104 
CUCKOO FALCON. 
A viceda cuculoides, Swains. 
PLATE I. 
Above cinereous, with the back and scapulars brown ; the 
throat and breast pale cinereous ; body whitish, crossed by 
broad brown bars ; vent and under tail-covers fulvous, im- 
maculate ; tail even, cinereous, with a broad terminal bar. 
The true Falcons are well known to have hut a single 
tooth in the upper mandible of their hill, which, 
■with their long and pointed wings, readily distin- 
guishes them from all others. There is, however, 
in tropical America, another race, forming the genus 
Harpagus, which is characterised by the upper 
mandible having two distinct teeth, like projections 
on each side, and possessing shorter and more 
rounded wings : these two groups follow each other 
in the natural series, for they are connected by the 
Harpagus coirulescens, one of those aberrant species 
which is essential to every natural group or sub- 
genus, in order to unite it with that which follows. 
These being the two most typical genera, we next 
have the crested form, after which, as we conjecture, 
comes the beautifulFalcon here describedand figured, 
we believe, for the first time. It is such a perfect 
