320 PROF. ST. GEORGE MIVART ON THE 
lateral position, and sometimes in the smaller size, of the postcatapophysial subcentral 
foramen of each side (fig. 8, f). 
Metapophyses and hyperapophyses are rather more marked; the prezygapophyses 
look rather more preaxiad ; and the postzygapophyses look slightly more externad. 
The postaxial part of the centrum extends more ventrad than in the fifth vertebra, 
so that, when laterally viewed, the vertebra appears bent ventrad postaxially. 
The SEVENTH VERTEBRA about equals the sixth in size. Unlike that of Struthio, it 
does not differ from its serial predecessor as to the preaxiad development of the prezy- 
gapophyses, since these extend preaxially beyond the centrum and parapophyses as 
much as they do in the sixth vertebra, and the postzygapophyses project postaxially 
beyond the centrum much more than in the sixth vertebra. It also differs from the 
seventh vertebra of Dromeus, as well as from that of Struthio, in that the rib-like 
process is very much shorter, and the lateral vertebral canal is much less capacious—dif- 
ferences which all obtain in the preceding vertebre (Plate LV. figs. 9-12). 
The postaxial ends of the lamine bounding the antero-posterior subcentral groove 
are more or less marked as processes. 
Compared with the sixth vertebra, the seventh one has a rather more prominent 
neural spine ; and this is confined to the antero-posterior middle third of the neural arch. 
It has also more marked catapophyses and a deeper subcentral groove. The postzyga- 
pophyses are longer and look more externad. ‘The hyperapophyses are smaller and 
have advanced more preaxiad of the postaxial ends of the postzygapophyses. 
There is a marked and sudden difference from the foregoing vertebre in the appear- 
ance (when the vertebra is viewed dorsally) of a deeply concave postaxial margin of the 
neural arch. The pleurapophysial lamella is antero-posteriorly shorter ; and thus the 
subcentral oval foramen of each side, leading into the vertebral-artery canal, appears 
close behind its postaxial margin, and can be seen when the vertebra is viewed laterally 
(fig. 9, f). ‘There is no free rib-like process, or but a rudimentary one. The postaxial 
surface of the centrum looks almost entirely postaxiad, and very little dorsad. 
The ventral margin of the postaxial surface of the centrum is more deeply notched 
than heretofore. 
Viewed /aterally this vertebra is seen to be bent ventrad postaxially, as is the sixth 
vertebra; but the more antero-posteriorly continuous development of the catapophysial 
ridges makes this less evident. 
When this vertebra is viewed ventrally we see at the preaxial part of each catapo- 
physial ridge two small antero-posterior grooves, the inner one of which (fig. 11, ¢, g) 
might be taken as corresponding with the apparently similar grooves of the sixth 
vertebra. Really, however, it is the outer groove (g) which does so, while the inner 
groove is very different, not being bordered externally (as in the sixth vertebra) by the 
parapophysis, but by the preaxial end of the catapophysial ridge, while it is bounded 
medianly by a prominence which has no place in the sixth vertebra, but which is in 
