OPHTHALMOSAUEUS. 



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the pubis and ischium {/.), the other, the larger of the two, forming the upper part 

 of the acetabulum (acet.). The inner face (i.s.) of the upper end of the blade bears 

 an elongated roughened surface, which may indicate the persistence of some 

 loose ligamentous connection with the vertebral column. The pubis and ischium 

 (text-figs. 39, 40), as already noticed, are fused together, and, as might be expected 

 in bones undergoing reduction, they differ in form to a great extent in different 

 individuals. The upper end of the fused bones is thickened considerably and 

 terminates in cartilage-capped surfaces, the smaller of which is on the inner side and 

 forms the articulation for the ilium {il.f., text-fig. 40) ; the larger occupies the greater 



Text-fig. 38. 



acet 



Eight ilium of OpJitlialmosaurus (E. 2853, f nat. size) : A, inner side ; B, outer side. 

 acet., acetabulum ; /., facet for union with the ischio-pubis ; i.s., inner surface ; o.s., outer surface. 



part of the proximal ends of the combined bones and formed part of the acetabulum 

 {acet.). Ventrally the bones become greatly flattened from within out, so that at 

 their lower end they form a thin plate of bone. About the middle of their leno-th 

 occurs the slit-like obturator foramen (ob.f.), a persistent portion of the ori<^inal 

 separation of the two elements, which also is sometimes indicated by a notch at their 

 distal ends. The iscJdum (isch.) is by far the larger of the two bones, formino- a 

 comparatively broad plate at its ventral end. The lower border is convex and it is 

 doubtful whether the bone actually met its fellow in a median symphysis. The ^^lobis 

 (pu.) is relatively narrow, widening out a little ventrally. The fusion of the two bones 



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