329 
Of the tracheal rings referred to Dinornis crassus some are preserved in groups, 
cemented in their consecutive arrangement upon and by the matrix. These groups 
include one of seven rings (fig. 4), two of six rings, one of five rings (fig. 5), two of four 
rings with part of a fifth (fig, 6), as many of three rings, and more of two rings so kept 
in natural sequence. In three instances of the “two rings” these show broader and 
narrower parts of the outer surface, alternating, the extremes being at the small ends 
of the ellipse, or at the sides of the tube. This character has been noted in recent 
birds, especially in the Waders', the appearance being that presented by the tracheal 
rings of the present extinct Moa (fig. 7, @,4,¢); but the analogy of Apteryx (anted, 
p- 526) led me to test the relation of the appearance to reality, 
Succeeding in working out the cementing matrix in one instance, and exposing the 
inner surfaces of the two interlocked rings, I found, as I had anticipated, that the outward 
appearance was due in some degree to intussusception, the inner surface being broader 
where the outer surface was narrower, and vice versd. Nevertheless a slight inequality 
of breadth is shown in some detached rings at the ends of the ellipse; and it may 
indicate that they come from a part of the windpipe situated where it was subject to 
most flexure in the bendings of the bird’s neck. 
§ 4. Laryna of Dinornis crassus? 
The portion of a thin, hollowed, shield-shaped piece of bone (Pl. XCIII. fig. 8, a, 4) 
I take to belong to the upper larynx, and to be part of the thyroid element. ‘To its 
lower border has coalesced, as is sometimes found in existing birds, the first tracheal 
bone or hoop (¢), which, as usual, is incomplete; the coalescence is limited to the two 
ends of this half ring; the slit of separation between it and the thyroid is 9 lines in 
extent, giving the breadth of this slender bone as half a line; it projects anteriorly 
like a folded lower border in advance of the actual lower border of the thyroid, which 
is the more prominent part on the inner or concave side of the thyroid, One might 
expect the rings near to or following this to have similar slender proportions, like those 
worked out of the matrix beneath the skull of Dinornis crassus; lower down the wind- 
pipe they gained in depth, 
From another mass of matrix, exhibiting a portion of a broad tracheal ring, 1 worked 
out the part of the expanded terminal one, to which, in the entire or recent state of the 
parts, the bronchi are attached; it answers to that supporting the cross bar shown at 
t, fig. 103, ‘ Anatomy of Vertebrates,’ vol. ii. p. 222, in the Raven, and ranks among the 
parts of the lower larynx. The specimen shows the contiguous portions of two cavities, 
meeting at a sharp straight ridge (fig. 9, a), 8 lines in extent, which was produced into 
the cavity of the trachea, dividing the tube from before backward; the concavities on 
i «They are alternately narrower at certain parts of their circumference and broader at others; and in these 
cases the rings are closely approximated, as it were interlocked. This structure is most common in the Gral- 
latores, where the rings are broadest alternately on the right and left sides,”—Anat. of Vertebrates, ti. p. 219. 
2q 
