268 ON PLATYGONUS COMPRESSUS : 



head is oblique inwards ; the articular surface is regularly concave 

 behind ; anteriorly it has two pulley-shaped grooves, the interior 

 being broader, but not shallower, than the exterior ; the interven- 

 ing ridge is obtusely rounded, broad, and as much elevated as the 

 sides ; a transverse depression separates the articular surface from 

 the edge of the foramen ; the internal condyle is fractured, the ex- 

 ternal is flatly truncate anteriorly, with a groove continuous with 

 the transverse depression just mentioned ; this groove runs down- 

 wards, and vanishes towards the lower edge of the condyle. Pos- 

 teriorly, as shown by another much mutilated specimen, this condyle 

 is marked with two small grooves, which run in the direction of the 

 interior or nanow pulley-shaped surface ; but this part being covered 

 by cement, I know not whether they meet the articular surface. 

 Other peculiarities will be better seen in the figure than expressed 

 in description. Immediately above the groove, on the outer truncate 

 surface of the condyle, the bone is dilated, and then regularly con- 

 tracted to the shaft. The cavity for the olecranon is very deep. 



The bone of the cubitus (fig. 21, left side) is comparatively thick, 

 and much bent, the concavity of the curve looking backwards. 

 The radius and ulna are so fused together as to be scarcely distin- 

 guishable. The shaft is subtriangular, the external edge being 

 acute and much compressed ; the anterior and internal edges are 

 indistinct. The anterior face is broadly concave, adjacent to the 

 compressed edge. The superior head of the bone is furnished witli 

 articular surfaces corresponding to those of the humerus ; they are 

 separated by two elevations extending from before backwards. 

 The internal surface looks inwards and upwards, and is equal to 

 the middle one ; the external surface looks outwards and upwards ; 

 behind the middle surface, at the base of the olecranon, is a deep 

 concavity, separated at the bottom into three unequal parts : dividing 



