VIREONID&. 3825 
restricted, is so slight, while those agreeing in one or other feature 
differ so much in the remaining points of structure, that it is almost 
impossible to group them satisfactorily, and we can only make a few 
arbitrary sections of no great sharpness of definition, to aid in 
identifying the species—one of them Vireo proper, with longer, 
more pointed wings; the other Vireonella (Baird), with the wings 
shorter and more rounded.* 
The following synopsis is intended to show the characters of the 
higher divisions of the group just referred to :— 
Virgosyty1a. Wings long and pointed, one-third or one-fourth longer than 
the nearly even or slightly rounded tail. First quill very small (less than 
one-third the second), sometimes apparently wanting. Second quill 
longer than the seventh, much longer than the secondaries. Tarsi short 
@ (scarcely exceeding .70 of an inch) ; toes rather long. 
Vireosylvia. Body slender and elongated. Bill slender, narrow, straight ; 
the culmen straight for its basal half, the commissure quite straight ; 
light horn color, paler beneath. Feet weak. Type V. olivaceus. 
Species V. olivacea, flavoviridis, campestris, barbatula, agilis, chivi, 
philadelphica, gilva, swainsoni, josephe. 
1 Allusion has already been made, on page 160 of the present work, to the 
possibility of detecting a rudimentary primary in nearly or quite all the 
Oscines which seem to have but nine. While the apparent presence or 
absence of this outer quill is sometimes useful in characterizing genera or even 
families, in Vireosylvia it is only of specific importance—the difference being 
merely one of development and position of the quill. In V. flavifrons, in 
which this outer primary is supposed to be wanting, its presence may easily 
be appreciated. One of the peculiar characters of this species consists in a 
narrow edging of white to all the primary quills, while the primary coverts 
(the small feathers covering their bases, as distinguished from what are usu- 
ally termed the wing coverts, which more properly belong to the forearm or 
secondaries) are without them. If these coverts are carefully pushed aside, 
two small feathers, considerably shorter than the others will be disclosed, one 
overlying the other, which (the subjacent one) springs from the base of the 
exposed portion of the long outermost primary, and lies immediately against 
the outer edge. This small subjacent feather is stiff, falcate, and edged with 
white like the other quills, and can be brought partly round on the inner 
edge of the large primary, when it will look like any spurious quill. The 
overlying feather is soft, and without light edge. 
In the other Vireos with appreciable spurious or short outer primary, a 
similar examination will reveal only one small feather at the outer side of the 
base of the exterior large primary. In all the families of Passeres where the 
existence of nine primaries is supposed to be characteristic, I have invariably 
found, as far as my examinations have extended, that there were two of the 
small feathers referred to, while in those of ten primaries but one could be 
detected. 
