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 (PI. XLVI. D 7). 



The sixth dorsal (ib. D 6) 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 vertebrae : 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 (ib. D 3) much resembles the fourth ; but with a slight 

 diminution of size and a somewhat lower position of the parapophysis : this is asso- 

 ciated with a 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 {ib. D 1), the h)'papophysis 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 



