160 PROFESSOR OWEN ON THE GENUS DINORNIS. 
to articulate with the two processes ; it supported an appendage, but does not join the 
sternum. The above-described vertebra is the seventh dorsal, or the last free vertebra 
that supports moveable ribs (Pl. XLVI. D 7). 
The sixth dorsal (tb. D6) is narrower and with a spine somewhat shorter than the 
seventh. The posterior hypapophyses are nearer together: the anterior one is more 
developed: the spine, besides being shorter, is more compressed ; but the diapophysis 
is longer, and the base of the neural arch is of greater fore-and-aft extent. The rib is 
stronger and longer ; it supported an appendage, but is equally free from junction with 
the sternum. At the under part of the base of the diapophysis is the large pneumatic 
opening. 
The fifth dorsal (ib. D 5) presents a corresponding decrease in transverse and vertical 
diameter, without any loss of fore-and-aft extent. The posterior hypapophyses have 
coalesced into a single process: the anterior hypapophysis is a strong ridge, with the 
fore part a little in advance of the anterior articular surface of the centrum. The 
shorter and more compressed spine has a somewhat greater fore-and-aft breadth than 
in the sixth vertebra: its height is not quite three inches. 
In the fourth vertebra (ib. D 4) the anterior and posterior hypapophyses have 
coalesced into a single ridge, with a tuberosity on each side of its fore part; the ridge 
appearing to be a downward continuation or termination of the sides of the compressed 
centrum. The diapophysis is thicker but shorter than in the foregoing vertebre: the 
spine, though shorter and somewhat thinner, has a greater fore-and-aft diameter ; it is 
truncate a-top, like the rest. 
The ribs of this and the succeeding vertebra, the fifth, are the largest; they each 
support a lamelliform appendage articulated to a well-marked surface at the back part, 
below the middle of the rib. The appendage is three inches in length and one in 
breadth; ascending obliquely and overlapping the succeeding rib, The sternal portion 
of the rib of the fourth dorsal joins the sternum. 
The third dorsal vertebra (2b. D3) much resembles the fourth; but with a slight 
diminution of size and a somewhat lower position of the parapophysis: this is asso- 
ciated witha rather longer and more bent-down neck of the rib. The sternal part of 
this rib joins the sternum. 
In the second dorsal vertebra (ib. D 2) the inferior ridge is divided by a notch into 
an anterior and posterior hypapophysis ; but the diminished size of the vertebra, the 
lower parapophysis, with a smaller articular surface for the rib, and shorter diapo- 
physis, distinguish it from a fifth dorsal. The spine is somewhat shorter, and inclines 
more forward than that of the third dorsal. 
In the first dorsal (1b. D 1), the hypapophysis is a ridge projecting from rather more 
than the anterior half of the centrum: the parapophysis has a smaller cup for the head 
of the rib than in the second dorsal: the diapophysis is proportionately diminished in 
size: the neural spine is smaller in every dimension, and slopes more forward. There 
