THORAX AND RIBS. 29 



process corresponding with the eminence on the human linea ileopectinea, 

 from the internal side of which extends a branch of the pubes and ischium, 

 excavated in the middle, and separated from the branch of the ischium 

 by the ischiatic ridge. This face terminates inferiorly and posteriorly in 

 the arch of the pubes, which is distinctly seen within, although not visible 

 on the outside of the pelvis. Just above the acetabula, near the union of 

 the ilium and pubes, are two deep vascular depressions, passing outwards 

 towards the anterior spinous processes. 



The posterior superior face of the os innominatum is slightly excavated 

 at its sacral portion ; near the acetabulum it becomes rough ; and inferiorly, 

 smooth. The acetabulum is not of great depth ; its diameter is nine inches ; 

 it has a deep groove on its anterior or pubic face, for the admission of blood- 

 vessels and nerves to the articulation. There is no depression for a round 

 or inter-articular ligament. 



The ischium has a very small spinous process. The spinous process 

 of the pubes is represented by a roughness of the bone. The inferior 

 anterior spinous process of the ilium is continuous with the thick superior 

 anterior spinous process. The posterior superior spinous process is promi- 

 nent, and not thick. The posterior inferior spinous process has the same 

 appearances. 



THORAX AND RIBS. 



The thorax (Large Plate) has a rounded, barrel-like form, flattened 

 above at the vertebral column. Its anterior opening is two feet long from 

 above downwards, and one foot across ; the posterior looks obliquely towards 

 the cavity of the abdomen. 



