544 MR. W. A. FORBES ON THE GENUS ORTHONYX. [June 6, 



6. Contributions to tlie Anatomy of Passerine Birds. — Part 

 V.' On the Structure of the Genus Orthonyx. By W. 

 A. Forbes^ B.A., Prosector to the Society. 



[Received June 5, 1882.] 



The position in the series of Passeres of the genus Orthonyx has 

 for many years been a moot point with ornithologists, Johannes 

 Miiller having long ago^ surmised that these birds might be tracheo- 

 phones, and so connected with the Neotropical DendrocolaptidjB. 

 Some recent writers (e. g. (i. R. Gray, Bonaparte, and Salvadori) 

 have placed them in, or in the neighbourhood of, the Menuridae ; 

 Sundevall, on the other haud^, assigns them a position amongst his 

 Cichlomorphae Brevipennes. 



Up to the present time the formation of their soft parts, and par- 

 ticularly of the syrinx, has remained unknown — a deficiency in our 

 knowledge I am now able to supply by my dissection of both the 

 Australian and New-Zealand forms. For my specimens of the 

 former {Orthonyx spijiicauda) I am indebted to the kindness of Mr. 

 E. P. Ramsay, of the Australian Museum ; for a pair of the latter 

 (O. ochrocephala) to that of my friend Prof. Jeffery Parker, of the 

 University of Otago. 



Both forms are ^y/jiVa/ Singing-birds (" Oscines Normales"), with 

 a well-developed Oscinine syrinx with its normal complement ot'/oiir 

 pairs of muscles. Of these the short anterior muscle runs to the an- 

 terior end of the third bronchial semiring alone in O. spinicauda ; 

 whilst in O. ochrocephala this ring receives its muscular supply 

 from a fasciculus of the long anterior muscle. They thus differ 

 essentially from Menura, with which they have been associated, that 

 bird having but three pairs of muscles, peculiarly arranged ^. 



In this, as in all other points examined — with one exception in the 

 case of Orthonyx spinicauda — these birds quite resemble the normal 

 Passeres, as they do in having the bilaminate tarsus and reduced 

 "first" (tenth) primary nearly always associated with the normal 

 Acromyodian syrinx. Orthonyx spinicauda, however, has a pecu- 

 liarity quite unknown to me in any other bird, inasmuch as its 

 carotid artery, the left alone of these vessels (as in all Passeres) 

 being developed, is not contained anywhere in the subvertebral canal, 

 but runs up superficially in company ivith the left vagus nerve to 

 near the head, where it bifurcates in the usual manner. This is 

 just the same arrangement as that which occurs in many of the 

 Parrots — all those in fact included in Garrud's " Psittacidoe," ^ — save 

 tiiat in them the right carotid artery as well is present, running as 

 usual in the hypapophysial canal. 



' For Part, IV. see P. Z. S. 1881, p. 435. 



^ In 1848. Vide ' Vocal Organs of Passeres,' Garrod's edition, p. 36. 



3 ' Tentamen,' pp. 9 & 11. 



* GaiTod, Coll. Papers, pp. 362-364. 



' Coll. Papers, p. 2.>"). 



