PROFESSOR OWEN ON CNEMIORNIS. 261 
Besides size, the chief difference is in the greater relative breadth of the entire 
vertebra, and more especially of the neural arch (as shown in fig. 3, pl. 63. tom. cit.). 
This breadth is due in the anterior fourth of the cervical region to a diapophysial ridge 
extending from the side of the pre- to that of the postzygapophysis, near which the 
ridge (ib. fig. 1, z) stands out furthest, and has its margin thickened and roughened for 
tendinous attachment. In the middle third of the cervical region the diapophysis 
loses in antero-posterior extent of origin, but gains in length, or outstanding, and in 
greater thickness of its free border for muscular attachment. The eighth cervical, for 
example, is here 23 inches in breadth. The outer surface of the base of the anchylosed 
cervical rib is strongly sculptured by irregular longitudinal ridges and furrows. 
No Anserine comes near to Cnemiornis in this respect. Its cervical vertebre recall 
the proportions of those in Megaceros, and have a like relation to the muscular powers 
brought to bear upon the head. In the extinct Anserine this probably related to the 
gripe and tug exercised by the broad, short, but strong beak upon the vegetable growths 
torn up for food. 
The third cervical (ib. fig. 1), like the fourth, is broader than it is long. The hyp- 
apophysis is represented by a sharp ridge, 8 lines in length, at the hinder half of the 
centrum, terminating in a short tuberosity (ib. hy) projecting beyond the hinder 
articular facet. The parapophysial plate extends from the lower angle of the anterior 
articular surface of the centrum to the hinder half of that element, ascending upon its 
side, and forming the floor (ib. p) of a vertebrarterial canal, 10 lines in length, and 
8 lines in diameter at the hinder outlet (vy). The end of the rib-element (ib. p/) 
forming the outer wall of the canal is broken off. In the fourth cervical the neural 
spine is entire; it is also short and rounded, as in the third (fig. 1, 2s); and more of 
the pleurapophysis is preserved. ‘The hypapophysis has its base shortened to an extent 
of 5 lines; but its apex extends downwards, 3 lines below the hinder articular facet 
(h, fig. 2, pl. 63, tom. cit.). 
The side view of the twelfth cervical vertebra (ib. fig. 6) shows the division of the 
hinder part of the vertebrarterial canal into two foramina (ib. v, v') by the bony bar 
passing from the pleurapophysial plate backward and downward to the lower part 
of the side of the centrum. In Cereopsis (ib. fig. 9) and Tachyeres (ib. fig. 10) the 
vertebrarterial canal of the answerable vertebra has also two hinder outlets (v & v'); but 
the dividing bar passes from the hind border of the rib-plate upward to coalesce with 
the neural arch, and the upper outlet (v') is much less than the lower one (v). The 
diapophysis (ib. fig. 6, d) projects freely, in Cnemiornis, above the longitudinal ridges : 
these alone mark the rib-prominence below the prezygapophysis in Cereopsis (ib.fig. 9) 
and Tachyeres (ib. fig. 10). 
The vertebrz bearing freely-movable ribs are nine in number in Cnemiornis, of which 
the last three are anchylosed with the sacral mass. The rib of the first dorsal is free at 
the distal end; the centrum has a hypapophysial tuberosity at its fore part, the size of 
VoL. 1xX.—Part 1. May, 1875. 2N 
