228 PatmMerR, Zhe Maryland Vellow-throat. hy 
males give, wings, 54-59; females, wings, 53-56.5. These and 
numerous others show that the size increases northwards, also 
the length of the outer primary. In Pennsylvania in the same 
latitude, different sized birds are found on opposite sides of the 
mountain divide, the larger, curiously enough, occurring at a gen- 
erally lower elevation on the western side. The cause is explained 
under migration. The females of all the forms are smaller than 
the males of its subspecies and, except in brachidactyla and occi- 
dentalis, have relatively stouter bills. 
The western bird, occidentalis, is a little larger than drachidactyla, 
but grayer in dorsal coloration with a broad white posterior edging 
of the facial black. The yellow of the throat is more intense and 
the black of the forehead is relatively narrower. Freshly molted 
adult birds are but slightly paler dorsally than eastern birds, but 
immature birds are fully as dark and as brown above as in similar 
aged eastern birds. The females in summer are as a rule less 
yellowish and paler than eastern birds. A few have decidedly 
yellow throats but it is far from the rule. The immature females 
are browner and duller above and beneath with a much browner 
tinge across the breast than in either ¢richas or brachidactyla. Asa 
rule the 4th primary is slightly the longest, but wearing in many 
cases soon makes the 3rd the longest, and sometimes the 3rd is 
the longest in immature birds. The wing formula is usually 
4—3-2-5-1—6—7-8 ; rarely the 6th is longer than the 1st, and some- 
times the sth is slightly longer than the 2nd ; wearing reduces the 
inner primaries so that the formula becomes 3~4—-2-5—6—1~—7-8 or 
3-4-2-5-1-6-7-8. 
Melanops differs from the other forms in havinga yellow border 
to the ashy crown band,’ an indication of the more tropical forms 
beldingt, flaviceps and flavovelata. The type is the only one that I 
have seen. It is in partially worn plumage, the yellow bordering 
the crown band being almost completely obscured by brown tips 
to the feathers. If the tail was unworn it would undoubtedly ex- 
ceed the wing in length. This bird differs from occidentalis by its 
shorter outer primaries, longer and larger tail and feet, and the 
‘All the ¢richas group have a trace of yellow back of the ear-coverts in many 
specimens, but in this form the yellow is well developed. 
