1869.] HFLKE KIMMEEIDGE-CLAT SAUKIAly'. 387 



uninjured, forms a prominent rounded angle "with the corresponding 

 posterior (inner) border of the extremity. Here it has a width of 1 

 inch, which increases to 4 5 inches at the summit of the curve (the 

 increase being chiefly caused by a swelling of the upper surface of 

 the extremity, the terminal aspect of which is separated by a groove 

 from the rest of the terminal surface), whence it again diminishes to 

 1*5 inch near the anterior (outer) missing angle. The under (ante- 

 rior) surface is generally flat, with a slight longitudinal and trans- 

 verse hollowing of its posterior (inner) half. The upper (posterior) 

 surface is transversely slightly convex for 1*8 inch from its posterior 

 (inner) border, then slightly hollow for another inch ; and from this 

 to within a short distance of its anterior (outer) margin it is ren- 

 dered strongly convex by the large subpyramidal swelling just men- 

 tioned, the base of which forms part of the terminal surface. 



Distal extremity. — This is much more massive than the proximal 

 end. Its form is somewhat cubical. The terminal surface is flatter 

 and of an oblong figure, divided into a couple of condyles by a de- 

 pression in its upper (posterior) border, and by two angular excur- 

 sions of its lower (anterior) margin. The posterior (inner) condy- 

 loid surface is the larger one. The upper surface exhibits a broad, 

 shallow, longitudinal, median groove, 5 inches wide at the edge of 

 the terminal surface, growing narrower as it recedes from this, and 

 dividing at about 8 inches distance from it to receive the distal end 

 of a low median ridge prolonged from the shaft. The anterior 

 (outer) branch of this hollow ends about 1 inch sooner than the 

 posterior (inner) one. On the under (anterior) surface two strong 

 subpyramidal swellings -9 inch high, corresponding to the two ex- 

 cursions mentioned in the lower (anterior) border of the terminal 

 surface, and, indicating the greater projection of the condyles in this 

 direction, immediately arrest the eye. The anterior (outer) swell- 

 ing, with a base 1-8 inch wide at the terminal border, begins to rise 

 at 1 inch from the anterior (outer or radial) border of the extre- 

 mity. A deep intercondjioid notch, -8 inch wide, separates it from 

 the posterior (inner) swelling of nearly the same size and form. 

 Between this and the posterior (inner or ulnar) border of the extre- 

 mity the surface is first longitudinally grooved by a shallow depres- 

 sion which has been slightly increased by compression, and then 

 gently convex. The anterior (outer) and posterior (inner) margins 

 are so broad and flat near the terminal border, that here they might 

 be properly called surfaces ; but towards the shaft they grow nar- 

 rower and become transversely convex. 



Shaft. — Of a subcylindrical form, this comprises about the middle 

 third of the bone. Its upper (posterior) surface is strongly convex 

 transversely. The under surface is transversely convex in its pos- 

 terior (inner) half ; but it has a shallow longitudinal median hol- 

 low, widening towards the proximal extremity, and merging into the 

 shallow depression mentioned in the posterior half of the under sur- 

 face of this. The anterior (outer) border of this longitudinal hollow 

 rises sharply, as if it were the beginning of a deltoid crest. 



Contour. — 'V^Tien the bone is placed horizontally the outline of the 



