GEOTHLYPIS. 523 



Smaller, and duller in color ; the whole belly and 

 sides buify whitish, the bright yellow being con- 

 fined to chin, throat, chest, breast, and under tail- 

 coverts; black mask bordered posteriorly by a 

 band (usually narrow) of light ash-gray ; length 

 4.40-5.65, wing 1.90-2.20 (2.04), tail 1.85-2.20 

 (2.04), exposed culmen .38-.42 (.40), tarsus .71- 

 .80 (.77). Nest on or near ground, supported be- 

 tween weed- or coarse sedge-stalks, deeply cup- 

 shaped, usually with a deep foundation of dried 

 leaves. Eggs .70 X -52, white, finely speckled on 

 laro-er end with dark brown and black, sometimes 

 with a few larger spots, or " pen-lines," or both. 

 Hah. Eastern United States (chiefly east of Alle- 

 ghanies ?), north to Canada and Nova Scotia ; in 

 winter, southern Atlantic (and Gulf?) States, Ba- 

 hamas, Greater Antilles, eastern Mexico, and Cen- 

 tral America, as far as Panama.... 681. G, trichas 

 (Linn.). Maryland YeUow-throat. 



Larger, and brighter-colored, the lower parts entirely 

 bright yellow except anal region and flanks ; black 

 mask bordered posteriorly by a band (usually 

 broad) of white or grayish white; yellow of 

 throat, etc., richer, and olive-green of posterior 

 upper parts more yellowish ; length 4.75-5.85, 

 wing 2.10-2.40 (2.24), tail 2.15-2.40 (2.24), ex- 

 posed culmen .40-.45 (.42), tarsus .75-.83 (.80). 

 Nest and eggs as in G. trichas, the latter averaging 

 about .67 X -53. Hab. Western United States, 

 east to Mississippi Valley (and Georgia ?) ; in 

 winter, more southern United States (chiefly west 

 of the Mississippi) and south through western and 

 central Mexico.... 681a. G. trichas occidentalis 

 Brewst. Western Yellow-throat.^ 



1 While there is no difficulty in distinguishing at a glance specimens from the region west of the Great 

 Plains from those obtained along the Atlantic coast, it is a very difficult matter to refer satisfactorily specimens 

 from the intermediate region. This arises from the fact that the latter are, as a rule, intermediate in character, 

 occasional examples being more like one extreme than the other, as the case may be. The majority of speci- 

 mens from the Mississippi Valley are more like occidentalis in the greater extent and richness of the yellow of 

 the lower parts, but more like trichas in the decided ashy tint bordering the black mask ; some, however, are not 

 distinguishable in the latter respect from typical occidentalis from Arizona and other far western localities. It 

 is very difficult in many cases to determine satisfactorily winter specimens, which necessarily include a large 

 proportion of young birds, and on this account the winter range of the two forms as given above will probably 

 require some modification. The measurements given above are in the case of trichas taken from 19 adults 

 from the Atlantic coast of the United States, and for occidentalis from 18 specimens all representing ](xcalities 

 west of the Great Plains. Measurements of 20 adults from the Mississippi Valley give the following results : 



