784 MR. W. A. FORBES ON THE [June 21, 



As compared with Strut/do and Apteryx, all the tracheal and 

 hronchial rings are much less firm and more cartilaginous in Casuarius, 

 as also in Dronixus. 



The membrana tymprtniformis completing the trachea below is a 

 simple membrane, passing continuously from one bronchus to the 

 other, with no intervening pessulus. 



Internally, a very slight thickening of this membrane in an antero- 

 posterior direction, at the bifurcation of the tube, may be seen ; but 

 there is nothing that can be properly called a membra?ia semilunaris 

 present. The external A'ocal cord, on the other hand, situated over 

 the first two bronchial semirings, is very well-developed, with a 

 sharply-defined margin. 



On the internal wall of the bronchus there is, in addition, a second, 

 much slighter and less prominent fold, slightly concave forwards, run- 

 ning somewhat obliquely backwards and downwards, and supported 

 by the anterior ends of the third and sixth bronchial semi-rings. 



Besides Casuarius galealus, I have examined trachest of GG. bec~ 

 carii, bennetti, uni-appendiculatus (2 specimens), and w^es^erwa/n'; and 

 in none of these species can I detect any difference of importance 

 from the arrangement I have described above. In the last-named 

 species (an adult specimen) there is a considerable amount of ossifica- 

 tion in the last tracheal and first bronchial rings. The mucous 

 fold on the internal walls of the bronchi varies much in develop- 

 ment in different specimens. In adults there is a great accumu- 

 lation of the fibrous and elastic tissures of the mucous membrane 

 in the region of the tracheal tympanum. 



Of Bromaus novce-hollandice I have only, as yet, been able to 

 examine one trachea, and that too from a young specimen. 

 This closely resembles that of Casuarius ; but the number of im- 

 perfect tracheal rings seems to be considerably smaller, in the 

 specimen in question only the last three being incomplete behind. 

 The third and fourth bronchial sem.irings are considerably stronger 

 than the first two and the immediately preceding tracheal rings. 

 There is no pessulus ; but the membrana semilunaris, especially pos- 

 teriorly, seems to be better developed. 



The insertion of the sterno-tracheales is as in Casuarius. The 

 lateral tracheal muscles extend down to within about I'o inch of the 

 end of the trachea. 



In the genus llhea (as represented by R. americana and R. ma- 

 crorhyncha) a very dififerent condition of things occurs, tliere being 

 a highly-specialized and peculiar syrinx, provided with a pair of in- 

 trinsic muscles '. 



' I had observed the peculiar syrinx of Ekea some months before I met with 

 M. Alix's short paper on this bird in the " Bulletin " of the Societ(S Philoma- 

 tique for 1874 (p. 38), in which he points out. for the first time, the fact that 

 llhca possesses a true syrinx. His account, which I here reproduce, runs as 

 follows : — " II y a ehez le Nandou un larynx inferieur. Les cordes Tocales sont 

 placees a I'origine des bronches, dont les premiers anneaux sont incomplet.s, en 

 sort que la parol interne qui leur coi-respond a I'aspect d'une membi'aue tym- 

 pauiloriue. Le reste des bronches e.st forrn^ par des anneaux complets." j?his 

 description is, as will be seen, very incomplete, and, in the last statement, in- 

 correct. 



