ws AXIAL SKELETON OF THE STRUTHIONIDA, oS) 
neural spine is excavated, but not obliquely so, at each end. ‘The ventral angles of the 
postaxial central articular surface are more drawn out than in the preceding vertebre, 
or than in the sixth vertebra of Struthio. 
The seventh vertebra.—All that has been said of the seventh vertebra of Struthio 
applies to that of Rhea, except that in the latter the rib is rudimentary, and the neural 
spine is much smaller. 
The eighth, ninth, and tenth vertebre also agree with those of Struthio, except that 
the neural spine is hardly excavated in the eighth, and in the others only behind, and 
that the ribs are rudimentary—although the pleurapophysial continuation of the para- 
pophysis projects much more preaxiad than does the preezygapophysis, which is not the 
case in Struthio. 
ELEVENTH VERTEBRA OF RHEA (natural size). 
Fig. 6. : Fig. 7. 

Fig. 6. Postaxial view. Fig. 7. Lateral view. 
Letters as before (see p. 3), except that c denotes the catapophysis, m the metapophysis, p the 
parapophysis, and ps the rudimentary rib. 
The eleventh vertebra.—This appears more or less to replace the eleventh, twelfth, 
and thirteenth vertebree of Struthio. It is very like its predecessor, but is slightly more 
massive. Its neural spine is grooved above, the groove widening postaxially. The pre- 
zygapophysis projects but very slightly, if at all, preaxiad of the most preaxial part of 
the pleurapophysis. The ventral angles of the postaxial central surface are much 
drawn out (fig. 6); and thus (unlike Struthio) its ventral margin is greatly in excess of 
its dorsal margin, the ventral surface of the centrum being very concave transversely. 
The twelfth vertebra seems to answer to the thirteenth and fourteenth vertebre of 
Struthio, and differs from its predecessors as does the fourteenth vertebra of the Ostrich 
from its predecessors. Unlike the fourteenth vertebra of Struthio, however, it is still 
rather slender (pre- and postaxially lengthened), and the ventral angles of the postaxial 
surface of the centrum are greatly drawn out. 
