2. _Mules between the Canary and the Siskin._--If the mother be a green canary, the mules will resemble a female siskin; but, if she is white or yellow, their colours are lighter, yet without differing greatly from those of the siskin, which they always resemble in shape.
3. _Mules between a Canary and a Green-bird, or a Citril Finch._--If the hen canary is neither white nor yellow, the mules differ little from the common grey or green canary, except in being more slender, and having the beak shorter and thicker.
4. _Mules between a Canary and a Linnet_ will be speckled if the mother is white or yellow, but if she is grey they will be like her, except that the tail will be longer.
The other mules are rarer, because more difficult to obtain, as we shall see elsewhere.
HABITATION.--Except in the breeding season the male canaries are kept alone in separate cages, which, whatever the shape, ought not to be less than eight inches in diameter and a foot in height, with two sticks placed across for the bird to perch on. The females may be allowed to range the room with one wing clipped, or, what is better, kept in large cages, where, from having plenty of exercise, their health and strength are better preserved. In the small cages, glass vases should be placed on the outside, at the extremities of the lower stick, to hold the food and water. These may be surmounted with a cap of tin, or something of the kind, to prevent the seed from being so easily scattered. It is for this reason that the large seed drawers in an aviary are covered with iron wire-work, leaving only sufficient spaces for the heads of the birds to pass through. Cleanliness being a great preservative against most of their disorders, the bottom of the cage should be made to draw out, that it may the easier be cleaned and covered with sand. This should be done every day, or at least several times a week. These tender birds, being natives of a warm climate, and becoming more delicate instead of hardier from being kept in the house, require a temperature analogous to that of their native climate. They must be protected from the cold, and never allowed to remain in winter in a cold room, which would occasion many diseases, or even death. But, in summer, it is proper to place them in the open air, and they enjoy it very much. Never do they sing so gaily as on fine days, and their cages should therefore be placed at the open window, that they may have the advantage of the light and heat of the sun, which is particularly serviceable to them whilst bathing.