( 401 ) 



species ^^i australis, A. Imnsfi, A. nireiti, and A. mantelli, between which he noted 

 certain differences which will be referred to presently. Owen observed of the 

 Apterijx that there was no lower larynx — by which, of conrse, he meant syrinx. As 

 Forbes remarked of this question of the alleged absence of a syrinx, it is difficult to 

 answer definitely in the case of many of the Ratite birds, because the nature of 

 a^syrinx has not been accurately defined. In any case I am able to add a somewhat 

 imi)ortaut fact to Forbes' description, which removes all doubt as to the truly 

 syringeal nature of the bifurcation of tlie trachea in Apteryx. 



As to the form of the syrinx itself, Mr. Forbes, who has figured back and front 

 views of that of A. mantelli, has pointed out some slight variations from species to 

 species. In A. mantelli and in ^4. kaasti the last tracheal ring is incomplete behind, 

 thongh complete in front ; on the other hand, in .4. australis and A. oweni the last 

 three tracheal rings are incomplete posteriorly. 



I find that Mr. Forbes is perfectly correct in this statement so far as concerns 

 three of the species which he mentions. 



In Mr. Rothschild's species, A. occidentalis, only the last tracheal ring was 

 split posteriorly ; but then, as I had only a single individual to e.xamine, it would be 

 rash to base or support a specitic difference on the fact. In this species both 

 the penultimate and antepenultimate ring are produced posteriorly in a triangular 

 fashion. In front the last three are thus produced. 



As Mr. Forbes showed, there is some modification of at least the last two tracheal 

 rings, and, though there is no pessulus, the membrana tympanifornis is well- 

 developed. There is therefore, so far, every essential of a properly developed syrinx, 

 save the pessulus and the intrinsic syringeal muscles. The latter I find to be 

 present and to be especially ])lainly developed in Apter>/x australis. There is a thin 

 band of muscle continuous above with the extrinsic muscle ; this passes down the 

 side of the trachea and gradually thins out into fibrous tissue, which seems to die 

 away upon the last tracheal ring, hardly reaching the bronchi. Its state, in fact, 

 is clearly one of degeneration, and very much on a par with the state of the 

 corresponding muscle in the Hoatzin {OpistJiocomus). In A. mantelli the same 

 muscle was visible ; but it did not seem to me to be anything like so well developed 

 as it is in the species just referred to. 



In neither A. haasti nor ^4. oweni could I observe the presence of this muscle 

 at all. I looked for it, moreover, in a fresh ^4. haasti which died in the Zoological 

 Society's Gardens early in March. It is perhaps noteworthy, in connection with the 

 better develo})ment of the intrinsic syringeal muscles in .1. australis, that the lower 

 end of the trachea in this species is a more consolidated structure than it is in the 

 other Apteryges. In the meantime it is clear that Apte.ryx, like Rhea (and these 

 are the only Struthiones which are so characterised), possesses a pair of intrinsic 

 syringeal muscles, but that these are much more on the wane in Apteryx than 

 in Rhea. 



5. THE SPECIES OF APTERYX. 



I shall now attempt to deduce from the foregoing facts the characters of the 

 several species of Apteryx. 



Apteryx oweni perhajis differs more from the rest than they do among them- 

 selves : it is to be distinguished by its smaller size, the characters of its plumage, 

 the three open rings of the trachea below, and the great length of the prepubic 

 process, besides possibly a number of niiunr points. 



