10 MR. ST. GEORGE MIVART ON THE 



against the ilium, though the neural arch and spine are quite rudimentary. At a more 

 advanced stage (as seen in No. 1057') all that remains in an osseous condition is a long 

 and narrow body with a pair of transverse processes of very cancellous texture. Post- 

 axial to this vertebra the vertebrae become atrophied in the adult to such a degree that 

 merely a long narrow osseous band, of very cancellous structure, represents the bodies, 

 (from that of the thirty-seventh to the forty-fourth inclusive) of the vertebrae ; and these 

 have diverging parapophysial processes of similar unsubstantial texture. 



The thirty-seventh, -eighth, and -ninth vertebrae are elongated vertebrae enclosed between 

 the posterior parts of the ilia. Behind these and above the ischia are four (in No. 1057), 

 or five (in Nos. 1361 & 1361 f) vertebrae, which gradually become less imperfect as we 

 proceed postaxially — the bodies broadening out and the neural spines getting shorter, 

 thicker, and more stumpy, — the ultimate vertebrae more or less ankylosing with the 

 ischia. 



THE CAUDAL VEETEBR.^. 



The forty-ffth, -sixth, -seventh, -eighth, -ninth, axidjlftieth vertebrae. — Postaxialto the 

 ischia are six vertebrae, which gradually diminish postaxially. None have transverse 

 processes. The first three, sometimes the first five, have more and more minute neural 

 arches. The last vertebra is grooved dorsally ; and sometimes the last three are so 

 grooved. 



The last apparent vertebra, the pygostyle, is not dorso-ventrally expanded into an 

 osseous plate, as it is in Struthio, but is cylindrical and short, not being twice the 

 length of the vertebra preceding it (fig. 2). It looks as if made up of only two 

 vertebrae ankylosed together. 



THE PELVIS. 



In the adult the pelvis consists of twenty vertebrae and two ossa innominata. 



When viewed preasially, its aspect difi'ers greatly from that presented by the pelvis 

 of Struthio, on account of the absence of the descending pubes and pubic symphysis, in 

 Bhea, as also because the ischia curve inwards, converge, and unite together just post- 

 axiad to (and, of course, on the ventral side of) the acetabula, and thence continue 

 onwards, so united, postaxiad. The iliac roof of the first pelvic vertebra is much more 

 concave on each side than in Struthio. The ilium also sends out a sharper process 

 (the supratrochanteric process) above each trochanteric process (fig. 2, st). 



When viewed postaxially, the same absence of a pubic symphysis and the presence of 

 an ischiatic one produces a very great difiierence of aspect fi'om this point of view also. 

 Again, the summit of the pentagonal mass is horizontal, owing to the crest of the ilium 

 not rising dorsally as much as in Struthio. 



Viewed laterally, the part which was, in the description of the pelvis of Struthio, 

 ' In the Museum of the College of Surgeons. 



