•I02 LlFE-HISTORlES OP BIRDS 



Two grades of fibres are readily identified, differ- 

 ing slightjy in color and texture; perhaps the pro- 

 ducts p{ Linum virginianum, and possibly of usi- 

 tatissimum which is occasionally spontaneous in 

 cultivated grounds. The interior is lined with the 

 woolly furze of Eriophorum virginicuvt, and that of 

 various ferns, which render the fabric both cozy 

 and comfortable. 



To build a nest is the work of three days. Ovipo- 

 sition follows close upon its completion. After 

 the full complement of eggs islaid, incubation im- 

 mediately fcmows, and continues during a period 

 of 1 1 days. This Warbler is famous for its de- 

 votion to its young and the anxiety which it mani- 

 fests evenwheij the nest is unoccupied; this latter 

 feeling frequently betraying its whereabouts. In 

 this latitude two broods are generally raised in a 

 season, although instances are known, where a 

 third has been successfully raised. The middle of 

 September is fixed upon as the date of their de- 

 parture for more genial climes. 



The eggs of this species are ordinarily five, and 

 occasionally six in . number. They have a light 

 green groundcolor, and are variously marked with 

 light purple, purplish-brown and lilac dots and 

 blotches. They vary in length from .61 to .70 of 

 an inch, and from .48 to .52 in breadth. 



De^tdrceca virens, Baird. 



The Black-throated Green Warbler is rather 

 abiindant in Eastern Pennsylvania during its ver- 



