Avifauna of Centred America. 765 



Tracheoplionge and the Tyrannidse must be regarded as 

 descendants of a common stock, and probably came from 

 Africa. The balance of evidence is in favour of some pri- 

 mitive Eurylaemid ancestor, if only because the Eurylsemidse 

 show many striking evidences of affinity with the (lotingidse, 

 another family exclusively American. So far, it is true, 

 no Euryljemidse have been found in Africa; but there 

 is a possibility that Smitkornis, hitherto regarded as a 

 Flycatcher, may prove to belong to this primitive group. 

 Until comparatively recently the Pittidse were also regarded 

 as al)sent from Africa. 



As touching the Oscinine Passeres, it is to be remarked 

 that the evidence, on the whole, goes to prove that 

 they are an Old World group. This being so, then the 

 New World members of this group must have entered 

 the New World by two very different routes. The oldest 

 of these was by way of the ancient land-bridge between 

 West Africa and Brazil ; the other by way of North 

 America, crossing by way of the Behring Sea on the 

 one side and by way of Iceland and Greenland on the 

 other. As a matter of fact, these two latter routes are 

 being used to-day. 



On the whole, it will be found more expedient to analyze 

 the various families now under discussion seriatim, according 

 to the arrangement adopted in the late Dr. Bowdler Sharpens 

 ' Hand-list of Birds," than to endeavour to arrange them 

 according to their relation to Central America — as species 

 derived from North or South America, as the case 

 may be. 



Whether the Muscicapidse have any representatives in the 

 New World depends entirely upon the evidence which an 

 appeal to anatomy must furnish as to the position of the 

 genus Poliopti/a, numerous species of which range from 

 North America to Paraguay and Argentina. According to 

 some authorities, this genus is undoubtedly Muscicapine^ 

 but according to others it belongs to the Turdidse. A 

 decision on this point is important, since if it belongs to 

 the Flycatchers then its nearest ally is the African genus. 



