the Structure of Hierococcyx ^'c. 603 



simplified ventral feather-tracts, would also possess a syrinx 

 arranged on the tracheo-bronchial plan. This, again, is exactly 

 the form of syrinx which that genus of Cuckoos does possess, 

 and the following is a more detailed description of it. The 

 syrinx of Hierococcyx varius is displayed in the annexed 

 illustrations (figs. 16, 17, p. 602). 



The last tracheal ring and the first three bronchial semi- 

 rings are very plainly to be distinguished from the preceding 

 tracheal rings and the succeeding bronchial semi-rings. They 

 are obvious and different from them on account of their red 

 colour. As will be gathered from this colour, the rings and 

 serai-rings in question are ossified. But so also, though 

 diff'ering in colour, are the tracheal rings which precede. 

 On the other hand, the bronchial semi-rings which follow 

 after the first three are soft and cartilaginous. The pessulus 

 of this syrinx is quite well developed. It marks by its origin 

 on both sides of the windpipe the last tracheal ring. The 

 three strong semi-rings which follow are thus plainly bronchial 

 in spite of their resemblance to split tracheal rings, and their 

 great difference from the soft cartilaginous bronchial rings 

 which immediately ensue. Or, to be probably more accurate, 

 they are really rings belonging to the tracheal section of the 

 windpipe which have taken on the characters of bronchial 

 semi-rings. This matter, however, will be referred to again 

 in considering other forms of syrinx in this family of l)irds. 

 Hierococcyx possesses the nsual pair of intrinsic syringeal 

 musc]es_, which are thin and not easy to see. These muscles 

 fan out at their insertion, which is on the third bronchial 

 semi-ring, of the three that are ossified, of course. 



I shall now proceed to compare the windpipe of Hierococcyx 

 with that of tlie closely related genus Cuculus. I gave in ray 

 earliest paper upon Cuckoo anatomy a brief account of the 

 syrinx of Cuculus cnnorus. I may supplement this by a more 

 detailed account of the syrinx of the Eastern Cuculus micro- 

 pterus, a specimen of which, presented to the Zoological 

 Society by Mr. E. W. Harper, of Calcutta, died in the 

 Society's Gardens last year. The syrinx of this bird presents 

 an interesting and significant departure in structure from 



