358 OX THE GENUS ORTHONYX. 



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. Orihonyx spinicauda, however, has a peculiarity 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 any- 

 where in the sub vertebral canal, but runs up superficially in company 

 with 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 Grarrod's " Psitta- 

 cidaB"t, save that in them the right carotid artery as well is present, 

 running as usual in the hypapophysial canal. 



P. Z. 8. 1882, I n Orthonyx ochrocephala the left carotid retains its normal situation, 

 p. 545. though the point of entrance into the canal is somewhat higher up than 

 is usual in other Passeres. 



Examination of my spirit-specimens of these two birds has convinced 

 me that the two forms are not really congeneric, the New-Zealand bird 

 (0. ochrocephala} differing from the Australian in its more slender bill, 

 less development of the nasal operculum, less spiny tail, and more slender 

 claws. The coloration of the two forms is quite unlike ; whilst internally 

 the skull and syrinx exhibit differences, slight in amount, but greater 

 than those usually found in birds of the same genus. Under these cir- 

 cumstances it seems that Clitonyx of Eeichenbach $ will be the correct 

 generic term for the New-Zealand birds, as Lesson's name Mohoua, 

 though of prior application , is not only barbarous but, what is more 

 important, liable to be confounded with Mohoa, also a genus of Passeres 

 from the Pacific Subregion. 



In the present unsatisfactory condition of the systematic grouping of 

 the Oscinine Passeres, it is impossible for me to point out clearly any 

 definite position either for Orthonyx or Clitonyx, though both forms 

 might, I apprehend, be safely placed in Mr. Sharpe's somewhat vaguely- 

 defined " Timeliida?." 



The determination of the not-intimate relation of Orthonyx to Clitonyx 

 is a point of some importance, from its bearing on the question of the 

 general relationships of the fauna of New Zealand to that of Australia, 



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

 t Coll. Papers, p. 255. 

 J Handb. Spec. Ornitb. p. 167 (1851). 

 Hist. Natur. Oiseaux, iii. p. 139 (1837). 



