158 PROFESSOR OWEN ON THE GENUS DINORNIS. 
figures 34 and 39 of Mivart, which show the same aspect (hemal or ventral) of the 
vertebre compared. And here I may note that the processes seen in profile in 
Mivart’s figures 33 and 34 are indicated by the symbol ¢ in the sixteenth vertebra, and 
by the symbol fy in the seventeenth; similarly, they are described as ‘ catapophyses’ at 
p. 405, and ‘ hypapophyses’ at p. 406. I note them, under the latter denomination, in 
the thirteenth as in the fourteenth vertebra of Dinornis maximus, and the similarity is 
such between these vertebra that I proceed to the description of the fourteenth. 
In the fourteenth cervical (fig. 17) the more approximated hypapophyses, hy, arise 
from a low common prominence further back from the preaxial surface, and the lon- 
gitudinal channel in the lower surface, in the twelfth and thirteenth vertebra, is here 
somewhat interrupted by such prominence. ‘The transition of these into a single medial 
hypapophysis is thus indicated. The present vertebra in Dinornis maximus approaches 
the character of the seventeenth vertebra in the Ostrich, especially in the above 
modification of the heemal surface 2, to which view of the vertebra of Dinornis maximus, 
corresponding to the seventeenth of Struthio, I here restrict my illustrations of such 
vertebra. 
The processes (¢ in Mivart’s fig. 34, hy in his figure 39) are serial homotypes. The 
recognition of this fact led me to speak of Mivart’s ‘ catapophyses’ as “ parial hypa- 
pophyses” inthe Memoir on Cnemiornis (Trans. Zool. Soc. ix. p. 260), and again, under 
a sense of the convenience of a substantive term, as ‘ prehypapophyses’ (ib. ib.), in 
contradistinction with the ‘hypapophyses’ at the hind part of the centrum in the axis 
and third cervical. The antero-posterior extent of the pleurapophysial plate is 
shortened in the fourteenth vertebra of Dinornis, as in the seventeenth of Struthio ; but 
the pleurapophysis itself is less produced in Dinornis. The neural spines have not 
approximated and coalesced as*in Séruthio. ‘The section of the supporting column of 
the parial neural spines is transversely quadrate; both fore and hind surfaces are 
impressed by a definite rough tract for the elastic ligaments. The preaxial surface 
retains a greater relative breadth to the postaxial than in Struthio; the vertebrarterial 
canals are relatively wider. 
The next step in the transmutation of Mivart’s ‘catapophysis’ into the normally 
situated single hypapophysis in birds is presented by the fifteenth cervical of Dinornis 
maximus (figs. 18-21), which is the last of that series in the present skeleton. 
A single obtuse process descends from a low base coextensive nearly with the 
hemal surface of the centrum (fig. 19, hy) ; but the base of this process in one example 
is connected by a ridge continued from each side to the hind border of the pleur- 
apophysis (ib. p/), and there is a slight swelling (the final trace of the parial character) 
at the beginning of each ridge. A pair of low tuberosities, connected by a ridge, mark 
the hind border of the lower surface of the centrum. 
With the vertical extension of bone, hy, from this surface for muscular attachments, 
? Mivart, loc. cit. p. 406, figs, 35-39, ? Tb. ib. fig. 39. 
