OF EASTERN PENNSYLVANIA. 211 



very low key, so as to be almost inaudible at a dis- 

 tance of twenty paces, and which may be re- 

 presented by tze 2 produced with considerable 



uniformity of sound. 



The eggs are slate-color, with a tinge of olive, 

 and marked with blotches of dark purplish-brown, 

 with penumbne of light purple surrounding the 

 darker spots. The average length is .86 of an 

 inch, and the average breadth .65. In shape they 

 vary from oblong-oval to nearly rounded forms. 



Family Vireonidae. Vireos and Greenlets. 



This family which was formerly united with the 

 Laniidtz which it resembles in the structure of the 

 bill, has structural peculiarities in the feet by which 

 it may be readily discriminated. The Greenlets 

 are peculiar to America, and embrace five or six 

 genera with nearly seventy recorded species, one- 

 sixth of them being probably not genuine. The 

 typical genus Vireo embraces thirty species, 

 specially characteristic of N. America, seven oc- 

 curring in the West Indies and Central America, 

 one being exclusively West Indian, and the rest 

 occupants of South and Central America. 



Vireo olivaceus, Vieill.' 



The Red-eyed Vireo is one of the most abundant 

 of our breeding species, in Eastern Pennsylvania. 

 It arrives generally during the last week of April, 

 but, occasionally, as late as the second week of 

 May. It is a bold and fearless creature, entering 



