Mr. 0. Salvin on the Genus Geothlypis. 151 



whole of the United States, passes southward in winter to some of 

 theWest-Tndia Islands, and even touches Bermuda on passage. It 

 spreads over Mexico and Guatemala, being extremely common 

 from autumn to spring in the latter country. It would appear 

 to occur but sparingly in Costa Rica, as Mr. Lawrence in his list 

 of the birds of that country has to quote an instance, recorded 

 by Cabanis, for its appearance there. We now trace it to Chi- 

 riqui ; and a single specimen lately received from there gives the 

 most southern point on record touched in the winter migration 

 of this species. 



The two grey-throated species of the northern continent are 

 also migrants. G. Philadelphia of the Eastern States never, to 

 my knowledge, occux's as a winter visitant at any point of Central 

 America north of Costa Rica*. There appears to be no re- 

 cord of its occurrence in winter in any of the West-India Islands ; 

 so that it must perform its migration at one flight from the 

 Southern States to Costa Rica, Veragua, and the U. S. of 

 Columbia, from all of which places we possess skins. 



Costa Rica, the most western of these places, lies nearly due 

 south of the peninsula of Florida, and is distant about twelve 

 hundred miles. I doubt, however, if G. Philadelphia flies in a due 

 southerly direction, as the trade- wind would almost inevitably 

 carry it to the westward, and hence to Yucatan ; and if to Yucatan, 

 we should find the species in Guatemala, which we do not. It 

 seems more probable that the birds start with a south-easterly 

 course and make someway to windward before being carried by the 

 trades to the South American coast. When arriving there their 

 course would be south-westerly; and thus we see how the promon- 

 tories of Yucatan and Honduras are missed, and the highlands 

 of Costa Rica are the first land touched. It is also worthy of 

 note that, if the birds travel at the usually computed rate of about 

 J 00 miles in three hours, the time occupied in the journey 

 would be 36 hours, or, if they start at night, two nights and 

 a day. It will also be seen that, both in the northward and 



* I have examined the specimens from Mexico called G. Philadelphia 

 by Sclater (Cat. Am. B. p. 27), and find that they really belong to G. 

 macgilUvrayi. The skins are in bad condition, and the eye-lids injured 

 and discoloured ; but 1 am satisfied that they belon<: to the western form. 



