ONTARIO. 



ciliary line ; below palest possible yellowish, whitening on throat and belly, 

 slightly olive-shaded on sides; sometimes a slight creamy or buffy shade 

 throughout the underparts ; no obvious wing bars ; no spurious quill. 

 Length, 4^-5^; wing, about 2 ; tail, about 2^ ; bill, hardly or about ; 

 tarsus, . 



HAB. Eastern North America, north to Hudson's Bay ; south, in winter, 

 to Costa Rica. 



The only record of the nest and eggs of this species I have 

 ever seen is published by Mr. E. R. T. Seton in the "Auk" for 

 July, 1885. He says : " On the gth of June, 1884, while camped 

 near Duck Mountain, I found a nest of this species. It was 

 hung from a forked twig, about 8 feet from the ground, in a 

 willow which was the reverse of dense, as it grew in the shade 

 of a poplar grove. The nest was pensile, as is usual with the 

 genus ; formed of fine grass and birch bark. The eggs were 4 

 in number, and presented no obvious difference from those of 

 the Red-eyed Vireo, but unfortunately they were destroyed by 

 an accident before they were measured." 



The owners were not secured. 



Very many of the more recent additions to the list of our 

 American birds have been made by the discovery that within 

 certain well-known groups were individuals differing in some 

 respects from the others. If these differences were found to be 

 uncertain and irregular they received only a passing notice, but 

 if they were found to be constant they were made the basis on 

 which to build a new species. 



Thus, although the American Vireos had passed in review 

 before many distinguished ornithologists, it was not until 1842 

 that John Cassin found one closely resembling several of the 

 others, and yet differing in some respects from all of them. 



In 1851 he published a description of the bird he had found, 

 pointed out its peculiarities, claimed for it specific distinction, 

 and named it after the city near which he first observed it. 

 For many succeeding years it was again lost sight of, most 

 likely because no one was looking for it, but as the number of 

 collectors increased and rare birds were sought after, the species 

 was again observed, and at far distant points, giving it an exten- 



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