1 
PROFESSOR OWEN ON THE GENUS DINORNIS. 38 
the mid line of the back part of the tube. The incomplete rings of the bronchi resume 
the dimensions of those at the beginning and middle of the trachea. 
In the Ostrich the bronchial rings are more slender than any of those of the trachea, 
and rapidly diminish in size as they approach the lungs. 
In both Ostrich and Cassowary the tracheal rings examined by me were gristly, or 
were hardened with a very small proportion of bone-earth. 
§ 7. Trachea of Dinornis crassus. 
The more completely ossified state of the tracheal rings of Dinornis has led to their 
preservation in more than one species; and I have received from time to time specimens 
of such rings more or less closely associated with parts of the skeleton, in largest 
numbers with that collection of Dimornis remains obtained by Mr. Walter Mantell 
from the fine dark soil, or morass, at Ruamoa, Middle Island of New Zealand, and pur- 
chased for the British Museum. 
In working out this matrix from the base of the skulls of Dinornis crassus, described 
in a former Memoir’, I detached from beneath the position of the palato-nares a group 
of four bony hoops or rings of an oval form, averaging 9 lines in long diameter, 7 lines 
in short diameter; the depth of the rim of the bony hoop varied from one line to half 
a line; its thickness was about a quarter of a line. The outside of the ring is convex 
and finely rugose; the inside is less convex and smooth. 
It is probable, though I cannot hold it as certain, that, because these slender rings 
were found at or near the position of the upper larynx, therefore they were from the 
beginning of the windpipe; for the dislocation of the parts of the skeleton in all the 
individuals so represented in the marshes of Ruamoa, as far as can be gathered from 
the account given by Mr. Mantell, might well admit of displacement of parts of the 
bony trachea. 
Admitting this doubt as to their precise position in the windpipe, still the proba- 
bility is so great that tracheal rings preserved in contact with parts of the skeleton were 
parts of the same bird, that the rings here described may be reasonably referred to the 
Dinornis crassus. 
There is, moreover, a significant degree of correspondence between the number of 
tracheal rings of the type of those attached to the skull, but collected without note of 
precise relations, probably scattered in the matrix, and the number of individuals of 
Dinornis crassus indicated by bones of the skeleton; that is to say, both tracheal rings 
and skeletons or bony evidences of J. crassus are amongst the most plentiful of the 
species there found. 
The rings or hoops, upwards of 150 in number, provisionally referred to Dinornis 
crassus, axe associated together by the character of shape and size. In general they are 
less slender than those cemented to the skull-base; but they present a certain range in 
' Part XIII., Trans. Zool. Soc. vol. vii. p. 129. 
