154 PROFESSOR OWEN ON THE GENUS DINORNIS. 
The fourth cervical vertebra of Dinornis maximus (figs. 12, 13), representing, with 
increase of size, the proportional characteristics of the third, resembles that of the 
Ostrich in the greater production of the pleurapophysis, p/, and in the absence of the 
hypapophysis. 
The interzygapophysial plate, 7, not extending to the postzygapophysis, z, does not 
circumscribe the space forming the foramen, s, in figs. 8 & 11; and the pneumatic 
foramen (fig. 12, pn) comes into view. The zygapophysial articulations, z, z, become 
elongated; the posterior outlets of the vertebrarterial canals expand. 
There is little, if any, modification of the pre- or post-axial articular surfaces (ae, pe) 
of the centrum. ‘The hemal depression (fig. 13, ¢) behind the preaxial surface (ac) is 
deeper than in the third cervical; and the angle between this and the hind half of the 
centrum, c’, owing to the non-development of the hypapophysis, is more marked. The 
spine (fig. 12, ns) repeats its small basal extent and bifid character. 
The diapophysial plate (fig. 12, d) extends its origin from the outer side of the 
prezygapophysis, z, halfway towards that of the postzygapophysis, before it bends 
down to coalesce with the pleurapophysis, p/; the broad outer wall of the vertebrarterial 
canal (fig. 13, v) thus formed is the ‘pleurapophysial band’ of Mivart'. It sends 
forward from its lower anterior angle a short obtuse parapophysis (fig. 12, p). The 
riblet, p/, extends backward from the opposite or hinder angle. ‘The vertical hind 
border of the ‘band’ has two semilunar insertional impressions, the angle (fig. 12, a) 
between which is less produced than in Struthio. 
The pleurapophysial band has a relatively greater vertical extent than in Struthio; 
and this relates to the corresponding excess of vertical over longitudinal dimensions in 
the entire vertebra of Dinornis as compared with Struthio. 
In the direct under view (fig. 15) the pleurapophysis extends almost to the vertical 
level of the postzygapophysis, 2’ (compare with fig. 24, Mivart, Joc. cit.); a more 
marked difference from Struthio is in the bifid neural spine of Dinornis. There is no 
medial hypapophysial ridge in D. maximus. 
In D. elephantopus the fourth cervical has the hinder half of the lower surface of the 
centrum relatively wider than in fig. 13,¢; the prezygapophyses are less produced 
forward than in fig. 12, z. 
Glancing along the cervical region, in the articulated skeleton of Dinornis maximus, 
one sees, as in that of D. elephantopus, that the two (parial) neural spines continue to 
be developed throughout that series of vertebra, the uniting basal band subsiding some- 
what in the fifth cervical, and each spine being then represented by a ridge continued 
forward from the hyperapophysis, converging toward its fellow as it rises; but it 
attains no great height in any vertebra. In the fourteenth cervical, where the parial 
neural spines are most marked in this respect, the uniting base gains in vertical extent. 
» Loc. cit. p. 398. 
