AXIAL SKELETON OF THE OSTRICH. 449 
The centra may or may not develop parapophysial, catapophysial, or hypapophysial 
processes. 
The pre- and postaxial diameter of centra may greatly exceed their transverse 
dimension, as in the cervical vertebre. 
The reverse condition may obtain, as in the thirty-first to thirty-seventh vertebre. 
The ventral surface of the centrum may be much excavated antero-posteriorly, as in 
the caudal vertebra. 
Neural Lamine. 
The neural lamine are attached to their own centra only, except in the thirty-second 
to the thirty-sixth vertebree. 
In the thirty-second, thirty-third, and thirty-fourth vertebre the neural arch rests on 
part of the centrum of the adjacent preaxial vertebra; but the arch may, as in the 
thirty-first vertebra, partly rest on the centrum postaxial to its own. 
The neural arches are highest relatively to their transverse extent in the lumbar 
vertebre ; they are most pre- and postaxially developed in the cervical vertebre, and 
least so in the caudal vertebre. 
Adjacent neural arches may join each other by suture, as in the lumbar and sacral 
vertebre in the young condition—by anchylosis, as in the sacral region of the adult—by 
articular processes, as in most parts of the axial skeleton—or in none of these ways, as 
in the caudal region. 
The neural laminz almost always develop diapophyses. 
Neural Spines. 
These parts attain their maximum height in the lumbar region, where (in the adult) 
they unite together by anchylosis. 
They are most pre- and postaxially extended in the cervical region, and most trans- 
versely extended, relatively, in the caudal region. 
A neural spine may be trifid, as in the eighth caudal. 
Prezygapophyses. 
These surfaces may be wanting when the postzygapophyses exist in the same vertebra, 
as in the atlas; they may be wanting as well as the postzygapophyses, as in the post- 
dorsal vertebrz. 
Very much longer (pre- and postaxially) than broad, they may broaden considerably, 
as in the dorsal vertebre. 
Having become larger they may again diminish in size, as in the posterior dorsals. 
Strongly convex pre- and postaxially, as in the cervical region, they may become 
nearly flat, as in the dorsal region. 
VOL. VIII.—PART vil. March, 1874. BR 
