356 ON THE ANATOMY OF AN AUSTRALIAN DUCK. 



certain Bustards. This is the possession of a small, but distinct, subgular 

 P. Z. S. 1882, pouch, formed, as in the males of Otis tarda, by the duplicature of the 

 p. 4o7. frcenum linguce *. On opening the mouth, the tongue being forced up 

 against the roof of the mouth as is depicted in fig. 2, there is seen at its 

 base, some way behind the level of the basihyal, a small circular aperture, 

 about the size of a pea, lying between the two folds of the fr&num, the 

 left of which is much stronger and better developed than the right. 

 This aperture is the mouth of a small pouch, almost large enough to 

 receive the end of the little finger, which extends backwards for some 

 little distance to the base of the tongue, its breadth being nearly as great 

 as that of that organ. This pouch is lined by mucous membrane of 

 similar character to that found over the adjacent parts of the mouth ; its 

 anterior limit extends forwards as far as the posterior end of the curious 

 wattle attached to the lower jaw ; but there is no connexion between the 

 two, the wattle being merely formed by a fold of the. integuments, with 

 no cavity contained in it. 



The observations hitherto made on the habits of Biziura in its native 

 state fail to throw any light on the use or raison d'etre of this curious 

 structure, though, judging from analogy, it is nearly certain that it is in 

 some way connected with display during sexual excitement, and therefore 

 confined, as we know the wattle is, to the male sex. The first specimen 

 I examined had, I may remark, the pouch less developed than in the 

 second one, probably an older bird. It is not improbable that further 

 observations may show that, in thoroughly adult and breeding birds, this 

 pouch acquires much greater dimensions than was the case in these two 

 specimens. 



As regards other points, Biziura is in most of its features thoroughly 

 Anatine. The tongue is quite duck-like, though very broad. There is 

 a well-developed penis of the peculiar type found in other Anatiaaj. 

 The number of remiges is 28, of which ten are, as usual, primaries. The 

 pollex bears a small claw. There are 24 rectrices, a number not exceeded 

 in any of the Anseres, though found in certain Swans. All are peculiarly 

 stiff and curved, with flat lamellar rhachises. The caeca are long, measuring 

 6*75 and 7*75 inches respectively in the two specimens. The ambieus 

 muscle is large, and peculiar in that its tendon perforates the large-sized 

 triangular patella, just as it does in Phalacrocorax and the extinct Hes- 

 perornis. 



The carina sterni is shallow, as might have been expected in a bird 

 with such weak powers of flight as Biziura has. There is a minor 

 myological peculiarity in the hind limb of Biziura, such as I have not yet 

 observed in other Anserine birds. In all these the flexor longus Jiallucis 



* Murio, P. Z. S. 1869, p. 140; and Garrod, Coll. Papers, p. 245. 



