mouth, and in being on an average somewhat larger, though the smaller mocking- 

 birds are not so large as the largest wrens. Like all the birds of the present group 

 they are eminently American, and seem to have the centre of their distribution in 

 Central America, the West Indian Islands, and the southwestern United States. 

 The mocking-bird (Mimus polyylottus), the rival of the nightingale for the 'cham- 

 pionship of the world' as a songster, the cat-bird ( Galeoscoptes carolinensis), and 

 the brown thrasher (Harporliytichus riff its) are representative birds of this family, 

 and their song and habits too familiar to American readers to require further notice 

 in this connection. 



Whether the place here assigned to the Polioptilinae, or gnat-catchers, is correct 

 mar perhaps be questioned, but I think it safe to say that its position with the Mimidre 

 is more satisfactory than either with the Sylviidre, Parida?, or Mniotiltida?. Indeed, I 

 see little to separate them from the mocking-birds except the slightly more depressed 

 bill and the size, the gnat-catcher belonging to the smallest of passerine birds. Musci- 

 capine relationship has been suggested, but the form and position of the nostrils 

 opposes such a view, as does also the geographical distribution, Polioptila being 

 exclusively American, and the Muscicapidae exclusively Old World forms. However, 

 I may quote what Mr. R. B. Sharpe says about the question : 



"I believe that the most natural position for the genus will be in the vicinity of 

 the muscicapine genus /Stenostira, to which, both in form and style of coloration, 

 Polioptila bears a striking resemblance, as has already been pointed out by Bonaparte, 

 Sclater, and other ornithologists. Should this classification turn out to be correct, it 

 will afford another instance of the affinity of the avifauna of North America with 

 that of South Africa, as already noticed in the occurrence of Petrochelidon spilodera 

 at the Cape, a close ally of P, pyrrhonota [P. Innifrons] of North America." I may 

 here remark, that the swallow genus Petrochelidon is found both in South America, 

 Australia, India, and South Africa ; that the swallows are very uniform both in form 

 and coloration all over the' world ; that they are the fastest travelers of all passerine 

 birds ; consequently the similarity between the American and the African species is 

 not so extemely surprising. On the other hand, the true fly-catchers are very poly- 

 morphic, and the distribution of the gnat-catchers and the Stenostira so disconnected 

 that I prefer to regard the former as nearly related to their countrymen, the mocking- 

 birds, especially as character of structure or coloration seems to make such a view 

 untenable. The habits do not point either way, so far as I know. The gnat-catchers, 

 a little over a dozen species, belonging to one genus only, inhabit all parts of America 

 except the most southern and most northern portions. 



Contrary to the general run of passeroid families, that of the swallows, the HIRTJX- 

 DINID^E, is as well defined and isolated as any of the picarian families, at least exter- 

 nally. They are possessed of extremely long and pointed wings, with nine primaries ; 

 the feet are reduced very much in size ; the bill is short but extremely broad, and the 



