Unlike the Bee-eaters, these birds are very quarrelsome and unsociable, biting at any intruder, even of their own species, and quite incapable of living peaceably with any other kind. Their voice corresponds well with their German name of _Rake_, consisting of a loud, rattling repetition of "raker, raker, raker"--a cry occasionally exchanged for "rak, rak, jack." These birds live principally upon insects, all sorts of which they greedily devour; sometimes they will have no objection to a mouse, or a bird, a lizard, a frog, or any other small animal. It is a very common opinion that the Blue Roller can dispense with water altogether, that it neither drinks it nor uses it for a bath; and truly any one who has seen it, as we have done, in the midst of the arid plains in which it seems to be most at home, will scarcely feel inclined to doubt the possibility of the statement being well founded. The usual nesting-place of this Roller is in some hollow tree, and its nest is usually constructed of roots and straw, lined with hair and feathers; in the south of Europe it not unfrequently builds in rifts and chinks in old walls, or even excavates for itself a hole in the ground, much in the same way as the Bee-eaters. The brood consists of from four to six white and polished eggs. Both sexes co-operate in the work of incubation, and so assiduously do they maintain their post when sitting, that they may be sometimes caught with the hand while upon the nest. The young are fed upon insects and grubs. They soon learn to fly, but remain with their parents, and accompany them in their winter migrations. * * * * * The DOLLAR BIRDS (_Eurystomus_) are recognisable by their short, flat beak, which is broad at its sides, rounded at the culmen, and very decidedly hooked; the second wing-quill is the longest; the tail is either short and straight or slightly rounded; the structure of the foot and coloration of the plumage resemble that of the group above described. THE AUSTRALIAN DOLLAR BIRD. The AUSTRALIAN DOLLAR BIRD (_Eurystomus Australis_, or _Pacificus_) is of a deep brown on the head and neck, the rest of the mantle being sea-green; the region of the cheek is black; the feathers on the throat a bright green; the secondary quills, roots of the outer web of the primaries, and the outer web of the roots of the tail-feathers, are bright blue; and there is a blueish-white spot on the centre of the wing. The eye is dark brown; the eyelids, beak, and legs are red. The length of this species is ten inches; the wing measures six inches and three-quarters, and the tail three inches and a half. According to Gould, the Dollar Bird appears in New South Wales in the spring, and again retires north as soon as the young are fully grown. On dull days, or at early morning, and in the evening, it is to be seen most actively employed in pursuit of the beetles and other insects on which it subsists.