When pursued it frequently attempts to elude the sight by suddenly squatting down amongst the bushes, which have a grey foliage, to which the colour of its plumage closely assimilates. When hard pressed it possesses the same habit as the Common Rhea of raising the wings alternately and holding them up vertically; and also doubles suddenly like that species. Its speed is greater than that of the Common Rhea, but it is sooner exhausted. In running it carries its neck stretched forward almost horizontally, which makes it seem lower in stature than the allied species,--hence the vernacular name of "short Ostrich." It is found in flocks of from three or four to thirty or more individuals. It begins to lay at the end of July, that is a month before the _Rhea americana_. Several females lay in one nest, which is merely a slight depression lined with a little dry rubbish; as many as fifty eggs are sometimes found in one nest. A great many wasted or _huacho_ eggs, as they are called, are also found at a distance from the nest. I examined a number of eggs brought in by the hunters, and found them vary greatly in shape, size, and colour. The average size of the eggs was the same as those of the Common Rhea; in shape they were more or less elliptical, scarcely any two being precisely alike. The shell has a fine polish, and when newly laid the colour is deep rich green. They soon fade, however, and the side exposed to the sun first assumes a dull mottled green; then this colour fades to yellowish, and again to pale stone-blue, becoming at last almost white. The comparative age of each egg in the nest may be known by the colour of the shell. The male incubates and rears the young; and the procreant habits seem altogether like those of _Rhea americana_. The young are hatched with the legs feathered to the toes; these leg-feathers are not shed, but are gradually worn off as the bird grows old by continual friction against the stiff scrubby vegetation. In adults usually a few scattered feathers remain, often worn down to mere stumps; but the hunters told me that old birds are sometimes taken with the legs entirely feathered, and that these birds frequent plains where there is very little scrub. The plumage of the young is dusky grey, without white and black feathers. When a year old they acquire by moulting the mottled plumage of the adults, but do not attain their full size until the third year. APPENDIX. I. _List of the principal Authorities upon the Ornithology of the Argentine Republic referred to in the present Work._ AZARA, DON FELIX DE. Apuntamientos para la historia natural de los páxaros del Paragüay y Rio de la Plata. 3 vols. Madrid, 1802.