The Crow-Tits have undoubted close affinities with the Tits and through them with the Crows, but they form a very isolated group in some respects, all of them being restricted to the mountains and hills of Northern and Eastern India and some of the mountain-ranges of China.
The position of these birds has been much disputed, but looking to the facts that they have ten primaries, that the young are identical in plumage with the adult, and that the nostrils are completely hidden by stiff bristles, their location with the Crows and Tits seems the proper course to adopt.
The three species regarding the nidification of which anything is known construct cup-shaped nests in trees and lay eggs which are marked with yellowish brown and purple.
The plumage of all the species is copious and soft, and they have a very ample crest, not of great Length, but very thick. With one exception the bills of all the genera are extremely deep, the depth being greater than the Length of the bill. The culmen is very rounded transversely, and the margins of the mandibles in most of the species are curiously sinuated.
Their food, judging from what Mr. Gammie tells, us, is not grain and seeds but insects, and consequently there is nothing anomalous in their habits in this respect as was at one time thought to be the case.
Key to the Genera.
a. Tail longer than wing.
a1. Tail less graduated; the outermost pair of feathers fully three quarters Length of tail……………….CONOSTOMA, p. 60.
b1. Tail more graduated; the outermost pair of feathers not exceeding two thirds Length of tail.
a2. Height of bill greater than its Length; commissure with deep sigmoid curve……………….PARADOXORNIS, p. 61.
b2. Height of bill not greater than its Length; commissure with a slight sigmoid curve……………….SUTHORA, p. 63.
b. Tail equal to or shorter than wing……………….SCAEORHYNCHUS, p. 68.