570 ON THE ANATOMY OF PASSERINE BIRDS. [June 20, 
syringeal muscle whatsoever. The box has a well-developed antero- 
posterior pessular piece. The bronchial rings are throughout of 
quite simple form, and are separated by but narrow intervals. 
None are modified in form to serve for the insertion of a vocal 
muscle, as the latter terminates higher up, as already described, on 
the tracheal box, and therefore quite out of the region of the 
bronchi. 
The lateral position of the single syringeal muscle is that charac- 
teristic of all the Mesomyodian Passeres, though in most of these it 
terminates on one of the bronchial rings, and not, as in the birds 
under consideration, on the sides of the trachea. This may easily 
be seen by comparing the accompanying figures of Xenicus with the 
Syrinx of Xenicus longipes, much enlarged. 
A. From in front. B. From behind. 
m. Lateral tracheal muscle. 
beautiful series given by Johannes Miiller of the syrinx of many of the 
Neotropical Mesomyodi ', with those of Garrod of Pifta*, or my own 
of Eurylemus, Cymbirhynchus’, and Philepitta*. In fact it resembles 
rather that of Todus, as lately described and figured by myself >®. 
Externally the non-oscine nature of Xenicus and Acanthisitta is at 
once proclaimed by the structure of their wings, which have a “ first ’® 
(tenth) primary nearly as long as the preceding one, and by the 
non-bilaminate tarsus. The latter is covered almost completely by a 
single large scute, with only some very obsolete traces of transverse 
division below, whilst behind its edges are contiguous for the 
greater length of the tarsus, leaving only;small areas at each end of 
that bone, which are covered by very small scutelize of irregular 
form. The digits are slender and compressed, the foot being slightly 
syndactyle by the union of the fourth toe to the third for the 
greater part of its two most basal joints. The tail is short and 
weak; and there are only ten rectrices in each of my specimens. As 
there is no evidence of a pair more having been present, this number 
! Vocal Organs of Passeres: Garrod’s ed., Oxford, 1878. 
2 Coll. Papers, pl. xxvi. 
5 P.Z.8. 1880, pp. 384, 385. 4 L.c. p. 389. 5 Anted, p. 444. 
§ Sundevall is in error in assigning to these birds only nine remiges (‘Ten- 
tamen, p. 47). 
