web, and on the outer reduced to a narrow border. C. caboti from Cozumel, near the eastern coast of Yucatan, exhibits the Continental impress in possessing the character last mentioned.
Certhiola flaveola.
In all the species from the Greater Antilles and the portion of Continental America west and directly south of this group, there is a distinct external white patch at base of quills; while this disappears in the species of the Lesser Antilles and eastern South America, or is only faintly traceable. Again, in the species of the Lesser Antilles, with the disappearance of the white wing-patch, the greater and middle wing-coverts show a faint edging of lighter, by which, as well as by the darker back, they are distinguished from their South American allies.
The shape of the white patch at base of the quills on the outer web furnishes, in combination with the color of the throat, excellent and permanent specific characters. This in the Jamaican, Haytien, and Bahaman forms is elongated, extending gradually and uniformly behind to the outer edge of the quill, while in those of Porto Rico, St. Thomas, Cozumel, and the South American species, where it exists, the posterior outline is nearly transverse, and only running out a little along outer web.
As a general rule South American species have shorter tails than the West Indian.
It is a nice question what are really species in this genus, and what merely races or varieties; but it would probably be not far from correct to assume that the various forms described are simply modifications of one primitive species, produced by geographical distribution and external physical conditions. In the following diagnosis I shall treat all the varieties as occupying the same rank, without attempting any discrimination. Although but one of these belongs to the United States, and that as a straggler from the Bahamas, I give the table of the whole, to show the interesting relationship between them.
Common Characters. Above dusky-olive or blackish; the rump olivaceous or yellowish; the head and cheeks always black, and sometimes darker than back. Chin and throat ashy or black. Rest of under part yellow, duller behind. A broad white stripe from bill above eye to nape. A white patch at base of primaries; generally visible externally, sometimes concealed. Lateral tail-feathers tipped with white. Bill black; legs dusky.
A. Head uniform in color with rest of upper parts; dark sooty-brown or blackish. Both webs of outer tail-feather tipped with white (except in luteola). All West Indian except luteola, which, however, occurs in Tobago and Trinidad, and generally belongs to the shores of the Carribean Sea.
1. A distinct and conspicuous external white patch at base of primaries. Wing-coverts not margined with paler.