24 MR. ST. GEORGE MIVART ON THE 
Tue Pusis (figs. 13 & 18, p). 
This bone does not join the ischium, but ends freely distad, as it does in the young 
Rhea. It projects least postaxiad of the three pelvic bones. 
Tue Iscuium (figs. 13 & 18, 2). 
This bone also ends freely distad, as it does in the young Rhea. Its ridges are con- 
ditioned as in Struthio. It expands slightly distad in both directions, as a hammer. It 
is the pelvic bone which extends furthest postaxially, yet very little beyond the ilium. 
THE VERTEBRAL RIBS (fig. 12). 
There are nine vertebral ribs, the last of which becomes ankylosed with the pelvis 
in the adult. The fourth, fifth, sixth, and seventh vertebral ribs join sternal ones. 
The first rib is much longer than broad. It remains unankylosed in the adult, and 
is attached to the nineteenth vertebra. 
The second rib is broader than in Rhea or Struthio. It has a convexity on its post- 
axial margin, a little below the tuberculum. 
The third rib is broader and more convex than in Rhea or Struthio. The tubercular 
articular surface is a good deal larger than in the second rib. The postaxial margin is 
convex dorsally, and ventrally concave. 
The fourth rib is like that of Rhea; but the uncinate process may be absent or pre- 
sent, when it is short and broad. 
The jifth rib is very like its predecessor, but is slightly shorter and more curved, and 
the angle formed by the capitulum and tuberculum is rather more obtuse. There may 
or may not be a short, thick uncinate process. 
The sivth is like that of Rhea, and is shorter and more curved than its predecessor. 
There is no uncinate process. 
The seventh rib differs from that of Rhea in that it is not free distally. It is rather 
slighter, shorter, and more curved than its serial predecessor, while its diapophysial 
surface is quite as large. Its preaxial prominence is not more marked. 
The eighth rib is but very slightly, if at all, longer than the second rib. The pre- 
axial convexity does not project much; but the ridge which crosses that part where the 
head and tubercle diverge is very strong. 
The ninth rib, which may be articulated with or ankylosed to its vertebra, is shorter, 
more slender, and less curved than its predecessor. It is more curved than in Struthio, 
and less so than in Khea. 
THE STERNAL RIBS (fig. 12). 
Of these there are four; and they increase in length postaxiad with very much greater 
rapidity than in Rhea, the third being twice the length of the first. 
