1896.] NATURAL SCIENCES OF PHILADELPHIA. 157 



more buff and olive-yellow beneath than the nuptial dress. No 

 young birds in the first molt have been examined. 



Vireo flavifrons Vieill. Yellow-throated Yireo. 

 Vireo solitarius (Wils.). Solitary Vireo. 



These two birds seem to correspond exactly in the condition of 

 their plumages. The tertials of some individuals show so little 

 abrasion and have the light edgings so perfect that it seems as if 

 they must be renewed in the spring. A young V. flavifrons in the 

 first molt, is renewing only the body plumage. 

 Vireo noveboracensis (Gmel.). White-eyed Vireo. 



A young bird in first molt is renewing its tail exactly as in V. 

 olivaceus. Spring specimens show more abrasion than any of the 

 other Vireos, and the edge of the tertials are very much worn, in 

 striking contrast to the last two species. 



Family MNIOTILTID^. 



A more or less complete spring molt of the body plumage seems 

 to be the rule in the Warblers but as is usually the case with spring 

 molts we have a very unsatisfactory series of specimens available 

 for study, and are thrown back largely upon a comparison of spring 

 and autumn material. Species of which I have actually seen speci- 

 mens in the process of molting in spring are Dendroica blackburnice, 

 D. discolor, D. castanea, D. palmarum, D. tigrina, D. eoronata, and 

 Geothlypis trichas. The question of course arisesas to the extent of this 

 molt after the first year. The young of most Warblers in the first 

 autumn differ materially from the adults, and an extensive molt is 

 necessary in the following spring, but upon once gaining the adult 

 plumage they do not change their appearance materially at the next 

 annual molt and, therefore, a complete spring molt in subsequent 

 years is not necessary. Some species, however, change regularly, 

 twice a year. Probably nearly all Warblers have some spring molt, 

 but in many it is restricted to the head and breast after the first 

 season. Regarding the relation of their seasonal plumages, the spe- 

 cies may be grouped as follows : 



1. Adult male at all seasons and young of the year practically alike, 

 Seiurus, Helmitherus, Sylvania mitrata (winter plumage with 

 light tips on black parts). 



2. Winter and nuptial dress of adult male different : Mniotilta 

 varia, Dendroica pensylvanica, D. maculosa, D. striata, D. castanea, 

 D. hlackhurni(E. 



