GENERAL AND INTRODUCTORY. 33 
commence from the outside area of a very considerable space, and gradually work 
in towards the centre. Examples of this species, were some years since successfully 
kept at the London Zoological Gardens, and exhibited there their characteristic nest- 
building habits, and deposited eggs, which were duly hatched. It was observed, under 
these artificial conditions, that the male bird paid considerable attention to the eggs 
when deposited, always maintaining a perpendicular, cylindrical opening in the centre 
of the nest-heap for the purposes of ventilation. The young birds, as soon as hatched, 
were for the first: twelve hours kept covered up in the material of the mound, but 
on the following day emerged with their wing-feathers well developed, but encased in 
membranous sheaths, which soon burst, leaving the limb completely free. On the 
third day the young birds were capable of strong flight. The relatively large size of 
the eggs, and the egress of the birds from them in a more highly advanced state of 
development than obtains with any other known species, is common to all of the 
members of this remarkable family, and is held to be a fact indicative of their 
remote ancestry. In the case of Megapodium, it has been observed that the mound- 
constructing instinct is so strongly ingrained by heredity, that young birds taken 
fresh from the nest, and confined under favourable conditions, have at once commenced 
to construct mounds after the characteristic manner of their tribe. 
The third member of the Megapodide or Mound-builders is the handsome bird 
Leipoa ocellata, known in South Australia as the Leipoa or Native Pheasant, and in 
Western Australia as the Gnow. This species has much the form of a pheasant, but 
in its shorter tail and ocellated markings more nearly resembles the Indian Tragopan, 
Ceriornis Lathami. The mound constructed by the Leipoa is relatively small, compared 
with that of the Talegalla and Megapodium, rarely exceeding eight or nine feet in 
diameter, and two or three feet in height. A larger quantity of sand and soil 
being, moreover, mixed with the vegetable substances, it acquires so much more solid 
a consistence that it may be readily mistaken for an ant-heap. For the table this 
species is esteemed more highly than the two preceding forms, the eggs also, of which 
about a dozen are deposited in a single nest, being greatly prized. 
One of the most essentially Australian bird groups is that of the Bower Birds, 
usually relegated by ornithologists to a position near the Starlings, and remarkable, as 
in the case of the Megapodide, for their architectural propensities. In this instance, 
however, the edifice raised is a supplementary structure in no way associated with the 
nidamental functions that characterise the mound of the Megapodide, for which 
purpose an ordinary nest is constructed. The Bower Birds, in point of fact, possess 
E 
