1882. ] ON THE ANATOMY OF PASSERINE BIRDS. 569 
tures in its dorsal wall, and give off branches to the outer face of 
the lung, representing the ectobronchial system of birds. The ori- 
fices with which the surfaces of all these canals, except the anterior 
half of the mesobronchium, are thickly set, lead into depressious, 
which are often so deep as to become cylindrical passages, simulating 
the parabronchia of birds. 
Thus, notwithstanding all the points of difference, there is a 
fundamental resemblance between the respiratory orgaus of Birds 
and those of Crocodiles, pointing to some common form (doubtless 
exemplified by some of the extinct Dinosauria), of which both are 
modifications. 
3. Contributions to the Anatomy of Passerine Birds.—Part 
VI. On Xenicus and Acanthisitta as types of a new 
Family (Xenicide) of Mesomyodian Passeres from New 
Zealand. By W. A. Forszs, B.A., Fellow of St. John’s 
College, Cambridge, Prosector to the Society. 
[Received June 19, 1882.] 
A few months ago I received, through the kindness of my friend 
Prof. Jeffrey Parker, of the University of Otago, New Zealand, a 
small collection of birds in spirit from that country, which included 
most of the “peculiar forms of Passeres found there. Amongst them 
were single specimens of Xenicus longipes and Acanthisitta chloris, 
the examination of which has proved to be of especial interest. 
The genus Xenicus was founded by the late Mr. G. R. Gray ? for 
the reception of the Motacilla longipes of Gmelin®, Lafresnaye 
having some twenty years previously established Acanthisitta for 
Sparrman’s Sitta chloris *. 
Subsequent ornithological writers have pretty unanimously assigned 
both these forms to the ‘‘Certhiide ” or their immediate neigh- 
bourhood, in company with Sitta, Sittella, and their allies. The 
peculiar structure of the tarsus in Xenicus first induced me to 
examine these birds more closely, with the unexpected result that I 
find that the two genera in question are true Mesomyodian forms, and 
therefore in no intimate degree related to such Oscines as those just 
mentioned. 
The subjoined drawings of the syrinx of Xenicus—with which in 
all points Acanthisitta appears to agree in every essential respect— 
will show that it has none of the complex nature of that organ in 
the Oscines, the thin lateral tracheal muscle terminating on the 
upper edge of a somewhat osseous box formed by the consolidation 
of the last few tracheal rings, and there being no other intrinsic 
’ For Part V. vide anted, p. 544. 3 Rey. Mag. Zool. 1842, Ois. pl. xxy 
? This, 1862, p. 218. 4 Mus. Oarls. fase. 2, no. ey 
38 
