Ixxx 
That this peculiar organization is connected with the vo- 
cal powers of this bird, I conceive there can be very little 
question ; it is with surprise I have read the remark of Meckel, 
that this bird has no voice. ‘Those who have frequently 
visited these birds in the Zoological Gardens, must have no- 
ticed the different sounds they emit; in fact, they have two 
distinct voices, just as they possess distinct organs; the most 
ordinary isa harsh, disagreeable, hissing voice, not unlike that 
of the common goose; this is frequently heard, as the bird 
follows visitors round the enclosure in expectation of food ; 
this voice I attribute to the structure, or organization of the 
_ superior glottis. The other, and more peculiar sound, is only 
occasionally emitted, probably because, while in a state of 
captivity, the ordinary excitements are not so frequently pre- 
sent; this resembles a low, hollow sound, not unlike that 
caused by gently striking a large drum, or moving an empty 
barrel; sometimes it is sharp, short, and sudden; at other 
times it is long and muffled, like the rolling of thunder, or of 
a smoothly-running distant carriage; sometimes it is soft, 
continued, and rather melodious; but at others it is disagre- 
ably interrupted by harsh and rough grunting sounds. ‘The 
animal only occasionally emits this voice; on visiting the 
Gardens, in hope of hearing it, I have been frequently disap- 
pointed; on other occasions, the birds have repeated it several 
times. ‘The care-taker informs me that in his morning visits 
to open the aviary and feed the birds, they frequently make 
this extraordinary noise, and which he compares to the sound 
of thunder. The ear detects this sound as proceeding from 
the upper part of the sternum, that is, from the position of the 
sac, and, while making it, the animal extends and alters the 
curve of the neck, and fills this tracheal bag ; there can be no 
doubt, therefore, that this voice is connected, in part, with 
the inferior glottis, or the two narrow bronchial openings, and, 
in part, if not essentially, with this peculiar appendix; there 
is nothing in the superior larynx, or in the inferior, alone, that 
