lower jaw in the males than in the females. The Doves are very difficult to sex where colour-characters are wanting, but the males usually, if not always, show a more prominent forehead than the females.
If there were no truth in these differences, it would be impossible for the aviculturist, when dealing with species in which the sexes showed no colour differences, to select pairs for breeding purposes. If we take the common Java Sparrow (Padda oryzivora) as an example, I may state that at various times I have picked out pairs repeatedly, both for myself and others, for breeding purposes, and hitherto have never been wrong in my selection; or, if we take the Crested Cardinal (Paroaria cucullata)—from five specimens which I purchased some years ago, I selected a pair, and placed them together in an aviary. Presently the cock began to sing and show off to the hen, a nest was built, and one or two eggs dropped on the floor, proving conclusively that my pairing had been correct.
It has been objected that, allowing the sexual differences in the beaks of birds to be reliable when the creatures are alive, so much shrinkage takes place after death, that the character of the beak is modified so as to be untrustworthy for comparison. This, however, is an error based upon supposition rather than experiment. The beak, being the horny sheath of a bony structure, changes its character very little; indeed, if it did it would hardly form a suitable basis for generic or specific diagnosis.
Touching the construction of nests by birds, a great deal of poetic nonsense has been written. Most nests are pleasing objects, and some are extremely artistic; but it is not true that the most elaborate nest is entirely beyond imitation by a skilled workman; indeed, I am satisfied that a Chinese artist would be able to fashion an excellent copy of the nest of a Long-tailed Tit (that most beautiful of English types) in a tithe of the time occupied by the birds. As for the cup-shaped nest, it is formed in the most rough-and-ready fashion, and its beauty is dependent largely upon the materials used in its construction. If you watch a Finch building in a bush, as I have frequently done in my aviaries, you will be astonished to discover how easily it is managed. The hen bird picks up a long piece of hay or a grass-
