The intrinsic muscles of the syrinx fixed to the ends of the bronchial semi-rings; the edges of the mandibles smooth ; the hinder part, of the tarsus longitudinally bilaminated, the laminae entire and smooth; the front of the tarsus scutellated; wing with nine visible primaries, the first and second subequal in length; secondary quills reaching about three-quarters the length of the wing; bill more or less conical; tail of twelve feat hers ; nostrils pierced close to the line of forehead and close to the culmen; rictal bristles few and short; sexes generally dissimilar; plumage of young various.
As already stated in reference to the Ploceidae, practically the only constant difference between that family and the present one consists in the latter having only nine visible primaries.
The Fringillidae contains a very large number of species of birds generally described as Finches, which have a strong family resemblance to one another.
The Finches have, as a rule, only one moult a year but their Summer and Winter plumage is often very different. This is owing to the effect of abrasion wearing off the margins of the feathers, which are in so many cases coloured differently to the rest of the feather.
The majority of the Finches are migratory but in many cases migratory birds are represented in some areas by local breeding residents, a fact which has rendered discrimination in geographical races very difficult and, even now, far more material is urgently required in the British Museum.
The Fringillidae may be divided into three fairly well-defined groups.
Upper mandible produced backwards behind the front line of the bony orbit; inferior outline of lower mandible straight or nearly so …………Coccothraustinae, p. 99.
Upper mandible not produced backwards behind the front line of orbit; inferior outline of lower mandible with a slight re-entering angle; cutting-edges of both mandibles everywhere in contact…………Fringillinae, p. 107.
Upper mandible not produced backwards behind front line of orbit; inferior line of lower mandible greatly angulate; cutting-edges of mandibles not everywhere in contact but leaving a gap of greater or less extent……………….Emberizinae, p. 195.