AXIAL SKELETON OF THE OSTRICH. 451 
pophyses, as also in the posterior caudal vertebre, though in the latter a tendency to 
diverge is shown by the projecting extremities of each transverse process. 
Parapophyses. 
These are very constant structures, existing either as lower transverse processes or as 
articular surfaces for the capitula of the ribs. 
In the lumbar region their place of development singularly descends, being there 
placed quite at the ventral edge of the sides of the centra. 
They ascend through the three true sacral vertebre, till in the most anterior caudal 
(or anterior sacro-caudal) vertebre they reassume the same position they occupied in 
the posterior dorsal region. In the more postaxial vertebre their place of origin again 
descends, and occupies the side of quite the ventral surface of each centrum. 
The parapophysis of the thirty-first vertebra is almost entirely formed by the neural 
arch; but in the three succeeding vertebre each parapophysial prominence is produced 
by the concurrence of processes from the centra of adjoining vertebri, the thirty-second, 
thirty-third, and thirty-fourth vertebre having each such a projection from each end 
of each side of each centrum. 
These low complex parapophysial projections abut against the ischium and ventral 
margin of the acetabulum. 
Pleurapophyses. 
By plewrapophyses I mean ribs and all elements of the paraxial system which are 
serially homologous with ribs, including their capitula and tubercula. 
Consequently when the diapophyses and parapophyses are respectively connected by 
an osseous bridge, such bridge is pleurapophysial. 
To the thirty-sixth, thirty-seventh, and thirty-eighth vertebre three capitula of large 
size are attached; they expand as they extend postaxiad and dorsad to abut against the 
ilium. 
Hypapophyses. 
These are developed as twofold or azygos processes from beneath certain vertebre., 
generally from the seventeenth to the twenty-first inclusive, as already described. 
Catapophyses. 
These have been already noticed as developed from the more postaxial of the true 
cervical vertebra, generally anterior to the seventeenth vertebra. 
