434 



MR. ST. GEORGE MIVART ON THE 



one of which proceeds directly postaxiad, while on each side of it two pieces proceed 

 postaxiad and obliquely outwards till they reach a transverse line nearly coinciding with 

 the postaxial end of the median piece, after which they bend inwards, at an angle of 

 about 90°, to meet in the middle line. 



The median piece consists of the postacetabular parts of the two ilia with the post- 

 acetabular sacral vertebrae ; its lateral margins are gently concave ; and it terminates 

 postaxially in two diverging horns, which consist of the two postaxial ends of the two 

 ilia projecting postaxiad beyond the last sacral vertebra. Between the antitrochanteric 

 processes each ilium presents a rather wide convex surface ; but this very rapidly 

 narrows postaxially till at about the last sacral vertebra but two, whence it again 

 slightly expands laterally to about the postaxial margin of the last sacral vertebra, after 

 which it gently contracts to a bluntly pointed termination directed postaxiad, ventrad, 

 and slightly outward. 



The two postacetabular dorsal expansions of the ilia are separated irom the conjoined 

 expansions of the spines of the sacral vertebrte (cs) by two very elongated narrow 

 fissui-es, which run pre- and postaxiad nearly parallel to each other. The primitive 

 distinctness of those conjoined sacral spines is indicated by successive foramina or 

 defects of ossification. 



The two lateral diverging pieces {i & j?) on each side of the median postacetabular 

 ilio-sacral piece are, of course, the ischium and pubis on each side. 



The two ischia (i) seem to diverge at an angle of about 20°, the two pubes (p) at an 

 angle of about nearly 30°; but the latter curve inwards and join the ischia at the lateral 

 expansion before mentioned. Preaxiad of this junction the outer margin of the pubis 

 is convex, and its inner margin concave, while the outer margin of the ischium is 

 concave and its inner margin convex. 



DORSAL ASPECT OF PELVIS (i natural size). 

 Fig. 72. 

 at p 



Letters as last, except cs, median crest formed by the coalesced spinous processes of the sacral vertebrte. 



Postaxiad of the lateral expansions the two pubes converge and meet in the sym- 

 physis (sy), and then project sharply preaxiad. Each pubis, therefore, postaxially to 

 the lateral expansion, has a postaxial margin which is convex, and a preaxial margin 

 which is concave. 



