AESINOITHEEIUM. 47 



Hind Limb. — The best example of the pelvis is a complete specimen in the Cairo 

 Museum (C. 8413), and it is upon this that the following description and figures 

 (text-figs. 26, 27) are founded. 



The ilia [il.) are immensely expanded bones, of which the gluteal surface is slightly 

 convex except towards the superior angle, which is somewhat everted so that the 

 outer surface there becomes concave. The pelvic (inner) surface is slightly concave, 

 except towards the upper border, where the everted portion just referred to bears 

 a deeply hollowed surface for union with the sacral vertebrae. The superior angle 

 formed by the meeting of the superior border {crista ilii, c.i.) with the posterior 

 is almost a right angle. In front the crista ilii sweeps round into the anterior 

 border, which is greatly thickened, broadly convex, and terminates below in the 

 prominent external angle {e.a.), which, like the superior angle, is capped by a 

 large rough epiphysis, that on the lower angle {e.a.) being the larger. The 

 acetabular border {a.h.) is concave, and just before reaching the acetabulum («.) 



Text-fig. 25. 

 unc^.^^ cu. 



Fifth left metacarpal of Arsinoitherium zitteli. 

 cu., surface of contact with cuneiform ; mc. 4, facet for fourth metacarpal ; wic, facet for unciform. 



I nat. size. 



it is interrupted by a roughened notch, probably for the attachment of the rectus 

 femoris muscle. 



The inner border running down from the superior angle is concave except in 

 its upper portion opposite the sacral facet, where it is straight; a little ab ve the 

 level of the glenoid cavity it divides into an anterior ridge continuous below with 

 the anterior edge of the pubis, and a posterior ischial ridge, Mhich runs back to 

 the ischial tuberosities. The surface between these two ridges is deeply concave. 

 The acetabulum («.) is oval, its long axis corresponding with the Ipng axis of the 

 OS innominatum. The pit for the ligamentum teres is very deep and extends 

 upwards beyond the middle of the cavity ; posteriorly the pit opens on the ischial 

 surface by a deep notch in the border of the glenoid cavity. 



The anterior border of the united pubes {pu.) is slightly concave, while the posterior 



