610 ON SOME NEW FORMS OF AMERICAN BIRDS. 
a concave. No bristles at base of paa ig rounded, rather shorter than the 
Tarsi longer than the middle s brown? on t peusile and arched. 
Rape ith yellowish ground dotted ae ‘ae aka spo ji 
This genus is one of those especially characterizing the West 
Indies, almost every island as far as known having its peculiar 
species, differing, it is true, in very slight characters, but always 
constant to the normal type. Cuba alone has so far furnished no 
representative of this genus, its place being supplied apparently 
by Cereba cyanea, distributed besides throughout the continental 
tropical regions. The specimens from St. Thomas I cannot dis- 
tinguish from those of Porto Rico, but this is, so far as the series 
before me indicates, the only case where one species occurs on 
two islands. All the West Indian species, nine or ten in number, 
agree in having the whole upper part nearly uniformly dusky or 
blackish ; the head and back being concolored, while of the three or 
four South American, all but one (C. luteola) have the back more 
olivaceous, the head much darker. Again, the West Indian spe- 
cies, with a single exception (C. bananivora), have both webs of 
lateral tail feathers broadly and about equally tipped with white ; 
while in all the South American this white is more restricted on 
the inner web, and on the outer reduced to a narrow border. C. 
Caboti from Cozumel, near eastern coast of Yucatan, exhibits the 
continental impress in possessing the character last mentioned. 
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 spe- 
cies 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, e excel- 
lent 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 Ameri- 
an species, where it exists, the posterior outline is nearly trans- 
- verse, and only running out a little along the outer web. 
