150 



green ; tail slaty blue tinged with green, the four central feathers 

 largely tipped with chestnut ; band across the rump sulphur-yellow ; 

 tbroat and cheeks white, blending into the light blue of the breast 

 and abdomen ; thighs rich chestnut ; under tail-coverts blood-red ; 

 feet greenish blue, with a lilac tinge on their under surface ; bill black, 

 with a mark of obscure brownish red at the base of the upper man- 

 dible, which, when viewed in front, much resembles the letter W, 

 this colour advancing for a short distance on each side of the culmen, 

 and extending down the sides of the base. 



Total length, 18 inches; bill, 3f ; wing, 7 ; tail, 1\ ; tarsi, If. 



Hub. Forest of Beza, on the eastern side of the Cordillera in 

 Ecuador, 



The following papers were read : — 



1. Note on the Variation of the Form of the Upper 

 Mandible in a Rapacious Bird. By Philip Lutley 

 Sclater. 



Mr. J. H. Gurney has called my attention to the great variation 

 in the form of the upper mandible of Urubitinga unicincta, as ob- 

 servable in the specimens now before the Society, which form part of 

 his collection. I have seen the same sort of thing in the case of 

 other Accipitres, but never carried to such an extent as in the pre- 

 sent instance. In one of these birds (fig. l)the lateral margins of 

 the upper mandible are strongly festooned, and project far down 



Fig. 1. Fig. 2. 



over the edges of the lower. In a second specimen (fig. 2) — appa- 

 rently of about the same age, both being in immature plumage — the 

 commissure is very nearly straight. In other examples there is 

 merely a slight festoon. As the formation of the edges of the upper 

 mandible is much in use as a generic character — rightly enough, I 

 believe, and not generally liable to lead to error — the present abnor- 

 mal variation seems worthy of notice. 



