BLUE-BILLED NUT-CRACKER. ] 65 
strengthens this belief. It is also one of the most 
natural characters of Tenuirostral types that the 
sexes vary ; witness the whole family of humming- 
birds, and that of the fruit-eaters ( Ampelidce J, and 
we may therefore expect to find the same in the 
Tenuirostral genus of the hard-bills. 
The form of the wings and hill differ from all in 
this group. The former are yery short, and more 
rounded than in Dertroides. The first quill is not 
spurious, but formed like the second, which is only 
half as long again ; the third quill resembles the 
second of Dertroides, that is to say, it is slightly 
shorter than the fourth, which is nearly as long as 
any of the others ; the tertials are not lengthened ; 
the end of the wings reach only to the base of the 
tail, which is rounded, having the feathers broad 
and soft. The feet are much like those of Der- 
troides, hut the inner toe is shorter than the outer ; 
while the nostrils are behind the basal edge of the 
hill, and hid by the frontal feathers. The bill is 
lengthened-conic ; the culmen slightly curved, al- 
though the gonys is straight ; the upper mandible is 
thickest, and the commissure sinuated, as in Der- 
troides and the ordinary weavers ( Ploceus )■ 
The colouring is simple, — that of the hill is very 
peculiar in some lights; at a distance it appears 
almost black ; when viewed more closely, however, 
it becomes of the darkest indigo-blue, hut with 
reflections of a much lighter colour, nearly resem- 
bling ultramarine, the tips being rich orange. If 
that which we conjecture he the male sex, the upper 
